planner: fix a corner case in column pruning rule #10974
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@@ Coverage Diff @@
## master #10974 +/- ##
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Coverage 81.0119% 81.0119%
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Files 418 418
Lines 89335 89335
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Hits 72372 72372
Misses 11731 11731
Partials 5232 5232 |
planner/core/rule_column_pruning.go
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| return err | ||
| } | ||
| la.AggFuncs = []*aggregation.AggFuncDesc{one} | ||
| la.schema.Columns = []*expression.Column{{TblName: model.NewCIStr("dummy_cnt"), RetType: types.NewFieldType(mysql.TypeLonglong)}} |
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Fill ColName and UniqueID as well?
planner/core/rule_column_pruning.go
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| if len(la.GroupByItems) == 0 && len(la.AggFuncs) == 0 { | ||
| // If all the aggregate functions are pruned and there is no group-by item, we should add | ||
| // an aggregate function to keep the correctness. | ||
| one, err := aggregation.NewAggFuncDesc(la.ctx, ast.AggFuncCount, []expression.Expression{expression.One}, false) |
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I prefer using first_row(1) here.
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You're right... first_row is better
planner/core/rule_column_pruning.go
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| @@ -117,6 +119,17 @@ func (la *LogicalAggregation) PruneColumns(parentUsedCols []*expression.Column) | |||
| for _, aggrFunc := range la.AggFuncs { | |||
| selfUsedCols = expression.ExtractColumnsFromExpressions(selfUsedCols, aggrFunc.Args, nil) | |||
| } | |||
| if len(la.GroupByItems) == 0 && len(la.AggFuncs) == 0 { | |||
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If len(la.GroupByItems) > 0 && len(la.AggFuncs) == 0, we'd better add this dummy aggregation function as well. Though the result is correct now, we are depending on the specific implementation of executor, if executor is changed in the future, we may have problem for this case then.
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Thanks for the explanation
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addressed, thank you @eurekaka |
zz-jason
added
status/LGT2
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/run-all-tests |
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needs to be cherry-picked to release-2.1 and release-3.0 |
OKay |
What problem does this PR solve?
This PR tries to close #9125
What is changed and how it works?
For a
LogicalAggregation, if all of its functions are pruned and it doesn't have group-by items, a dummy aggregate function is added to keep the correctness.Check List
Tests
Side effects
Related changes