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Posted to dev@parquet.apache.org by "ConeyLiu (via GitHub)" <gi...@apache.org> on 2023/11/03 09:22:12 UTC

[PR] PARQUET-2372: Avoid unnecessary reading of RowGroup data during rewriting [parquet-mr]

ConeyLiu opened a new pull request, #1183:
URL: https://github.com/apache/parquet-mr/pull/1183

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   This patch aims to reduce the unnecessary RowGroup data reading during rewriting.
   


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Re: [PR] PARQUET-2372: Avoid unnecessary reading of RowGroup data during rewriting [parquet-mr]

Posted by "ConeyLiu (via GitHub)" <gi...@apache.org>.
ConeyLiu commented on PR #1183:
URL: https://github.com/apache/parquet-mr/pull/1183#issuecomment-1792112960

   @wgtmac A small improvement, please take a look when you are free. Thanks a lot.


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Re: [PR] PARQUET-2372: Avoid unnecessary reading of RowGroup data during rewriting [parquet-mr]

Posted by "wgtmac (via GitHub)" <gi...@apache.org>.
wgtmac commented on code in PR #1183:
URL: https://github.com/apache/parquet-mr/pull/1183#discussion_r1382413034


##########
parquet-hadoop/src/main/java/org/apache/parquet/hadoop/rewrite/ParquetRewriter.java:
##########
@@ -265,14 +265,9 @@ public void processBlocks() throws IOException {
   }
 
   private void processBlocksFromReader(IndexCache indexCache) throws IOException {
-    PageReadStore store = reader.readNextRowGroup();
-    ColumnReadStoreImpl crStore = new ColumnReadStoreImpl(store, new DummyGroupConverter(), schema, originalCreatedBy);
-
-    int blockId = 0;
-    while (store != null) {
-      writer.startBlock(store.getRowCount());
-
+    for (int blockId = 0; blockId < meta.getBlocks().size(); blockId ++) {
       BlockMetaData blockMetaData = meta.getBlocks().get(blockId);
+      writer.startBlock(blockMetaData.getRowCount());

Review Comment:
   Make sense!



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Re: [PR] PARQUET-2372: Avoid unnecessary reading of RowGroup data during rewriting [parquet-mr]

Posted by "ConeyLiu (via GitHub)" <gi...@apache.org>.
ConeyLiu commented on code in PR #1183:
URL: https://github.com/apache/parquet-mr/pull/1183#discussion_r1381382668


##########
parquet-hadoop/src/main/java/org/apache/parquet/hadoop/rewrite/ParquetRewriter.java:
##########
@@ -265,14 +265,9 @@ public void processBlocks() throws IOException {
   }
 
   private void processBlocksFromReader(IndexCache indexCache) throws IOException {
-    PageReadStore store = reader.readNextRowGroup();
-    ColumnReadStoreImpl crStore = new ColumnReadStoreImpl(store, new DummyGroupConverter(), schema, originalCreatedBy);
-
-    int blockId = 0;
-    while (store != null) {
-      writer.startBlock(store.getRowCount());

Review Comment:
   We don't need to get the row count from the `PageReadStore` since getting the `PageReadStore` will force read the whole row group data into memory.



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Re: [PR] PARQUET-2372: Avoid unnecessary reading of RowGroup data during rewriting [parquet-mr]

Posted by "ConeyLiu (via GitHub)" <gi...@apache.org>.
ConeyLiu commented on code in PR #1183:
URL: https://github.com/apache/parquet-mr/pull/1183#discussion_r1381384113


##########
parquet-hadoop/src/main/java/org/apache/parquet/hadoop/rewrite/ParquetRewriter.java:
##########
@@ -323,7 +318,7 @@ private void processBlocksFromReader(IndexCache indexCache) throws IOException {
           }
 
           // Translate compression and/or encryption
-          writer.startColumn(descriptor, crStore.getColumnReader(descriptor).getTotalValueCount(), newCodecName);
+          writer.startColumn(descriptor, chunk.getValueCount(), newCodecName);

Review Comment:
   Same here, just get the value count from the ColumnChunkMetaData



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Re: [PR] PARQUET-2372: Avoid unnecessary reading of RowGroup data during rewriting [parquet-mr]

Posted by "wgtmac (via GitHub)" <gi...@apache.org>.
wgtmac merged PR #1183:
URL: https://github.com/apache/parquet-mr/pull/1183


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Re: [PR] PARQUET-2372: Avoid unnecessary reading of RowGroup data during rewriting [parquet-mr]

Posted by "ConeyLiu (via GitHub)" <gi...@apache.org>.
ConeyLiu commented on PR #1183:
URL: https://github.com/apache/parquet-mr/pull/1183#issuecomment-1803078643

   Thanks @wgtmac 


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Re: [PR] PARQUET-2372: Avoid unnecessary reading of RowGroup data during rewriting [parquet-mr]

Posted by "ConeyLiu (via GitHub)" <gi...@apache.org>.
ConeyLiu commented on code in PR #1183:
URL: https://github.com/apache/parquet-mr/pull/1183#discussion_r1381383424


##########
parquet-hadoop/src/main/java/org/apache/parquet/hadoop/rewrite/ParquetRewriter.java:
##########
@@ -265,14 +265,9 @@ public void processBlocks() throws IOException {
   }
 
   private void processBlocksFromReader(IndexCache indexCache) throws IOException {
-    PageReadStore store = reader.readNextRowGroup();
-    ColumnReadStoreImpl crStore = new ColumnReadStoreImpl(store, new DummyGroupConverter(), schema, originalCreatedBy);
-
-    int blockId = 0;
-    while (store != null) {
-      writer.startBlock(store.getRowCount());
-
+    for (int blockId = 0; blockId < meta.getBlocks().size(); blockId ++) {
       BlockMetaData blockMetaData = meta.getBlocks().get(blockId);
+      writer.startBlock(blockMetaData.getRowCount());

Review Comment:
   Just get the row count from the `BlockMetaData`



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Re: [PR] PARQUET-2372: Avoid unnecessary reading of RowGroup data during rewriting [parquet-mr]

Posted by "ConeyLiu (via GitHub)" <gi...@apache.org>.
ConeyLiu commented on code in PR #1183:
URL: https://github.com/apache/parquet-mr/pull/1183#discussion_r1381384663


##########
parquet-hadoop/src/main/java/org/apache/parquet/hadoop/rewrite/ParquetRewriter.java:
##########
@@ -666,6 +658,8 @@ private void nullifyColumn(ColumnDescriptor descriptor,
 
     long totalChunkValues = chunk.getValueCount();
     int dMax = descriptor.getMaxDefinitionLevel();
+    PageReadStore pageReadStore = reader.readRowGroup(blockIndex);

Review Comment:
   Only get the `PageReadStore` when needed.



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