diff --git a/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp b/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
index 5fc20ea..81997b7 100644
--- a/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
+++ b/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
@@ -291,7 +291,7 @@
     if (shortcutTarget) {
         env->GetIntArrayRegion(shortcutTarget, 0, shortcutLength, shortcutTargetCodePoints);
     }
-    dictionary->addUnigramWord(codePoints, wordLength, probability);
+    dictionary->addUnigramWord(codePoints, wordLength, probability, timeStamp);
 }
 
 static void latinime_BinaryDictionary_addBigramWords(JNIEnv *env, jclass clazz, jlong dict,
@@ -307,7 +307,7 @@
     int word1CodePoints[word1Length];
     env->GetIntArrayRegion(word1, 0, word1Length, word1CodePoints);
     dictionary->addBigramWords(word0CodePoints, word0Length, word1CodePoints,
-            word1Length, probability);
+            word1Length, probability, timeStamp);
 }
 
 static void latinime_BinaryDictionary_removeBigramWords(JNIEnv *env, jclass clazz, jlong dict,
@@ -342,13 +342,15 @@
     jclass languageModelParamClass = env->GetObjectClass(languageModelParam);
     env->DeleteLocalRef(languageModelParam);
 
-    // TODO: Support shortcut, timestamp and flags.
+    // TODO: Support shortcut and flags.
     jfieldID word0FieldId = env->GetFieldID(languageModelParamClass, "mWord0", "[I");
     jfieldID word1FieldId = env->GetFieldID(languageModelParamClass, "mWord1", "[I");
     jfieldID unigramProbabilityFieldId =
             env->GetFieldID(languageModelParamClass, "mUnigramProbability", "I");
     jfieldID bigramProbabilityFieldId =
             env->GetFieldID(languageModelParamClass, "mBigramProbability", "I");
+    jfieldID timeStampFieldId =
+            env->GetFieldID(languageModelParamClass, "mTimeStamp", "I");
     env->DeleteLocalRef(languageModelParamClass);
 
     for (int i = startIndex; i < languageModelParamCount; ++i) {
@@ -369,11 +371,12 @@
         int word1CodePoints[word1Length];
         env->GetIntArrayRegion(word1, 0, word1Length, word1CodePoints);
         jint unigramProbability = env->GetIntField(languageModelParam, unigramProbabilityFieldId);
-        dictionary->addUnigramWord(word1CodePoints, word1Length, unigramProbability);
+        jint timeStamp = env->GetIntField(languageModelParam, timeStampFieldId);
+        dictionary->addUnigramWord(word1CodePoints, word1Length, unigramProbability, timeStamp);
         if (word0) {
             jint bigramProbability = env->GetIntField(languageModelParam, bigramProbabilityFieldId);
             dictionary->addBigramWords(word0CodePoints, word0Length, word1CodePoints, word1Length,
-                    bigramProbability);
+                    bigramProbability, timeStamp);
         }
         if (dictionary->needsToRunGC(true /* mindsBlockByGC */)) {
             return i + 1;
diff --git a/native/jni/src/suggest/core/dictionary/dictionary.cpp b/native/jni/src/suggest/core/dictionary/dictionary.cpp
index a990418..f62d06b 100644
--- a/native/jni/src/suggest/core/dictionary/dictionary.cpp
+++ b/native/jni/src/suggest/core/dictionary/dictionary.cpp
@@ -93,14 +93,16 @@
     return mBigramDictionary.get()->getBigramProbability(word0, length0, word1, length1);
 }
 
-void Dictionary::addUnigramWord(const int *const word, const int length, const int probability) {
-    mDictionaryStructureWithBufferPolicy.get()->addUnigramWord(word, length, probability);
+void Dictionary::addUnigramWord(const int *const word, const int length, const int probability,
+        const int timestamp) {
+    mDictionaryStructureWithBufferPolicy.get()->addUnigramWord(word, length, probability,
+            timestamp);
 }
 
 void Dictionary::addBigramWords(const int *const word0, const int length0, const int *const word1,
-        const int length1, const int probability) {
+        const int length1, const int probability, const int timestamp) {
     mDictionaryStructureWithBufferPolicy.get()->addBigramWords(word0, length0, word1, length1,
-            probability);
+            probability, timestamp);
 }
 
 void Dictionary::removeBigramWords(const int *const word0, const int length0,
diff --git a/native/jni/src/suggest/core/dictionary/dictionary.h b/native/jni/src/suggest/core/dictionary/dictionary.h
index 977ad35..8862b2b 100644
--- a/native/jni/src/suggest/core/dictionary/dictionary.h
+++ b/native/jni/src/suggest/core/dictionary/dictionary.h
@@ -71,10 +71,11 @@
 
     int getBigramProbability(const int *word0, int length0, const int *word1, int length1) const;
 
-    void addUnigramWord(const int *const word, const int length, const int probability);
+    void addUnigramWord(const int *const word, const int length, const int probability,
+            const int timestamp);
 
     void addBigramWords(const int *const word0, const int length0, const int *const word1,
-            const int length1, const int probability);
+            const int length1, const int probability, const int timestamp);
 
     void removeBigramWords(const int *const word0, const int length0, const int *const word1,
             const int length1);
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 d7de48a..92debc0 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
@@ -67,11 +67,11 @@
 
     // Returns whether the update was success or not.
     virtual bool addUnigramWord(const int *const word, const int length,
-            const int probability) = 0;
+            const int probability, const int timestamp) = 0;
 
     // Returns whether the update was success or not.
     virtual bool addBigramWords(const int *const word0, const int length0, const int *const word1,
-            const int length1, const int probability) = 0;
+            const int length1, const int probability, const int timestamp) = 0;
 
     // Returns whether the update was success or not.
     virtual bool removeBigramWords(const int *const word0, const int length0,
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 dc2adb4..7160f6f 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
@@ -36,7 +36,7 @@
 }
 
 bool Ver4BigramListPolicy::addNewEntry(const int terminalId, const int newTargetTerminalId,
-        const int newProbability, bool *const outAddedNewEntry) {
+        const int newProbability, const int timestamp, bool *const outAddedNewEntry) {
     if (outAddedNewEntry) {
         *outAddedNewEntry = false;
     }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.h b/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.h
index ed8bdb8..c095911 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.h
@@ -44,7 +44,7 @@
     }
 
     bool addNewEntry(const int terminalId, const int newTargetTerminalId, const int newProbability,
-            bool *const outAddedNewEntry);
+            const int timestamp, bool *const outAddedNewEntry);
 
     bool removeEntry(const int terminalId, const int targetTerminalId);
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp
index eb072fb..d01e7a7 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp
@@ -27,6 +27,9 @@
 const char *const HeaderPolicy::UNIGRAM_COUNT_KEY = "UNIGRAM_COUNT";
 const char *const HeaderPolicy::BIGRAM_COUNT_KEY = "BIGRAM_COUNT";
 const char *const HeaderPolicy::EXTENDED_REGION_SIZE_KEY = "EXTENDED_REGION_SIZE";
+// Historical info is information that is needed to support decaying such as timestamp, level and
+// count.
+const char *const HeaderPolicy::HAS_HISTORICAL_INFO_KEY = "HAS_HISTORICAL_INFO";
 const int HeaderPolicy::DEFAULT_MULTIPLE_WORDS_DEMOTION_RATE = 100;
 const float HeaderPolicy::MULTIPLE_WORD_COST_MULTIPLIER_SCALE = 100.0f;
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h
index 7c06a71..8161249 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h
@@ -47,7 +47,9 @@
               mBigramCount(HeaderReadWriteUtils::readIntAttributeValue(&mAttributeMap,
                       BIGRAM_COUNT_KEY, 0 /* defaultValue */)),
               mExtendedRegionSize(HeaderReadWriteUtils::readIntAttributeValue(&mAttributeMap,
-                      EXTENDED_REGION_SIZE_KEY, 0 /* defaultValue */)) {}
+                      EXTENDED_REGION_SIZE_KEY, 0 /* defaultValue */)),
+              mHasHistoricalInfoOfWords(HeaderReadWriteUtils::readBoolAttributeValue(
+                      &mAttributeMap, HAS_HISTORICAL_INFO_KEY, false /* defaultValue */)) {}
 
     // Constructs header information using an attribute map.
     HeaderPolicy(const FormatUtils::FORMAT_VERSION dictFormatVersion,
@@ -62,7 +64,9 @@
                       LAST_UPDATED_TIME_KEY, time(0) /* defaultValue */)),
               mLastDecayedTime(HeaderReadWriteUtils::readIntAttributeValue(&mAttributeMap,
                       LAST_UPDATED_TIME_KEY, time(0) /* defaultValue */)),
-              mUnigramCount(0), mBigramCount(0), mExtendedRegionSize(0) {}
+              mUnigramCount(0), mBigramCount(0), mExtendedRegionSize(0),
+              mHasHistoricalInfoOfWords(HeaderReadWriteUtils::readBoolAttributeValue(
+                      &mAttributeMap, HAS_HISTORICAL_INFO_KEY, false /* defaultValue */)) {}
 
     ~HeaderPolicy() {}
 
@@ -110,6 +114,10 @@
         return mExtendedRegionSize;
     }
 
+    AK_FORCE_INLINE bool hasHistricalInfoOfWords() const {
+        return mHasHistoricalInfoOfWords;
+    }
+
     void readHeaderValueOrQuestionMark(const char *const key,
             int *outValue, int outValueSize) const;
 
@@ -127,6 +135,7 @@
     static const char *const UNIGRAM_COUNT_KEY;
     static const char *const BIGRAM_COUNT_KEY;
     static const char *const EXTENDED_REGION_SIZE_KEY;
+    static const char *const HAS_HISTORICAL_INFO_KEY;
     static const int DEFAULT_MULTIPLE_WORDS_DEMOTION_RATE;
     static const float MULTIPLE_WORD_COST_MULTIPLIER_SCALE;
 
@@ -141,6 +150,7 @@
     const int mUnigramCount;
     const int mBigramCount;
     const int mExtendedRegionSize;
+    const bool mHasHistoricalInfoOfWords;
 
     float readMultipleWordCostMultiplier() const;
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/pt_common/pt_node_writer.h b/native/jni/src/suggest/policyimpl/dictionary/structure/pt_common/pt_node_writer.h
index 9af5a37..9957387 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/pt_common/pt_node_writer.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/pt_common/pt_node_writer.h
@@ -49,7 +49,7 @@
             const int movedPos, const int bigramLinkedNodePos) = 0;
 
     virtual bool updatePtNodeProbability(const PtNodeParams *const toBeUpdatedPtNodeParams,
-            const int probability) = 0;
+            const int probability, const int timestamp) = 0;
 
     virtual bool updateChildrenPosition(const PtNodeParams *const toBeUpdatedPtNodeParams,
                 const int newChildrenPosition) = 0;
@@ -58,10 +58,10 @@
             int *const ptNodeWritingPos) = 0;
 
     virtual bool writeNewTerminalPtNodeAndAdvancePosition(const PtNodeParams *const ptNodeParams,
-            int *const ptNodeWritingPos) = 0;
+            const int timestamp, int *const ptNodeWritingPos) = 0;
 
     virtual bool addNewBigramEntry(const PtNodeParams *const sourcePtNodeParams,
-            const PtNodeParams *const targetPtNodeParam, const int probability,
+            const PtNodeParams *const targetPtNodeParam, const int probability, const int timestamp,
             bool *const outAddedNewBigram) = 0;
 
     virtual bool removeBigramEntry(const PtNodeParams *const sourcePtNodeParams,
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 f8644c0..6ad848e 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
@@ -76,14 +76,15 @@
         return &mShortcutListPolicy;
     }
 
-    bool addUnigramWord(const int *const word, const int length, const int probability) {
+    bool addUnigramWord(const int *const word, const int length, const int probability,
+            const int timestamp) {
         // This method should not be called for non-updatable dictionary.
         AKLOGI("Warning: addUnigramWord() is called for non-updatable dictionary.");
         return false;
     }
 
     bool addBigramWords(const int *const word0, const int length0, const int *const word1,
-            const int length1, const int probability) {
+            const int length1, const int probability, const int timestamp) {
         // This method should not be called for non-updatable dictionary.
         AKLOGI("Warning: addBigramWords() is called for non-updatable dictionary.");
         return false;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.cpp
index 223933f..22d4f7a 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.cpp
@@ -30,12 +30,14 @@
     // PtNode is useless when the PtNode is not a terminal and doesn't have any not useless
     // children.
     bool isUselessPtNode = !ptNodeParams->isTerminal();
-    if (ptNodeParams->isTerminal() && mIsDecayingDict) {
+    if (ptNodeParams->isTerminal() && mNeedsToDecayWhenUpdating) {
+        // TODO: Avoid decaying probability during GC.
         const int newProbability =
                 ForgettingCurveUtils::getEncodedProbabilityToSave(ptNodeParams->getProbability(),
                         mHeaderPolicy);
         // Update probability.
-        if (!mPtNodeWriter->updatePtNodeProbability(ptNodeParams, newProbability)) {
+        if (!mPtNodeWriter->updatePtNodeProbability(ptNodeParams, newProbability,
+                0 /* timestamp */)) {
             return false;
         }
         if (!ForgettingCurveUtils::isValidEncodedProbability(newProbability)) {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.h
index fe82910..edd6928 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.h
@@ -43,10 +43,10 @@
         TraversePolicyToUpdateUnigramProbabilityAndMarkUselessPtNodesAsDeleted(
                 const DictionaryHeaderStructurePolicy *const headerPolicy,
                 PtNodeWriter *const ptNodeWriter, BufferWithExtendableBuffer *const buffer,
-                const bool isDecayingDict)
+                const bool needsToDecayWhenUpdating)
                 : mHeaderPolicy(headerPolicy), mPtNodeWriter(ptNodeWriter), mBuffer(buffer),
-                  mIsDecayingDict(isDecayingDict), mValueStack(), mChildrenValue(0),
-                  mValidUnigramCount(0) {}
+                  mNeedsToDecayWhenUpdating(needsToDecayWhenUpdating), mValueStack(),
+                  mChildrenValue(0), mValidUnigramCount(0) {}
 
         ~TraversePolicyToUpdateUnigramProbabilityAndMarkUselessPtNodesAsDeleted() {};
 
@@ -80,7 +80,7 @@
         const DictionaryHeaderStructurePolicy *const mHeaderPolicy;
         PtNodeWriter *const mPtNodeWriter;
         BufferWithExtendableBuffer *const mBuffer;
-        const bool mIsDecayingDict;
+        const bool mNeedsToDecayWhenUpdating;
         std::vector<int> mValueStack;
         int mChildrenValue;
         int mValidUnigramCount;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.cpp
index aa200b2..d925a7e 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.cpp
@@ -102,7 +102,8 @@
 }
 
 bool DynamicPatriciaTrieNodeWriter::updatePtNodeProbability(
-        const PtNodeParams *const toBeUpdatedPtNodeParams, const int newProbability) {
+        const PtNodeParams *const toBeUpdatedPtNodeParams, const int newProbability,
+        const int timestamp) {
     if (!toBeUpdatedPtNodeParams->isTerminal()) {
         return false;
     }
@@ -127,7 +128,7 @@
 }
 
 bool DynamicPatriciaTrieNodeWriter::writeNewTerminalPtNodeAndAdvancePosition(
-        const PtNodeParams *const ptNodeParams, int *const ptNodeWritingPos) {
+        const PtNodeParams *const ptNodeParams, const int timestamp, int *const ptNodeWritingPos) {
     int probabilityFieldPos = NOT_A_DICT_POS;
     if (!writePtNodeAndGetProbabilityFieldPosAndAdvancePosition(ptNodeParams, &probabilityFieldPos,
             ptNodeWritingPos)) {
@@ -144,7 +145,7 @@
 
 bool DynamicPatriciaTrieNodeWriter::addNewBigramEntry(
         const PtNodeParams *const sourcePtNodeParams,
-        const PtNodeParams *const targetPtNodeParam, const int probability,
+        const PtNodeParams *const targetPtNodeParam, const int probability, const int timestamp,
         bool *const outAddedNewBigram) {
     const int newNodePos = mBuffer->getTailPosition();
     int writingPos = newNodePos;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.h
index 20b0ca4..b0fec34 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.h
@@ -52,7 +52,7 @@
             const int movedPos, const int bigramLinkedNodePos);
 
     virtual bool updatePtNodeProbability(const PtNodeParams *const toBeUpdatedPtNodeParams,
-            const int newProbability);
+            const int newProbability, const int timestamp);
 
     virtual bool updateChildrenPosition(const PtNodeParams *const toBeUpdatedPtNodeParams,
             const int newChildrenPosition);
@@ -60,11 +60,11 @@
     virtual bool writePtNodeAndAdvancePosition(const PtNodeParams *const ptNodeParams,
             int *const ptNodeWritingPos);
 
-    virtual bool writeNewTerminalPtNodeAndAdvancePosition(
-            const PtNodeParams *const ptNodeParams, int *const ptNodeWritingPos);
+    virtual bool writeNewTerminalPtNodeAndAdvancePosition(const PtNodeParams *const ptNodeParams,
+            const int timestamp, int *const ptNodeWritingPos);
 
     virtual bool addNewBigramEntry(const PtNodeParams *const sourcePtNodeParams,
-            const PtNodeParams *const targetPtNodeParam, const int probability,
+            const PtNodeParams *const targetPtNodeParam, const int probability, const int timestamp,
             bool *const outAddedNewBigram);
 
     virtual bool removeBigramEntry(const PtNodeParams *const sourcePtNodeParams,
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 e80c758..4468754 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
@@ -141,7 +141,7 @@
 }
 
 bool DynamicPatriciaTriePolicy::addUnigramWord(const int *const word, const int length,
-        const int probability) {
+        const int probability, const int timestamp) {
     if (!mMmappedBuffer.get()->isUpdatable()) {
         AKLOGI("Warning: addUnigramWord() is called for non-updatable dictionary.");
         return false;
@@ -154,7 +154,7 @@
     DynamicPatriciaTrieReadingHelper readingHelper(&mBufferWithExtendableBuffer, &mNodeReader);
     readingHelper.initWithPtNodeArrayPos(getRootPosition());
     bool addedNewUnigram = false;
-    if (mUpdatingHelper.addUnigramWord(&readingHelper, word, length, probability,
+    if (mUpdatingHelper.addUnigramWord(&readingHelper, word, length, probability, timestamp,
             &addedNewUnigram)) {
         if (addedNewUnigram) {
             mUnigramCount++;
@@ -166,7 +166,8 @@
 }
 
 bool DynamicPatriciaTriePolicy::addBigramWords(const int *const word0, const int length0,
-        const int *const word1, const int length1, const int probability) {
+        const int *const word1, const int length1, const int probability,
+        const int timestamp) {
     if (!mMmappedBuffer.get()->isUpdatable()) {
         AKLOGI("Warning: addBigramWords() is called for non-updatable dictionary.");
         return false;
@@ -187,7 +188,8 @@
         return false;
     }
     bool addedNewBigram = false;
-    if (mUpdatingHelper.addBigramWords(word0Pos, word1Pos, probability, &addedNewBigram)) {
+    if (mUpdatingHelper.addBigramWords(word0Pos, word1Pos, probability, timestamp,
+            &addedNewBigram)) {
         if (addedNewBigram) {
             mBigramCount++;
         }
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 fec9efc..0b21e57 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
@@ -88,10 +88,11 @@
         return &mShortcutListPolicy;
     }
 
-    bool addUnigramWord(const int *const word, const int length, const int probability);
+    bool addUnigramWord(const int *const word, const int length, const int probability,
+            const int timestamp);
 
     bool addBigramWords(const int *const word0, const int length0, const int *const word1,
-            const int length1, const int probability);
+            const int length1, const int probability, const int timestamp);
 
     bool removeBigramWords(const int *const word0, const int length0, const int *const word1,
             const int length1);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_updating_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_updating_helper.cpp
index e70c0ec..bef45a6 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_updating_helper.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_updating_helper.cpp
@@ -30,7 +30,7 @@
 bool DynamicPatriciaTrieUpdatingHelper::addUnigramWord(
         DynamicPatriciaTrieReadingHelper *const readingHelper,
         const int *const wordCodePoints, const int codePointCount, const int probability,
-        bool *const outAddedNewUnigram) {
+        const int timestamp, bool *const outAddedNewUnigram) {
     int parentPos = NOT_A_DICT_POS;
     while (!readingHelper->isEnd()) {
         const PtNodeParams ptNodeParams(readingHelper->getPtNodeParams());
@@ -52,18 +52,18 @@
             if (nextIndex >= codePointCount || !readingHelper->isMatchedCodePoint(ptNodeParams, j,
                     wordCodePoints[matchedCodePointCount + j])) {
                 *outAddedNewUnigram = true;
-                return reallocatePtNodeAndAddNewPtNodes(&ptNodeParams, j, probability,
+                return reallocatePtNodeAndAddNewPtNodes(&ptNodeParams, j, probability, timestamp,
                         wordCodePoints + matchedCodePointCount,
                         codePointCount - matchedCodePointCount);
             }
         }
         // All characters are matched.
         if (codePointCount == readingHelper->getTotalCodePointCount(ptNodeParams)) {
-            return setPtNodeProbability(&ptNodeParams, probability, outAddedNewUnigram);
+            return setPtNodeProbability(&ptNodeParams, probability, timestamp, outAddedNewUnigram);
         }
         if (!ptNodeParams.hasChildren()) {
             *outAddedNewUnigram = true;
-            return createChildrenPtNodeArrayAndAChildPtNode(&ptNodeParams, probability,
+            return createChildrenPtNodeArrayAndAChildPtNode(&ptNodeParams, probability, timestamp,
                     wordCodePoints + readingHelper->getTotalCodePointCount(ptNodeParams),
                     codePointCount - readingHelper->getTotalCodePointCount(ptNodeParams));
         }
@@ -79,17 +79,18 @@
     *outAddedNewUnigram = true;
     return createAndInsertNodeIntoPtNodeArray(parentPos,
             wordCodePoints + readingHelper->getPrevTotalCodePointCount(),
-            codePointCount - readingHelper->getPrevTotalCodePointCount(), probability, &pos);
+            codePointCount - readingHelper->getPrevTotalCodePointCount(), probability,
+            timestamp, &pos);
 }
 
 bool DynamicPatriciaTrieUpdatingHelper::addBigramWords(const int word0Pos, const int word1Pos,
-        const int probability, bool *const outAddedNewBigram) {
+        const int probability, const int timestamp, bool *const outAddedNewBigram) {
     const PtNodeParams sourcePtNodeParams(
             mPtNodeReader->fetchNodeInfoInBufferFromPtNodePos(word0Pos));
     const PtNodeParams targetPtNodeParams(
             mPtNodeReader->fetchNodeInfoInBufferFromPtNodePos(word1Pos));
     return mPtNodeWriter->addNewBigramEntry(&sourcePtNodeParams, &targetPtNodeParams, probability,
-            outAddedNewBigram);
+            timestamp, outAddedNewBigram);
 }
 
 // Remove a bigram relation from word0Pos to word1Pos.
@@ -103,23 +104,23 @@
 
 bool DynamicPatriciaTrieUpdatingHelper::createAndInsertNodeIntoPtNodeArray(const int parentPos,
         const int *const nodeCodePoints, const int nodeCodePointCount, const int probability,
-        int *const forwardLinkFieldPos) {
+        const int timestamp, int *const forwardLinkFieldPos) {
     const int newPtNodeArrayPos = mBuffer->getTailPosition();
     if (!DynamicPatriciaTrieWritingUtils::writeForwardLinkPositionAndAdvancePosition(mBuffer,
             newPtNodeArrayPos, forwardLinkFieldPos)) {
         return false;
     }
     return createNewPtNodeArrayWithAChildPtNode(parentPos, nodeCodePoints, nodeCodePointCount,
-            probability);
+            probability, timestamp);
 }
 
 bool DynamicPatriciaTrieUpdatingHelper::setPtNodeProbability(
-        const PtNodeParams *const originalPtNodeParams, const int probability,
+        const PtNodeParams *const originalPtNodeParams, const int probability, const int timestamp,
         bool *const outAddedNewUnigram) {
     if (originalPtNodeParams->isTerminal()) {
         // Overwrites the probability.
         *outAddedNewUnigram = false;
-        return mPtNodeWriter->updatePtNodeProbability(originalPtNodeParams, probability);
+        return mPtNodeWriter->updatePtNodeProbability(originalPtNodeParams, probability, timestamp);
     } else {
         // Make the node terminal and write the probability.
         *outAddedNewUnigram = true;
@@ -130,7 +131,7 @@
                 originalPtNodeParams->getCodePointCount(), originalPtNodeParams->getCodePoints(),
                 probability));
         if (!mPtNodeWriter->writeNewTerminalPtNodeAndAdvancePosition(&ptNodeParamsToWrite,
-                &writingPos)) {
+                timestamp, &writingPos)) {
             return false;
         }
         if (!mPtNodeWriter->markPtNodeAsMoved(originalPtNodeParams, movedPos, movedPos)) {
@@ -141,19 +142,19 @@
 }
 
 bool DynamicPatriciaTrieUpdatingHelper::createChildrenPtNodeArrayAndAChildPtNode(
-        const PtNodeParams *const parentPtNodeParams, const int probability,
+        const PtNodeParams *const parentPtNodeParams, const int probability, const int timestamp,
         const int *const codePoints, const int codePointCount) {
     const int newPtNodeArrayPos = mBuffer->getTailPosition();
     if (!mPtNodeWriter->updateChildrenPosition(parentPtNodeParams, newPtNodeArrayPos)) {
         return false;
     }
     return createNewPtNodeArrayWithAChildPtNode(parentPtNodeParams->getHeadPos(), codePoints,
-            codePointCount, probability);
+            codePointCount, probability, timestamp);
 }
 
 bool DynamicPatriciaTrieUpdatingHelper::createNewPtNodeArrayWithAChildPtNode(
         const int parentPtNodePos, const int *const nodeCodePoints, const int nodeCodePointCount,
-        const int probability) {
+        const int probability, const int timestamp) {
     int writingPos = mBuffer->getTailPosition();
     if (!DynamicPatriciaTrieWritingUtils::writePtNodeArraySizeAndAdvancePosition(mBuffer,
             1 /* arraySize */, &writingPos)) {
@@ -161,7 +162,7 @@
     }
     const PtNodeParams ptNodeParamsToWrite(getPtNodeParamsForNewPtNode(true /* isTerminal */,
             parentPtNodePos, nodeCodePointCount, nodeCodePoints, probability));
-    if (!mPtNodeWriter->writeNewTerminalPtNodeAndAdvancePosition(&ptNodeParamsToWrite,
+    if (!mPtNodeWriter->writeNewTerminalPtNodeAndAdvancePosition(&ptNodeParamsToWrite, timestamp,
             &writingPos)) {
         return false;
     }
@@ -175,7 +176,7 @@
 // Returns whether the dictionary updating was succeeded or not.
 bool DynamicPatriciaTrieUpdatingHelper::reallocatePtNodeAndAddNewPtNodes(
         const PtNodeParams *const reallocatingPtNodeParams, const int overlappingCodePointCount,
-        const int probabilityOfNewPtNode, const int *const newNodeCodePoints,
+        const int probabilityOfNewPtNode, const int timestamp, const int *const newNodeCodePoints,
         const int newNodeCodePointCount) {
     // When addsExtraChild is true, split the reallocating PtNode and add new child.
     // Reallocating PtNode: abcde, newNode: abcxy.
@@ -201,7 +202,7 @@
                 reallocatingPtNodeParams->getParentPos(), overlappingCodePointCount,
                 reallocatingPtNodeParams->getCodePoints(), probabilityOfNewPtNode));
         if (!mPtNodeWriter->writeNewTerminalPtNodeAndAdvancePosition(&ptNodeParamsToWrite,
-                &writingPos)) {
+                timestamp, &writingPos)) {
             return false;
         }
     }
@@ -227,7 +228,7 @@
                 firstPartOfReallocatedPtNodePos, newNodeCodePointCount - overlappingCodePointCount,
                 newNodeCodePoints + overlappingCodePointCount, probabilityOfNewPtNode));
         if (!mPtNodeWriter->writeNewTerminalPtNodeAndAdvancePosition(&extraChildPtNodeParams,
-                &writingPos)) {
+                timestamp, &writingPos)) {
             return false;
         }
     }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_updating_helper.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_updating_helper.h
index cc51d4b..56d1e36 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_updating_helper.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_updating_helper.h
@@ -42,11 +42,11 @@
     // Add a word to the dictionary. If the word already exists, update the probability.
     bool addUnigramWord(DynamicPatriciaTrieReadingHelper *const readingHelper,
             const int *const wordCodePoints, const int codePointCount, const int probability,
-            bool *const outAddedNewUnigram);
+            const int timestamp, bool *const outAddedNewUnigram);
 
     // Add a bigram relation from word0Pos to word1Pos.
     bool addBigramWords(const int word0Pos, const int word1Pos, const int probability,
-            bool *const outAddedNewBigram);
+            const int timestamp, bool *const outAddedNewBigram);
 
     // Remove a bigram relation from word0Pos to word1Pos.
     bool removeBigramWords(const int word0Pos, const int word1Pos);
@@ -61,21 +61,23 @@
     PtNodeWriter *const mPtNodeWriter;
 
     bool createAndInsertNodeIntoPtNodeArray(const int parentPos, const int *const nodeCodePoints,
-            const int nodeCodePointCount, const int probability, int *const forwardLinkFieldPos);
+            const int nodeCodePointCount, const int probability, const int timestamp,
+            int *const forwardLinkFieldPos);
 
     bool setPtNodeProbability(const PtNodeParams *const originalPtNodeParams, const int probability,
-            bool *const outAddedNewUnigram);
+            const int timestamp, bool *const outAddedNewUnigram);
 
     bool createChildrenPtNodeArrayAndAChildPtNode(const PtNodeParams *const parentPtNodeParams,
-            const int probability, const int *const codePoints, const int codePointCount);
+            const int probability, const int timestamp, const int *const codePoints,
+            const int codePointCount);
 
     bool createNewPtNodeArrayWithAChildPtNode(const int parentPos, const int *const nodeCodePoints,
-            const int nodeCodePointCount, const int probability);
+            const int nodeCodePointCount, const int probability, const int timestamp);
 
     bool reallocatePtNodeAndAddNewPtNodes(
             const PtNodeParams *const reallocatingPtNodeParams, const int overlappingCodePointCount,
-            const int probabilityOfNewPtNode, const int *const newNodeCodePoints,
-            const int newNodeCodePointCount);
+            const int probabilityOfNewPtNode, const int timestamp,
+            const int *const newNodeCodePoints, const int newNodeCodePointCount);
 
     const PtNodeParams getUpdatedPtNodeParams(const PtNodeParams *const originalPtNodeParams,
             const bool isTerminal, const int parentPos, const int codePointCount,
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.cpp
index eab344e..6019d76 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.cpp
@@ -28,7 +28,9 @@
     if (terminalId < 0 || terminalId >= mSize) {
         return NOT_A_PROBABILITY;
     }
-    return Ver4PatriciaTrieReadingUtils::getProbability(getBuffer(), terminalId);
+    const int probabilityFieldPos =
+            getEntryPos(terminalId) + Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE;
+    return getBuffer()->readUint(Ver4DictConstants::PROBABILITY_SIZE, probabilityFieldPos);
 }
 
 bool ProbabilityDictContent::setProbability(const int terminalId, const int probability) {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.cpp
index a27d0bc..3632151 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.cpp
@@ -38,11 +38,13 @@
 const int Ver4DictConstants::MAX_DICT_EXTENDED_REGION_SIZE = 1 * 1024 * 1024;
 
 const int Ver4DictConstants::NOT_A_TERMINAL_ID = -1;
+const int Ver4DictConstants::NOT_A_TIME_STAMP = -1;
 const int Ver4DictConstants::PROBABILITY_SIZE = 1;
 const int Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE = 1;
 const int Ver4DictConstants::TERMINAL_ADDRESS_TABLE_ADDRESS_SIZE = 3;
 const int Ver4DictConstants::NOT_A_TERMINAL_ADDRESS = 0;
 const int Ver4DictConstants::TERMINAL_ID_FIELD_SIZE = 4;
+const int Ver4DictConstants::TIME_STAMP_FIELD_SIZE = 4;
 
 const int Ver4DictConstants::BIGRAM_ADDRESS_TABLE_BLOCK_SIZE = 4;
 const int Ver4DictConstants::BIGRAM_ADDRESS_TABLE_DATA_SIZE = 4;
@@ -57,6 +59,7 @@
 const int Ver4DictConstants::BIGRAM_FLAGS_FIELD_SIZE = 1;
 const int Ver4DictConstants::BIGRAM_PROBABILITY_MASK = 0x0F;
 const int Ver4DictConstants::BIGRAM_HAS_NEXT_MASK = 0x80;
+const int Ver4DictConstants::BIGRAM_LARGE_PROBABILITY_FIELD_SIZE = 1;
 
 const int Ver4DictConstants::SHORTCUT_FLAGS_FIELD_SIZE = 1;
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h
index 96d5f6d..536b713 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h
@@ -38,11 +38,15 @@
     static const int MAX_DICT_EXTENDED_REGION_SIZE;
 
     static const int NOT_A_TERMINAL_ID;
+    static const int NOT_A_TIME_STAMP;
     static const int PROBABILITY_SIZE;
     static const int FLAGS_IN_PROBABILITY_FILE_SIZE;
     static const int TERMINAL_ADDRESS_TABLE_ADDRESS_SIZE;
     static const int NOT_A_TERMINAL_ADDRESS;
     static const int TERMINAL_ID_FIELD_SIZE;
+    static const int TIME_STAMP_FIELD_SIZE;
+    static const int WORD_LEVEL_FIELD_SIZE;
+    static const int WORD_COUNT_FIELD_SIZE;
 
     static const int BIGRAM_ADDRESS_TABLE_BLOCK_SIZE;
     static const int BIGRAM_ADDRESS_TABLE_DATA_SIZE;
@@ -54,6 +58,8 @@
     static const int INVALID_BIGRAM_TARGET_TERMINAL_ID;
     static const int BIGRAM_PROBABILITY_MASK;
     static const int BIGRAM_HAS_NEXT_MASK;
+    // Used when bigram list has time stamp.
+    static const int BIGRAM_LARGE_PROBABILITY_FIELD_SIZE;
 
     static const int SHORTCUT_FLAGS_FIELD_SIZE;
 
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 2775457..6a41827 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
@@ -112,7 +112,8 @@
 }
 
 bool Ver4PatriciaTrieNodeWriter::updatePtNodeProbability(
-        const PtNodeParams *const toBeUpdatedPtNodeParams, const int newProbability) {
+        const PtNodeParams *const toBeUpdatedPtNodeParams, const int newProbability,
+        const int timestamp) {
     if (!toBeUpdatedPtNodeParams->isTerminal()) {
         return false;
     }
@@ -143,7 +144,7 @@
 
 
 bool Ver4PatriciaTrieNodeWriter::writeNewTerminalPtNodeAndAdvancePosition(
-        const PtNodeParams *const ptNodeParams, int *const ptNodeWritingPos) {
+        const PtNodeParams *const ptNodeParams, const int timestamp, int *const ptNodeWritingPos) {
     int terminalId = Ver4DictConstants::NOT_A_TERMINAL_ID;
     if (!writePtNodeAndGetTerminalIdAndAdvancePosition(ptNodeParams, &terminalId,
             ptNodeWritingPos)) {
@@ -158,10 +159,10 @@
 
 bool Ver4PatriciaTrieNodeWriter::addNewBigramEntry(
         const PtNodeParams *const sourcePtNodeParams,
-        const PtNodeParams *const targetPtNodeParam, const int probability,
+        const PtNodeParams *const targetPtNodeParam, const int probability, const int timestamp,
         bool *const outAddedNewBigram) {
     return mBigramPolicy->addNewEntry(sourcePtNodeParams->getTerminalId(),
-            targetPtNodeParam->getTerminalId(), probability, outAddedNewBigram);
+            targetPtNodeParam->getTerminalId(), probability, timestamp, outAddedNewBigram);
 }
 
 bool Ver4PatriciaTrieNodeWriter::removeBigramEntry(
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 2d83635..36b714b 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
@@ -54,7 +54,7 @@
             const int movedPos, const int bigramLinkedNodePos);
 
     virtual bool updatePtNodeProbability(const PtNodeParams *const toBeUpdatedPtNodeParams,
-            const int newProbability);
+            const int newProbability, const int timestamp);
 
     virtual bool updateChildrenPosition(const PtNodeParams *const toBeUpdatedPtNodeParams,
             const int newChildrenPosition);
@@ -65,11 +65,11 @@
     virtual bool writePtNodeAndAdvancePosition(const PtNodeParams *const ptNodeParams,
             int *const ptNodeWritingPos);
 
-    virtual bool writeNewTerminalPtNodeAndAdvancePosition(
-            const PtNodeParams *const ptNodeParams, int *const ptNodeWritingPos);
+    virtual bool writeNewTerminalPtNodeAndAdvancePosition(const PtNodeParams *const ptNodeParams,
+            const int timestamp, int *const ptNodeWritingPos);
 
     virtual bool addNewBigramEntry(const PtNodeParams *const sourcePtNodeParams,
-            const PtNodeParams *const targetPtNodeParam, const int probability,
+            const PtNodeParams *const targetPtNodeParam, const int probability, const int timestamp,
             bool *const outAddedNewBigram);
 
     virtual bool removeBigramEntry(const PtNodeParams *const sourcePtNodeParams,
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 7c4025a..719f358 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
@@ -137,7 +137,7 @@
 }
 
 bool Ver4PatriciaTriePolicy::addUnigramWord(const int *const word, const int length,
-        const int probability) {
+        const int probability, const int timestamp) {
     if (!mBuffers.get()->isUpdatable()) {
         AKLOGI("Warning: addUnigramWord() is called for non-updatable dictionary.");
         return false;
@@ -150,7 +150,7 @@
     DynamicPatriciaTrieReadingHelper readingHelper(mDictBuffer, &mNodeReader);
     readingHelper.initWithPtNodeArrayPos(getRootPosition());
     bool addedNewUnigram = false;
-    if (mUpdatingHelper.addUnigramWord(&readingHelper, word, length, probability,
+    if (mUpdatingHelper.addUnigramWord(&readingHelper, word, length, probability, timestamp,
             &addedNewUnigram)) {
         if (addedNewUnigram) {
             mUnigramCount++;
@@ -162,7 +162,8 @@
 }
 
 bool Ver4PatriciaTriePolicy::addBigramWords(const int *const word0, const int length0,
-        const int *const word1, const int length1, const int probability) {
+        const int *const word1, const int length1, const int probability,
+        const int timestamp) {
     if (!mBuffers.get()->isUpdatable()) {
         AKLOGI("Warning: addBigramWords() is called for non-updatable dictionary.");
         return false;
@@ -183,7 +184,8 @@
         return false;
     }
     bool addedNewBigram = false;
-    if (mUpdatingHelper.addBigramWords(word0Pos, word1Pos, probability, &addedNewBigram)) {
+    if (mUpdatingHelper.addBigramWords(word0Pos, word1Pos, probability, timestamp,
+            &addedNewBigram)) {
         if (addedNewBigram) {
             mBigramCount++;
         }
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 f2ce529..360b6b8 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
@@ -89,10 +89,11 @@
         return &mShortcutPolicy;
     }
 
-    bool addUnigramWord(const int *const word, const int length, const int probability);
+    bool addUnigramWord(const int *const word, const int length, const int probability,
+            const int timestamp);
 
     bool addBigramWords(const int *const word0, const int length0, const int *const word1,
-            const int length1, const int probability);
+            const int length1, const int probability, const int timestamp);
 
     bool removeBigramWords(const int *const word0, const int length0, const int *const word1,
             const int length1);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_reading_utils.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_reading_utils.cpp
index 321fd6d..254022d 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_reading_utils.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_reading_utils.cpp
@@ -16,8 +16,6 @@
 
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_reading_utils.h"
 
-#include "suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h"
-#include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
 #include "suggest/policyimpl/dictionary/utils/byte_array_utils.h"
 
 namespace latinime {
@@ -27,12 +25,4 @@
     return ByteArrayUtils::readUint32AndAdvancePosition(buffer, pos);
 }
 
-/* static */ int Ver4PatriciaTrieReadingUtils::getProbability(
-        const BufferWithExtendableBuffer *const probabilityBuffer, const int terminalId) {
-    const int pos = terminalId * (Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE
-            + Ver4DictConstants::PROBABILITY_SIZE)
-                    + Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE;
-    return probabilityBuffer->readUint(Ver4DictConstants::PROBABILITY_SIZE, pos);
-}
-
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_reading_utils.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_reading_utils.h
index 19e6dd3..e418c49 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_reading_utils.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_reading_utils.h
@@ -30,9 +30,6 @@
     static int getTerminalIdAndAdvancePosition(const uint8_t *const buffer,
             int *const pos);
 
-    static int getProbability(const BufferWithExtendableBuffer *const probabilityBuffer,
-            const int terminalId);
-
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(Ver4PatriciaTrieReadingUtils);
 };