Add flag in SQL to disable left base filter optimization for joins#10947
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maytasm merged 7 commits intoapache:masterfrom Mar 9, 2021
Merged
Add flag in SQL to disable left base filter optimization for joins#10947maytasm merged 7 commits intoapache:masterfrom
maytasm merged 7 commits intoapache:masterfrom
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clintropolis
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Mar 9, 2021
| // This flag control whether a sql join query with left scan should be attempted to be run as direct table access | ||
| // instead of being wrapped inside a query. With direct table access enabled, druid can push down the join operation to | ||
| // data servers. | ||
| public static final String SQL_JOIN_LEFT_SCAN_DIRECT = "enableSQLLeftTableScanDirect"; |
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this should maybe be enableJoinLeftTableScanDirect to be more consistent with other join related query context parameters. I also think it should probably be documented, but none of the other join query context parameters are documented (not sure why), so not sure its a blocker for this PR.
clintropolis
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k8s integration test failed which is unrelated to changes in this PR. |
kgyrtkirk
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Relates to apache#10947 Some note about disabling it was added [here](https://github.com/apache/druid/pull/10947/files#diff-39158f6b501cd2bcc925a57cbe8d07affbeaa683e33b3ec3f533cde8d8249094R62) > Please note that the flag could be applicable to queries even if there is no explicit join. since queries can internally translated into a join by the SQL planner.
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Follow up on #10697 where we added an optimization to push joins to historicals when left child is a scan with a filter. However, the change could actually underperform depending on the kind of query. This PR introduces a flag to switch between two behaviors. Default value of this flag is false.
Also fixed a bug pointed out by @gianm - https://github.com/apache/druid/pull/10697/files#r587924983