Hello Riza Suminto, Joe McDonnell, Csaba Ringhofer, Michael Smith, Impala
Public Jenkins,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/24896
to look at the new patch set (#3).
Change subject: IMPALA-15381: Reduce reservoir RNG state
......................................................................
IMPALA-15381: Reduce reservoir RNG state
boost::mt19937_64 makes ReservoirSampleState 2536 bytes. FreePool
rounds the allocation to 4 KiB, so sampling aggregates use 4624
bytes per function and group with their initial sample array.
Use pcg32 to reduce the state to 48 bytes. The sampling sequence
changes, so approximate results can change.
Testing:
- Full release build
- HistogramTest.*
- Large appx_median(), sample(), and histogram() queries
Change-Id: I9e046e3f0c1b91f1761ce578601a330bd864eb84
Assisted-by: gpt-5.6-sol (OpenAI Codex)
---
M be/src/exprs/aggregate-functions-ir.cc
1 file changed, 7 insertions(+), 11 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/96/24896/3
--
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I9e046e3f0c1b91f1761ce578601a330bd864eb84
Gerrit-Change-Number: 24896
Gerrit-PatchSet: 3
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]>
