sachouche commented on a change in pull request #1330: DRILL-6147: Adding
Columnar Parquet Batch Sizing functionality
URL: https://github.com/apache/drill/pull/1330#discussion_r198930977
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File path:
exec/java-exec/src/main/java/org/apache/drill/exec/ExecConstants.java
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@@ -315,6 +315,13 @@ private ExecConstants() {
public static final String PARQUET_FLAT_READER_BULK =
"store.parquet.flat.reader.bulk";
public static final OptionValidator PARQUET_FLAT_READER_BULK_VALIDATOR = new
BooleanValidator(PARQUET_FLAT_READER_BULK);
+ // Controls the flat parquet reader batching constraints (number of record
and memory limit)
+ public static final String PARQUET_FLAT_BATCH_NUM_RECORDS =
"store.parquet.flat.batch.num_records";
Review comment:
- First of all, these constraints are meant for internal use
- Providing a constraint on the number of rows allows us a) to cap this
number (e.g., less than 64k-1 to avoid overflowing vectors with offsets or
nullables) and b) to all allow the performance team tune the best number of
rows per batch; for example, the memory constraint could be 32/16MB but yet a
batch of 8k rows is more than enough for a good performance. The higher memory
is to handle wide selection..
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