diff --git a/java/src/com/android/inputmethod/latin/settings/SettingsFragment.java b/java/src/com/android/inputmethod/latin/settings/SettingsFragment.java
index 5c60a73..f841f20 100644
--- a/java/src/com/android/inputmethod/latin/settings/SettingsFragment.java
+++ b/java/src/com/android/inputmethod/latin/settings/SettingsFragment.java
@@ -48,7 +48,6 @@
 import com.android.inputmethod.latin.utils.ApplicationUtils;
 import com.android.inputmethod.latin.utils.FeedbackUtils;
 import com.android.inputmethod.latin.utils.SubtypeLocaleUtils;
-import com.android.inputmethod.research.ResearchLogger;
 import com.android.inputmethodcommon.InputMethodSettingsFragment;
 
 import java.util.TreeSet;
@@ -143,12 +142,7 @@
                 feedbackSettings.setOnPreferenceClickListener(new OnPreferenceClickListener() {
                     @Override
                     public boolean onPreferenceClick(final Preference pref) {
-                        if (ProductionFlag.USES_DEVELOPMENT_ONLY_DIAGNOSTICS) {
-                            // Use development-only feedback mechanism
-                            ResearchLogger.getInstance().presentFeedbackDialogFromSettings();
-                        } else {
-                            FeedbackUtils.showFeedbackForm(getActivity());
-                        }
+                        FeedbackUtils.showFeedbackForm(getActivity());
                         return true;
                     }
                 });
diff --git a/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp b/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
index c4383d7..db0c189 100644
--- a/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
+++ b/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
@@ -343,7 +343,7 @@
     static const int GET_PROPERTY_RESULT_LENGTH = 100;
     char resultChars[GET_PROPERTY_RESULT_LENGTH];
     resultChars[0] = '\0';
-    dictionary->getProperty(queryChars, resultChars, GET_PROPERTY_RESULT_LENGTH);
+    dictionary->getProperty(queryChars, queryUtf8Length, resultChars, GET_PROPERTY_RESULT_LENGTH);
     return env->NewStringUTF(resultChars);
 }
 
diff --git a/native/jni/src/suggest/core/dictionary/dictionary.cpp b/native/jni/src/suggest/core/dictionary/dictionary.cpp
index 7b83f27..a990418 100644
--- a/native/jni/src/suggest/core/dictionary/dictionary.cpp
+++ b/native/jni/src/suggest/core/dictionary/dictionary.cpp
@@ -120,9 +120,10 @@
     return mDictionaryStructureWithBufferPolicy.get()->needsToRunGC(mindsBlockByGC);
 }
 
-void Dictionary::getProperty(const char *const query, char *const outResult,
+void Dictionary::getProperty(const char *const query, const int queryLength, char *const outResult,
         const int maxResultLength) {
-    return mDictionaryStructureWithBufferPolicy.get()->getProperty(query, outResult, maxResultLength);
+    return mDictionaryStructureWithBufferPolicy.get()->getProperty(query, queryLength, outResult,
+            maxResultLength);
 }
 
 void Dictionary::logDictionaryInfo(JNIEnv *const env) const {
diff --git a/native/jni/src/suggest/core/dictionary/dictionary.h b/native/jni/src/suggest/core/dictionary/dictionary.h
index e52a40f..977ad35 100644
--- a/native/jni/src/suggest/core/dictionary/dictionary.h
+++ b/native/jni/src/suggest/core/dictionary/dictionary.h
@@ -85,7 +85,7 @@
 
     bool needsToRunGC(const bool mindsBlockByGC);
 
-    void getProperty(const char *const query, char *const outResult,
+    void getProperty(const char *const query, const int queryLength, char *const outResult,
             const int maxResultLength);
 
     const DictionaryStructureWithBufferPolicy *getDictionaryStructurePolicy() const {
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 e649844..d7de48a 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
@@ -85,7 +85,7 @@
 
     // Currently, this method is used only for testing. You may want to consider creating new
     // dedicated method instead of this if you want to use this in the production.
-    virtual void getProperty(const char *const query, char *const outResult,
+    virtual void getProperty(const char *const query, const int queryLength, char *const outResult,
             const int maxResultLength) = 0;
 
  protected:
diff --git a/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.cpp
index 8bbbacd..628d3ab 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.cpp
@@ -52,6 +52,9 @@
                 false /* hasNext */, newTargetTerminalId, &writingPos)) {
             return false;
         }
+        if (outAddedNewEntry) {
+            *outAddedNewEntry = true;
+        }
         return true;
     }
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h
index 5d99632..f8644c0 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h
@@ -112,7 +112,7 @@
         return false;
     }
 
-    void getProperty(const char *const query, char *const outResult,
+    void getProperty(const char *const query, const int queryLength, char *const outResult,
             const int maxResultLength) {
         // getProperty is not supported for this class.
         if (maxResultLength > 0) {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_policy.cpp
index b25589c..d4fb937 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_policy.cpp
@@ -34,7 +34,7 @@
 
 namespace latinime {
 
-// Note that these are corresponding definitions in Java side in BinaryDictionaryTests and
+// Note that there are corresponding definitions in Java side in BinaryDictionaryTests and
 // BinaryDictionaryDecayingTests.
 const char *const DynamicPatriciaTriePolicy::UNIGRAM_COUNT_QUERY = "UNIGRAM_COUNT";
 const char *const DynamicPatriciaTriePolicy::BIGRAM_COUNT_QUERY = "BIGRAM_COUNT";
@@ -277,21 +277,22 @@
     return false;
 }
 
-void DynamicPatriciaTriePolicy::getProperty(const char *const query, char *const outResult,
-        const int maxResultLength) {
-    if (strncmp(query, UNIGRAM_COUNT_QUERY, maxResultLength) == 0) {
+void DynamicPatriciaTriePolicy::getProperty(const char *const query, const int queryLength,
+        char *const outResult, const int maxResultLength) {
+    const int compareLength = queryLength + 1 /* terminator */;
+    if (strncmp(query, UNIGRAM_COUNT_QUERY, compareLength) == 0) {
         snprintf(outResult, maxResultLength, "%d", mUnigramCount);
-    } else if (strncmp(query, BIGRAM_COUNT_QUERY, maxResultLength) == 0) {
+    } else if (strncmp(query, BIGRAM_COUNT_QUERY, compareLength) == 0) {
         snprintf(outResult, maxResultLength, "%d", mBigramCount);
-    } else if (strncmp(query, MAX_UNIGRAM_COUNT_QUERY, maxResultLength) == 0) {
+    } else if (strncmp(query, MAX_UNIGRAM_COUNT_QUERY, compareLength) == 0) {
         snprintf(outResult, maxResultLength, "%d",
                 mHeaderPolicy.isDecayingDict() ? ForgettingCurveUtils::MAX_UNIGRAM_COUNT :
                         static_cast<int>(DynamicPatriciaTrieWritingHelper::MAX_DICTIONARY_SIZE));
-    } else if (strncmp(query, MAX_BIGRAM_COUNT_QUERY, maxResultLength) == 0) {
+    } else if (strncmp(query, MAX_BIGRAM_COUNT_QUERY, compareLength) == 0) {
         snprintf(outResult, maxResultLength, "%d",
                 mHeaderPolicy.isDecayingDict() ? ForgettingCurveUtils::MAX_BIGRAM_COUNT :
                         static_cast<int>(DynamicPatriciaTrieWritingHelper::MAX_DICTIONARY_SIZE));
-    } else if (strncmp(query, SET_NEEDS_TO_DECAY_FOR_TESTING_QUERY, maxResultLength) == 0) {
+    } else if (strncmp(query, SET_NEEDS_TO_DECAY_FOR_TESTING_QUERY, compareLength) == 0) {
         mNeedsToDecayForTesting = true;
     }
 }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_policy.h
index 4546984..636c9bf 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_policy.h
@@ -103,7 +103,7 @@
 
     bool needsToRunGC(const bool mindsBlockByGC) const;
 
-    void getProperty(const char *const query, char *const outResult,
+    void getProperty(const char *const query, const int queryLength, char *const outResult,
             const int maxResultLength);
 
  private:
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.cpp
index c22b9b4..9066876 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.cpp
@@ -72,4 +72,66 @@
     return true;
 }
 
+bool BigramDictContent::runGC(const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
+        const BigramDictContent *const originalBigramDictContent,
+        int *const outBigramEntryCount) {
+    for (TerminalPositionLookupTable::TerminalIdMap::const_iterator it = terminalIdMap->begin();
+            it != terminalIdMap->end(); ++it) {
+        const int originalBigramListPos =
+                originalBigramDictContent->getBigramListHeadPos(it->first);
+        if (originalBigramListPos == NOT_A_DICT_POS) {
+            // This terminal does not have a bigram list.
+            continue;
+        }
+        const int bigramListPos = getContentBuffer()->getTailPosition();
+        int bigramEntryCount = 0;
+        // Copy bigram list with GC from original content.
+        if (!runGCBigramList(originalBigramListPos, originalBigramDictContent, bigramListPos,
+                terminalIdMap, &bigramEntryCount)) {
+            return false;
+        }
+        if (bigramEntryCount == 0) {
+            // All bigram entries are useless. This terminal does not have a bigram list.
+            continue;
+        }
+        *outBigramEntryCount += bigramEntryCount;
+        // Set bigram list position to the lookup table.
+        if (!getUpdatableAddressLookupTable()->set(it->second, bigramListPos)) {
+            return false;
+        }
+    }
+    return true;
+}
+
+bool BigramDictContent::runGCBigramList(const int bigramListPos,
+        const BigramDictContent *const sourceBigramDictContent, const int toPos,
+        const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
+        int *const outEntrycount) {
+    bool hasNext = true;
+    int readingPos = bigramListPos;
+    int writingPos = toPos;
+    while (hasNext) {
+        int probability = NOT_A_PROBABILITY;
+        int targetTerminalId = Ver4DictConstants::NOT_A_TERMINAL_ID;
+        sourceBigramDictContent->getBigramEntryAndAdvancePosition(&probability, &hasNext,
+                &targetTerminalId, &readingPos);
+        if (targetTerminalId == Ver4DictConstants::NOT_A_TERMINAL_ID) {
+            continue;
+        }
+        TerminalPositionLookupTable::TerminalIdMap::const_iterator it =
+                terminalIdMap->find(targetTerminalId);
+        if (it == terminalIdMap->end()) {
+            AKLOGE("terminal Id %d is not in the terminal position map. map size: %zd",
+                    targetTerminalId, terminalIdMap->size());
+            return false;
+        }
+        if (!writeBigramEntryAndAdvancePosition(probability, hasNext, it->second,
+                &writingPos)) {
+            return false;
+        }
+        *outEntrycount += 1;
+    }
+    return true;
+}
+
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.h
index c5410b8..ec0d756 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.h
@@ -19,6 +19,7 @@
 
 #include "defines.h"
 #include "suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.h"
+#include "suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.h"
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h"
 
 namespace latinime {
@@ -65,6 +66,10 @@
                 Ver4DictConstants::BIGRAM_FILE_EXTENSION);
     }
 
+    bool runGC(const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
+            const BigramDictContent *const originalBigramDictContent,
+            int *const outBigramEntryCount);
+
  private:
     DISALLOW_COPY_AND_ASSIGN(BigramDictContent);
 
@@ -72,6 +77,11 @@
         return (probability & Ver4DictConstants::BIGRAM_PROBABILITY_MASK)
                 | (hasNext ? Ver4DictConstants::BIGRAM_HAS_NEXT_MASK : 0);
     }
+
+    bool runGCBigramList(const int bigramListPos,
+            const BigramDictContent *const sourceBigramDictContent, const int toPos,
+            const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
+            int *const outEntryCount);
 };
 } // namespace latinime
 #endif /* LATINIME_BIGRAM_DICT_CONTENT_H */
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.h
index 73a472a..0958dd1 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.h
@@ -19,6 +19,7 @@
 
 #include "defines.h"
 #include "suggest/policyimpl/dictionary/structure/v4/content/single_dict_content.h"
+#include "suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.h"
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h"
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_reading_utils.h"
 #include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
@@ -28,13 +29,14 @@
 class ProbabilityDictContent : public SingleDictContent {
  public:
     ProbabilityDictContent(const char *const dictDirPath, const bool isUpdatable)
-            : SingleDictContent(dictDirPath, Ver4DictConstants::FREQ_FILE_EXTENSION,
-                    isUpdatable) {}
+            : SingleDictContent(dictDirPath, Ver4DictConstants::FREQ_FILE_EXTENSION, isUpdatable),
+              mSize(getBuffer()->getTailPosition() / (Ver4DictConstants::PROBABILITY_SIZE
+                      + Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE)) {}
 
-    ProbabilityDictContent() {}
+    ProbabilityDictContent() : mSize(0) {}
 
     int getProbability(const int terminalId) const {
-        if (terminalId < 0 || terminalId >= getSize()) {
+        if (terminalId < 0 || terminalId >= mSize) {
             return NOT_A_PROBABILITY;
         }
         return Ver4PatriciaTrieReadingUtils::getProbability(getBuffer(), terminalId);
@@ -44,7 +46,7 @@
         if (terminalId < 0) {
             return false;
         }
-        if (terminalId >= getSize()) {
+        if (terminalId >= mSize) {
             // Write new entry.
             int writingPos = getBuffer()->getTailPosition();
             while (writingPos <= getEntryPos(terminalId)) {
@@ -58,6 +60,7 @@
                         Ver4DictConstants::PROBABILITY_SIZE, &writingPos)) {
                     return false;
                 }
+                mSize++;
             }
         }
         const int probabilityWritingPos = getEntryPos(terminalId)
@@ -67,7 +70,32 @@
     }
 
     bool flushToFile(const char *const dictDirPath) const {
-        return flush(dictDirPath, Ver4DictConstants::FREQ_FILE_EXTENSION);
+        if (getEntryPos(mSize) < getBuffer()->getTailPosition()) {
+            ProbabilityDictContent probabilityDictContentToWrite;
+            for (int i = 0; i < mSize; ++i) {
+                if (!probabilityDictContentToWrite.setProbability(i, getProbability(i))) {
+                    return false;
+                }
+            }
+            return probabilityDictContentToWrite.flush(dictDirPath,
+                    Ver4DictConstants::FREQ_FILE_EXTENSION);
+        } else {
+            return flush(dictDirPath, Ver4DictConstants::FREQ_FILE_EXTENSION);
+        }
+    }
+
+    bool runGC(const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
+            const ProbabilityDictContent *const originalProbabilityDictContent) {
+        mSize = 0;
+        for (TerminalPositionLookupTable::TerminalIdMap::const_iterator it = terminalIdMap->begin();
+                it != terminalIdMap->end(); ++it) {
+            if (!setProbability(it->second,
+                    originalProbabilityDictContent->getProbability(it->first))) {
+                return false;
+            }
+            mSize++;
+        }
+        return true;
     }
 
  private:
@@ -78,10 +106,7 @@
                 + Ver4DictConstants::PROBABILITY_SIZE);
     }
 
-    int getSize() const {
-        return getBuffer()->getTailPosition() / (Ver4DictConstants::PROBABILITY_SIZE
-                + Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE);
-    }
+    int mSize;
 };
 } // namespace latinime
 #endif /* LATINIME_PROBABILITY_DICT_CONTENT_H */
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp
index f09bd44..14eff67 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp
@@ -48,6 +48,30 @@
             Ver4DictConstants::SHORTCUT_FILE_EXTENSION);
 }
 
+bool ShortcutDictContent::runGC(
+        const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
+        const ShortcutDictContent *const originalShortcutDictContent) {
+   for (TerminalPositionLookupTable::TerminalIdMap::const_iterator it = terminalIdMap->begin();
+           it != terminalIdMap->end(); ++it) {
+       const int originalShortcutListPos =
+               originalShortcutDictContent->getShortcutListHeadPos(it->first);
+       if (originalShortcutListPos == NOT_A_DICT_POS) {
+           continue;
+       }
+       const int shortcutListPos = getContentBuffer()->getTailPosition();
+       // Copy shortcut list with GC from original content.
+       if (!copyShortcutList(originalShortcutListPos, originalShortcutDictContent,
+               shortcutListPos)) {
+           return false;
+       }
+       // Set shortcut list position to the lookup table.
+       if (!getUpdatableAddressLookupTable()->set(it->second, shortcutListPos)) {
+           return false;
+       }
+   }
+   return true;
+}
+
 bool ShortcutDictContent::copyShortcutList(const int shortcutListPos,
         const ShortcutDictContent *const sourceShortcutDictContent, const int toPos) {
     bool hasNext = true;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.h
index 71a8f6b..902016a 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.h
@@ -47,6 +47,9 @@
 
    bool flushToFile(const char *const dictDirPath) const;
 
+   bool runGC(const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
+           const ShortcutDictContent *const originalShortcutDictContent);
+
  private:
     DISALLOW_COPY_AND_ASSIGN(ShortcutDictContent);
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.cpp
index 1c5caa1..c654206 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.cpp
@@ -18,22 +18,6 @@
 
 namespace latinime {
 
-bool SparseTableDictContent::copyContent(
-        const SparseTableDictContent *const sparseTableDictContent) {
-    if (!mExpandableLookupTableBuffer.copy(
-            &sparseTableDictContent->mExpandableLookupTableBuffer)) {
-        return false;
-    }
-    if (!mExpandableAddressTableBuffer.copy(
-            &sparseTableDictContent->mExpandableAddressTableBuffer)) {
-        return false;
-    }
-    if (!mExpandableContentBuffer.copy(&sparseTableDictContent->mExpandableContentBuffer)) {
-        return false;
-    }
-    return true;
-}
-
 bool SparseTableDictContent::flush(const char *const dictDirPath,
         const char *const lookupTableFileName, const char *const addressTableFileName,
         const char *const contentFileName) const {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.h
index 1515687..9a4f1e1 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.h
@@ -75,8 +75,6 @@
                 || mExpandableContentBuffer.isNearSizeLimit();
     }
 
-    bool copyContent(const SparseTableDictContent *const sparseTableDictContent);
-
  protected:
     SparseTable *getUpdatableAddressLookupTable() {
         return &mAddressLookupTable;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.cpp
index 0717925..e8a3142 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.cpp
@@ -126,6 +126,12 @@
             newChildrenPosition, &childrenPosFieldPos);
 }
 
+bool Ver4PatriciaTrieNodeWriter::updateTerminalId(const PtNodeParams *const toBeUpdatedPtNodeParams,
+        const int newTerminalId) {
+    return mTrieBuffer->writeUint(newTerminalId, Ver4DictConstants::TERMINAL_ID_FIELD_SIZE,
+            toBeUpdatedPtNodeParams->getTerminalIdFieldPos());
+}
+
 bool Ver4PatriciaTrieNodeWriter::writePtNodeAndAdvancePosition(
         const PtNodeParams *const ptNodeParams, int *const ptNodeWritingPos) {
     const int nodePos = *ptNodeWritingPos;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.h
index 23e54cc..1245152 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.h
@@ -57,6 +57,9 @@
     virtual bool updateChildrenPosition(const PtNodeParams *const toBeUpdatedPtNodeParams,
             const int newChildrenPosition);
 
+    bool updateTerminalId(const PtNodeParams *const toBeUpdatedPtNodeParams,
+            const int newTerminalId);
+
     virtual bool writePtNodeAndAdvancePosition(const PtNodeParams *const ptNodeParams,
             int *const ptNodeWritingPos);
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
index eeab312..7c4025a 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
@@ -25,6 +25,14 @@
 
 namespace latinime {
 
+// Note that there are corresponding definitions in Java side in BinaryDictionaryTests and
+// BinaryDictionaryDecayingTests.
+const char *const Ver4PatriciaTriePolicy::UNIGRAM_COUNT_QUERY = "UNIGRAM_COUNT";
+const char *const Ver4PatriciaTriePolicy::BIGRAM_COUNT_QUERY = "BIGRAM_COUNT";
+const char *const Ver4PatriciaTriePolicy::MAX_UNIGRAM_COUNT_QUERY = "MAX_UNIGRAM_COUNT";
+const char *const Ver4PatriciaTriePolicy::MAX_BIGRAM_COUNT_QUERY = "MAX_BIGRAM_COUNT";
+const char *const Ver4PatriciaTriePolicy::SET_NEEDS_TO_DECAY_FOR_TESTING_QUERY =
+        "SET_NEEDS_TO_DECAY_FOR_TESTING";
 const int Ver4PatriciaTriePolicy::MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS = 1024;
 const int Ver4PatriciaTriePolicy::MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS =
         Ver4DictConstants::MAX_DICTIONARY_SIZE - MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS;
@@ -257,9 +265,24 @@
     return false;
 }
 
-void Ver4PatriciaTriePolicy::getProperty(const char *const query, char *const outResult,
-        const int maxResultLength) {
-    // TODO: Implement.
+void Ver4PatriciaTriePolicy::getProperty(const char *const query, const int queryLength,
+        char *const outResult, const int maxResultLength) {
+    const int compareLength = queryLength + 1 /* terminator */;
+    if (strncmp(query, UNIGRAM_COUNT_QUERY, compareLength) == 0) {
+        snprintf(outResult, maxResultLength, "%d", mUnigramCount);
+    } else if (strncmp(query, BIGRAM_COUNT_QUERY, compareLength) == 0) {
+        snprintf(outResult, maxResultLength, "%d", mBigramCount);
+    } else if (strncmp(query, MAX_UNIGRAM_COUNT_QUERY, compareLength) == 0) {
+        snprintf(outResult, maxResultLength, "%d",
+                mHeaderPolicy.isDecayingDict() ? ForgettingCurveUtils::MAX_UNIGRAM_COUNT :
+                        static_cast<int>(Ver4DictConstants::MAX_DICTIONARY_SIZE));
+    } else if (strncmp(query, MAX_BIGRAM_COUNT_QUERY, compareLength) == 0) {
+        snprintf(outResult, maxResultLength, "%d",
+                mHeaderPolicy.isDecayingDict() ? ForgettingCurveUtils::MAX_BIGRAM_COUNT :
+                        static_cast<int>(Ver4DictConstants::MAX_DICTIONARY_SIZE));
+    } else if (strncmp(query, SET_NEEDS_TO_DECAY_FOR_TESTING_QUERY, compareLength) == 0) {
+        mNeedsToDecayForTesting = true;
+    }
 }
 
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
index 4d35caf..6fe978d 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
@@ -103,12 +103,17 @@
 
     bool needsToRunGC(const bool mindsBlockByGC) const;
 
-    void getProperty(const char *const query, char *const outResult,
+    void getProperty(const char *const query, const int queryLength, char *const outResult,
             const int maxResultLength);
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(Ver4PatriciaTriePolicy);
 
+    static const char *const UNIGRAM_COUNT_QUERY;
+    static const char *const BIGRAM_COUNT_QUERY;
+    static const char *const MAX_UNIGRAM_COUNT_QUERY;
+    static const char *const MAX_BIGRAM_COUNT_QUERY;
+    static const char *const SET_NEEDS_TO_DECAY_FOR_TESTING_QUERY;
     // When the dictionary size is near the maximum size, we have to refuse dynamic operations to
     // prevent the dictionary from overflowing.
     static const int MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
index 11adf2c..f141d52 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
@@ -20,7 +20,6 @@
 
 #include "suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.h"
 #include "suggest/policyimpl/dictionary/header/header_policy.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.h"
 #include "suggest/policyimpl/dictionary/shortcut/ver4_shortcut_list_policy.h"
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.h"
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h"
@@ -141,15 +140,6 @@
     Ver4PatriciaTrieNodeWriter newPtNodeWriter(buffersToWrite->getWritableTrieBuffer(),
             buffersToWrite, &newPtNodeReader, &newBigramPolicy, &newShortcutPolicy);
 
-    if(!buffersToWrite->getUpdatableBigramDictContent()->copyContent(
-            mBuffers->getBigramDictContent())) {
-        return false;
-    }
-    if(!buffersToWrite->getUpdatableShortcutDictContent()->copyContent(
-            mBuffers->getShortcutDictContent())) {
-        return false;
-    }
-
     DynamicPatriciaTrieReadingHelper newDictReadingHelper(buffersToWrite->getTrieBuffer(),
             &newPtNodeReader);
     newDictReadingHelper.initWithPtNodeArrayPos(rootPtNodeArrayPos);
@@ -160,11 +150,50 @@
         return false;
     }
 
-    // TODO: GC for dict contents.
-
+    // Re-assign terminal IDs for valid terminal PtNodes.
+    TerminalPositionLookupTable::TerminalIdMap terminalIdMap;
+    if(!buffersToWrite->getUpdatableTerminalPositionLookupTable()->runGCTerminalIds(
+            &terminalIdMap)) {
+        return false;
+    }
+    TraversePolicyToUpdateAllTerminalIds traversePolicyToUpdateAllTerminalIds(&newPtNodeWriter,
+            &terminalIdMap);
+    if (!newDictReadingHelper.traverseAllPtNodesInPostorderDepthFirstManner(
+            &traversePolicyToUpdateAllTerminalIds)) {
+        return false;
+    }
+    // Run GC for probability dict content.
+    if (!buffersToWrite->getUpdatableProbabilityDictContent()->runGC(&terminalIdMap,
+            mBuffers->getProbabilityDictContent())) {
+        return false;
+    }
+    // Run GC for bigram dict content.
+    if(!buffersToWrite->getUpdatableBigramDictContent()->runGC(&terminalIdMap,
+            mBuffers->getBigramDictContent(), outBigramCount)) {
+        return false;
+    }
+    // Run GC for shortcut dict content.
+    if(!buffersToWrite->getUpdatableShortcutDictContent()->runGC(&terminalIdMap,
+            mBuffers->getShortcutDictContent())) {
+        return false;
+    }
     *outUnigramCount = traversePolicyToUpdateAllPositionFields.getUnigramCount();
-    *outBigramCount = traversePolicyToUpdateAllPositionFields.getBigramCount();
     return true;
 }
 
+bool Ver4PatriciaTrieWritingHelper::TraversePolicyToUpdateAllTerminalIds::onVisitingPtNode(
+        const PtNodeParams *const ptNodeParams) {
+    if (!ptNodeParams->isTerminal()) {
+        return true;
+    }
+    TerminalPositionLookupTable::TerminalIdMap::const_iterator it =
+            mTerminalIdMap->find(ptNodeParams->getTerminalId());
+    if (it == mTerminalIdMap->end()) {
+        AKLOGE("terminal Id %d is not in the terminal position map. map size: %zd",
+                ptNodeParams->getTerminalId(), mTerminalIdMap->size());
+        return false;
+    }
+    return mPtNodeWriter->updateTerminalId(ptNodeParams, it->second);
+}
+
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h
index 8072aa3..ea2fd53 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h
@@ -18,11 +18,14 @@
 #define LATINIME_VER4_PATRICIA_TRIE_WRITING_HELPER_H
 
 #include "defines.h"
+#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.h"
+#include "suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.h"
 
 namespace latinime {
 
 class HeaderPolicy;
 class Ver4DictBuffers;
+class Ver4PatriciaTrieNodeWriter;
 
 class Ver4PatriciaTrieWritingHelper {
  public:
@@ -39,6 +42,28 @@
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(Ver4PatriciaTrieWritingHelper);
 
+    class TraversePolicyToUpdateAllTerminalIds
+            : public DynamicPatriciaTrieReadingHelper::TraversingEventListener {
+     public:
+          TraversePolicyToUpdateAllTerminalIds(Ver4PatriciaTrieNodeWriter *const ptNodeWriter,
+                const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap)
+                : mPtNodeWriter(ptNodeWriter), mTerminalIdMap(terminalIdMap) {};
+
+        bool onAscend() { return true; }
+
+        bool onDescend(const int ptNodeArrayPos) { return true; }
+
+        bool onReadingPtNodeArrayTail() { return true; }
+
+        bool onVisitingPtNode(const PtNodeParams *const ptNodeParams);
+
+     private:
+        DISALLOW_IMPLICIT_CONSTRUCTORS(TraversePolicyToUpdateAllTerminalIds);
+
+        Ver4PatriciaTrieNodeWriter *const mPtNodeWriter;
+        const TerminalPositionLookupTable::TerminalIdMap *const mTerminalIdMap;
+    };
+
     bool runGC(const int rootPtNodeArrayPos, const HeaderPolicy *const headerPolicy,
             Ver4DictBuffers *const buffersToWrite, int *const outUnigramCount,
             int *const outBigramCount, const bool needsToDecay);