Hello Marton Greber, Alexey Serbin, Kudu Jenkins,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/24158
to look at the new patch set (#2).
Change subject: [tablet] optimize MemRowSet scan to single-pass changelist
application
......................................................................
[tablet] optimize MemRowSet scan to single-pass changelist application
Previously, ApplyMutationsToProjectedRow applied mutations by iterating
through the RowChangeList once per projected column, creating a new
RowChangeListDecoder for each column and calling ApplyToOneColumn. This
resulted in O(P * C) complexity where P is the number of projected
columns and C is the number of column updates in the changelist.
This patch replaces the multi-pass approach with a single-pass
traversal: decode each column update once and use the projection
schema's find_column_by_id() (via DecodedUpdate::Validate()) as the
reverse mapping to locate the destination column. Updates for columns
not in the projection are simply skipped. This reduces the complexity
to O(C).
The improvement is most significant for wide-table scans with many
projected columns and long mutation chains, where the old code would
re-decode the same changelist bytes P times.
Change-Id: I7ccdfcf207680261907d025b64a9b046bb108f13
---
M src/kudu/tablet/memrowset-test.cc
M src/kudu/tablet/memrowset.cc
2 files changed, 844 insertions(+), 9 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/58/24158/2
--
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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I7ccdfcf207680261907d025b64a9b046bb108f13
Gerrit-Change-Number: 24158
Gerrit-PatchSet: 2
Gerrit-Owner: Yan-Daojiang <[email protected]>
Gerrit-Reviewer: Alexey Serbin <[email protected]>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Marton Greber <[email protected]>
Gerrit-Reviewer: Yan-Daojiang <[email protected]>
