diff --git a/java/res/values/keypress-vibration-durations.xml b/java/res/values/keypress-vibration-durations.xml
index 53448c3..ee0ac00 100644
--- a/java/res/values/keypress-vibration-durations.xml
+++ b/java/res/values/keypress-vibration-durations.xml
@@ -55,8 +55,8 @@
         <item>MODEL=HTL22:MANUFACTURER=HTC,15</item>
         <!-- Motorola Razor M -->
         <item>MODEL=XT907:MANUFACTURER=motorola,30</item>
-        <!-- Sony Xperia Z -->
-        <item>MODEL=C6603:MANUFACTURER=Sony,35</item>
+        <!-- Sony Xperia Z, Z Ultra -->
+        <item>MODEL=C6603|C6806:MANUFACTURER=Sony,35</item>
         <!-- Default value for unknown device. The negative value means system default. -->
         <item>,-1</item>
     </string-array>
diff --git a/java/res/xml/rowkeys_khmer1.xml b/java/res/xml/rowkeys_khmer1.xml
index e4bfb6c..25da664 100644
--- a/java/res/xml/rowkeys_khmer1.xml
+++ b/java/res/xml/rowkeys_khmer1.xml
@@ -45,7 +45,8 @@
             <Key
                 latin:keyLabel="&#x17DB;"
                 latin:keyHintLabel="$"
-                latin:moreKeys="$,&#x20AC;" />
+                latin:moreKeys="$,&#x20AC;"
+                latin:keyLabelFlags="fontNormal" />
             <!-- U+17D6: "៖" KHMER SIGN CAMNUC PII KUUH -->
             <Key
                 latin:keyLabel="%"
@@ -179,14 +180,14 @@
             <Key
                 latin:keyLabel="&#x17A5;"
                 latin:keyHintLabel="&#x17A6;"
-                latin:moreKeys=",&#x17A6;,."
+                latin:moreKeys=",&#x17A6;"
                 latin:keyLabelFlags="fontNormal" />
             <!-- U+17B2: "ឲ" KHMER INDEPENDENT VOWEL QOO TYPE TWO
                  U+17B1: "ឱ" KHMER INDEPENDENT VOWEL QOO TYPE ONE -->
             <Key
                 latin:keyLabel="&#x17B2;"
                 latin:keyHintLabel="&#x17B1;"
-                latin:moreKeys="&#x17B1;,\\,"
+                latin:moreKeys="&#x17B1;"
                 latin:keyLabelFlags="fontNormal" />
         </default>
     </switch>
diff --git a/java/src/com/android/inputmethod/latin/ContactsBinaryDictionary.java b/java/src/com/android/inputmethod/latin/ContactsBinaryDictionary.java
index 67eb7f3..ffeb927 100644
--- a/java/src/com/android/inputmethod/latin/ContactsBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/ContactsBinaryDictionary.java
@@ -22,6 +22,7 @@
 import android.content.Context;
 import android.database.ContentObserver;
 import android.database.Cursor;
+import android.database.sqlite.SQLiteException;
 import android.net.Uri;
 import android.os.SystemClock;
 import android.provider.BaseColumns;
@@ -145,8 +146,10 @@
                     cursor.close();
                 }
             }
-        } catch (IllegalStateException e) {
-            Log.e(TAG, "Contacts DB is having problems");
+        } catch (final SQLiteException e) {
+            Log.e(TAG, "SQLiteException in the remote Contacts process.", e);
+        } catch (final IllegalStateException e) {
+            Log.e(TAG, "Contacts DB is having problems", e);
         }
     }
 
@@ -173,14 +176,18 @@
     private int getContactCount() {
         // TODO: consider switching to a rawQuery("select count(*)...") on the database if
         // performance is a bottleneck.
-        final Cursor cursor = mContext.getContentResolver().query(
-                Contacts.CONTENT_URI, PROJECTION_ID_ONLY, null, null, null);
-        if (cursor != null) {
-            try {
-                return cursor.getCount();
-            } finally {
-                cursor.close();
+        try {
+            final Cursor cursor = mContext.getContentResolver().query(
+                    Contacts.CONTENT_URI, PROJECTION_ID_ONLY, null, null, null);
+            if (cursor != null) {
+                try {
+                    return cursor.getCount();
+                } finally {
+                    cursor.close();
+                }
             }
+        } catch (final SQLiteException e) {
+            Log.e(TAG, "SQLiteException in the remote Contacts process.", e);
         }
         return 0;
     }
diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index f4f0620..270dc4c 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -2797,6 +2797,7 @@
         final TextRange range = mConnection.getWordRangeAtCursor(currentSettings.mWordSeparators,
                 0 /* additionalPrecedingWordsCount */);
         if (null == range) return; // Happens if we don't have an input connection at all
+        if (range.length() <= 0) return; // Race condition. No text to resume on, so bail out.
         // If for some strange reason (editor bug or so) we measure the text before the cursor as
         // longer than what the entire text is supposed to be, the safe thing to do is bail out.
         final int numberOfCharsInWordBeforeCursor = range.getNumberOfCharsInWordBeforeCursor();
diff --git a/java/src/com/android/inputmethod/latin/UserBinaryDictionary.java b/java/src/com/android/inputmethod/latin/UserBinaryDictionary.java
index a241b55..864a173 100644
--- a/java/src/com/android/inputmethod/latin/UserBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/UserBinaryDictionary.java
@@ -22,10 +22,12 @@
 import android.content.Context;
 import android.database.ContentObserver;
 import android.database.Cursor;
+import android.database.sqlite.SQLiteException;
 import android.net.Uri;
 import android.os.Build;
 import android.provider.UserDictionary.Words;
 import android.text.TextUtils;
+import android.util.Log;
 
 import com.android.inputmethod.compat.UserDictionaryCompatUtils;
 import com.android.inputmethod.latin.utils.LocaleUtils;
@@ -39,6 +41,7 @@
  * dictionary file to use it from native code.
  */
 public class UserBinaryDictionary extends ExpandableBinaryDictionary {
+    private static final String TAG = ExpandableBinaryDictionary.class.getSimpleName();
 
     // The user dictionary provider uses an empty string to mean "all languages".
     private static final String USER_DICTIONARY_ALL_LANGUAGES = "";
@@ -168,12 +171,19 @@
         } else {
             requestArguments = localeElements;
         }
-        final Cursor cursor = mContext.getContentResolver().query(
-                Words.CONTENT_URI, PROJECTION_QUERY, request.toString(), requestArguments, null);
+        Cursor cursor = null;
         try {
+            cursor = mContext.getContentResolver().query(
+                Words.CONTENT_URI, PROJECTION_QUERY, request.toString(), requestArguments, null);
             addWords(cursor);
+        } catch (final SQLiteException e) {
+            Log.e(TAG, "SQLiteException in the remote User dictionary process.", e);
         } finally {
-            if (null != cursor) cursor.close();
+            try {
+                if (null != cursor) cursor.close();
+            } catch (final SQLiteException e) {
+                Log.e(TAG, "SQLiteException in the remote User dictionary process.", e);
+            }
         }
     }
 
diff --git a/java/src/com/android/inputmethod/latin/utils/TextRange.java b/java/src/com/android/inputmethod/latin/utils/TextRange.java
index 5793e41..48b443d 100644
--- a/java/src/com/android/inputmethod/latin/utils/TextRange.java
+++ b/java/src/com/android/inputmethod/latin/utils/TextRange.java
@@ -40,6 +40,10 @@
         return mWordAtCursorEndIndex - mCursorIndex;
     }
 
+    public int length() {
+        return mWord.length();
+    }
+
     /**
      * Gets the suggestion spans that are put squarely on the word, with the exact start
      * and end of the span matching the boundaries of the word.
diff --git a/native/jni/src/suggest/core/dictionary/bigram_dictionary.cpp b/native/jni/src/suggest/core/dictionary/bigram_dictionary.cpp
index 5ba71c1..71f4ef6 100644
--- a/native/jni/src/suggest/core/dictionary/bigram_dictionary.cpp
+++ b/native/jni/src/suggest/core/dictionary/bigram_dictionary.cpp
@@ -147,7 +147,7 @@
     int pos = mDictionaryStructurePolicy->getTerminalNodePositionOfWord(prevWord, prevWordLength,
             forceLowerCaseSearch);
     if (NOT_A_DICT_POS == pos) return NOT_A_DICT_POS;
-    return mDictionaryStructurePolicy->getBigramsPositionOfNode(pos);
+    return mDictionaryStructurePolicy->getBigramsPositionOfPtNode(pos);
 }
 
 int BigramDictionary::getBigramProbability(const int *word0, int length0, const int *word1,
diff --git a/native/jni/src/suggest/core/dictionary/multi_bigram_map.h b/native/jni/src/suggest/core/dictionary/multi_bigram_map.h
index aecf413..4633c07 100644
--- a/native/jni/src/suggest/core/dictionary/multi_bigram_map.h
+++ b/native/jni/src/suggest/core/dictionary/multi_bigram_map.h
@@ -68,7 +68,7 @@
 
         void init(const DictionaryStructureWithBufferPolicy *const structurePolicy,
                 const int nodePos) {
-            const int bigramsListPos = structurePolicy->getBigramsPositionOfNode(nodePos);
+            const int bigramsListPos = structurePolicy->getBigramsPositionOfPtNode(nodePos);
             BinaryDictionaryBigramsIterator bigramsIt(structurePolicy->getBigramsStructurePolicy(),
                     bigramsListPos);
             while (bigramsIt.hasNext()) {
@@ -112,7 +112,7 @@
             const DictionaryStructureWithBufferPolicy *const structurePolicy, const int nodePos,
             const int nextWordPosition, const int unigramProbability) {
         int bigramProbability = NOT_A_PROBABILITY;
-        const int bigramsListPos = structurePolicy->getBigramsPositionOfNode(nodePos);
+        const int bigramsListPos = structurePolicy->getBigramsPositionOfPtNode(nodePos);
         BinaryDictionaryBigramsIterator bigramsIt(structurePolicy->getBigramsStructurePolicy(),
                 bigramsListPos);
         while (bigramsIt.hasNext()) {
diff --git a/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h b/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
index 24d1b8b..b95488e 100644
--- a/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
+++ b/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
@@ -52,9 +52,9 @@
 
     virtual int getUnigramProbabilityOfPtNode(const int nodePos) const = 0;
 
-    virtual int getShortcutPositionOfNode(const int nodePos) const = 0;
+    virtual int getShortcutPositionOfPtNode(const int nodePos) const = 0;
 
-    virtual int getBigramsPositionOfNode(const int nodePos) const = 0;
+    virtual int getBigramsPositionOfPtNode(const int nodePos) const = 0;
 
     virtual const DictionaryHeaderStructurePolicy *getHeaderStructurePolicy() const = 0;
 
diff --git a/native/jni/src/suggest/core/suggest.cpp b/native/jni/src/suggest/core/suggest.cpp
index 0c925be..b1340e1 100644
--- a/native/jni/src/suggest/core/suggest.cpp
+++ b/native/jni/src/suggest/core/suggest.cpp
@@ -223,7 +223,7 @@
             BinaryDictionaryShortcutIterator shortcutIt(
                     traverseSession->getDictionaryStructurePolicy()->getShortcutsStructurePolicy(),
                     traverseSession->getDictionaryStructurePolicy()
-                            ->getShortcutPositionOfNode(terminalDicNode->getPos()));
+                            ->getShortcutPositionOfPtNode(terminalDicNode->getPos()));
             // Shortcut is not supported for multiple words suggestions.
             // TODO: Check shortcuts during traversal for multiple words suggestions.
             const bool sameAsTyped = TRAVERSAL->sameAsTyped(traverseSession, terminalDicNode);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_policy.h b/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_policy.h
index 26015d5..6ff95ca 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_policy.h
@@ -33,10 +33,9 @@
 
     void getNextBigram(int *const outBigramPos, int *const outProbability, bool *const outHasNext,
             int *const pos) const {
-        const BigramListReadWriteUtils::BigramFlags flags =
-                BigramListReadWriteUtils::getFlagsAndForwardPointer(mBigramsBuf, pos);
-        *outBigramPos = BigramListReadWriteUtils::getBigramAddressAndForwardPointer(
-                        mBigramsBuf, flags, pos);
+        BigramListReadWriteUtils::BigramFlags flags;
+        BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(mBigramsBuf, &flags,
+                outBigramPos, pos);
         *outProbability = BigramListReadWriteUtils::getProbabilityFromFlags(flags);
         *outHasNext = BigramListReadWriteUtils::hasNext(flags);
     }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.cpp b/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.cpp
index 09e832f..f8ed2b9 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.cpp
@@ -17,6 +17,7 @@
 #include "suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.h"
 
 #include "suggest/policyimpl/dictionary/utils/byte_array_utils.h"
+#include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
 
 namespace latinime {
 
@@ -38,23 +39,31 @@
         BigramListReadWriteUtils::MASK_ATTRIBUTE_PROBABILITY = 0x0F;
 const int BigramListReadWriteUtils::ATTRIBUTE_ADDRESS_SHIFT = 4;
 
-/* static */ BigramListReadWriteUtils::BigramFlags
-        BigramListReadWriteUtils::getFlagsAndForwardPointer(const uint8_t *const bigramsBuf,
-                int *const pos) {
-    return ByteArrayUtils::readUint8AndAdvancePosition(bigramsBuf, pos);
+/* static */ void BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(
+        const uint8_t *const bigramsBuf, BigramFlags *const outBigramFlags,
+        int *const outTargetPtNodePos, int *const bigramEntryPos) {
+    const BigramFlags bigramFlags = ByteArrayUtils::readUint8AndAdvancePosition(bigramsBuf,
+            bigramEntryPos);
+    if (outBigramFlags) {
+        *outBigramFlags = bigramFlags;
+    }
+    const int targetPos = getBigramAddressAndAdvancePosition(bigramsBuf, bigramFlags,
+            bigramEntryPos);
+    if (outTargetPtNodePos) {
+        *outTargetPtNodePos = targetPos;
+    }
 }
 
 /* static */ void BigramListReadWriteUtils::skipExistingBigrams(const uint8_t *const bigramsBuf,
-        int *const pos) {
-    BigramFlags flags = getFlagsAndForwardPointer(bigramsBuf, pos);
-    while (hasNext(flags)) {
-        *pos += attributeAddressSize(flags);
-        flags = getFlagsAndForwardPointer(bigramsBuf, pos);
-    }
-    *pos += attributeAddressSize(flags);
+        int *const bigramListPos) {
+    BigramFlags flags;
+    do {
+        getBigramEntryPropertiesAndAdvancePosition(bigramsBuf, &flags, 0 /* outTargetPtNodePos */,
+                bigramListPos);
+    } while(hasNext(flags));
 }
 
-/* static */ int BigramListReadWriteUtils::getBigramAddressAndForwardPointer(
+/* static */ int BigramListReadWriteUtils::getBigramAddressAndAdvancePosition(
         const uint8_t *const bigramsBuf, const BigramFlags flags, int *const pos) {
     int offset = 0;
     const int origin = *pos;
@@ -79,4 +88,59 @@
     }
 }
 
+/* static */ bool BigramListReadWriteUtils::createAndWriteBigramEntry(
+        BufferWithExtendableBuffer *const buffer, const int targetPos, const int probability,
+        const bool hasNext, int *const writingPos) {
+    BigramFlags flags;
+    if (!createAndGetBigramFlags(*writingPos, targetPos, probability, hasNext, &flags)) {
+        return false;
+    }
+    return writeBigramEntry(buffer, flags, targetPos, writingPos);
+}
+
+/* static */ bool BigramListReadWriteUtils::writeBigramEntry(
+        BufferWithExtendableBuffer *const bufferToWrite, const BigramFlags flags,
+        const int targetPtNodePos, int *const writingPos) {
+    if (!bufferToWrite->writeUintAndAdvancePosition(flags, 1 /* size */, writingPos)) {
+        return false;
+    }
+    const int offset = (targetPtNodePos != NOT_A_DICT_POS) ? targetPtNodePos - *writingPos : 0;
+    const uint32_t absOffest = abs(offset);
+    const int bigramTargetFieldSize = attributeAddressSize(flags);
+    return bufferToWrite->writeUintAndAdvancePosition(absOffest, bigramTargetFieldSize,
+            writingPos);
+}
+
+// Returns true if the bigram entry is valid and put entry flags into out*.
+/* static */ bool BigramListReadWriteUtils::createAndGetBigramFlags(const int entryPos,
+        const int targetPos, const int probability, const bool hasNext,
+        BigramFlags *const outBigramFlags) {
+    BigramFlags flags = probability & MASK_ATTRIBUTE_PROBABILITY;
+    if (hasNext) {
+        flags |= FLAG_ATTRIBUTE_HAS_NEXT;
+    }
+    const int targetFieldPos = entryPos + 1;
+    const int offset = (targetPos != NOT_A_DICT_POS) ? targetPos - targetFieldPos : 0;
+    if (offset < 0) {
+        flags |= FLAG_ATTRIBUTE_OFFSET_NEGATIVE;
+    }
+    const uint32_t absOffest = abs(offset);
+    if ((absOffest >> 24) != 0) {
+        // Offset is too large.
+        return false;
+    } else if ((absOffest >> 16) != 0) {
+        flags |= FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES;
+    } else if ((absOffest >> 8) != 0) {
+        flags |= FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES;
+    } else {
+        flags |= FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE;
+    }
+    // Currently, all newly written bigram position fields are 3 bytes to simplify dictionary
+    // writing.
+    // TODO: Remove following 2 lines and optimize memory space.
+    flags = (flags & (~MASK_ATTRIBUTE_ADDRESS_TYPE)) | FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES;
+    *outBigramFlags = flags;
+    return true;
+}
+
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.h b/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.h
index 9092a80..234a0ea 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.h
@@ -24,11 +24,15 @@
 
 namespace latinime {
 
+class BufferWithExtendableBuffer;
+
 class BigramListReadWriteUtils {
 public:
    typedef uint8_t BigramFlags;
 
-   static BigramFlags getFlagsAndForwardPointer(const uint8_t *const bigramsBuf, int *const pos);
+   static void getBigramEntryPropertiesAndAdvancePosition(const uint8_t *const bigramsBuf,
+           BigramFlags *const outBigramFlags, int *const outTargetPtNodePos,
+           int *const bigramEntryPos);
 
    static AK_FORCE_INLINE int getProbabilityFromFlags(const BigramFlags flags) {
        return flags & MASK_ATTRIBUTE_PROBABILITY;
@@ -39,10 +43,7 @@
    }
 
    // Bigrams reading methods
-   static void skipExistingBigrams(const uint8_t *const bigramsBuf, int *const pos);
-
-   static int getBigramAddressAndForwardPointer(const uint8_t *const bigramsBuf,
-           const BigramFlags flags, int *const pos);
+   static void skipExistingBigrams(const uint8_t *const bigramsBuf, int *const bigramListPos);
 
    // Returns the size of the bigram position field that is stored in bigram flags.
    static AK_FORCE_INLINE int attributeAddressSize(const BigramFlags flags) {
@@ -67,48 +68,11 @@
        return (flags & (~MASK_ATTRIBUTE_PROBABILITY)) | (probability & MASK_ATTRIBUTE_PROBABILITY);
    }
 
-   // Returns true if the bigram entry is valid and put entry values into out*.
-   static AK_FORCE_INLINE bool createBigramEntryAndGetFlagsAndOffsetAndOffsetFieldSize(
-           const int entryPos, const int targetPos, const int probability, const bool hasNext,
-           BigramFlags *const outBigramFlags, uint32_t *const outOffset,
-           int *const outOffsetFieldSize) {
-       if (targetPos == NOT_A_DICT_POS) {
-           return false;
-       }
-       BigramFlags flags = probability & MASK_ATTRIBUTE_PROBABILITY;
-       if (hasNext) {
-           flags |= FLAG_ATTRIBUTE_HAS_NEXT;
-       }
-       const int targetFieldPos = entryPos + 1;
-       const int offset = targetPos - targetFieldPos;
-       if (offset < 0) {
-           flags |= FLAG_ATTRIBUTE_OFFSET_NEGATIVE;
-       }
-       const uint32_t absOffest = abs(offset);
-       if ((absOffest >> 24) != 0) {
-           // Offset is too large.
-           return false;
-       } else if ((absOffest >> 16) != 0) {
-           flags |= FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES;
-           *outOffsetFieldSize = 3;
-       } else if ((absOffest >> 8) != 0) {
-           flags |= FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES;
-           *outOffsetFieldSize = 2;
-       } else {
-           flags |= FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE;
-           *outOffsetFieldSize = 1;
-       }
+   static bool createAndWriteBigramEntry(BufferWithExtendableBuffer *const buffer,
+           const int targetPos, const int probability, const bool hasNext, int *const writingPos);
 
-       // Currently, all newly written bigram position fields are 3 bytes to simplify dictionary
-       // writing.
-       // TODO: Remove following 2 lines and optimize memory space.
-       flags = (flags & (~MASK_ATTRIBUTE_ADDRESS_TYPE)) | FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES;
-       *outOffsetFieldSize = 3;
-
-       *outBigramFlags = flags;
-       *outOffset = absOffest;
-       return true;
-   }
+   static bool writeBigramEntry(BufferWithExtendableBuffer *const buffer, const BigramFlags flags,
+           const int targetOffset, int *const writingPos);
 
 private:
    DISALLOW_IMPLICIT_CONSTRUCTORS(BigramListReadWriteUtils);
@@ -122,9 +86,16 @@
    static const BigramFlags MASK_ATTRIBUTE_PROBABILITY;
    static const int ATTRIBUTE_ADDRESS_SHIFT;
 
+   // Returns true if the bigram entry is valid and put entry flags into out*.
+   static bool createAndGetBigramFlags(const int entryPos, const int targetPos,
+           const int probability, const bool hasNext, BigramFlags *const outBigramFlags);
+
    static AK_FORCE_INLINE bool isOffsetNegative(const BigramFlags flags) {
        return (flags & FLAG_ATTRIBUTE_OFFSET_NEGATIVE) != 0;
    }
+
+   static int getBigramAddressAndAdvancePosition(const uint8_t *const bigramsBuf,
+           const BigramFlags flags, int *const pos);
 };
 } // namespace latinime
 #endif // LATINIME_BIGRAM_LIST_READ_WRITE_UTILS_H
diff --git a/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.cpp
index bd58b99..ba43bdb 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.cpp
@@ -16,41 +16,47 @@
 
 #include "suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h"
 
+#include "suggest/core/policy/dictionary_shortcuts_structure_policy.h"
+#include "suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.h"
+#include "suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.h"
+#include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
+
 namespace latinime {
 
-const int DynamicBigramListPolicy::BIGRAM_LINK_COUNT_LIMIT = 10000;
+const int DynamicBigramListPolicy::CONTINUING_BIGRAM_LINK_COUNT_LIMIT = 10000;
+const int DynamicBigramListPolicy::BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT = 100000;
 
 void DynamicBigramListPolicy::getNextBigram(int *const outBigramPos, int *const outProbability,
-        bool *const outHasNext, int *const pos) const {
-    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(*pos);
+        bool *const outHasNext, int *const bigramEntryPos) const {
+    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(*bigramEntryPos);
     const uint8_t *const buffer = mBuffer->getBuffer(usesAdditionalBuffer);
     if (usesAdditionalBuffer) {
-        *pos -= mBuffer->getOriginalBufferSize();
+        *bigramEntryPos -= mBuffer->getOriginalBufferSize();
     }
-    const BigramListReadWriteUtils::BigramFlags flags =
-            BigramListReadWriteUtils::getFlagsAndForwardPointer(buffer, pos);
-    int originalBigramPos = BigramListReadWriteUtils::getBigramAddressAndForwardPointer(
-            buffer, flags, pos);
+    BigramListReadWriteUtils::BigramFlags bigramFlags;
+    int originalBigramPos;
+    BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(buffer, &bigramFlags,
+            &originalBigramPos, bigramEntryPos);
     if (usesAdditionalBuffer && originalBigramPos != NOT_A_DICT_POS) {
         originalBigramPos += mBuffer->getOriginalBufferSize();
     }
     *outBigramPos = followBigramLinkAndGetCurrentBigramPtNodePos(originalBigramPos);
-    *outProbability = BigramListReadWriteUtils::getProbabilityFromFlags(flags);
-    *outHasNext = BigramListReadWriteUtils::hasNext(flags);
+    *outProbability = BigramListReadWriteUtils::getProbabilityFromFlags(bigramFlags);
+    *outHasNext = BigramListReadWriteUtils::hasNext(bigramFlags);
     if (usesAdditionalBuffer) {
-        *pos += mBuffer->getOriginalBufferSize();
+        *bigramEntryPos += mBuffer->getOriginalBufferSize();
     }
 }
 
-void DynamicBigramListPolicy::skipAllBigrams(int *const pos) const {
-    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(*pos);
+void DynamicBigramListPolicy::skipAllBigrams(int *const bigramListPos) const {
+    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(*bigramListPos);
     const uint8_t *const buffer = mBuffer->getBuffer(usesAdditionalBuffer);
     if (usesAdditionalBuffer) {
-        *pos -= mBuffer->getOriginalBufferSize();
+        *bigramListPos -= mBuffer->getOriginalBufferSize();
     }
-    BigramListReadWriteUtils::skipExistingBigrams(buffer, pos);
+    BigramListReadWriteUtils::skipExistingBigrams(buffer, bigramListPos);
     if (usesAdditionalBuffer) {
-        *pos += mBuffer->getOriginalBufferSize();
+        *bigramListPos += mBuffer->getOriginalBufferSize();
     }
 }
 
@@ -61,13 +67,19 @@
         *fromPos -= mBuffer->getOriginalBufferSize();
     }
     *outBigramsCount = 0;
-    BigramListReadWriteUtils::BigramFlags flags;
+    BigramListReadWriteUtils::BigramFlags bigramFlags;
+    int bigramEntryCount = 0;
     do {
+        if (++bigramEntryCount > BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT) {
+            AKLOGE("Too many bigram entries. %d", BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT);
+            ASSERT(false);
+            return false;
+        }
         // The buffer address can be changed after calling buffer writing methods.
-        const uint8_t *const buffer = mBuffer->getBuffer(usesAdditionalBuffer);
-        flags = BigramListReadWriteUtils::getFlagsAndForwardPointer(buffer, fromPos);
-        int originalBigramPos = BigramListReadWriteUtils::getBigramAddressAndForwardPointer(
-                buffer, flags, fromPos);
+        int originalBigramPos;
+        BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(
+                mBuffer->getBuffer(usesAdditionalBuffer), &bigramFlags, &originalBigramPos,
+                fromPos);
         if (originalBigramPos == NOT_A_DICT_POS) {
             // skip invalid bigram entry.
             continue;
@@ -76,132 +88,163 @@
             originalBigramPos += mBuffer->getOriginalBufferSize();
         }
         const int bigramPos = followBigramLinkAndGetCurrentBigramPtNodePos(originalBigramPos);
-        BigramListReadWriteUtils::BigramFlags newBigramFlags;
-        uint32_t newBigramOffset;
-        int newBigramOffsetFieldSize;
-        if(!BigramListReadWriteUtils::createBigramEntryAndGetFlagsAndOffsetAndOffsetFieldSize(
-                *toPos, bigramPos, BigramListReadWriteUtils::getProbabilityFromFlags(flags),
-                BigramListReadWriteUtils::hasNext(flags), &newBigramFlags, &newBigramOffset,
-                &newBigramOffsetFieldSize)) {
-            continue;
-        }
-        // Write bigram entry. Target buffer is always the additional buffer.
-        if (!bufferToWrite->writeUintAndAdvancePosition(newBigramFlags, 1 /* size */,toPos)) {
-            return false;
-        }
-        if (!bufferToWrite->writeUintAndAdvancePosition(newBigramOffset, newBigramOffsetFieldSize,
-                toPos)) {
+        if (!BigramListReadWriteUtils::createAndWriteBigramEntry(bufferToWrite, bigramPos,
+                BigramListReadWriteUtils::getProbabilityFromFlags(bigramFlags),
+                BigramListReadWriteUtils::hasNext(bigramFlags), toPos)) {
             return false;
         }
         (*outBigramsCount)++;
-    } while(BigramListReadWriteUtils::hasNext(flags));
+    } while(BigramListReadWriteUtils::hasNext(bigramFlags));
     if (usesAdditionalBuffer) {
         *fromPos += mBuffer->getOriginalBufferSize();
     }
     return true;
 }
 
-bool DynamicBigramListPolicy::addNewBigramEntryToBigramList(const int bigramPos,
-        const int probability, int *const pos) {
-    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(*pos);
+// Finding useless bigram entries and remove them. Bigram entry is useless when the target PtNode
+// has been deleted or is not a valid terminal.
+bool DynamicBigramListPolicy::updateAllBigramEntriesAndDeleteUselessEntries(
+        int *const bigramListPos) {
+    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(*bigramListPos);
     if (usesAdditionalBuffer) {
-        *pos -= mBuffer->getOriginalBufferSize();
+        *bigramListPos -= mBuffer->getOriginalBufferSize();
     }
-    BigramListReadWriteUtils::BigramFlags flags;
+    DynamicPatriciaTrieNodeReader nodeReader(mBuffer, this /* bigramsPolicy */, mShortcutPolicy);
+    BigramListReadWriteUtils::BigramFlags bigramFlags;
+    int bigramEntryCount = 0;
     do {
-        int entryPos = *pos;
+        if (++bigramEntryCount > BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT) {
+            AKLOGE("Too many bigram entries. %d", BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT);
+            ASSERT(false);
+            return false;
+        }
+        int bigramEntryPos = *bigramListPos;
+        int originalBigramPos;
+        // The buffer address can be changed after calling buffer writing methods.
+        BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(
+                mBuffer->getBuffer(usesAdditionalBuffer), &bigramFlags, &originalBigramPos,
+                bigramListPos);
+        if (usesAdditionalBuffer) {
+            bigramEntryPos += mBuffer->getOriginalBufferSize();
+        }
+        if (originalBigramPos == NOT_A_DICT_POS) {
+            // This entry has already been removed.
+            continue;
+        }
+        if (usesAdditionalBuffer) {
+            originalBigramPos += mBuffer->getOriginalBufferSize();
+        }
+        const int bigramTargetNodePos =
+                followBigramLinkAndGetCurrentBigramPtNodePos(originalBigramPos);
+        nodeReader.fetchNodeInfoInBufferFromPtNodePos(bigramTargetNodePos);
+        // TODO: Update probability for supporting probability decaying.
+        if (nodeReader.isDeleted() || !nodeReader.isTerminal()
+                || bigramTargetNodePos == NOT_A_DICT_POS) {
+            // The target is no longer valid terminal. Invalidate the current bigram entry.
+            if (!BigramListReadWriteUtils::writeBigramEntry(mBuffer, bigramFlags,
+                    NOT_A_DICT_POS /* targetOffset */, &bigramEntryPos)) {
+                return false;
+            }
+        }
+    } while(BigramListReadWriteUtils::hasNext(bigramFlags));
+    return true;
+}
+
+bool DynamicBigramListPolicy::addNewBigramEntryToBigramList(const int bigramTargetPos,
+        const int probability, int *const bigramListPos) {
+    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(*bigramListPos);
+    if (usesAdditionalBuffer) {
+        *bigramListPos -= mBuffer->getOriginalBufferSize();
+    }
+    BigramListReadWriteUtils::BigramFlags bigramFlags;
+    int bigramEntryCount = 0;
+    do {
+        if (++bigramEntryCount > BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT) {
+            AKLOGE("Too many bigram entries. %d", BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT);
+            ASSERT(false);
+            return false;
+        }
+        int entryPos = *bigramListPos;
         if (usesAdditionalBuffer) {
             entryPos += mBuffer->getOriginalBufferSize();
         }
+        int originalBigramPos;
         // The buffer address can be changed after calling buffer writing methods.
-        const uint8_t *const buffer = mBuffer->getBuffer(usesAdditionalBuffer);
-        flags = BigramListReadWriteUtils::getFlagsAndForwardPointer(buffer, pos);
-        int originalBigramPos = BigramListReadWriteUtils::getBigramAddressAndForwardPointer(
-                buffer, flags, pos);
+        BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(
+                mBuffer->getBuffer(usesAdditionalBuffer), &bigramFlags, &originalBigramPos,
+                bigramListPos);
         if (usesAdditionalBuffer && originalBigramPos != NOT_A_DICT_POS) {
             originalBigramPos += mBuffer->getOriginalBufferSize();
         }
-        if (followBigramLinkAndGetCurrentBigramPtNodePos(originalBigramPos) == bigramPos) {
+        if (followBigramLinkAndGetCurrentBigramPtNodePos(originalBigramPos) == bigramTargetPos) {
             // Update this bigram entry.
             const BigramListReadWriteUtils::BigramFlags updatedFlags =
-                    BigramListReadWriteUtils::setProbabilityInFlags(flags, probability);
-            return mBuffer->writeUintAndAdvancePosition(updatedFlags, 1 /* size */, &entryPos);
+                    BigramListReadWriteUtils::setProbabilityInFlags(bigramFlags, probability);
+            return BigramListReadWriteUtils::writeBigramEntry(mBuffer, updatedFlags,
+                    originalBigramPos, &entryPos);
         }
-        if (BigramListReadWriteUtils::hasNext(flags)) {
+        if (BigramListReadWriteUtils::hasNext(bigramFlags)) {
             continue;
         }
         // The current last entry is found.
         // First, update the flags of the last entry.
         const BigramListReadWriteUtils::BigramFlags updatedFlags =
-                BigramListReadWriteUtils::setHasNextFlag(flags);
-        if (!mBuffer->writeUintAndAdvancePosition(updatedFlags, 1 /* size */, &entryPos)) {
+                BigramListReadWriteUtils::setHasNextFlag(bigramFlags);
+        if (!BigramListReadWriteUtils::writeBigramEntry(mBuffer, updatedFlags, originalBigramPos,
+                &entryPos)) {
             return false;
         }
         if (usesAdditionalBuffer) {
-            *pos += mBuffer->getOriginalBufferSize();
+            *bigramListPos += mBuffer->getOriginalBufferSize();
         }
         // Then, add a new entry after the last entry.
-        return writeNewBigramEntry(bigramPos, probability, pos);
-    } while(BigramListReadWriteUtils::hasNext(flags));
+        return writeNewBigramEntry(bigramTargetPos, probability, bigramListPos);
+    } while(BigramListReadWriteUtils::hasNext(bigramFlags));
     // We return directly from the while loop.
     ASSERT(false);
     return false;
 }
 
-bool DynamicBigramListPolicy::writeNewBigramEntry(const int bigramPos, const int probability,
+bool DynamicBigramListPolicy::writeNewBigramEntry(const int bigramTargetPos, const int probability,
         int *const writingPos) {
-    BigramListReadWriteUtils::BigramFlags newBigramFlags;
-    uint32_t newBigramOffset;
-    int newBigramOffsetFieldSize;
-    if(!BigramListReadWriteUtils::createBigramEntryAndGetFlagsAndOffsetAndOffsetFieldSize(
-            *writingPos, bigramPos, probability, false /* hasNext */, &newBigramFlags,
-            &newBigramOffset, &newBigramOffsetFieldSize)) {
-        return false;
-    }
-    // Write bigram flags.
-    if (!mBuffer->writeUintAndAdvancePosition(newBigramFlags, 1 /* size */, writingPos)) {
-        return false;
-    }
-    // Write bigram positon offset.
-    if (!mBuffer->writeUintAndAdvancePosition(newBigramOffset, newBigramOffsetFieldSize,
-            writingPos)) {
-        return false;
-    }
-    return true;
+    // hasNext is false because we are adding a new bigram entry at the end of the bigram list.
+    return BigramListReadWriteUtils::createAndWriteBigramEntry(mBuffer, bigramTargetPos,
+            probability, false /* hasNext */, writingPos);
 }
 
-bool DynamicBigramListPolicy::removeBigram(const int bigramListPos, const int targetBigramPos) {
+bool DynamicBigramListPolicy::removeBigram(const int bigramListPos, const int bigramTargetPos) {
     const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(bigramListPos);
     int pos = bigramListPos;
     if (usesAdditionalBuffer) {
         pos -= mBuffer->getOriginalBufferSize();
     }
-    BigramListReadWriteUtils::BigramFlags flags;
+    BigramListReadWriteUtils::BigramFlags bigramFlags;
+    int bigramEntryCount = 0;
     do {
-        // The buffer address can be changed after calling buffer writing methods.
-        const uint8_t *const buffer = mBuffer->getBuffer(usesAdditionalBuffer);
-        flags = BigramListReadWriteUtils::getFlagsAndForwardPointer(buffer, &pos);
-        int bigramOffsetFieldPos = pos;
-        if (usesAdditionalBuffer) {
-            bigramOffsetFieldPos += mBuffer->getOriginalBufferSize();
+        if (++bigramEntryCount > BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT) {
+            AKLOGE("Too many bigram entries. %d", BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT);
+            ASSERT(false);
+            return false;
         }
-        int originalBigramPos = BigramListReadWriteUtils::getBigramAddressAndForwardPointer(
-                buffer, flags, &pos);
+        int bigramEntryPos = pos;
+        int originalBigramPos;
+        // The buffer address can be changed after calling buffer writing methods.
+        BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(
+                mBuffer->getBuffer(usesAdditionalBuffer), &bigramFlags, &originalBigramPos, &pos);
+        if (usesAdditionalBuffer) {
+            bigramEntryPos += mBuffer->getOriginalBufferSize();
+        }
         if (usesAdditionalBuffer && originalBigramPos != NOT_A_DICT_POS) {
             originalBigramPos += mBuffer->getOriginalBufferSize();
         }
         const int bigramPos = followBigramLinkAndGetCurrentBigramPtNodePos(originalBigramPos);
-        if (bigramPos != targetBigramPos) {
+        if (bigramPos != bigramTargetPos) {
             continue;
         }
-        // Target entry is found. Write 0 into the bigram pos field to mark the bigram invalid.
-        const int bigramOffsetFieldSize = BigramListReadWriteUtils::attributeAddressSize(flags);
-        if (!mBuffer->writeUintAndAdvancePosition(0 /* data */, bigramOffsetFieldSize,
-                &bigramOffsetFieldPos)) {
-            return false;
-        }
-        return true;
-    } while(BigramListReadWriteUtils::hasNext(flags));
+        // Target entry is found. Write an invalid target position to mark the bigram invalid.
+        return BigramListReadWriteUtils::writeBigramEntry(mBuffer, bigramFlags,
+                NOT_A_DICT_POS /* targetOffset */, &bigramEntryPos);
+    } while(BigramListReadWriteUtils::hasNext(bigramFlags));
     return false;
 }
 
@@ -212,14 +255,14 @@
     }
     int currentPos = originalBigramPos;
     DynamicPatriciaTrieNodeReader nodeReader(mBuffer, this /* bigramsPolicy */, mShortcutPolicy);
-    nodeReader.fetchNodeInfoFromBuffer(currentPos);
+    nodeReader.fetchNodeInfoInBufferFromPtNodePos(currentPos);
     int bigramLinkCount = 0;
     while (nodeReader.getBigramLinkedNodePos() != NOT_A_DICT_POS) {
         currentPos = nodeReader.getBigramLinkedNodePos();
-        nodeReader.fetchNodeInfoFromBuffer(currentPos);
+        nodeReader.fetchNodeInfoInBufferFromPtNodePos(currentPos);
         bigramLinkCount++;
-        if (bigramLinkCount > BIGRAM_LINK_COUNT_LIMIT) {
-            AKLOGI("Bigram link is invalid. start position: %d", bigramPos);
+        if (bigramLinkCount > CONTINUING_BIGRAM_LINK_COUNT_LIMIT) {
+            AKLOGE("Bigram link is invalid. start position: %d", bigramPos);
             ASSERT(false);
             return NOT_A_DICT_POS;
         }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h b/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h
index 5d02d32..16b080a 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h
@@ -21,13 +21,12 @@
 
 #include "defines.h"
 #include "suggest/core/policy/dictionary_bigrams_structure_policy.h"
-#include "suggest/core/policy/dictionary_shortcuts_structure_policy.h"
-#include "suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.h"
-#include "suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h"
-#include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
 
 namespace latinime {
 
+class BufferWithExtendableBuffer;
+class DictionaryShortcutsStructurePolicy;
+
 /*
  * This is a dynamic version of BigramListPolicy and supports an additional buffer.
  */
@@ -40,9 +39,9 @@
     ~DynamicBigramListPolicy() {}
 
     void getNextBigram(int *const outBigramPos, int *const outProbability, bool *const outHasNext,
-            int *const pos) const;
+            int *const bigramEntryPos) const;
 
-    void skipAllBigrams(int *const pos) const;
+    void skipAllBigrams(int *const bigramListPos) const;
 
     // Copy bigrams from the bigram list that starts at fromPos in mBuffer to toPos in
     // bufferToWrite and advance these positions after bigram lists. This method skips invalid
@@ -50,18 +49,22 @@
     bool copyAllBigrams(BufferWithExtendableBuffer *const bufferToWrite, int *const fromPos,
             int *const toPos, int *const outBigramsCount) const;
 
-    bool addNewBigramEntryToBigramList(const int bigramPos, const int probability, int *const pos);
+    bool updateAllBigramEntriesAndDeleteUselessEntries(int *const bigramListPos);
 
-    bool writeNewBigramEntry(const int bigramPos, const int probability,
+    bool addNewBigramEntryToBigramList(const int bigramTargetPos, const int probability,
+            int *const bigramListPos);
+
+    bool writeNewBigramEntry(const int bigramTargetPos, const int probability,
             int *const writingPos);
 
     // Return if targetBigramPos is found or not.
-    bool removeBigram(const int bigramListPos, const int targetBigramPos);
+    bool removeBigram(const int bigramListPos, const int bigramTargetPos);
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicBigramListPolicy);
 
-    static const int BIGRAM_LINK_COUNT_LIMIT;
+    static const int CONTINUING_BIGRAM_LINK_COUNT_LIMIT;
+    static const int BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT;
 
     BufferWithExtendableBuffer *const mBuffer;
     const DictionaryShortcutsStructurePolicy *const mShortcutPolicy;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_gc_event_listeners.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_gc_event_listeners.cpp
index 9b82673..ffa02e3 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_gc_event_listeners.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_gc_event_listeners.cpp
@@ -20,7 +20,8 @@
 
 bool DynamicPatriciaTrieGcEventListeners
         ::ListenerForUpdatingUnigramProbabilityAndMarkingUselessPtNodesAsDeleted
-                ::onVisitingPtNode(const DynamicPatriciaTrieNodeReader *const node) {
+                ::onVisitingPtNode(const DynamicPatriciaTrieNodeReader *const node,
+                        const int *const nodeCodePoints) {
     // PtNode is useless when the PtNode is not a terminal and doesn't have any not useless
     // children.
     bool isUselessPtNode = !node->isTerminal();
@@ -45,4 +46,53 @@
     return true;
 }
 
+// Writes dummy PtNode array size when the head of PtNode array is read.
+bool DynamicPatriciaTrieGcEventListeners::ListenerForPlacingAndWritingValidPtNodesToBuffer
+        ::onDescend(const int ptNodeArrayPos) {
+    mValidPtNodeCount = 0;
+    int writingPos = mBufferToWrite->getTailPosition();
+    mPositionMap->insert(hash_map_compat<int, int>::value_type(ptNodeArrayPos,  writingPos));
+    // Writes dummy PtNode array size because arrays can have a forward link or needles PtNodes.
+    // This field will be updated later in onReadingPtNodeArrayTail() with actual PtNode count.
+    mPtNodeArraySizeFieldPos = writingPos;
+    return DynamicPatriciaTrieWritingUtils::writePtNodeArraySizeAndAdvancePosition(
+            mBufferToWrite, 0 /* arraySize */, &writingPos);
+}
+
+// Write PtNode array terminal and actual PtNode array size.
+bool DynamicPatriciaTrieGcEventListeners::ListenerForPlacingAndWritingValidPtNodesToBuffer
+        ::onReadingPtNodeArrayTail() {
+    int writingPos = mBufferToWrite->getTailPosition();
+    // Write PtNode array terminal.
+    if (!DynamicPatriciaTrieWritingUtils::writeForwardLinkPositionAndAdvancePosition(
+            mBufferToWrite, NOT_A_DICT_POS /* forwardLinkPos */, &writingPos)) {
+        return false;
+    }
+    // Write actual PtNode array size.
+    if (!DynamicPatriciaTrieWritingUtils::writePtNodeArraySizeAndAdvancePosition(
+            mBufferToWrite, mValidPtNodeCount, &mPtNodeArraySizeFieldPos)) {
+        return false;
+    }
+    return true;
+}
+
+// Write valid PtNode to buffer and memorize mapping from the old position to the new position.
+bool DynamicPatriciaTrieGcEventListeners::ListenerForPlacingAndWritingValidPtNodesToBuffer
+        ::onVisitingPtNode(const DynamicPatriciaTrieNodeReader *const node,
+                const int *const nodeCodePoints) {
+    if (node->isDeleted()) {
+        // Current PtNode is not written in new buffer because it has been deleted.
+        mPositionMap->insert(hash_map_compat<int, int>::value_type(node->getHeadPos(),
+                NOT_A_DICT_POS));
+        return true;
+    }
+    int writingPos = mBufferToWrite->getTailPosition();
+    mPositionMap->insert(hash_map_compat<int, int>::value_type(node->getHeadPos(), writingPos));
+    mValidPtNodeCount++;
+    // Writes current PtNode.
+    return mWritingHelper->writePtNodeToBufferByCopyingPtNodeInfo(mBufferToWrite, node,
+            node->getParentPos(),  nodeCodePoints, node->getCodePointCount(),
+            node->getProbability(), &writingPos);
+}
+
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_gc_event_listeners.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_gc_event_listeners.h
index 8569a29..7285593 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_gc_event_listeners.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_gc_event_listeners.h
@@ -20,9 +20,12 @@
 #include <vector>
 
 #include "defines.h"
+#include "suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h"
 #include "suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h"
 #include "suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h"
 #include "suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_utils.h"
+#include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
+#include "utils/hash_map_compat.h"
 
 namespace latinime {
 
@@ -51,12 +54,15 @@
             return true;
         }
 
-        bool onDescend() {
+        bool onDescend(const int ptNodeArrayPos) {
             valueStack.push_back(0);
             return true;
         }
 
-        bool onVisitingPtNode(const DynamicPatriciaTrieNodeReader *const node);
+        bool onReadingPtNodeArrayTail() { return true; }
+
+        bool onVisitingPtNode(const DynamicPatriciaTrieNodeReader *const node,
+                const int *const nodeCodePoints);
 
      private:
         DISALLOW_IMPLICIT_CONSTRUCTORS(
@@ -68,6 +74,73 @@
         int mChildrenValue;
     };
 
+    // Updates all bigram entries that are held by valid PtNodes. This removes useless bigram
+    // entries.
+    class ListenerForUpdatingBigramProbability
+            : public DynamicPatriciaTrieReadingHelper::TraversingEventListener {
+     public:
+        ListenerForUpdatingBigramProbability(DynamicBigramListPolicy *const bigramPolicy)
+                : mBigramPolicy(bigramPolicy) {}
+
+        bool onAscend() { return true; }
+
+        bool onDescend(const int ptNodeArrayPos) { return true; }
+
+        bool onReadingPtNodeArrayTail() { return true; }
+
+        bool onVisitingPtNode(const DynamicPatriciaTrieNodeReader *const node,
+                const int *const nodeCodePoints) {
+            if (!node->isDeleted()) {
+                int pos = node->getBigramsPos();
+                if (pos != NOT_A_DICT_POS) {
+                    if (!mBigramPolicy->updateAllBigramEntriesAndDeleteUselessEntries(&pos)) {
+                        return false;
+                    }
+                }
+            }
+            return true;
+        }
+
+     private:
+        DISALLOW_IMPLICIT_CONSTRUCTORS(ListenerForUpdatingBigramProbability);
+
+        DynamicBigramListPolicy *const mBigramPolicy;
+    };
+
+    class ListenerForPlacingAndWritingValidPtNodesToBuffer
+            : public DynamicPatriciaTrieReadingHelper::TraversingEventListener {
+     public:
+        ListenerForPlacingAndWritingValidPtNodesToBuffer(
+                DynamicPatriciaTrieWritingHelper *const writingHelper,
+                BufferWithExtendableBuffer *const bufferToWrite,
+                hash_map_compat<int, int> *const positionMap)
+                : mWritingHelper(writingHelper), mBufferToWrite(bufferToWrite),
+                  mPositionMap(positionMap), mValidPtNodeCount(0),
+                  mPtNodeArraySizeFieldPos(NOT_A_DICT_POS) {};
+
+        bool onAscend() { return true; }
+
+        bool onDescend(const int ptNodeArrayPos);
+
+        bool onReadingPtNodeArrayTail();
+
+        bool onVisitingPtNode(const DynamicPatriciaTrieNodeReader *const node,
+                const int *const nodeCodePoints);
+
+        hash_map_compat<int, int> *getPositionMap() const {
+            return mPositionMap;
+        }
+
+     private:
+        DISALLOW_IMPLICIT_CONSTRUCTORS(ListenerForPlacingAndWritingValidPtNodesToBuffer);
+
+        DynamicPatriciaTrieWritingHelper *const mWritingHelper;
+        BufferWithExtendableBuffer *const mBufferToWrite;
+        hash_map_compat<int, int> *const mPositionMap;
+        int mValidPtNodeCount;
+        int mPtNodeArraySizeFieldPos;
+    };
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicPatriciaTrieGcEventListeners);
 };
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp
index 7370984..d52de7a 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp
@@ -23,26 +23,26 @@
 
 namespace latinime {
 
-void DynamicPatriciaTrieNodeReader::fetchNodeInfoFromBufferAndProcessMovedNode(const int nodePos,
-        const int maxCodePointCount, int *const outCodePoints) {
-    if (nodePos < 0 || nodePos >= mBuffer->getTailPosition()) {
+void DynamicPatriciaTrieNodeReader::fetchPtNodeInfoFromBufferAndProcessMovedPtNode(
+        const int ptNodePos, const int maxCodePointCount, int *const outCodePoints) {
+    if (ptNodePos < 0 || ptNodePos >= mBuffer->getTailPosition()) {
         AKLOGE("Fetching PtNode info form invalid dictionary position: %d, dictionary size: %d",
-                nodePos, mBuffer->getTailPosition());
+                ptNodePos, mBuffer->getTailPosition());
         ASSERT(false);
         invalidatePtNodeInfo();
         return;
     }
-    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(nodePos);
+    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(ptNodePos);
     const uint8_t *const dictBuf = mBuffer->getBuffer(usesAdditionalBuffer);
-    int pos = nodePos;
-    mHeadPos = nodePos;
+    int pos = ptNodePos;
+    mHeadPos = ptNodePos;
     if (usesAdditionalBuffer) {
         pos -= mBuffer->getOriginalBufferSize();
     }
     mFlags = PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(dictBuf, &pos);
     const int parentPos =
             DynamicPatriciaTrieReadingUtils::getParentPosAndAdvancePosition(dictBuf, &pos);
-    mParentPos = (parentPos != 0) ? nodePos + parentPos : NOT_A_DICT_POS;
+    mParentPos = (parentPos != 0) ? ptNodePos + parentPos : NOT_A_DICT_POS;
     if (outCodePoints != 0) {
         mCodePointCount = PatriciaTrieReadingUtils::getCharsAndAdvancePosition(
                 dictBuf, mFlags, maxCodePointCount, outCodePoints, &pos);
@@ -99,7 +99,8 @@
     // Read destination node if the read node is a moved node.
     if (DynamicPatriciaTrieReadingUtils::isMoved(mFlags)) {
         // The destination position is stored at the same place as the parent position.
-        fetchNodeInfoFromBufferAndProcessMovedNode(mParentPos, maxCodePointCount, outCodePoints);
+        fetchPtNodeInfoFromBufferAndProcessMovedPtNode(mParentPos, maxCodePointCount,
+                outCodePoints);
     }
 }
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.h
index 6ef5f58..3b36d42 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.h
@@ -48,17 +48,17 @@
 
     ~DynamicPatriciaTrieNodeReader() {}
 
-    // Reads node information from dictionary buffer and updates members with the information.
-    AK_FORCE_INLINE void fetchNodeInfoFromBuffer(const int nodePos) {
-        fetchNodeInfoFromBufferAndGetNodeCodePoints(nodePos , 0 /* maxCodePointCount */,
-                0 /* outCodePoints */);
+    // Reads PtNode information from dictionary buffer and updates members with the information.
+    AK_FORCE_INLINE void fetchNodeInfoInBufferFromPtNodePos(const int ptNodePos) {
+        fetchNodeInfoInBufferFromPtNodePosAndGetNodeCodePoints(ptNodePos ,
+                0 /* maxCodePointCount */, 0 /* outCodePoints */);
     }
 
-    AK_FORCE_INLINE void fetchNodeInfoFromBufferAndGetNodeCodePoints(const int nodePos,
-            const int maxCodePointCount, int *const outCodePoints) {
+    AK_FORCE_INLINE void fetchNodeInfoInBufferFromPtNodePosAndGetNodeCodePoints(
+            const int ptNodePos, const int maxCodePointCount, int *const outCodePoints) {
         mSiblingPos = NOT_A_DICT_POS;
         mBigramLinkedNodePos = NOT_A_DICT_POS;
-        fetchNodeInfoFromBufferAndProcessMovedNode(nodePos, maxCodePointCount, outCodePoints);
+        fetchPtNodeInfoFromBufferAndProcessMovedPtNode(ptNodePos, maxCodePointCount, outCodePoints);
     }
 
     // HeadPos is different from NodePos when the current PtNode is a moved PtNode.
@@ -154,8 +154,8 @@
     int mBigramPos;
     int mSiblingPos;
 
-    void fetchNodeInfoFromBufferAndProcessMovedNode(const int nodePos, const int maxCodePointCount,
-            int *const outCodePoints);
+    void fetchPtNodeInfoFromBufferAndProcessMovedPtNode(const int ptNodePos,
+            const int maxCodePointCount, int *const outCodePoints);
 
     void invalidatePtNodeInfo();
 };
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
index f91dd0e..70a09c2 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
@@ -35,7 +35,7 @@
     }
     DynamicPatriciaTrieReadingHelper readingHelper(&mBufferWithExtendableBuffer,
             getBigramsStructurePolicy(), getShortcutsStructurePolicy());
-    readingHelper.initWithNodeArrayPos(dicNode->getChildrenPos());
+    readingHelper.initWithPtNodeArrayPos(dicNode->getChildrenPos());
     const DynamicPatriciaTrieNodeReader *const nodeReader = readingHelper.getNodeReader();
     while (!readingHelper.isEnd()) {
         childDicNodes->pushLeavingChild(dicNode, nodeReader->getHeadPos(),
@@ -48,7 +48,7 @@
 }
 
 int DynamicPatriciaTriePolicy::getCodePointsAndProbabilityAndReturnCodePointCount(
-        const int nodePos, const int maxCodePointCount, int *const outCodePoints,
+        const int ptNodePos, const int maxCodePointCount, int *const outCodePoints,
         int *const outUnigramProbability) const {
     // This method traverses parent nodes from the terminal by following parent pointers; thus,
     // node code points are stored in the buffer in the reverse order.
@@ -56,9 +56,9 @@
     DynamicPatriciaTrieReadingHelper readingHelper(&mBufferWithExtendableBuffer,
             getBigramsStructurePolicy(), getShortcutsStructurePolicy());
     // First, read the terminal node and get its probability.
-    readingHelper.initWithNodePos(nodePos);
+    readingHelper.initWithPtNodePos(ptNodePos);
     if (!readingHelper.isValidTerminalNode()) {
-        // Node at the nodePos is not a valid terminal node.
+        // Node at the ptNodePos is not a valid terminal node.
         *outUnigramProbability = NOT_A_PROBABILITY;
         return 0;
     }
@@ -67,7 +67,7 @@
     // Then, following parent node link to the dictionary root and fetch node code points.
     while (!readingHelper.isEnd()) {
         if (readingHelper.getTotalCodePointCount() > maxCodePointCount) {
-            // The nodePos is not a valid terminal node position in the dictionary.
+            // The ptNodePos is not a valid terminal node position in the dictionary.
             *outUnigramProbability = NOT_A_PROBABILITY;
             return 0;
         }
@@ -98,7 +98,7 @@
     }
     DynamicPatriciaTrieReadingHelper readingHelper(&mBufferWithExtendableBuffer,
             getBigramsStructurePolicy(), getShortcutsStructurePolicy());
-    readingHelper.initWithNodeArrayPos(getRootPosition());
+    readingHelper.initWithPtNodeArrayPos(getRootPosition());
     const DynamicPatriciaTrieNodeReader *const nodeReader = readingHelper.getNodeReader();
     while (!readingHelper.isEnd()) {
         const int matchedCodePointCount = readingHelper.getPrevTotalCodePointCount();
@@ -148,39 +148,39 @@
     }
 }
 
-int DynamicPatriciaTriePolicy::getUnigramProbabilityOfPtNode(const int nodePos) const {
-    if (nodePos == NOT_A_DICT_POS) {
+int DynamicPatriciaTriePolicy::getUnigramProbabilityOfPtNode(const int ptNodePos) const {
+    if (ptNodePos == NOT_A_DICT_POS) {
         return NOT_A_PROBABILITY;
     }
     DynamicPatriciaTrieNodeReader nodeReader(&mBufferWithExtendableBuffer,
             getBigramsStructurePolicy(), getShortcutsStructurePolicy());
-    nodeReader.fetchNodeInfoFromBuffer(nodePos);
+    nodeReader.fetchNodeInfoInBufferFromPtNodePos(ptNodePos);
     if (nodeReader.isDeleted() || nodeReader.isBlacklisted() || nodeReader.isNotAWord()) {
         return NOT_A_PROBABILITY;
     }
     return getProbability(nodeReader.getProbability(), NOT_A_PROBABILITY);
 }
 
-int DynamicPatriciaTriePolicy::getShortcutPositionOfNode(const int nodePos) const {
-    if (nodePos == NOT_A_DICT_POS) {
+int DynamicPatriciaTriePolicy::getShortcutPositionOfPtNode(const int ptNodePos) const {
+    if (ptNodePos == NOT_A_DICT_POS) {
         return NOT_A_DICT_POS;
     }
     DynamicPatriciaTrieNodeReader nodeReader(&mBufferWithExtendableBuffer,
             getBigramsStructurePolicy(), getShortcutsStructurePolicy());
-    nodeReader.fetchNodeInfoFromBuffer(nodePos);
+    nodeReader.fetchNodeInfoInBufferFromPtNodePos(ptNodePos);
     if (nodeReader.isDeleted()) {
         return NOT_A_DICT_POS;
     }
     return nodeReader.getShortcutPos();
 }
 
-int DynamicPatriciaTriePolicy::getBigramsPositionOfNode(const int nodePos) const {
-    if (nodePos == NOT_A_DICT_POS) {
+int DynamicPatriciaTriePolicy::getBigramsPositionOfPtNode(const int ptNodePos) const {
+    if (ptNodePos == NOT_A_DICT_POS) {
         return NOT_A_DICT_POS;
     }
     DynamicPatriciaTrieNodeReader nodeReader(&mBufferWithExtendableBuffer,
             getBigramsStructurePolicy(), getShortcutsStructurePolicy());
-    nodeReader.fetchNodeInfoFromBuffer(nodePos);
+    nodeReader.fetchNodeInfoInBufferFromPtNodePos(ptNodePos);
     if (nodeReader.isDeleted()) {
         return NOT_A_DICT_POS;
     }
@@ -195,7 +195,7 @@
     }
     DynamicPatriciaTrieReadingHelper readingHelper(&mBufferWithExtendableBuffer,
             getBigramsStructurePolicy(), getShortcutsStructurePolicy());
-    readingHelper.initWithNodeArrayPos(getRootPosition());
+    readingHelper.initWithPtNodeArrayPos(getRootPosition());
     DynamicPatriciaTrieWritingHelper writingHelper(&mBufferWithExtendableBuffer,
             &mBigramListPolicy, &mShortcutListPolicy);
     return writingHelper.addUnigramWord(&readingHelper, word, length, probability);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
index ebe1f32..06d8095 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
@@ -51,7 +51,7 @@
             DicNodeVector *const childDicNodes) const;
 
     int getCodePointsAndProbabilityAndReturnCodePointCount(
-            const int terminalNodePos, const int maxCodePointCount, int *const outCodePoints,
+            const int terminalPtNodePos, const int maxCodePointCount, int *const outCodePoints,
             int *const outUnigramProbability) const;
 
     int getTerminalNodePositionOfWord(const int *const inWord,
@@ -59,11 +59,11 @@
 
     int getProbability(const int unigramProbability, const int bigramProbability) const;
 
-    int getUnigramProbabilityOfPtNode(const int nodePos) const;
+    int getUnigramProbabilityOfPtNode(const int ptNodePos) const;
 
-    int getShortcutPositionOfNode(const int nodePos) const;
+    int getShortcutPositionOfPtNode(const int ptNodePos) const;
 
-    int getBigramsPositionOfNode(const int nodePos) const;
+    int getBigramsPositionOfPtNode(const int ptNodePos) const;
 
     const DictionaryHeaderStructurePolicy *getHeaderStructurePolicy() const {
         return &mHeaderPolicy;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.cpp
index 59e39a5..754b679 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.cpp
@@ -25,18 +25,22 @@
 const int DynamicPatriciaTrieReadingHelper::MAX_NODE_ARRAY_COUNT_TO_AVOID_INFINITE_LOOP = 100000;
 const size_t DynamicPatriciaTrieReadingHelper::MAX_READING_STATE_STACK_SIZE = MAX_WORD_LENGTH;
 
+// Visits all PtNodes in post-order depth first manner.
+// For example, visits c -> b -> y -> x -> a for the following dictionary:
+// a _ b _ c
+//   \ x _ y
 bool DynamicPatriciaTrieReadingHelper::traverseAllPtNodesInPostorderDepthFirstManner(
         TraversingEventListener *const listener) {
     bool alreadyVisitedChildren = false;
     // Descend from the root to the root PtNode array.
-    if (!listener->onDescend()) {
+    if (!listener->onDescend(getPosOfLastPtNodeArrayHead())) {
         return false;
     }
     while (!isEnd()) {
         if (!alreadyVisitedChildren) {
             if (mNodeReader.hasChildren()) {
                 // Move to the first child.
-                if (!listener->onDescend()) {
+                if (!listener->onDescend(mNodeReader.getChildrenPos())) {
                     return false;
                 }
                 pushReadingStateToStack();
@@ -45,13 +49,16 @@
                 alreadyVisitedChildren = true;
             }
         } else {
-            if (!listener->onVisitingPtNode(&mNodeReader)) {
+            if (!listener->onVisitingPtNode(&mNodeReader, mMergedNodeCodePoints)) {
                 return false;
             }
             readNextSiblingNode();
             if (isEnd()) {
                 // All PtNodes in current linked PtNode arrays have been visited.
                 // Return to the parent.
+                if (!listener->onReadingPtNodeArrayTail()) {
+                    return false;
+                }
                 if (!listener->onAscend()) {
                     return false;
                 }
@@ -70,9 +77,78 @@
     return !isError();
 }
 
+// Visits all PtNodes in PtNode array level pre-order depth first manner, which is the same order
+// that PtNodes are written in the dictionary buffer.
+// For example, visits a -> b -> x -> c -> y for the following dictionary:
+// a _ b _ c
+//   \ x _ y
+bool DynamicPatriciaTrieReadingHelper::traverseAllPtNodesInPtNodeArrayLevelPreorderDepthFirstManner(
+        TraversingEventListener *const listener) {
+    bool alreadyVisitedAllPtNodesInArray = false;
+    bool alreadyVisitedChildren = false;
+    // Descend from the root to the root PtNode array.
+    if (!listener->onDescend(getPosOfLastPtNodeArrayHead())) {
+        return false;
+    }
+    pushReadingStateToStack();
+    while (!isEnd()) {
+        if (alreadyVisitedAllPtNodesInArray) {
+            if (alreadyVisitedChildren) {
+                // Move to next sibling PtNode's children.
+                readNextSiblingNode();
+                if (isEnd()) {
+                    // Return to the parent PTNode.
+                    if (!listener->onAscend()) {
+                        return false;
+                    }
+                    popReadingStateFromStack();
+                    alreadyVisitedChildren = true;
+                    alreadyVisitedAllPtNodesInArray = true;
+                } else {
+                    alreadyVisitedChildren = false;
+                }
+            } else {
+                if (mNodeReader.hasChildren()) {
+                    // Move to the first child.
+                    if (!listener->onDescend(mNodeReader.getChildrenPos())) {
+                        return false;
+                    }
+                    pushReadingStateToStack();
+                    readChildNode();
+                    // Push state to return the head of PtNode array.
+                    pushReadingStateToStack();
+                    alreadyVisitedAllPtNodesInArray = false;
+                    alreadyVisitedChildren = false;
+                } else {
+                    alreadyVisitedChildren = true;
+                }
+            }
+        } else {
+            if (!listener->onVisitingPtNode(&mNodeReader, mMergedNodeCodePoints)) {
+                return false;
+            }
+            readNextSiblingNode();
+            if (isEnd()) {
+                if (!listener->onReadingPtNodeArrayTail()) {
+                    return false;
+                }
+                // Return to the head of current PtNode array.
+                popReadingStateFromStack();
+                alreadyVisitedAllPtNodesInArray = true;
+            }
+        }
+    }
+    popReadingStateFromStack();
+    // Ascend from the root PtNode array to the root.
+    if (!listener->onAscend()) {
+        return false;
+    }
+    return !isError();
+}
+
 // Read node array size and process empty node arrays. Nodes and arrays are counted up in this
 // method to avoid an infinite loop.
-void DynamicPatriciaTrieReadingHelper::nextNodeArray() {
+void DynamicPatriciaTrieReadingHelper::nextPtNodeArray() {
     mReadingState.mPosOfLastPtNodeArrayHead = mReadingState.mPos;
     const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(mReadingState.mPos);
     const uint8_t *const dictBuf = mBuffer->getBuffer(usesAdditionalBuffer);
@@ -123,7 +199,7 @@
     if (DynamicPatriciaTrieReadingUtils::isValidForwardLinkPosition(forwardLinkPosition)) {
         // Follow the forward link.
         mReadingState.mPos += forwardLinkPosition;
-        nextNodeArray();
+        nextPtNodeArray();
     } else {
         // All node arrays have been read.
         mReadingState.mPos = NOT_A_DICT_POS;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h
index 08ab072..b033eee 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h
@@ -45,10 +45,14 @@
         virtual bool onAscend() = 0;
 
         // Returns whether the event handling was succeeded or not.
-        virtual bool onDescend() = 0;
+        virtual bool onDescend(const int ptNodeArrayPos) = 0;
 
         // Returns whether the event handling was succeeded or not.
-        virtual bool onVisitingPtNode(const DynamicPatriciaTrieNodeReader *const node) = 0;
+        virtual bool onReadingPtNodeArrayTail() = 0;
+
+        // Returns whether the event handling was succeeded or not.
+        virtual bool onVisitingPtNode(const DynamicPatriciaTrieNodeReader *const node,
+                const int *const nodeCodePoints) = 0;
 
      protected:
         TraversingEventListener() {};
@@ -73,32 +77,32 @@
         return mReadingState.mPos == NOT_A_DICT_POS;
     }
 
-    // Initialize reading state with the head position of a node array.
-    AK_FORCE_INLINE void initWithNodeArrayPos(const int nodeArrayPos) {
-        if (nodeArrayPos == NOT_A_DICT_POS) {
+    // Initialize reading state with the head position of a PtNode array.
+    AK_FORCE_INLINE void initWithPtNodeArrayPos(const int ptNodeArrayPos) {
+        if (ptNodeArrayPos == NOT_A_DICT_POS) {
             mReadingState.mPos = NOT_A_DICT_POS;
         } else {
             mIsError = false;
-            mReadingState.mPos = nodeArrayPos;
+            mReadingState.mPos = ptNodeArrayPos;
             mReadingState.mPrevTotalCodePointCount = 0;
             mReadingState.mTotalNodeCount = 0;
             mReadingState.mNodeArrayCount = 0;
             mReadingState.mPosOfLastForwardLinkField = NOT_A_DICT_POS;
             mReadingStateStack.clear();
-            nextNodeArray();
+            nextPtNodeArray();
             if (!isEnd()) {
-                fetchNodeInfo();
+                fetchPtNodeInfo();
             }
         }
     }
 
     // Initialize reading state with the head position of a node.
-    AK_FORCE_INLINE void initWithNodePos(const int nodePos) {
-        if (nodePos == NOT_A_DICT_POS) {
+    AK_FORCE_INLINE void initWithPtNodePos(const int ptNodePos) {
+        if (ptNodePos == NOT_A_DICT_POS) {
             mReadingState.mPos = NOT_A_DICT_POS;
         } else {
             mIsError = false;
-            mReadingState.mPos = nodePos;
+            mReadingState.mPos = ptNodePos;
             mReadingState.mNodeCount = 1;
             mReadingState.mPrevTotalCodePointCount = 0;
             mReadingState.mTotalNodeCount = 1;
@@ -106,7 +110,7 @@
             mReadingState.mPosOfLastForwardLinkField = NOT_A_DICT_POS;
             mReadingState.mPosOfLastPtNodeArrayHead = NOT_A_DICT_POS;
             mReadingStateStack.clear();
-            fetchNodeInfo();
+            fetchPtNodeInfo();
         }
     }
 
@@ -151,10 +155,10 @@
             // All nodes in the current node array have been read.
             followForwardLink();
             if (!isEnd()) {
-                fetchNodeInfo();
+                fetchPtNodeInfo();
             }
         } else {
-            fetchNodeInfo();
+            fetchPtNodeInfo();
         }
     }
 
@@ -167,9 +171,9 @@
             mReadingState.mPos = mNodeReader.getChildrenPos();
             mReadingState.mPosOfLastForwardLinkField = NOT_A_DICT_POS;
             // Read children node array.
-            nextNodeArray();
+            nextPtNodeArray();
             if (!isEnd()) {
-                fetchNodeInfo();
+                fetchPtNodeInfo();
             }
         } else {
             mReadingState.mPos = NOT_A_DICT_POS;
@@ -186,7 +190,7 @@
             mReadingState.mPos = mNodeReader.getParentPos();
             mReadingState.mPosOfLastForwardLinkField = NOT_A_DICT_POS;
             mReadingState.mPosOfLastPtNodeArrayHead = NOT_A_DICT_POS;
-            fetchNodeInfo();
+            fetchPtNodeInfo();
         } else {
             mReadingState.mPos = NOT_A_DICT_POS;
         }
@@ -202,12 +206,15 @@
 
     AK_FORCE_INLINE void reloadCurrentPtNodeInfo() {
         if (!isEnd()) {
-            fetchNodeInfo();
+            fetchPtNodeInfo();
         }
     }
 
     bool traverseAllPtNodesInPostorderDepthFirstManner(TraversingEventListener *const listener);
 
+    bool traverseAllPtNodesInPtNodeArrayLevelPreorderDepthFirstManner(
+            TraversingEventListener *const listener);
+
  private:
     DISALLOW_COPY_AND_ASSIGN(DynamicPatriciaTrieReadingHelper);
 
@@ -240,12 +247,12 @@
     int mMergedNodeCodePoints[MAX_WORD_LENGTH];
     std::vector<ReadingState> mReadingStateStack;
 
-    void nextNodeArray();
+    void nextPtNodeArray();
 
     void followForwardLink();
 
-    AK_FORCE_INLINE void fetchNodeInfo() {
-        mNodeReader.fetchNodeInfoFromBufferAndGetNodeCodePoints(mReadingState.mPos,
+    AK_FORCE_INLINE void fetchPtNodeInfo() {
+        mNodeReader.fetchNodeInfoInBufferFromPtNodePosAndGetNodeCodePoints(mReadingState.mPos,
                 MAX_WORD_LENGTH, mMergedNodeCodePoints);
         if (mNodeReader.getCodePointCount() <= 0) {
             // Empty node is not allowed.
@@ -271,7 +278,7 @@
         } else {
             mReadingState = mReadingStateStack.back();
             mReadingStateStack.pop_back();
-            fetchNodeInfo();
+            fetchPtNodeInfo();
         }
     }
 };
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp
index 4557547..3fc9c4c 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp
@@ -90,7 +90,7 @@
         const int probability) {
     int mMergedNodeCodePoints[MAX_WORD_LENGTH];
     DynamicPatriciaTrieNodeReader nodeReader(mBuffer, mBigramPolicy, mShortcutPolicy);
-    nodeReader.fetchNodeInfoFromBufferAndGetNodeCodePoints(word0Pos, MAX_WORD_LENGTH,
+    nodeReader.fetchNodeInfoInBufferFromPtNodePosAndGetNodeCodePoints(word0Pos, MAX_WORD_LENGTH,
             mMergedNodeCodePoints);
     // Move node to add bigram entry.
     const int newNodePos = mBuffer->getTailPosition();
@@ -104,7 +104,7 @@
             &writingPos)) {
         return false;
     }
-    nodeReader.fetchNodeInfoFromBuffer(newNodePos);
+    nodeReader.fetchNodeInfoInBufferFromPtNodePos(newNodePos);
     if (nodeReader.getBigramsPos() != NOT_A_DICT_POS) {
         // Insert a new bigram entry into the existing bigram list.
         int bigramListPos = nodeReader.getBigramsPos();
@@ -131,7 +131,7 @@
 // Remove a bigram relation from word0Pos to word1Pos.
 bool DynamicPatriciaTrieWritingHelper::removeBigramWords(const int word0Pos, const int word1Pos) {
     DynamicPatriciaTrieNodeReader nodeReader(mBuffer, mBigramPolicy, mShortcutPolicy);
-    nodeReader.fetchNodeInfoFromBuffer(word0Pos);
+    nodeReader.fetchNodeInfoInBufferFromPtNodePos(word0Pos);
     if (nodeReader.getBigramsPos() == NOT_A_DICT_POS) {
         return false;
     }
@@ -217,7 +217,7 @@
         // Update children's parent position.
         DynamicPatriciaTrieReadingHelper readingHelper(mBuffer, mBigramPolicy, mShortcutPolicy);
         const DynamicPatriciaTrieNodeReader *const nodeReader = readingHelper.getNodeReader();
-        readingHelper.initWithNodeArrayPos(originalNode->getChildrenPos());
+        readingHelper.initWithPtNodeArrayPos(originalNode->getChildrenPos());
         while (!readingHelper.isEnd()) {
             const int childPtNodeWrittenPos = nodeReader->getHeadPos();
             const int parentOffset = movedPos - childPtNodeWrittenPos;
@@ -452,7 +452,7 @@
     }
     // Load node info. Information of the 1st part will be fetched.
     DynamicPatriciaTrieNodeReader nodeReader(mBuffer, mBigramPolicy, mShortcutPolicy);
-    nodeReader.fetchNodeInfoFromBuffer(firstPartOfReallocatedPtNodePos);
+    nodeReader.fetchNodeInfoInBufferFromPtNodePos(firstPartOfReallocatedPtNodePos);
     // Update children position.
     int childrenPosFieldPos = nodeReader.getChildrenPosFieldPos();
     if (!DynamicPatriciaTrieWritingUtils::writeChildrenPositionAndAdvancePosition(mBuffer,
@@ -519,7 +519,7 @@
 bool DynamicPatriciaTrieWritingHelper::runGC(const int rootPtNodeArrayPos,
         BufferWithExtendableBuffer *const bufferToWrite) {
     DynamicPatriciaTrieReadingHelper readingHelper(mBuffer, mBigramPolicy, mShortcutPolicy);
-    readingHelper.initWithNodeArrayPos(rootPtNodeArrayPos);
+    readingHelper.initWithPtNodeArrayPos(rootPtNodeArrayPos);
     DynamicPatriciaTrieGcEventListeners
             ::ListenerForUpdatingUnigramProbabilityAndMarkingUselessPtNodesAsDeleted
                     listenerForUpdatingUnigramProbabilityAndMarkingUselessPtNodesAsDeleted(
@@ -528,6 +528,21 @@
             &listenerForUpdatingUnigramProbabilityAndMarkingUselessPtNodesAsDeleted)) {
         return false;
     }
+
+    readingHelper.initWithPtNodeArrayPos(rootPtNodeArrayPos);
+    DynamicPatriciaTrieGcEventListeners::ListenerForUpdatingBigramProbability
+            listenerForupdatingBigramProbability(mBigramPolicy);
+    if (!readingHelper.traverseAllPtNodesInPostorderDepthFirstManner(
+            &listenerForupdatingBigramProbability)) {
+        return false;
+    }
+
+    // Mapping from positions in mBuffer to positions in bufferToWrite.
+    hash_map_compat<int, int> positionMap;
+    readingHelper.initWithPtNodeArrayPos(rootPtNodeArrayPos);
+    DynamicPatriciaTrieGcEventListeners::ListenerForPlacingAndWritingValidPtNodesToBuffer
+            listenerForPlacingAndWritingLivingPtNodesToBuffer(this, mBuffer, &positionMap);
+
     // TODO: Implement.
     return false;
 }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h
index d164e43..e82b80a 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h
@@ -59,6 +59,13 @@
     // DynamicPatriciaTrieGcEventListeners.
     bool markNodeAsDeleted(const DynamicPatriciaTrieNodeReader *const nodeToUpdate);
 
+    // CAVEAT: This method must be called only from this class or inner classes of
+    // DynamicPatriciaTrieGcEventListeners.
+    bool writePtNodeToBufferByCopyingPtNodeInfo(BufferWithExtendableBuffer *const bufferToWrite,
+            const DynamicPatriciaTrieNodeReader *const originalNode, const int parentPos,
+            const int *const codePoints, const int codePointCount, const int probability,
+            int *const writingPos);
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicPatriciaTrieWritingHelper);
 
@@ -82,11 +89,6 @@
             const int parentPos, const int *const codePoints, const int codePointCount,
             const int probability, int *const writingPos);
 
-    bool writePtNodeToBufferByCopyingPtNodeInfo(BufferWithExtendableBuffer *const bufferToWrite,
-            const DynamicPatriciaTrieNodeReader *const originalNode, const int parentPos,
-            const int *const codePoints, const int codePointCount, const int probability,
-            int *const writingPos);
-
     bool createAndInsertNodeIntoPtNodeArray(const int parentPos, const int *const nodeCodePoints,
             const int nodeCodePointCount, const int probability, int *const forwardLinkFieldPos);
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp
index e6cff43..5269795 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp
@@ -49,7 +49,7 @@
 // with a z, it's the last PtNode of the root array, so all children addresses will be smaller
 // than the position we look for, and we have to descend the z node).
 /* Parameters :
- * nodePos: the byte position of the terminal PtNode of the word we are searching for (this is
+ * ptNodePos: the byte position of the terminal PtNode of the word we are searching for (this is
  *   what is stored as the "bigram position" in each bigram)
  * outCodePoints: an array to write the found word, with MAX_WORD_LENGTH size.
  * outUnigramProbability: a pointer to an int to write the probability into.
@@ -57,7 +57,7 @@
  */
 // TODO: Split this function to be more readable
 int PatriciaTriePolicy::getCodePointsAndProbabilityAndReturnCodePointCount(
-        const int nodePos, const int maxCodePointCount, int *const outCodePoints,
+        const int ptNodePos, const int maxCodePointCount, int *const outCodePoints,
         int *const outUnigramProbability) const {
     int pos = getRootPosition();
     int wordPos = 0;
@@ -78,7 +78,7 @@
                     PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(mDictRoot, &pos);
             const int character = PatriciaTrieReadingUtils::getCodePointAndAdvancePosition(
                     mDictRoot, &pos);
-            if (nodePos == startPos) {
+            if (ptNodePos == startPos) {
                 // We found the position. Copy the rest of the code points in the buffer and return
                 // the length.
                 outCodePoints[wordPos] = character;
@@ -121,7 +121,7 @@
                 // Here comes the tricky part. First, read the children position.
                 const int childrenPos = PatriciaTrieReadingUtils
                         ::readChildrenPositionAndAdvancePosition(mDictRoot, flags, &currentPos);
-                if (childrenPos > nodePos) {
+                if (childrenPos > ptNodePos) {
                     // If the children pos is greater than the position, it means the previous
                     // PtNode, which position is stored in lastCandidatePtNodePos, was the right
                     // one.
@@ -213,7 +213,7 @@
 
         }
     }
-    // If we have looked through all the PtNodes and found no match, the nodePos is
+    // If we have looked through all the PtNodes and found no match, the ptNodePos is
     // not the position of a terminal in this dictionary.
     return 0;
 }
@@ -319,11 +319,11 @@
     }
 }
 
-int PatriciaTriePolicy::getUnigramProbabilityOfPtNode(const int nodePos) const {
-    if (nodePos == NOT_A_DICT_POS) {
+int PatriciaTriePolicy::getUnigramProbabilityOfPtNode(const int ptNodePos) const {
+    if (ptNodePos == NOT_A_DICT_POS) {
         return NOT_A_PROBABILITY;
     }
-    int pos = nodePos;
+    int pos = ptNodePos;
     const PatriciaTrieReadingUtils::NodeFlags flags =
             PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(mDictRoot, &pos);
     if (!PatriciaTrieReadingUtils::isTerminal(flags)) {
@@ -341,11 +341,11 @@
             mDictRoot, &pos), NOT_A_PROBABILITY);
 }
 
-int PatriciaTriePolicy::getShortcutPositionOfNode(const int nodePos) const {
-    if (nodePos == NOT_A_DICT_POS) {
+int PatriciaTriePolicy::getShortcutPositionOfPtNode(const int ptNodePos) const {
+    if (ptNodePos == NOT_A_DICT_POS) {
         return NOT_A_DICT_POS;
     }
-    int pos = nodePos;
+    int pos = ptNodePos;
     const PatriciaTrieReadingUtils::NodeFlags flags =
             PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(mDictRoot, &pos);
     if (!PatriciaTrieReadingUtils::hasShortcutTargets(flags)) {
@@ -361,11 +361,11 @@
     return pos;
 }
 
-int PatriciaTriePolicy::getBigramsPositionOfNode(const int nodePos) const {
-    if (nodePos == NOT_A_DICT_POS) {
+int PatriciaTriePolicy::getBigramsPositionOfPtNode(const int ptNodePos) const {
+    if (ptNodePos == NOT_A_DICT_POS) {
         return NOT_A_DICT_POS;
     }
-    int pos = nodePos;
+    int pos = ptNodePos;
     const PatriciaTrieReadingUtils::NodeFlags flags =
             PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(mDictRoot, &pos);
     if (!PatriciaTrieReadingUtils::hasBigrams(flags)) {
@@ -385,8 +385,8 @@
 }
 
 int PatriciaTriePolicy::createAndGetLeavingChildNode(const DicNode *const dicNode,
-        const int nodePos, DicNodeVector *childDicNodes) const {
-    int pos = nodePos;
+        const int ptNodePos, DicNodeVector *childDicNodes) const {
+    int pos = ptNodePos;
     const PatriciaTrieReadingUtils::NodeFlags flags =
             PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(mDictRoot, &pos);
     int mergedNodeCodePoints[MAX_WORD_LENGTH];
@@ -404,7 +404,7 @@
     if (PatriciaTrieReadingUtils::hasBigrams(flags)) {
         getBigramsStructurePolicy()->skipAllBigrams(&pos);
     }
-    childDicNodes->pushLeavingChild(dicNode, nodePos, childrenPos, probability,
+    childDicNodes->pushLeavingChild(dicNode, ptNodePos, childrenPos, probability,
             PatriciaTrieReadingUtils::isTerminal(flags),
             PatriciaTrieReadingUtils::hasChildrenInFlags(flags),
             PatriciaTrieReadingUtils::isBlacklisted(flags) ||
diff --git a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
index 697d015..19155f9 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
@@ -58,11 +58,11 @@
 
     int getProbability(const int unigramProbability, const int bigramProbability) const;
 
-    int getUnigramProbabilityOfPtNode(const int nodePos) const;
+    int getUnigramProbabilityOfPtNode(const int ptNodePos) const;
 
-    int getShortcutPositionOfNode(const int nodePos) const;
+    int getShortcutPositionOfPtNode(const int ptNodePos) const;
 
-    int getBigramsPositionOfNode(const int nodePos) const;
+    int getBigramsPositionOfPtNode(const int ptNodePos) const;
 
     const DictionaryHeaderStructurePolicy *getHeaderStructurePolicy() const {
         return &mHeaderPolicy;
@@ -121,7 +121,7 @@
     const BigramListPolicy mBigramListPolicy;
     const ShortcutListPolicy mShortcutListPolicy;
 
-    int createAndGetLeavingChildNode(const DicNode *const dicNode, const int nodePos,
+    int createAndGetLeavingChildNode(const DicNode *const dicNode, const int ptNodePos,
             DicNodeVector *const childDicNodes) const;
 };
 } // namespace latinime
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
index cedd0df..a4d9426 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
@@ -494,7 +494,7 @@
                 formatOptions, "unigram"));
         results.add(runReadUnigramsAndBigramsBinary(sWords, sChainBigrams, bufferType,
                 formatOptions, "chain"));
-        results.add(runReadUnigramsAndBigramsBinary(sWords, sChainBigrams, bufferType,
+        results.add(runReadUnigramsAndBigramsBinary(sWords, sStarBigrams, bufferType,
                 formatOptions, "star"));
     }