Aleksandr Efimov has posted comments on this change. ( http://gerrit.cloudera.org:8080/24896 )
Change subject: IMPALA-15381: Reduce reservoir RNG state ...................................................................... Patch Set 2: (1 comment) http://gerrit.cloudera.org:8080/#/c/24896/2/be/src/exprs/aggregate-functions-ir.cc File be/src/exprs/aggregate-functions-ir.cc: http://gerrit.cloudera.org:8080/#/c/24896/2/be/src/exprs/aggregate-functions-ir.cc@1928 PS2, Line 1928: pcg32 rng_; > Since this is using 64-bit integers, shouldn't this be pcg64? (Which may im pcg32 is enough: uniform_int_distribution<int64_t> calls it twice when the range needs more than 32 bits, so the draws stay uniform. That only happens after a group has seen 2^32 rows. pcg64 would grow the state from 48 to 64 bytes, but FreePool rounds both to the same block, so I'm fine switching if you prefer. -- To view, visit http://gerrit.cloudera.org:8080/24896 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I9e046e3f0c1b91f1761ce578601a330bd864eb84 Gerrit-Change-Number: 24896 Gerrit-PatchSet: 2 Gerrit-Owner: Aleksandr Efimov <[email protected]> Gerrit-Reviewer: Aleksandr Efimov <[email protected]> Gerrit-Reviewer: Csaba Ringhofer <[email protected]> Gerrit-Reviewer: Impala Public Jenkins <[email protected]> Gerrit-Reviewer: Joe McDonnell <[email protected]> Gerrit-Reviewer: Michael Smith <[email protected]> Gerrit-Reviewer: Riza Suminto <[email protected]> Gerrit-Comment-Date: Mon, 21 Sep 2026 18:35:43 +0000 Gerrit-HasComments: Yes
