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From "Alex Behm (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] Release note updates for Impala 2.8
Date Wed, 01 Feb 2017 22:12:45 GMT
Alex Behm has posted comments on this change.

Change subject: Release note updates for Impala 2.8
......................................................................


Patch Set 7:

(2 comments)

http://gerrit.cloudera.org:8080/#/c/5668/7/docs/topics/impala_new_features.xml
File docs/topics/impala_new_features.xml:

Line 65:               <p rev="IMPALA-4572">
We should definitely also highlight IMPALA-1430 which fixes the slow COMPUTE STATS issue with
TIMESTAMP. COMPUTE STATS is now codegen'd even if there are TIMESTAMP columns. The JIRA is
not yet marked as fixed because there is some follow-on work, but the COMPUTE STATS issue
specifically has been fixed.


Line 130:                 format <codeph>TIMESTAMP</codeph> values, such as the
result
A naked now() function is a particularly bad example, because now() is already constant within
a query, so does not benefit from this improvement. A better example is something like:

WHERE date_col = to_date(now() - interval 1 day)

the right-hand size expression is somewhat complicated and expensive to evaluate for every
row. Constant folding makes this significantly faster.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I7c47f422e509cec6d3eb8aaa82294b584f393aed
Gerrit-PatchSet: 7
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: John Russell <jrussell@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Ambreen Kazi <ambreen.kazi@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhecht@cloudera.com>
Gerrit-Reviewer: Dimitris Tsirogiannis <dtsirogiannis@cloudera.com>
Gerrit-Reviewer: Greg Rahn <grahn@cloudera.com>
Gerrit-Reviewer: Henry Robinson <henry@cloudera.com>
Gerrit-Reviewer: Jim Apple <jbapple-impala@apache.org>
Gerrit-Reviewer: John Russell <jrussell@cloudera.com>
Gerrit-Reviewer: Laurel Hale <laurel@cloudera.com>
Gerrit-Reviewer: Matthew Jacobs <mj@cloudera.com>
Gerrit-Reviewer: Silvius Rus <srus@cloudera.com>
Gerrit-HasComments: Yes

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