Allow nodeSort to perform Datum sorts for byref types
David Rowley <drowley@postgresql.org>
Allow nodeSort to perform Datum sorts for byref types Here we add a new 'copy' parameter to tuplesort_getdatum so that we can instruct the function not to datumCopy() byref Datums before returning. Similar to 91e9e89dc, this can provide significant performance improvements in nodeSort when sorting by a single byref column and the sort's targetlist contains only that column. This allows us to re-enable Datum sorts for byref types which was disabled in 3a5817695 due to a reported memory leak. Additionally, here we slightly optimize DISTINCT aggregates so that we no longer perform any datumCopy() when we find the current value not to be distinct from the previous value. Previously the code would always take a copy of the most recent Datum and pfree the previous value, even when the values were the same. Testing shows a small but noticeable performance increase when aggregate transitions are skipped due to the current transition value being the same as the prior one. Author: David Rowley Discussion: https://postgr.es/m/CAApHDvqS6wC5U==k9Hd26E4EQXH3QR67-T4=Q1rQ36NGvjfVSg@mail.gmail.com Discussion: https://postgr.es/m/CAApHDvqHonfe9G1cVaKeHbDx70R_zCrM3qP2AGXpGrieSKGnhA@mail.gmail.com
Files
| Path | Change | +/− |
|---|---|---|
| src/backend/access/heap/heapam_handler.c | modified | +2 −6 |
| src/backend/executor/nodeAgg.c | modified | +20 −11 |
| src/backend/executor/nodeSort.c | modified | +4 −3 |
| src/backend/utils/adt/orderedsetaggs.c | modified | +14 −9 |
| src/backend/utils/sort/tuplesortvariants.c | modified | +16 −2 |
| src/include/utils/tuplesort.h | modified | +1 −1 |
Discussion
- Have nodeSort.c use datum sorts single-value byref types 3 messages · 2022-09-29 → 2022-10-27
- A potential memory leak on Merge Join when Sort node is not below Materialize node 21 messages · 2022-09-28 → 2022-09-29