jpisaac commented on code in PR #1495:
URL: https://github.com/apache/phoenix/pull/1495#discussion_r959852122
##########
phoenix-core/src/main/java/org/apache/phoenix/compile/WhereOptimizer.java:
##########
@@ -308,6 +322,30 @@ public static Expression
pushKeyExpressionsToScan(StatementContext context, Set<
slotSpanArray[cnf.size()] = clipLeftSpan-1;
cnf.add(keyRanges);
}
+
+ // Do not use the skipScanFilter when there is a large IN clause
(for e.g > 50k elements)
+ // Since the generation of point keys for skip scan filter will
blow up the memory usage.
+ // See ScanRanges.getPointKeys(...) where using the various slot
key ranges
+ // to generate point keys will lead to combinatorial explosion.
+ // The following check will ensure the cardinality of generated
point keys
+ // is below the configured max (maxInListSkipScanSize).
+ // We shall force a range scan if the configured max is exceeded.
+ // cnfStartPos => is the start slot of this IN list
+ if (checkMaxSkipScanCardinality) {
Review Comment:
@chrajeshbabu For some queries especially with RVC expression and mixed sort
orders, the cost of optimization results in huge memory allocations and
sometimes even exceeds the number of KEY_RANGES
[allowed](https://github.com/apache/phoenix/blob/8612c81dfec001c5b88b13d7a5c7ccc9038f41f7/phoenix-core/src/main/java/org/apache/phoenix/filter/SkipScanFilter.java#L580)
This JIRA provides a framework for opting out the optimization path when a
certain threshold is reached. We will be working towards an algorithm that is
more linear in nature than combinatorial as is the case today.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
