planner/core: force first column used if no columns required (#9125) #9754
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Codecov Report
@@ Coverage Diff @@
## master #9754 +/- ##
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- Coverage 67.191% 67.1668% -0.0243%
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Files 381 381
Lines 79835 79837 +2
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- Hits 53642 53624 -18
- Misses 21408 21422 +14
- Partials 4785 4791 +6 |
morgo
added
contribution
eurekaka
reviewed
Mar 18, 2019
| // For sql like `select count(1) from (select count(1) from t)`, no column used. | ||
| // tikv's response will be empty if the inner aggr is pushed down. | ||
| // We should force some column to be used. | ||
| used[0] = true |
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This fix looks pretty ad-hoc, IMHO a better approach would be extracting columns from aggregation(constant).
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You are right -_-. I had the same feeling when I tried to fix this issue. Thanks for your feedback and advice.
|
Thanks for your contribution. |
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What problem does this PR solve?
Fix issue #9125
What is changed and how it works?
For sql like
select count(1) from (select count(1) from t), no column used for the inner Aggregation. TiKV's response will be empty if the inner Aggregation is pushed down. So force some column to be used for the inner Aggregation.Check List
Tests
Code changes
Side effects
Related changes