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Downcast _SEQUENCE_NUMBER and _VALUE_KIND once per batch in sort merge #1192
Description
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Description
SortMergeCursor::sequence_number and value_kind look up and downcast _SEQUENCE_NUMBER and _VALUE_KIND from the batch for every row the merge emits. The column and its type don't change within a batch, so this can be done once when the cursor is created.
Measured on one instance, alternating main and the change over 8 rounds with 2M keys × 3 overlapping rounds:
| read | main (median) | change (median) |
|---|---|---|
| PK merge | 445–455 ms | 414–427 ms |
| PK DV merge-on-read | 446–451 ms | 412–427 ms |
The ranges don't overlap.
Are you willing to submit a PR?
- I'm willing to submit a PR!
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