Ben-Zvi commented on a change in pull request #1606: Drill 6845: Semi-Hash-Join
to skip incoming build duplicates, automatically stop skipping if too few
URL: https://github.com/apache/drill/pull/1606#discussion_r247747842
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/HashJoinBatch.java
##########
@@ -973,9 +973,32 @@ public IterOutcome executeBuildPhase() throws
SchemaChangeException {
// Do auto tuning
buildCalc = partitionNumTuning(maxBatchRowCount, buildCalc);
}
- // to be used in case of a Semi Join skippinging duplicates
- spillControlCalc = new HashJoinSpillControlImpl(allocator,
RECORDS_PER_BATCH,
- (int)
context.getOptions().getOption(ExecConstants.HASHJOIN_MIN_BATCHES_IN_AVAILABLE_MEMORY_VALIDATOR),
batchMemoryManager);
+ if ( semiSkipDuplicates ) {
+ // in case of a Semi Join skippinging duplicates, use a "spill
control" calc
+ // (may revert back to the buildCalc if the code decides to stop
skipping)
+ currentCalc = new HashJoinSpillControlImpl(allocator,
RECORDS_PER_BATCH,
+ (int)
context.getOptions().getOption(ExecConstants.HASHJOIN_MIN_BATCHES_IN_AVAILABLE_MEMORY_VALIDATOR),
Review comment:
The idea was to leave a small "slack" in memory to cover cases like
inaccurate estimates (e.g., probe side), or varchar buffer doubling, and that
"incoming" batch read from the spill file, etc.
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