gortiz opened a new pull request, #14212:
URL: https://github.com/apache/pinot/pull/14212
This PR fixes 2 non critical but annoying issues in multi-stage:
## Issue 1
Plans from different servers were not correctly merged when segments for
each server produced different plans. For example, in colocated join, the
following query:
```sql
EXPLAIN PLAN FOR
SELECT DISTINCT deviceOS, groupUUID
FROM userAttributes AS a
JOIN userGroups AS g
ON a.userUUID = g.userUUID
WHERE g.groupUUID = 'group-1'
LIMIT 100
```
Produced:
```
Execution Plan
LogicalSort(offset=[0], fetch=[100])
PinotLogicalSortExchange(distribution=[hash], collation=[[]],
isSortOnSender=[false], isSortOnReceiver=[false])
LogicalSort(fetch=[100])
PinotLogicalAggregate(group=[{0, 1}])
PinotLogicalExchange(distribution=[hash[0, 1]])
PinotLogicalAggregate(group=[{0, 2}])
LogicalJoin(condition=[=($1, $3)], joinType=[inner])
PinotLogicalExchange(distribution=[hash[1]])
LeafStageCombineOperator(table=[userAttributes])
StreamingInstanceResponse
StreamingCombineSelect(repeated=[4])
SelectStreaming(table=[userAttributes],
totalDocs=[10000])
Project(columns=[[deviceOS, userUUID]])
DocIdSet(maxDocs=[40000])
FilterMatchEntireSegment(numDocs=[10000])
IntermediateCombine
Alternative(servers=[1])
PinotLogicalExchange(distribution=[hash[1]])
LeafStageCombineOperator(table=[userGroups])
StreamingInstanceResponse
StreamingCombineSelect
SelectStreaming(segment=[userGroups_OFFLINE_0],
table=[userGroups], totalDocs=[7])
Project(columns=[[groupUUID, userUUID]])
DocIdSet(maxDocs=[10000])
FilterInvertedIndex(predicate=[groupUUID =
'group-1'], indexLookUp=[inverted_index], operator=[EQ])
SelectStreaming(segment=[userGroups_OFFLINE_4],
table=[userGroups], totalDocs=[4])
Project(columns=[[groupUUID, userUUID]])
DocIdSet(maxDocs=[10000])
FilterEmpty
SelectStreaming(segment=[userGroups_OFFLINE_6],
table=[userGroups], totalDocs=[4])
Project(columns=[[groupUUID, userUUID]])
DocIdSet(maxDocs=[10000])
FilterMatchEntireSegment(numDocs=[4])
Alternative(servers=[1])
PinotLogicalExchange(distribution=[hash[1]])
LeafStageCombineOperator(table=[userGroups])
StreamingInstanceResponse
StreamingCombineSelect(repeated=[4])
SelectStreaming(table=[userGroups],
totalDocs=[2471])
Project(columns=[[groupUUID, userUUID]])
DocIdSet(maxDocs=[40000])
FilterInvertedIndex(predicate=[groupUUID =
'group-1'], indexLookUp=[inverted_index], operator=[EQ])
```
While with these changes both alternatives are merged, producing the
following explain:
```
Execution Plan
LogicalSort(offset=[0], fetch=[100])
PinotLogicalSortExchange(distribution=[hash], collation=[[]],
isSortOnSender=[false], isSortOnReceiver=[false])
LogicalSort(fetch=[100])
PinotLogicalAggregate(group=[{0, 1}])
PinotLogicalExchange(distribution=[hash[0, 1]])
PinotLogicalAggregate(group=[{0, 2}])
LogicalJoin(condition=[=($1, $3)], joinType=[inner])
PinotLogicalExchange(distribution=[hash[1]])
LeafStageCombineOperator(table=[userAttributes])
StreamingInstanceResponse
StreamingCombineSelect
SelectStreaming(table=[userAttributes],
totalDocs=[10000])
Project(columns=[[deviceOS, userUUID]])
DocIdSet(maxDocs=[40000])
FilterMatchEntireSegment(numDocs=[10000])
PinotLogicalExchange(distribution=[hash[1]])
LeafStageCombineOperator(table=[userGroups])
StreamingInstanceResponse
StreamingCombineSelect
SelectStreaming(table=[userGroups], totalDocs=[2478])
Project(columns=[[groupUUID, userUUID]])
DocIdSet(maxDocs=[50000])
FilterInvertedIndex(predicate=[groupUUID =
'group-1'], indexLookUp=[inverted_index], operator=[EQ])
SelectStreaming(segment=[userGroups_OFFLINE_4],
table=[userGroups], totalDocs=[4])
Project(columns=[[groupUUID, userUUID]])
DocIdSet(maxDocs=[10000])
FilterEmpty
SelectStreaming(segment=[userGroups_OFFLINE_6],
table=[userGroups], totalDocs=[4])
Project(columns=[[groupUUID, userUUID]])
DocIdSet(maxDocs=[10000])
FilterMatchEntireSegment(numDocs=[4])
```
Which is easier to read.
## Issue 2
There was an error in how IDEMPOTENT and IGNORABLE attributes were merged,
which ended up randomly including the `segment` attribute `SelectStreaming`.
The expected behavior is that this attribute should only appear if there is a
single plan for that segment. Before this fix, the attribute was removed when
merging 2 plans with that attribute and different value, but was kept when
merging a plan without the attribute with another with the attribute.
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