I've looked through the updated patch. Overall it looks good enough.
Some minor things:
- PARALLEL_SORT macro is based on coordinate struct instead of state struct. In some calls(i.e. from _bt_spools_heapscan) coordinate could appear to be NULL, which can be a segfault on items dereference inside the macro.
- state->worker and coordinate->isWorker a little bit differ in semantics i.e.:
..............................................worker............... leader
state -> worker........................ >=0.....................-1
coordinate ->isWorker............. 1..........................0
- in tuplesort_begin_index_btree I suppose it should be base->nKeys instead of state->nKeys
- Cfbot reports gcc warnings due to mixed code and declarations. So I used this to beautify code in tuplesortvariants.c a little. (This is added as a separate patch 0007)
All these things are corrected/done in a new version 3 of a patchset (PFA). For me, the patchset seems like a long-needed thing to support PostgreSQL extensibility. Overall corrections in v3 are minor, so I'd like to mark the patch as RfC if there are no objections.
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Best regards,
Pavel Borisov
Supabase.
