Hello Tidy Bot, David Ribeiro Alves, Kudu Jenkins, Todd Lipcon,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/8869
to look at the new patch set (#3).
Change subject: KUDU-2231: sparse column predicate can cause excessive
data-block reads
......................................................................
KUDU-2231: sparse column predicate can cause excessive data-block reads
When scanning with a sparsely-matching predicate, the CFileIterator can
repeatedly materialize non-predicate column blocks multiple times. The
result is huge amounts of CPU wasted in block decoding and poor
performance.
The root cause is that CFileIterator::SeekToOrdinal does not check
whether the currently materialized data block contains the ordinal index
being seeked to. Instead, it throws away the currently prepared blocks
(in CFileIterator::PrepareForNewSeek), and re-materializes the blocks
again.
This commit is a very targeted fix. Since I've had some time to get
familiar with this codepath in the past few days, I've found some things
that I think we could improve and simplify in follow-up commits, which
I've filed as KUDU-2243.
Change-Id: I8eb3be4a809f882ccd80c48612099b2071306ff7
---
M src/kudu/cfile/cfile_reader.cc
M src/kudu/tablet/tablet-pushdown-test.cc
2 files changed, 86 insertions(+), 3 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/69/8869/3
--
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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I8eb3be4a809f882ccd80c48612099b2071306ff7
Gerrit-Change-Number: 8869
Gerrit-PatchSet: 3
Gerrit-Owner: Dan Burkert <[email protected]>
Gerrit-Reviewer: David Ribeiro Alves <[email protected]>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Tidy Bot
Gerrit-Reviewer: Todd Lipcon <[email protected]>
