diff --git a/native/jni/Android.mk b/native/jni/Android.mk
index 7511f4e..2b409d0 100644
--- a/native/jni/Android.mk
+++ b/native/jni/Android.mk
@@ -82,12 +82,10 @@
     $(addprefix suggest/policyimpl/dictionary/structure/v3/, \
         dynamic_patricia_trie_gc_event_listeners.cpp \
         dynamic_patricia_trie_node_reader.cpp \
-        dynamic_patricia_trie_node_writer.cpp \
         dynamic_patricia_trie_policy.cpp \
         dynamic_patricia_trie_reading_helper.cpp \
         dynamic_patricia_trie_reading_utils.cpp \
         dynamic_patricia_trie_updating_helper.cpp \
-        dynamic_patricia_trie_writing_helper.cpp \
         dynamic_patricia_trie_writing_utils.cpp) \
     $(addprefix suggest/policyimpl/dictionary/structure/v4/, \
         ver4_dict_buffers.cpp \
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 b21a606..768a91e 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
@@ -18,7 +18,6 @@
 
 #include "suggest/core/policy/dictionary_shortcuts_structure_policy.h"
 #include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_reader.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_helper.h"
 #include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
 #include "suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h"
 
@@ -66,278 +65,6 @@
     }
 }
 
-bool DynamicBigramListPolicy::copyAllBigrams(BufferWithExtendableBuffer *const bufferToWrite,
-        int *const fromPos, int *const toPos, int *const outBigramsCount) const {
-    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(*fromPos);
-    if (usesAdditionalBuffer) {
-        *fromPos -= mBuffer->getOriginalBufferSize();
-    }
-    *outBigramsCount = 0;
-    BigramListReadWriteUtils::BigramFlags bigramFlags;
-    int bigramEntryCount = 0;
-    int lastWrittenEntryPos = NOT_A_DICT_POS;
-    do {
-        if (++bigramEntryCount > BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT) {
-            AKLOGE("Too many bigram entries. Entry count: %d, Limit: %d",
-                    bigramEntryCount, BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT);
-            ASSERT(false);
-            return false;
-        }
-        // The buffer address can be changed after calling buffer writing methods.
-        int originalBigramPos;
-        BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(
-                mBuffer->getBuffer(usesAdditionalBuffer), &bigramFlags, &originalBigramPos,
-                fromPos);
-        if (originalBigramPos == NOT_A_DICT_POS) {
-            // skip invalid bigram entry.
-            continue;
-        }
-        if (usesAdditionalBuffer) {
-            originalBigramPos += mBuffer->getOriginalBufferSize();
-        }
-        const int bigramPos = followBigramLinkAndGetCurrentBigramPtNodePos(originalBigramPos);
-        if (bigramPos == NOT_A_DICT_POS) {
-            // Target PtNode has been invalidated.
-            continue;
-        }
-        lastWrittenEntryPos = *toPos;
-        if (!BigramListReadWriteUtils::createAndWriteBigramEntry(bufferToWrite, bigramPos,
-                BigramListReadWriteUtils::getProbabilityFromFlags(bigramFlags),
-                BigramListReadWriteUtils::hasNext(bigramFlags), toPos)) {
-            return false;
-        }
-        (*outBigramsCount)++;
-    } while(BigramListReadWriteUtils::hasNext(bigramFlags));
-    // Makes the last entry the terminal of the list. Updates the flags.
-    if (lastWrittenEntryPos != NOT_A_DICT_POS) {
-        if (!BigramListReadWriteUtils::setHasNextFlag(bufferToWrite, false /* hasNext */,
-                lastWrittenEntryPos)) {
-            return false;
-        }
-    }
-    if (usesAdditionalBuffer) {
-        *fromPos += mBuffer->getOriginalBufferSize();
-    }
-    return true;
-}
-
-// 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, int *const outValidBigramEntryCount) {
-    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(*bigramListPos);
-    if (usesAdditionalBuffer) {
-        *bigramListPos -= mBuffer->getOriginalBufferSize();
-    }
-    DynamicPatriciaTrieNodeReader nodeReader(mBuffer, this /* bigramsPolicy */, mShortcutPolicy);
-    BigramListReadWriteUtils::BigramFlags bigramFlags;
-    int bigramEntryCount = 0;
-    do {
-        if (++bigramEntryCount > BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT) {
-            AKLOGE("Too many bigram entries. Entry count: %d, Limit: %d",
-                    bigramEntryCount, 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);
-        const PtNodeParams ptNodeParams(nodeReader.fetchNodeInfoInBufferFromPtNodePos(
-                bigramTargetNodePos));
-        if (ptNodeParams.isDeleted() || !ptNodeParams.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 /* targetPtNodePos */, &bigramEntryPos)) {
-                return false;
-            }
-            continue;
-        }
-        bool isRemoved = false;
-        if (!updateProbabilityForDecay(bigramFlags, bigramTargetNodePos, &bigramEntryPos,
-                &isRemoved)) {
-            return false;
-        }
-        if (!isRemoved) {
-            (*outValidBigramEntryCount) += 1;
-        }
-    } while(BigramListReadWriteUtils::hasNext(bigramFlags));
-    return true;
-}
-
-// Updates bigram target PtNode positions in the list after the placing step in GC.
-bool DynamicBigramListPolicy::updateAllBigramTargetPtNodePositions(int *const bigramListPos,
-        const PtNodeWriter::PtNodePositionRelocationMap *const ptNodePositionRelocationMap,
-        int *const outBigramEntryCount) {
-    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. Entry count: %d, Limit: %d",
-                    bigramEntryCount, BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT);
-            ASSERT(false);
-            return false;
-        }
-        int bigramEntryPos = *bigramListPos;
-        if (usesAdditionalBuffer) {
-            bigramEntryPos += mBuffer->getOriginalBufferSize();
-        }
-        int bigramTargetPtNodePos;
-        // The buffer address can be changed after calling buffer writing methods.
-        BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(
-                mBuffer->getBuffer(usesAdditionalBuffer), &bigramFlags, &bigramTargetPtNodePos,
-                bigramListPos);
-        if (bigramTargetPtNodePos == NOT_A_DICT_POS) {
-            continue;
-        }
-        if (usesAdditionalBuffer) {
-            bigramTargetPtNodePos += mBuffer->getOriginalBufferSize();
-        }
-
-        PtNodeWriter::PtNodePositionRelocationMap::const_iterator it =
-                ptNodePositionRelocationMap->find(bigramTargetPtNodePos);
-        if (it != ptNodePositionRelocationMap->end()) {
-            bigramTargetPtNodePos = it->second;
-        } else {
-            bigramTargetPtNodePos = NOT_A_DICT_POS;
-        }
-        if (!BigramListReadWriteUtils::writeBigramEntry(mBuffer, bigramFlags,
-                bigramTargetPtNodePos, &bigramEntryPos)) {
-            return false;
-        }
-    } while(BigramListReadWriteUtils::hasNext(bigramFlags));
-    (*outBigramEntryCount) = bigramEntryCount;
-    return true;
-}
-
-bool DynamicBigramListPolicy::addNewBigramEntryToBigramList(const int bigramTargetPos,
-        const int probability, int *const bigramListPos, bool *const outAddedNewBigram) {
-    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. Entry count: %d, Limit: %d",
-                    bigramEntryCount, 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.
-        BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(
-                mBuffer->getBuffer(usesAdditionalBuffer), &bigramFlags, &originalBigramPos,
-                bigramListPos);
-        if (usesAdditionalBuffer && originalBigramPos != NOT_A_DICT_POS) {
-            originalBigramPos += mBuffer->getOriginalBufferSize();
-        }
-        if (followBigramLinkAndGetCurrentBigramPtNodePos(originalBigramPos) == bigramTargetPos) {
-            // Update this bigram entry.
-            *outAddedNewBigram = false;
-            const int originalProbability = BigramListReadWriteUtils::getProbabilityFromFlags(
-                    bigramFlags);
-            const int probabilityToWrite = mIsDecayingDict ?
-                    ForgettingCurveUtils::getUpdatedEncodedProbability(originalProbability,
-                            probability) : probability;
-            const BigramListReadWriteUtils::BigramFlags updatedFlags =
-                    BigramListReadWriteUtils::setProbabilityInFlags(bigramFlags,
-                            probabilityToWrite);
-            return BigramListReadWriteUtils::writeBigramEntry(mBuffer, updatedFlags,
-                    originalBigramPos, &entryPos);
-        }
-        if (BigramListReadWriteUtils::hasNext(bigramFlags)) {
-            continue;
-        }
-        // The current last entry is found.
-        // First, update the flags of the last entry.
-        if (!BigramListReadWriteUtils::setHasNextFlag(mBuffer, true /* hasNext */, entryPos)) {
-            *outAddedNewBigram = false;
-            return false;
-        }
-        if (usesAdditionalBuffer) {
-            *bigramListPos += mBuffer->getOriginalBufferSize();
-        }
-        // Then, add a new entry after the last entry.
-        *outAddedNewBigram = true;
-        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 bigramTargetPos, const int probability,
-        int *const writingPos) {
-    // hasNext is false because we are adding a new bigram entry at the end of the bigram list.
-    const int probabilityToWrite = mIsDecayingDict ?
-            ForgettingCurveUtils::getUpdatedEncodedProbability(NOT_A_PROBABILITY, probability) :
-                    probability;
-    return BigramListReadWriteUtils::createAndWriteBigramEntry(mBuffer, bigramTargetPos,
-            probabilityToWrite, false /* hasNext */, writingPos);
-}
-
-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 bigramFlags;
-    int bigramEntryCount = 0;
-    do {
-        if (++bigramEntryCount > BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT) {
-            AKLOGE("Too many bigram entries. Entry count: %d, Limit: %d",
-                    bigramEntryCount, BIGRAM_ENTRY_COUNT_IN_A_BIGRAM_LIST_LIMIT);
-            ASSERT(false);
-            return false;
-        }
-        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 != bigramTargetPos) {
-            continue;
-        }
-        // 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;
-}
-
 int DynamicBigramListPolicy::followBigramLinkAndGetCurrentBigramPtNodePos(
         const int originalBigramPos) const {
     if (originalBigramPos == NOT_A_DICT_POS) {
@@ -362,33 +89,4 @@
     return currentPos;
 }
 
-bool DynamicBigramListPolicy::updateProbabilityForDecay(
-        const BigramListReadWriteUtils::BigramFlags bigramFlags, const int targetPtNodePos,
-        int *const bigramEntryPos, bool *const outRemoved) const {
-    *outRemoved = false;
-    if (mIsDecayingDict) {
-        // Update bigram probability for decaying.
-        const int newProbability = ForgettingCurveUtils::getEncodedProbabilityToSave(
-                BigramListReadWriteUtils::getProbabilityFromFlags(bigramFlags), mHeaderPolicy);
-        if (ForgettingCurveUtils::isValidEncodedProbability(newProbability)) {
-            // Write new probability.
-            const BigramListReadWriteUtils::BigramFlags updatedBigramFlags =
-                    BigramListReadWriteUtils::setProbabilityInFlags(
-                            bigramFlags, newProbability);
-            if (!BigramListReadWriteUtils::writeBigramEntry(mBuffer, updatedBigramFlags,
-                    targetPtNodePos, bigramEntryPos)) {
-                return false;
-            }
-        } else {
-            // Remove current bigram entry.
-            *outRemoved = true;
-            if (!BigramListReadWriteUtils::writeBigramEntry(mBuffer, bigramFlags,
-                    NOT_A_DICT_POS /* targetPtNodePos */, bigramEntryPos)) {
-                return false;
-            }
-        }
-    }
-    return true;
-}
-
 } // namespace latinime
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 6cdf74a..f48c3a0 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
@@ -22,7 +22,6 @@
 #include "defines.h"
 #include "suggest/core/policy/dictionary_bigrams_structure_policy.h"
 #include "suggest/policyimpl/dictionary/bigram/bigram_list_read_write_utils.h"
-#include "suggest/policyimpl/dictionary/structure/pt_common/pt_node_writer.h"
 #include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.h"
 
 namespace latinime {
@@ -50,28 +49,6 @@
 
     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
-    // bigram entries and write the valid bigram entry count to outBigramsCount.
-    bool copyAllBigrams(BufferWithExtendableBuffer *const bufferToWrite, int *const fromPos,
-            int *const toPos, int *const outBigramsCount) const;
-
-    bool updateAllBigramEntriesAndDeleteUselessEntries(int *const bigramListPos,
-            int *const outBigramEntryCount);
-
-    bool updateAllBigramTargetPtNodePositions(int *const bigramListPos,
-            const PtNodeWriter::PtNodePositionRelocationMap *const
-                    ptNodePositionRelocationMap, int *const outValidBigramEntryCount);
-
-    bool addNewBigramEntryToBigramList(const int bigramTargetPos, const int probability,
-            int *const bigramListPos, bool *const outAddedNewBigram);
-
-    bool writeNewBigramEntry(const int bigramTargetPos, const int probability,
-            int *const writingPos);
-
-    // Return whether or not targetBigramPos is found.
-    bool removeBigram(const int bigramListPos, const int bigramTargetPos);
-
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicBigramListPolicy);
 
@@ -85,9 +62,6 @@
 
     // Follow bigram link and return the position of bigram target PtNode that is currently valid.
     int followBigramLinkAndGetCurrentBigramPtNodePos(const int originalBigramPos) const;
-
-    bool updateProbabilityForDecay(const BigramListReadWriteUtils::BigramFlags bigramFlags,
-            const int targetPtNodePos, int *const bigramEntryPos, bool *const outRemoved) const;
 };
 } // namespace latinime
 #endif // LATINIME_DYNAMIC_BIGRAM_LIST_POLICY_H
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
deleted file mode 100644
index 2225543..0000000
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.cpp
+++ /dev/null
@@ -1,338 +0,0 @@
-/*
- * Copyright (C) 2013, The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.h"
-
-#include "suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h"
-#include "suggest/policyimpl/dictionary/shortcut/dynamic_shortcut_list_policy.h"
-#include "suggest/policyimpl/dictionary/structure/v2/patricia_trie_reading_utils.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_reader.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_reading_utils.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_utils.h"
-#include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
-#include "suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h"
-
-namespace latinime {
-
-const int DynamicPatriciaTrieNodeWriter::CHILDREN_POSITION_FIELD_SIZE = 3;
-
-bool DynamicPatriciaTrieNodeWriter::markPtNodeAsDeleted(
-        const PtNodeParams *const toBeUpdatedPtNodeParams) {
-    int pos = toBeUpdatedPtNodeParams->getHeadPos();
-    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(pos);
-    const uint8_t *const dictBuf = mBuffer->getBuffer(usesAdditionalBuffer);
-    if (usesAdditionalBuffer) {
-        pos -= mBuffer->getOriginalBufferSize();
-    }
-    // Read original flags
-    const PatriciaTrieReadingUtils::NodeFlags originalFlags =
-            PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(dictBuf, &pos);
-    const PatriciaTrieReadingUtils::NodeFlags updatedFlags =
-            DynamicPatriciaTrieReadingUtils::updateAndGetFlags(originalFlags, false /* isMoved */,
-                    true /* isDeleted */);
-    int writingPos = toBeUpdatedPtNodeParams->getHeadPos();
-    // Update flags.
-    return DynamicPatriciaTrieWritingUtils::writeFlagsAndAdvancePosition(mBuffer, updatedFlags,
-            &writingPos);
-}
-
-bool DynamicPatriciaTrieNodeWriter::markPtNodeAsMoved(
-        const PtNodeParams *const toBeUpdatedPtNodeParams,
-        const int movedPos, const int bigramLinkedNodePos) {
-    int pos = toBeUpdatedPtNodeParams->getHeadPos();
-    const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(pos);
-    const uint8_t *const dictBuf = mBuffer->getBuffer(usesAdditionalBuffer);
-    if (usesAdditionalBuffer) {
-        pos -= mBuffer->getOriginalBufferSize();
-    }
-    // Read original flags
-    const PatriciaTrieReadingUtils::NodeFlags originalFlags =
-            PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(dictBuf, &pos);
-    const PatriciaTrieReadingUtils::NodeFlags updatedFlags =
-            DynamicPatriciaTrieReadingUtils::updateAndGetFlags(originalFlags, true /* isMoved */,
-                    false /* isDeleted */);
-    int writingPos = toBeUpdatedPtNodeParams->getHeadPos();
-    // Update flags.
-    if (!DynamicPatriciaTrieWritingUtils::writeFlagsAndAdvancePosition(mBuffer, updatedFlags,
-            &writingPos)) {
-        return false;
-    }
-    // Update moved position, which is stored in the parent offset field.
-    if (!DynamicPatriciaTrieWritingUtils::writeParentPosOffsetAndAdvancePosition(
-            mBuffer, movedPos, toBeUpdatedPtNodeParams->getHeadPos(), &writingPos)) {
-        return false;
-    }
-    // Update bigram linked node position, which is stored in the children position field.
-    int childrenPosFieldPos = toBeUpdatedPtNodeParams->getChildrenPosFieldPos();
-    if (!DynamicPatriciaTrieWritingUtils::writeChildrenPositionAndAdvancePosition(
-            mBuffer, bigramLinkedNodePos, &childrenPosFieldPos)) {
-        return false;
-    }
-    if (toBeUpdatedPtNodeParams->hasChildren()) {
-        // Update children's parent position.
-        mReadingHelper.initWithPtNodeArrayPos(toBeUpdatedPtNodeParams->getChildrenPos());
-        while (!mReadingHelper.isEnd()) {
-            const PtNodeParams childPtNodeParams(mReadingHelper.getPtNodeParams());
-            int parentOffsetFieldPos = childPtNodeParams.getHeadPos()
-                    + DynamicPatriciaTrieWritingUtils::NODE_FLAG_FIELD_SIZE;
-            if (!DynamicPatriciaTrieWritingUtils::writeParentPosOffsetAndAdvancePosition(
-                    mBuffer, bigramLinkedNodePos, childPtNodeParams.getHeadPos(),
-                    &parentOffsetFieldPos)) {
-                // Parent offset cannot be written because of a bug or a broken dictionary; thus,
-                // we give up to update dictionary.
-                return false;
-            }
-            mReadingHelper.readNextSiblingNode(childPtNodeParams);
-        }
-    }
-    return true;
-}
-
-bool DynamicPatriciaTrieNodeWriter::updatePtNodeProbability(
-        const PtNodeParams *const toBeUpdatedPtNodeParams, const int newProbability,
-        const int timestamp) {
-    if (!toBeUpdatedPtNodeParams->isTerminal()) {
-        return false;
-    }
-    const int probabilityToWrite = getUpdatedProbability(toBeUpdatedPtNodeParams->getProbability(),
-            newProbability);
-    int probabilityFieldPos = toBeUpdatedPtNodeParams->getProbabilityFieldPos();
-    return DynamicPatriciaTrieWritingUtils::writeProbabilityAndAdvancePosition(mBuffer,
-            probabilityToWrite, &probabilityFieldPos);
-}
-
-bool DynamicPatriciaTrieNodeWriter::updateChildrenPosition(
-        const PtNodeParams *const toBeUpdatedPtNodeParams, const int newChildrenPosition) {
-    int childrenPosFieldPos = toBeUpdatedPtNodeParams->getChildrenPosFieldPos();
-    return DynamicPatriciaTrieWritingUtils::writeChildrenPositionAndAdvancePosition(mBuffer,
-            newChildrenPosition, &childrenPosFieldPos);
-}
-
-bool DynamicPatriciaTrieNodeWriter::writePtNodeAndAdvancePosition(
-        const PtNodeParams *const ptNodeParams, int *const ptNodeWritingPos) {
-    return writePtNodeAndGetProbabilityFieldPosAndAdvancePosition(ptNodeParams,
-            0 /* outProbabilityFieldPos */, ptNodeWritingPos);
-}
-
-bool DynamicPatriciaTrieNodeWriter::writeNewTerminalPtNodeAndAdvancePosition(
-        const PtNodeParams *const ptNodeParams, const int timestamp, int *const ptNodeWritingPos) {
-    int probabilityFieldPos = NOT_A_DICT_POS;
-    if (!writePtNodeAndGetProbabilityFieldPosAndAdvancePosition(ptNodeParams, &probabilityFieldPos,
-            ptNodeWritingPos)) {
-        return false;
-    }
-    if (probabilityFieldPos == NOT_A_DICT_POS) {
-        return false;
-    }
-    const int probabilityToWrite = getUpdatedProbability(
-            NOT_A_PROBABILITY /* originalProbability */, ptNodeParams->getProbability());
-    return DynamicPatriciaTrieWritingUtils::writeProbabilityAndAdvancePosition(mBuffer,
-            probabilityToWrite, &probabilityFieldPos);
-}
-
-bool DynamicPatriciaTrieNodeWriter::addNewBigramEntry(
-        const PtNodeParams *const sourcePtNodeParams,
-        const PtNodeParams *const targetPtNodeParam, const int probability, const int timestamp,
-        bool *const outAddedNewBigram) {
-    const int newNodePos = mBuffer->getTailPosition();
-    int writingPos = newNodePos;
-    // Write a new PtNode using original PtNode's info to the tail of the dictionary in mBuffer.
-    if (!writePtNodeAndAdvancePosition(sourcePtNodeParams, &writingPos)) {
-        return false;
-    }
-    if (!markPtNodeAsMoved(sourcePtNodeParams, newNodePos, newNodePos)) {
-        return false;
-    }
-    const PtNodeParams newPtNodeParams(
-            mPtNodeReader->fetchNodeInfoInBufferFromPtNodePos(newNodePos));
-    if (newPtNodeParams.getBigramsPos() != NOT_A_DICT_POS) {
-        // Insert a new bigram entry into the existing bigram list.
-        int bigramListPos = newPtNodeParams.getBigramsPos();
-        return mBigramPolicy->addNewBigramEntryToBigramList(targetPtNodeParam->getHeadPos(),
-                probability, &bigramListPos, outAddedNewBigram);
-    } else {
-        // The PtNode doesn't have a bigram list.
-        *outAddedNewBigram = true;
-        // First, Write a bigram entry at the tail position of the PtNode.
-        if (!mBigramPolicy->writeNewBigramEntry(targetPtNodeParam->getHeadPos(), probability,
-                &writingPos)) {
-            return false;
-        }
-        // Then, Mark as the PtNode having bigram list in the flags.
-        const PatriciaTrieReadingUtils::NodeFlags updatedFlags =
-                PatriciaTrieReadingUtils::createAndGetFlags(newPtNodeParams.isBlacklisted(),
-                        newPtNodeParams.isNotAWord(), newPtNodeParams.isTerminal(),
-                        newPtNodeParams.getShortcutPos() != NOT_A_DICT_POS, true /* hasBigrams */,
-                        newPtNodeParams.getCodePointCount() > 1, CHILDREN_POSITION_FIELD_SIZE);
-        writingPos = newNodePos;
-        // Write updated flags into the moved PtNode's flags field.
-        return DynamicPatriciaTrieWritingUtils::writeFlagsAndAdvancePosition(mBuffer, updatedFlags,
-                &writingPos);
-    }
-}
-
-bool DynamicPatriciaTrieNodeWriter::removeBigramEntry(
-        const PtNodeParams *const sourcePtNodeParams, const PtNodeParams *const targetPtNodeParam) {
-    if (sourcePtNodeParams->getBigramsPos() == NOT_A_DICT_POS) {
-        return false;
-    }
-    return mBigramPolicy->removeBigram(sourcePtNodeParams->getBigramsPos(),
-            targetPtNodeParam->getHeadPos());
-}
-
-bool DynamicPatriciaTrieNodeWriter::updateAllBigramEntriesAndDeleteUselessEntries(
-        const PtNodeParams *const sourcePtNodeParams, int *const outBigramEntryCount) {
-    int bigramListPos = sourcePtNodeParams->getBigramsPos();
-    return mBigramPolicy->updateAllBigramEntriesAndDeleteUselessEntries(&bigramListPos,
-            outBigramEntryCount);
-}
-
-bool DynamicPatriciaTrieNodeWriter::updateAllPositionFields(
-        const PtNodeParams *const toBeUpdatedPtNodeParams,
-        const DictPositionRelocationMap *const dictPositionRelocationMap,
-        int *const outBigramEntryCount) {
-    int parentPos = toBeUpdatedPtNodeParams->getParentPos();
-    if (parentPos != NOT_A_DICT_POS) {
-        PtNodeWriter::PtNodePositionRelocationMap::const_iterator it =
-                dictPositionRelocationMap->mPtNodePositionRelocationMap.find(parentPos);
-        if (it != dictPositionRelocationMap->mPtNodePositionRelocationMap.end()) {
-            parentPos = it->second;
-        }
-    }
-    int writingPos = toBeUpdatedPtNodeParams->getHeadPos()
-            + DynamicPatriciaTrieWritingUtils::NODE_FLAG_FIELD_SIZE;
-    // Write an updated offset to the parent PtNode.
-    if (!DynamicPatriciaTrieWritingUtils::writeParentPosOffsetAndAdvancePosition(mBuffer,
-            parentPos, toBeUpdatedPtNodeParams->getHeadPos(), &writingPos)) {
-        return false;
-    }
-
-    // Updates children position that is a PtNodeArray position.
-    int childrenPos = toBeUpdatedPtNodeParams->getChildrenPos();
-    if (childrenPos != NOT_A_DICT_POS) {
-        PtNodeWriter::PtNodeArrayPositionRelocationMap::const_iterator it =
-                dictPositionRelocationMap->mPtNodeArrayPositionRelocationMap.find(childrenPos);
-        if (it != dictPositionRelocationMap->mPtNodeArrayPositionRelocationMap.end()) {
-            childrenPos = it->second;
-        }
-    }
-    if (!updateChildrenPosition(toBeUpdatedPtNodeParams, childrenPos)) {
-        return false;
-    }
-    // Updates bigram target PtNode positions in the bigram list.
-    int bigramsPos = toBeUpdatedPtNodeParams->getBigramsPos();
-    int bigramCount = 0;
-    if (bigramsPos != NOT_A_DICT_POS) {
-        int bigramEntryCount;
-        if (!mBigramPolicy->updateAllBigramTargetPtNodePositions(&bigramsPos,
-                &dictPositionRelocationMap->mPtNodePositionRelocationMap, &bigramEntryCount)) {
-            return false;
-        }
-        bigramCount += bigramEntryCount;
-    }
-    if (outBigramEntryCount) {
-        *outBigramEntryCount = bigramCount;
-    }
-    return true;
-}
-
-bool DynamicPatriciaTrieNodeWriter::writePtNodeAndGetProbabilityFieldPosAndAdvancePosition(
-        const PtNodeParams *const ptNodeParams, int *const outProbabilityFieldPos,
-        int *const ptNodeWritingPos) {
-    const int nodePos = *ptNodeWritingPos;
-    // Write dummy flags. The Node flags are updated with appropriate flags at the last step of the
-    // PtNode writing.
-    if (!DynamicPatriciaTrieWritingUtils::writeFlagsAndAdvancePosition(mBuffer,
-            0 /* nodeFlags */, ptNodeWritingPos)) {
-        return false;
-    }
-    // Calculate a parent offset and write the offset.
-    if (!DynamicPatriciaTrieWritingUtils::writeParentPosOffsetAndAdvancePosition(mBuffer,
-            ptNodeParams->getParentPos(), nodePos, ptNodeWritingPos)) {
-        return false;
-    }
-    // Write code points
-    if (!DynamicPatriciaTrieWritingUtils::writeCodePointsAndAdvancePosition(mBuffer,
-            ptNodeParams->getCodePoints(), ptNodeParams->getCodePointCount(), ptNodeWritingPos)) {
-        return false;
-    }
-    // Write probability when the probability is a valid probability, which means this node is
-    // terminal.
-    if (ptNodeParams->isTerminal()) {
-        if (outProbabilityFieldPos) {
-            *outProbabilityFieldPos = *ptNodeWritingPos;
-        }
-        if (ptNodeParams->getProbability() == NOT_A_PROBABILITY) {
-            // Write a dummy probability.
-            if (!DynamicPatriciaTrieWritingUtils::writeProbabilityAndAdvancePosition(mBuffer,
-                    0 /* probability */, ptNodeWritingPos)) {
-                return false;
-            }
-        } else {
-            if (!DynamicPatriciaTrieWritingUtils::writeProbabilityAndAdvancePosition(mBuffer,
-                    ptNodeParams->getProbability(), ptNodeWritingPos)) {
-                return false;
-            }
-        }
-    }
-    // Write children position
-    if (!DynamicPatriciaTrieWritingUtils::writeChildrenPositionAndAdvancePosition(mBuffer,
-            ptNodeParams->getChildrenPos(), ptNodeWritingPos)) {
-        return false;
-    }
-    // Copy shortcut list when the originalShortcutListPos is valid dictionary position.
-    if (ptNodeParams->getShortcutPos() != NOT_A_DICT_POS) {
-        int fromPos = ptNodeParams->getShortcutPos();
-        if (!mShortcutPolicy->copyAllShortcutsAndReturnIfSucceededOrNot(mBuffer, &fromPos,
-                ptNodeWritingPos)) {
-            return false;
-        }
-    }
-    // Copy bigram list when the originalBigramListPos is valid dictionary position.
-    int bigramCount = 0;
-    if (ptNodeParams->getBigramsPos() != NOT_A_DICT_POS) {
-        int fromPos = ptNodeParams->getBigramsPos();
-        if (!mBigramPolicy->copyAllBigrams(mBuffer, &fromPos, ptNodeWritingPos, &bigramCount)) {
-            return false;
-        }
-    }
-    // Create node flags and write them.
-    PatriciaTrieReadingUtils::NodeFlags nodeFlags =
-            PatriciaTrieReadingUtils::createAndGetFlags(ptNodeParams->isBlacklisted(),
-                    ptNodeParams->isNotAWord(), ptNodeParams->isTerminal(),
-                    ptNodeParams->getShortcutPos() != NOT_A_DICT_POS /* hasShortcutTargets */,
-                    bigramCount > 0 /* hasBigrams */,
-                    ptNodeParams->getCodePointCount() > 1 /* hasMultipleChars */,
-                    CHILDREN_POSITION_FIELD_SIZE);
-    int flagsFieldPos = nodePos;
-    if (!DynamicPatriciaTrieWritingUtils::writeFlagsAndAdvancePosition(mBuffer, nodeFlags,
-            &flagsFieldPos)) {
-        return false;
-    }
-    return true;
-}
-
-int DynamicPatriciaTrieNodeWriter::getUpdatedProbability(const int originalProbability,
-        const int newProbability) const {
-    if (mNeedsToDecayWhenUpdating) {
-        return ForgettingCurveUtils::getUpdatedEncodedProbability(originalProbability,
-                newProbability);
-    } else {
-        return newProbability;
-    }
-}
-
-}
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
deleted file mode 100644
index b0fec34..0000000
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.h
+++ /dev/null
@@ -1,99 +0,0 @@
-/*
- * Copyright (C) 2013, The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef LATINIME_DYNAMIC_PATRICIA_TRIE_NODE_WRITER_H
-#define LATINIME_DYNAMIC_PATRICIA_TRIE_NODE_WRITER_H
-
-#include <stdint.h>
-
-#include "defines.h"
-#include "suggest/policyimpl/dictionary/structure/pt_common/pt_node_params.h"
-#include "suggest/policyimpl/dictionary/structure/pt_common/pt_node_writer.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_reader.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_reading_helper.h"
-
-namespace latinime {
-
-class BufferWithExtendableBuffer;
-class DynamicBigramListPolicy;
-class DynamicShortcutListPolicy;
-
-/*
- * This class is used for helping to writes nodes of dynamic patricia trie.
- */
-class DynamicPatriciaTrieNodeWriter : public PtNodeWriter {
- public:
-    DynamicPatriciaTrieNodeWriter(BufferWithExtendableBuffer *const buffer,
-            const DynamicPatriciaTrieNodeReader *const ptNodeReader,
-            DynamicBigramListPolicy *const bigramPolicy,
-            DynamicShortcutListPolicy *const shortcutPolicy, const bool needsToDecayWhenUpdating)
-            : mBuffer(buffer), mPtNodeReader(ptNodeReader), mReadingHelper(mBuffer, ptNodeReader),
-              mBigramPolicy(bigramPolicy), mShortcutPolicy(shortcutPolicy),
-              mNeedsToDecayWhenUpdating(needsToDecayWhenUpdating) {}
-
-    virtual ~DynamicPatriciaTrieNodeWriter() {}
-
-    virtual bool markPtNodeAsDeleted(const PtNodeParams *const toBeUpdatedPtNodeParams);
-
-    virtual bool markPtNodeAsMoved(const PtNodeParams *const toBeUpdatedPtNodeParams,
-            const int movedPos, const int bigramLinkedNodePos);
-
-    virtual bool updatePtNodeProbability(const PtNodeParams *const toBeUpdatedPtNodeParams,
-            const int newProbability, const int timestamp);
-
-    virtual bool updateChildrenPosition(const PtNodeParams *const toBeUpdatedPtNodeParams,
-            const int newChildrenPosition);
-
-    virtual bool writePtNodeAndAdvancePosition(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 int timestamp,
-            bool *const outAddedNewBigram);
-
-    virtual bool removeBigramEntry(const PtNodeParams *const sourcePtNodeParams,
-            const PtNodeParams *const targetPtNodeParam);
-
-    virtual bool updateAllBigramEntriesAndDeleteUselessEntries(
-            const PtNodeParams *const sourcePtNodeParams, int *const outBigramEntryCount);
-
-    virtual bool updateAllPositionFields(const PtNodeParams *const toBeUpdatedPtNodeParams,
-            const DictPositionRelocationMap *const dictPositionRelocationMap,
-            int *const outBigramEntryCount);
-
- private:
-    DISALLOW_COPY_AND_ASSIGN(DynamicPatriciaTrieNodeWriter);
-
-    bool writePtNodeAndGetProbabilityFieldPosAndAdvancePosition(
-            const PtNodeParams *const ptNodeParams, int *const outProbabilityFieldPos,
-            int *const ptNodeWritingPos);
-
-    int getUpdatedProbability(const int originalProbability, const int newProbability) const;
-
-    static const int CHILDREN_POSITION_FIELD_SIZE;
-
-    BufferWithExtendableBuffer *const mBuffer;
-    const DynamicPatriciaTrieNodeReader *const mPtNodeReader;
-    DynamicPatriciaTrieReadingHelper mReadingHelper;
-    DynamicBigramListPolicy *const mBigramPolicy;
-    DynamicShortcutListPolicy *const mShortcutPolicy;
-    const bool mNeedsToDecayWhenUpdating;
-};
-} // namespace latinime
-#endif /* LATINIME_DYNAMIC_PATRICIA_TRIE_NODE_WRITER_H */
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 4468754..88af674 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
@@ -27,25 +27,11 @@
 #include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_reader.h"
 #include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_reading_helper.h"
 #include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_reading_utils.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_updating_helper.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_helper.h"
 #include "suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h"
 #include "suggest/policyimpl/dictionary/utils/probability_utils.h"
 
 namespace latinime {
 
-// 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";
-const char *const DynamicPatriciaTriePolicy::MAX_UNIGRAM_COUNT_QUERY = "MAX_UNIGRAM_COUNT";
-const char *const DynamicPatriciaTriePolicy::MAX_BIGRAM_COUNT_QUERY = "MAX_BIGRAM_COUNT";
-const char *const DynamicPatriciaTriePolicy::SET_NEEDS_TO_DECAY_FOR_TESTING_QUERY =
-        "SET_NEEDS_TO_DECAY_FOR_TESTING";
-const int DynamicPatriciaTriePolicy::MAX_DICT_EXTENDED_REGION_SIZE = 32 * 1024;
-const int DynamicPatriciaTriePolicy::MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS =
-        DynamicPatriciaTrieWritingHelper::MAX_DICTIONARY_SIZE - 1024;
-
 void DynamicPatriciaTriePolicy::createAndGetAllChildDicNodes(const DicNode *const dicNode,
         DicNodeVector *const childDicNodes) const {
     if (!dicNode->hasChildren()) {
@@ -140,163 +126,4 @@
     return ptNodeParams.getBigramsPos();
 }
 
-bool DynamicPatriciaTriePolicy::addUnigramWord(const int *const word, const int length,
-        const int probability, const int timestamp) {
-    if (!mMmappedBuffer.get()->isUpdatable()) {
-        AKLOGI("Warning: addUnigramWord() is called for non-updatable dictionary.");
-        return false;
-    }
-    if (mBufferWithExtendableBuffer.getTailPosition()
-            >= MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS) {
-        AKLOGE("The dictionary is too large to dynamically update.");
-        return false;
-    }
-    DynamicPatriciaTrieReadingHelper readingHelper(&mBufferWithExtendableBuffer, &mNodeReader);
-    readingHelper.initWithPtNodeArrayPos(getRootPosition());
-    bool addedNewUnigram = false;
-    if (mUpdatingHelper.addUnigramWord(&readingHelper, word, length, probability, timestamp,
-            &addedNewUnigram)) {
-        if (addedNewUnigram) {
-            mUnigramCount++;
-        }
-        return true;
-    } else {
-        return false;
-    }
-}
-
-bool DynamicPatriciaTriePolicy::addBigramWords(const int *const word0, const int length0,
-        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;
-    }
-    if (mBufferWithExtendableBuffer.getTailPosition()
-            >= MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS) {
-        AKLOGE("The dictionary is too large to dynamically update.");
-        return false;
-    }
-    const int word0Pos = getTerminalPtNodePositionOfWord(word0, length0,
-            false /* forceLowerCaseSearch */);
-    if (word0Pos == NOT_A_DICT_POS) {
-        return false;
-    }
-    const int word1Pos = getTerminalPtNodePositionOfWord(word1, length1,
-            false /* forceLowerCaseSearch */);
-    if (word1Pos == NOT_A_DICT_POS) {
-        return false;
-    }
-    bool addedNewBigram = false;
-    if (mUpdatingHelper.addBigramWords(word0Pos, word1Pos, probability, timestamp,
-            &addedNewBigram)) {
-        if (addedNewBigram) {
-            mBigramCount++;
-        }
-        return true;
-    } else {
-        return false;
-    }
-}
-
-bool DynamicPatriciaTriePolicy::removeBigramWords(const int *const word0, const int length0,
-        const int *const word1, const int length1) {
-    if (!mMmappedBuffer.get()->isUpdatable()) {
-        AKLOGI("Warning: removeBigramWords() is called for non-updatable dictionary.");
-        return false;
-    }
-    if (mBufferWithExtendableBuffer.getTailPosition()
-            >= MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS) {
-        AKLOGE("The dictionary is too large to dynamically update.");
-        return false;
-    }
-    const int word0Pos = getTerminalPtNodePositionOfWord(word0, length0,
-            false /* forceLowerCaseSearch */);
-    if (word0Pos == NOT_A_DICT_POS) {
-        return false;
-    }
-    const int word1Pos = getTerminalPtNodePositionOfWord(word1, length1,
-            false /* forceLowerCaseSearch */);
-    if (word1Pos == NOT_A_DICT_POS) {
-        return false;
-    }
-    if (mUpdatingHelper.removeBigramWords(word0Pos, word1Pos)) {
-        mBigramCount--;
-        return true;
-    } else {
-        return false;
-    }
-}
-
-void DynamicPatriciaTriePolicy::flush(const char *const filePath) {
-    if (!mMmappedBuffer.get()->isUpdatable()) {
-        AKLOGI("Warning: flush() is called for non-updatable dictionary.");
-        return;
-    }
-    DynamicPatriciaTrieWritingHelper writingHelper(&mBufferWithExtendableBuffer,
-            &mBigramListPolicy, &mShortcutListPolicy, false /* needsToDecay */);
-    writingHelper.writeToDictFile(filePath, &mHeaderPolicy, mUnigramCount, mBigramCount);
-}
-
-void DynamicPatriciaTriePolicy::flushWithGC(const char *const filePath) {
-    if (!mMmappedBuffer.get()->isUpdatable()) {
-        AKLOGI("Warning: flushWithGC() is called for non-updatable dictionary.");
-        return;
-    }
-    const bool needsToDecay = mHeaderPolicy.isDecayingDict()
-            && (mNeedsToDecayForTesting || ForgettingCurveUtils::needsToDecay(
-                    false /* mindsBlockByDecay */, mUnigramCount, mBigramCount, &mHeaderPolicy));
-    DynamicBigramListPolicy bigramListPolicyForGC(&mHeaderPolicy, &mBufferWithExtendableBuffer,
-            &mShortcutListPolicy, needsToDecay);
-    DynamicPatriciaTrieWritingHelper writingHelper(&mBufferWithExtendableBuffer,
-            &bigramListPolicyForGC, &mShortcutListPolicy, needsToDecay);
-    writingHelper.writeToDictFileWithGC(getRootPosition(), filePath, &mHeaderPolicy);
-    mNeedsToDecayForTesting = false;
-}
-
-bool DynamicPatriciaTriePolicy::needsToRunGC(const bool mindsBlockByGC) const {
-    if (!mMmappedBuffer.get()->isUpdatable()) {
-        AKLOGI("Warning: needsToRunGC() is called for non-updatable dictionary.");
-        return false;
-    }
-    if (mBufferWithExtendableBuffer.isNearSizeLimit()) {
-        // Additional buffer size is near the limit.
-        return true;
-    } else if (mHeaderPolicy.getExtendedRegionSize()
-            + mBufferWithExtendableBuffer.getUsedAdditionalBufferSize()
-                    > MAX_DICT_EXTENDED_REGION_SIZE) {
-        // Total extended region size exceeds the limit.
-        return true;
-    } else if (mBufferWithExtendableBuffer.getTailPosition()
-            >= MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS
-                    && mBufferWithExtendableBuffer.getUsedAdditionalBufferSize() > 0) {
-        // Needs to reduce dictionary size.
-        return true;
-    } else if (mHeaderPolicy.isDecayingDict()) {
-        return mNeedsToDecayForTesting || ForgettingCurveUtils::needsToDecay(
-                mindsBlockByGC, mUnigramCount, mBigramCount, &mHeaderPolicy);
-    }
-    return false;
-}
-
-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, 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>(DynamicPatriciaTrieWritingHelper::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>(DynamicPatriciaTrieWritingHelper::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/v3/dynamic_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_policy.h
index 0b21e57..3965e31 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
@@ -23,8 +23,6 @@
 #include "suggest/policyimpl/dictionary/header/header_policy.h"
 #include "suggest/policyimpl/dictionary/shortcut/dynamic_shortcut_list_policy.h"
 #include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_reader.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_updating_helper.h"
 #include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
 #include "suggest/policyimpl/dictionary/utils/format_utils.h"
 #include "suggest/policyimpl/dictionary/utils/mmapped_buffer.h"
@@ -47,12 +45,7 @@
               mShortcutListPolicy(&mBufferWithExtendableBuffer),
               mBigramListPolicy(&mHeaderPolicy, &mBufferWithExtendableBuffer, &mShortcutListPolicy,
                       mHeaderPolicy.isDecayingDict()),
-              mNodeReader(&mBufferWithExtendableBuffer, &mBigramListPolicy, &mShortcutListPolicy),
-              mNodeWriter(&mBufferWithExtendableBuffer, &mNodeReader, &mBigramListPolicy,
-                      &mShortcutListPolicy, mHeaderPolicy.isDecayingDict()),
-              mUpdatingHelper(&mBufferWithExtendableBuffer, &mNodeReader, &mNodeWriter),
-              mUnigramCount(mHeaderPolicy.getUnigramCount()),
-              mBigramCount(mHeaderPolicy.getBigramCount()), mNeedsToDecayForTesting(false) {}
+              mNodeReader(&mBufferWithExtendableBuffer, &mBigramListPolicy, &mShortcutListPolicy) {}
 
     AK_FORCE_INLINE int getRootPosition() const {
         return 0;
@@ -89,45 +82,59 @@
     }
 
     bool addUnigramWord(const int *const word, const int length, const int probability,
-            const int timestamp);
+            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 timestamp);
+            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;
+    }
 
     bool removeBigramWords(const int *const word0, const int length0, const int *const word1,
-            const int length1);
+            const int length1) {
+        // This method should not be called for non-updatable dictionary.
+        AKLOGI("Warning: removeBigramWords() is called for non-updatable dictionary.");
+        return false;
+    }
 
-    void flush(const char *const filePath);
+    void flush(const char *const filePath) {
+        // This method should not be called for non-updatable dictionary.
+        AKLOGI("Warning: flush() is called for non-updatable dictionary.");
+    }
 
-    void flushWithGC(const char *const filePath);
+    void flushWithGC(const char *const filePath) {
+        // This method should not be called for non-updatable dictionary.
+        AKLOGI("Warning: flushWithGC() is called for non-updatable dictionary.");
+    }
 
-    bool needsToRunGC(const bool mindsBlockByGC) const;
+    bool needsToRunGC(const bool mindsBlockByGC) const {
+        // This method should not be called for non-updatable dictionary.
+        AKLOGI("Warning: needsToRunGC() is called for non-updatable dictionary.");
+        return false;
+    }
 
     void getProperty(const char *const query, const int queryLength, char *const outResult,
-            const int maxResultLength);
+            const int maxResultLength) {
+        // getProperty is not supported for this class.
+        if (maxResultLength > 0) {
+            outResult[0] = '\0';
+        }
+    }
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicPatriciaTriePolicy);
 
-    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;
-    static const int MAX_DICT_EXTENDED_REGION_SIZE;
-    static const int MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS;
-
     const MmappedBuffer::MmappedBufferPtr mMmappedBuffer;
     const HeaderPolicy mHeaderPolicy;
     BufferWithExtendableBuffer mBufferWithExtendableBuffer;
     DynamicShortcutListPolicy mShortcutListPolicy;
     DynamicBigramListPolicy mBigramListPolicy;
     DynamicPatriciaTrieNodeReader mNodeReader;
-    DynamicPatriciaTrieNodeWriter mNodeWriter;
-    DynamicPatriciaTrieUpdatingHelper mUpdatingHelper;
-    int mUnigramCount;
-    int mBigramCount;
-    int mNeedsToDecayForTesting;
 };
 } // namespace latinime
 #endif // LATINIME_DYNAMIC_PATRICIA_TRIE_POLICY_H
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_helper.cpp
deleted file mode 100644
index 321189d..0000000
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_helper.cpp
+++ /dev/null
@@ -1,142 +0,0 @@
-/*
- * Copyright (C) 2013, The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_helper.h"
-
-#include "suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h"
-#include "suggest/policyimpl/dictionary/structure/pt_common/pt_node_reader.h"
-#include "suggest/policyimpl/dictionary/structure/pt_common/pt_node_writer.h"
-#include "suggest/policyimpl/dictionary/structure/v2/patricia_trie_reading_utils.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_gc_event_listeners.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_reader.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_node_writer.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_reading_helper.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_reading_utils.h"
-#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_utils.h"
-#include "suggest/policyimpl/dictionary/header/header_policy.h"
-#include "suggest/policyimpl/dictionary/shortcut/dynamic_shortcut_list_policy.h"
-#include "suggest/policyimpl/dictionary/utils/dict_file_writing_utils.h"
-#include "suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h"
-#include "utils/hash_map_compat.h"
-
-namespace latinime {
-
-// TODO: Make MAX_DICTIONARY_SIZE 8MB.
-const size_t DynamicPatriciaTrieWritingHelper::MAX_DICTIONARY_SIZE = 2 * 1024 * 1024;
-
-void DynamicPatriciaTrieWritingHelper::writeToDictFile(const char *const fileName,
-        const HeaderPolicy *const headerPolicy, const int unigramCount, const int bigramCount) {
-    BufferWithExtendableBuffer headerBuffer(
-            BufferWithExtendableBuffer::DEFAULT_MAX_ADDITIONAL_BUFFER_SIZE);
-    const int extendedRegionSize = headerPolicy->getExtendedRegionSize() +
-            mBuffer->getUsedAdditionalBufferSize();
-    if (!headerPolicy->writeHeaderToBuffer(&headerBuffer, false /* updatesLastUpdatedTime */,
-            false /* updatesLastDecayedTime */, unigramCount, bigramCount, extendedRegionSize)) {
-        return;
-    }
-    DictFileWritingUtils::flushAllHeaderAndBodyToFile(fileName, &headerBuffer, mBuffer);
-}
-
-void DynamicPatriciaTrieWritingHelper::writeToDictFileWithGC(const int rootPtNodeArrayPos,
-        const char *const fileName, const HeaderPolicy *const headerPolicy) {
-    BufferWithExtendableBuffer newDictBuffer(MAX_DICTIONARY_SIZE);
-    int unigramCount = 0;
-    int bigramCount = 0;
-    if (mNeedsToDecay) {
-        ForgettingCurveUtils::sTimeKeeper.setCurrentTime();
-    }
-    if (!runGC(rootPtNodeArrayPos, headerPolicy, &newDictBuffer, &unigramCount, &bigramCount)) {
-        return;
-    }
-    BufferWithExtendableBuffer headerBuffer(
-            BufferWithExtendableBuffer::DEFAULT_MAX_ADDITIONAL_BUFFER_SIZE);
-    if (!headerPolicy->writeHeaderToBuffer(&headerBuffer, true /* updatesLastUpdatedTime */,
-            mNeedsToDecay, unigramCount, bigramCount, 0 /* extendedRegionSize */)) {
-        return;
-    }
-    DictFileWritingUtils::flushAllHeaderAndBodyToFile(fileName, &headerBuffer, &newDictBuffer);
-}
-
-// TODO: Make this method version independent.
-bool DynamicPatriciaTrieWritingHelper::runGC(const int rootPtNodeArrayPos,
-        const HeaderPolicy *const headerPolicy, BufferWithExtendableBuffer *const bufferToWrite,
-        int *const outUnigramCount, int *const outBigramCount) {
-    DynamicPatriciaTrieNodeReader ptNodeReader(mBuffer, mBigramPolicy, mShortcutPolicy);
-    DynamicPatriciaTrieReadingHelper readingHelper(mBuffer, &ptNodeReader);
-    DynamicPatriciaTrieNodeWriter ptNodeWriter(mBuffer, &ptNodeReader, mBigramPolicy,
-            mShortcutPolicy, false /* needsToDecayWhenUpdating */);
-    readingHelper.initWithPtNodeArrayPos(rootPtNodeArrayPos);
-    DynamicPatriciaTrieGcEventListeners
-            ::TraversePolicyToUpdateUnigramProbabilityAndMarkUselessPtNodesAsDeleted
-                    traversePolicyToUpdateUnigramProbabilityAndMarkUselessPtNodesAsDeleted(
-                            headerPolicy, &ptNodeWriter, mBuffer, mNeedsToDecay);
-    if (!readingHelper.traverseAllPtNodesInPostorderDepthFirstManner(
-            &traversePolicyToUpdateUnigramProbabilityAndMarkUselessPtNodesAsDeleted)) {
-        return false;
-    }
-    if (mNeedsToDecay && traversePolicyToUpdateUnigramProbabilityAndMarkUselessPtNodesAsDeleted
-            .getValidUnigramCount() > ForgettingCurveUtils::MAX_UNIGRAM_COUNT_AFTER_GC) {
-        // TODO: Remove more unigrams.
-    }
-
-    readingHelper.initWithPtNodeArrayPos(rootPtNodeArrayPos);
-    DynamicPatriciaTrieGcEventListeners::TraversePolicyToUpdateBigramProbability
-            traversePolicyToUpdateBigramProbability(&ptNodeWriter);
-    if (!readingHelper.traverseAllPtNodesInPostorderDepthFirstManner(
-            &traversePolicyToUpdateBigramProbability)) {
-        return false;
-    }
-    if (mNeedsToDecay && traversePolicyToUpdateBigramProbability.getValidBigramEntryCount()
-            > ForgettingCurveUtils::MAX_BIGRAM_COUNT_AFTER_GC) {
-        // TODO: Remove more bigrams.
-    }
-
-    // Mapping from positions in mBuffer to positions in bufferToWrite.
-    PtNodeWriter::DictPositionRelocationMap dictPositionRelocationMap;
-    readingHelper.initWithPtNodeArrayPos(rootPtNodeArrayPos);
-    DynamicPatriciaTrieNodeWriter newPtNodeWriter(bufferToWrite, &ptNodeReader, mBigramPolicy,
-            mShortcutPolicy, false /* needsToDecayWhenUpdating */);
-    DynamicPatriciaTrieGcEventListeners::TraversePolicyToPlaceAndWriteValidPtNodesToBuffer
-            traversePolicyToPlaceAndWriteValidPtNodesToBuffer(&newPtNodeWriter, bufferToWrite,
-                    &dictPositionRelocationMap);
-    if (!readingHelper.traverseAllPtNodesInPtNodeArrayLevelPreorderDepthFirstManner(
-            &traversePolicyToPlaceAndWriteValidPtNodesToBuffer)) {
-        return false;
-    }
-
-    // Create policy instance for the GCed dictionary.
-    DynamicShortcutListPolicy newDictShortcutPolicy(bufferToWrite);
-    DynamicBigramListPolicy newDictBigramPolicy(headerPolicy, bufferToWrite, &newDictShortcutPolicy,
-            mNeedsToDecay);
-    // Create reading node reader and reading helper for the GCed dictionary.
-    DynamicPatriciaTrieNodeReader newDictNodeReader(bufferToWrite, &newDictBigramPolicy,
-            &newDictShortcutPolicy);
-    DynamicPatriciaTrieReadingHelper newDictReadingHelper(bufferToWrite, &newDictNodeReader);
-    DynamicPatriciaTrieNodeWriter newDictNodeWriter(bufferToWrite, &newDictNodeReader,
-            &newDictBigramPolicy, &newDictShortcutPolicy, false /* needsToDecayWhenUpdating */);
-    newDictReadingHelper.initWithPtNodeArrayPos(rootPtNodeArrayPos);
-    DynamicPatriciaTrieGcEventListeners::TraversePolicyToUpdateAllPositionFields
-            traversePolicyToUpdateAllPositionFields(&newDictNodeWriter, &dictPositionRelocationMap);
-    if (!newDictReadingHelper.traverseAllPtNodesInPtNodeArrayLevelPreorderDepthFirstManner(
-            &traversePolicyToUpdateAllPositionFields)) {
-        return false;
-    }
-    *outUnigramCount = traversePolicyToUpdateAllPositionFields.getUnigramCount();
-    *outBigramCount = traversePolicyToUpdateAllPositionFields.getBigramCount();
-    return true;
-}
-
-} // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_helper.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_helper.h
deleted file mode 100644
index 6d722e5..0000000
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_helper.h
+++ /dev/null
@@ -1,65 +0,0 @@
-/*
- * Copyright (C) 2013, The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef LATINIME_DYNAMIC_PATRICIA_TRIE_WRITING_HELPER_H
-#define LATINIME_DYNAMIC_PATRICIA_TRIE_WRITING_HELPER_H
-
-#include <cstddef>
-#include <stdint.h>
-
-#include "defines.h"
-
-namespace latinime {
-
-class BufferWithExtendableBuffer;
-class DynamicBigramListPolicy;
-class DynamicPatriciaTrieReadingHelper;
-class DynamicShortcutListPolicy;
-class HeaderPolicy;
-
-// TODO: Make it independent from a particular format and move to pt_common.
-class DynamicPatriciaTrieWritingHelper {
- public:
-    static const size_t MAX_DICTIONARY_SIZE;
-
-    DynamicPatriciaTrieWritingHelper(BufferWithExtendableBuffer *const buffer,
-            DynamicBigramListPolicy *const bigramPolicy,
-            DynamicShortcutListPolicy *const shortcutPolicy, const bool needsToDecay)
-            : mBuffer(buffer), mBigramPolicy(bigramPolicy), mShortcutPolicy(shortcutPolicy),
-              mNeedsToDecay(needsToDecay) {}
-
-    ~DynamicPatriciaTrieWritingHelper() {}
-
-    void writeToDictFile(const char *const fileName, const HeaderPolicy *const headerPolicy,
-            const int unigramCount, const int bigramCount);
-
-    void writeToDictFileWithGC(const int rootPtNodeArrayPos, const char *const fileName,
-            const HeaderPolicy *const headerPolicy);
-
- private:
-    DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicPatriciaTrieWritingHelper);
-
-    BufferWithExtendableBuffer *const mBuffer;
-    DynamicBigramListPolicy *const mBigramPolicy;
-    DynamicShortcutListPolicy *const mShortcutPolicy;
-    const bool mNeedsToDecay;
-
-    bool runGC(const int rootPtNodeArrayPos, const HeaderPolicy *const headerPolicy,
-            BufferWithExtendableBuffer *const bufferToWrite, int *const outUnigramCount,
-            int *const outBigramCount);
-};
-} // namespace latinime
-#endif /* LATINIME_DYNAMIC_PATRICIA_TRIE_WRITING_HELPER_H */
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_utils.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_utils.cpp
index 6773366..45eeefd 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_utils.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_utils.cpp
@@ -33,7 +33,6 @@
 const int DynamicPatriciaTrieWritingUtils::MAX_DICT_OFFSET_VALUE = 0x7FFFFF;
 const int DynamicPatriciaTrieWritingUtils::MIN_DICT_OFFSET_VALUE = -0x7FFFFF;
 const int DynamicPatriciaTrieWritingUtils::DICT_OFFSET_NEGATIVE_FLAG = 0x800000;
-const int DynamicPatriciaTrieWritingUtils::PROBABILITY_FIELD_SIZE = 1;
 const int DynamicPatriciaTrieWritingUtils::NODE_FLAG_FIELD_SIZE = 1;
 
 /* static */ bool DynamicPatriciaTrieWritingUtils::writeEmptyDictionary(
@@ -101,19 +100,6 @@
             hasMultipleCodePoints, codePointFieldPos);
 }
 
-/* static */ bool DynamicPatriciaTrieWritingUtils::writeProbabilityAndAdvancePosition(
-        BufferWithExtendableBuffer *const buffer, const int probability,
-        int *const probabilityFieldPos) {
-    if (probability < 0 || probability > MAX_PROBABILITY) {
-        AKLOGI("probability cannot be written because the probability is invalid: %d",
-                probability);
-        ASSERT(false);
-        return false;
-    }
-    return buffer->writeUintAndAdvancePosition(probability, PROBABILITY_FIELD_SIZE,
-            probabilityFieldPos);
-}
-
 /* static */ bool DynamicPatriciaTrieWritingUtils::writeChildrenPositionAndAdvancePosition(
         BufferWithExtendableBuffer *const buffer, const int childrenPosition,
         int *const childrenPositionFieldPos) {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_utils.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_utils.h
index 5654105..2c3b116 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_utils.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_utils.h
@@ -49,9 +49,6 @@
     static bool writeCodePointsAndAdvancePosition(BufferWithExtendableBuffer *const buffer,
             const int *const codePoints, const int codePointCount, int *const codePointFieldPos);
 
-    static bool writeProbabilityAndAdvancePosition(BufferWithExtendableBuffer *const buffer,
-            const int probability, int *const probabilityFieldPos);
-
     static bool writeChildrenPositionAndAdvancePosition(BufferWithExtendableBuffer *const buffer,
             const int childrenPosition, int *const childrenPositionFieldPos);
 
@@ -67,7 +64,6 @@
     static const int MAX_DICT_OFFSET_VALUE;
     static const int MIN_DICT_OFFSET_VALUE;
     static const int DICT_OFFSET_NEGATIVE_FLAG;
-    static const int PROBABILITY_FIELD_SIZE;
 
     static bool writeDictOffset(BufferWithExtendableBuffer *const buffer, const int targetPos,
             const int basePos, int *const offsetFieldPos);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.cpp b/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.cpp
index 2de8a60..ff762d7 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.cpp
@@ -32,8 +32,6 @@
 /* static */ bool DictFileWritingUtils::createEmptyDictFile(const char *const filePath,
         const int dictVersion, const HeaderReadWriteUtils::AttributeMap *const attributeMap) {
     switch (dictVersion) {
-        case 3:
-            return createEmptyV3DictFile(filePath, attributeMap);
         case 4:
             return createEmptyV4DictFile(filePath, attributeMap);
         default:
@@ -43,23 +41,6 @@
     }
 }
 
-/* static */ bool DictFileWritingUtils::createEmptyV3DictFile(const char *const filePath,
-        const HeaderReadWriteUtils::AttributeMap *const attributeMap) {
-    BufferWithExtendableBuffer headerBuffer(
-            BufferWithExtendableBuffer::DEFAULT_MAX_ADDITIONAL_BUFFER_SIZE);
-    HeaderPolicy headerPolicy(FormatUtils::VERSION_3, attributeMap);
-    headerPolicy.writeHeaderToBuffer(&headerBuffer, true /* updatesLastUpdatedTime */,
-            true /* updatesLastDecayedTime */, 0 /* unigramCount */, 0 /* bigramCount */,
-            0 /* extendedRegionSize */);
-    BufferWithExtendableBuffer bodyBuffer(
-            BufferWithExtendableBuffer::DEFAULT_MAX_ADDITIONAL_BUFFER_SIZE);
-    if (!DynamicPatriciaTrieWritingUtils::writeEmptyDictionary(&bodyBuffer, 0 /* rootPos */)) {
-        AKLOGE("Empty ver3 dictionary structure cannot be created on memory.");
-        return false;
-    }
-    return flushAllHeaderAndBodyToFile(filePath, &headerBuffer, &bodyBuffer);
-}
-
 /* static */ bool DictFileWritingUtils::createEmptyV4DictFile(const char *const dirPath,
         const HeaderReadWriteUtils::AttributeMap *const attributeMap) {
     Ver4DictBuffers::Ver4DictBuffersPtr dictBuffers = Ver4DictBuffers::createVer4DictBuffers();
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.h b/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.h
index 980a1ff..612d754 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.h
@@ -43,9 +43,6 @@
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DictFileWritingUtils);
 
-    static bool createEmptyV3DictFile(const char *const filePath,
-            const HeaderReadWriteUtils::AttributeMap *const attributeMap);
-
     static bool createEmptyV4DictFile(const char *const filePath,
             const HeaderReadWriteUtils::AttributeMap *const attributeMap);
 
diff --git a/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java b/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
index 140ab63..5b888ab 100644
--- a/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
+++ b/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
@@ -74,9 +74,7 @@
 
     private File createEmptyDictionaryAndGetFile(final String dictId,
             final int formatVersion) throws IOException {
-        if (formatVersion == 3) {
-            return createEmptyVer3DictionaryAndGetFile(dictId);
-        } else if (formatVersion == 4) {
+        if (formatVersion == 4) {
             return createEmptyVer4DictionaryAndGetFile(dictId);
         } else {
             throw new IOException("Dictionary format version " + formatVersion
@@ -102,26 +100,7 @@
         }
     }
 
-    private File createEmptyVer3DictionaryAndGetFile(final String dictId) throws IOException {
-        final File file = File.createTempFile(dictId, TEST_DICT_FILE_EXTENSION,
-                getContext().getCacheDir());
-        file.delete();
-        Map<String, String> attributeMap = new HashMap<String, String>();
-        attributeMap.put(FormatSpec.FileHeader.SUPPORTS_DYNAMIC_UPDATE_ATTRIBUTE,
-                FormatSpec.FileHeader.ATTRIBUTE_VALUE_TRUE);
-        attributeMap.put(FormatSpec.FileHeader.USES_FORGETTING_CURVE_ATTRIBUTE,
-                FormatSpec.FileHeader.ATTRIBUTE_VALUE_TRUE);
-        if (BinaryDictionary.createEmptyDictFile(file.getAbsolutePath(), 3 /* dictVersion */,
-                attributeMap)) {
-            return file;
-        } else {
-            throw new IOException(
-                    "Empty dictionary " + file.getAbsolutePath() + " cannot be created.");
-        }
-    }
-
     public void testAddValidAndInvalidWords() {
-        testAddValidAndInvalidWords(3 /* formatVersion */);
         testAddValidAndInvalidWords(4 /* formatVersion */);
     }
 
@@ -172,7 +151,6 @@
     }
 
     public void testDecayingProbability() {
-        testDecayingProbability(3 /* formatVersion */);
         testDecayingProbability(4 /* formatVersion */);
     }
 
@@ -231,7 +209,6 @@
     }
 
     public void testAddManyUnigramsToDecayingDict() {
-        testAddManyUnigramsToDecayingDict(3 /* formatVersion */);
         testAddManyUnigramsToDecayingDict(4 /* formatVersion */);
     }
 
@@ -288,7 +265,6 @@
     }
 
     public void testAddManyBigramsToDecayingDict() {
-        testAddManyBigramsToDecayingDict(3 /* formatVersion */);
         testAddManyBigramsToDecayingDict(4 /* formatVersion */);
     }
 
diff --git a/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java b/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
index dac0dba..29f8241 100644
--- a/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
+++ b/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
@@ -52,9 +52,7 @@
 
     private File createEmptyDictionaryAndGetFile(final String dictId,
             final int formatVersion) throws IOException {
-        if (formatVersion == 3) {
-            return createEmptyVer3DictionaryAndGetFile(dictId);
-        } else if (formatVersion == 4) {
+       if (formatVersion == 4) {
             return createEmptyVer4DictionaryAndGetFile(dictId);
         } else {
             throw new IOException("Dictionary format version " + formatVersion
@@ -79,24 +77,7 @@
         }
     }
 
-    private File createEmptyVer3DictionaryAndGetFile(final String dictId) throws IOException {
-        final File file = File.createTempFile(dictId, TEST_DICT_FILE_EXTENSION,
-                getContext().getCacheDir());
-        file.delete();
-        Map<String, String> attributeMap = new HashMap<String, String>();
-        attributeMap.put(FormatSpec.FileHeader.SUPPORTS_DYNAMIC_UPDATE_ATTRIBUTE,
-                FormatSpec.FileHeader.ATTRIBUTE_VALUE_TRUE);
-        if (BinaryDictionary.createEmptyDictFile(file.getAbsolutePath(), 3 /* dictVersion */,
-                attributeMap)) {
-            return file;
-        } else {
-            throw new IOException(
-                    "Empty dictionary " + file.getAbsolutePath() + " cannot be created.");
-        }
-    }
-
     public void testIsValidDictionary() {
-        testIsValidDictionary(3 /* formatVersion */);
         testIsValidDictionary(4 /* formatVersion */);
     }
 
@@ -125,7 +106,6 @@
     }
 
     public void testAddUnigramWord() {
-        testAddUnigramWord(3 /* formatVersion */);
         testAddUnigramWord(4 /* formatVersion */);
     }
 
@@ -168,7 +148,6 @@
     }
 
     public void testRandomlyAddUnigramWord() {
-        testRandomlyAddUnigramWord(3 /* formatVersion */);
         testRandomlyAddUnigramWord(4 /* formatVersion */);
     }
 
@@ -205,7 +184,6 @@
     }
 
     public void testAddBigramWords() {
-        testAddBigramWords(3 /* formatVersion */);
         testAddBigramWords(4 /* formatVersion */);
     }
 
@@ -274,7 +252,6 @@
     }
 
     public void testRandomlyAddBigramWords() {
-        testRandomlyAddBigramWords(3 /* formatVersion */);
         testRandomlyAddBigramWords(4 /* formatVersion */);
     }
 
@@ -336,7 +313,6 @@
     }
 
     public void testRemoveBigramWords() {
-        testRemoveBigramWords(3 /* formatVersion */);
         testRemoveBigramWords(4 /* formatVersion */);
     }
 
@@ -387,7 +363,6 @@
     }
 
     public void testFlushDictionary() {
-        testFlushDictionary(3 /* formatVersion */);
         testFlushDictionary(4 /* formatVersion */);
     }
 
@@ -440,7 +415,6 @@
     }
 
     public void testFlushWithGCDictionary() {
-        testFlushWithGCDictionary(3 /* formatVersion */);
         testFlushWithGCDictionary(4 /* formatVersion */);
     }
 
@@ -489,7 +463,6 @@
     }
 
     public void testAddBigramWordsAndFlashWithGC() {
-        testAddBigramWordsAndFlashWithGC(3 /* formatVersion */);
         testAddBigramWordsAndFlashWithGC(4 /* formatVersion */);
     }
 
@@ -559,7 +532,6 @@
     }
 
     public void testRandomOperationsAndFlashWithGC() {
-        testRandomOperationsAndFlashWithGC(3 /* formatVersion */);
         testRandomOperationsAndFlashWithGC(4 /* formatVersion */);
     }
 
@@ -671,7 +643,6 @@
     }
 
     public void testAddManyUnigramsAndFlushWithGC() {
-        testAddManyUnigramsAndFlushWithGC(3 /* formatVersion */);
         testAddManyUnigramsAndFlushWithGC(4 /* formatVersion */);
     }
 
@@ -720,7 +691,6 @@
     }
 
     public void testUnigramAndBigramCount() {
-        testUnigramAndBigramCount(3 /* formatVersion */);
         testUnigramAndBigramCount(4 /* formatVersion */);
     }
 
@@ -780,7 +750,6 @@
     }
 
     public void testAddMultipleDictionaryEntries() {
-        testAddMultipleDictionaryEntries(3 /* formatVersion */);
         testAddMultipleDictionaryEntries(4 /* formatVersion */);
     }