[kudu-CR] Short-circuit CheckRowDeleted if there are no deletes in DeltaFile

["Todd Lipcon (Code Review)" <ge...@cloudera.org>]

Hello Jean-Daniel Cryans, Adar Dembo,

I'd like you to do a code review.  Please visit

    http://gerrit.cloudera.org:8080/2975

to review the following change.

Change subject: Short-circuit CheckRowDeleted if there are no deletes in DeltaFile
......................................................................

Short-circuit CheckRowDeleted if there are no deletes in DeltaFile

For every mutation, we need to check whether the existing row has been deleted.
In the case that there are delta files, this causes a deltafile seek.

By looking at the deltafile stats up front, we can tell whether there are any
deletes at all, and if there aren't, we know that the row in question hasn't
been deleted.

Looking at a profile of a heavy update workload on a large table,
CheckRowDeleted() and its descendents were taking about 25% of the total CPU,
so this should be a substantial win.

Change-Id: Iaa35bab3f9a9fc82149d11821733e87a7aaf5e7a
---
M src/kudu/tablet/deltafile.cc
1 file changed, 9 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/75/2975/1
-- 
To view, visit http://gerrit.cloudera.org:8080/2975
To unsubscribe, visit http://gerrit.cloudera.org:8080/settings

Gerrit-MessageType: newchange
Gerrit-Change-Id: Iaa35bab3f9a9fc82149d11821733e87a7aaf5e7a
Gerrit-PatchSet: 1
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Todd Lipcon <to...@apache.org>
Gerrit-Reviewer: Adar Dembo <ad...@cloudera.com>
Gerrit-Reviewer: Jean-Daniel Cryans