Backport to 2.18.x: #7661: Optimize quals on segmentby columns in ColumnarScan #7671
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When filtering arrow slots in ColumnarScan, quals on segmentby columns should be executed separately from those on other columns because they don't require decompression and might filter the whole arrow slot in one go. Furthermore, the quals only need to be applied once per arrow slot since the segmentby value is the same for all compressed rows in the slot. This will speed up scans when filters on segmentby columns cannot be pushed down to Hypercore TAM as scankeys. For example, "<column> IN (1, 2, 3)" won't be pushed down as a scankey because only index scans support scankeys with such scalar array expressions. (cherry picked from commit 8cff1c2)
Fix a bug when backwards scanning a ColumnarScan and add a test case. (cherry picked from commit cde8185)
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This is an automated backport of #7661: Optimize quals on segmentby columns in ColumnarScan.
This PR will be merged automatically after all the relevant CI checks pass. If this fix should not be backported, or will be backported manually, just close this PR. You can use the backport branch to add your changes, it won't be modified automatically anymore.
For more details, please see the documentation
Original description
Optimize quals on segmentby columns in ColumnarScan
When filtering arrow slots in ColumnarScan, quals on segmentby columns should be executed separately from those on other columns because they don't require decompression and might filter the whole arrow slot in one go. Furthermore, the quals only need to be applied once per arrow slot since the segmentby value is the same for all compressed rows in the slot.
This will speed up scans when filters on segmentby columns cannot be pushed down to Hypercore TAM as scankeys. For example, " IN (1, 2, 3)" won't be pushed down as a scankey because only index scans support scankeys with such scalar array expressions.
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