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From "Alex Behm (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] [DOCS] Tighten up advice about first COMPUTE INCREMENTAL STATS
Date Fri, 06 Oct 2017 21:53:46 GMT
Alex Behm has posted comments on this change. ( http://gerrit.cloudera.org:8080/7999 )

Change subject: [DOCS] Tighten up advice about first COMPUTE INCREMENTAL STATS
......................................................................


Patch Set 4:

(5 comments)

http://gerrit.cloudera.org:8080/#/c/7999/4/docs/shared/impala_common.xml
File docs/shared/impala_common.xml:

http://gerrit.cloudera.org:8080/#/c/7999/4/docs/shared/impala_common.xml@1227
PS4, Line 1227:         <codeph>COMPUTE INCREMENTAL STATS</codeph> during the
lifetime of a table,
(or vice versa)


http://gerrit.cloudera.org:8080/#/c/7999/4/docs/shared/impala_common.xml@1243
PS4, Line 1243:         be cached on every <cmdname>impalad</cmdname> host that
is eligible to be a coordinator.
as it must be cached on the catalogd and on every ...


http://gerrit.cloudera.org:8080/#/c/7999/4/docs/shared/impala_common.xml@1244
PS4, Line 1244:         If this metadata for a table exceeds 2 GB, you might experience service
downtime.
It's worse than that. If the aggregate metadata of *all* tables combined gets to 2GB you may
experience downtime.


http://gerrit.cloudera.org:8080/#/c/7999/4/docs/topics/impala_partitioning.xml
File docs/topics/impala_partitioning.xml:

http://gerrit.cloudera.org:8080/#/c/7999/4/docs/topics/impala_partitioning.xml@612
PS4, Line 612:         as new partitions are added, Impala includes a variation of this statement
that is intended for use with
How about:

includes a variation of this statement that allows computing statistics on a per-partition
basis such that stats can be incrementally updated when new partitions are added.


http://gerrit.cloudera.org:8080/#/c/7999/4/docs/topics/impala_perf_stats.xml
File docs/topics/impala_perf_stats.xml:

http://gerrit.cloudera.org:8080/#/c/7999/4/docs/topics/impala_perf_stats.xml@361
PS4, Line 361:           <codeph>COMPUTE STATS</codeph> statement might take hours,
or even days. For such tables, use
Sorry, I disagree with the "For such tables, use COMPUTE INCREMENTAL STATS" part. I think
we need to be very careful about recommending incremental stats. We can document what it does,
but I think we should go out of out way to not explicitly recommend it for any reason.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Ia53a6518ce5541e5c9a2cd896856ce042a599b03
Gerrit-Change-Number: 7999
Gerrit-PatchSet: 4
Gerrit-Owner: John Russell <jrussell@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Greg Rahn <grahn@cloudera.com>
Gerrit-Reviewer: John Russell <jrussell@cloudera.com>
Gerrit-Reviewer: Mostafa Mokhtar <mmokhtar@cloudera.com>
Gerrit-Reviewer: Silvius Rus <srus@cloudera.com>
Gerrit-Reviewer: Vuk Ercegovac <vercegovac@cloudera.com>
Gerrit-Comment-Date: Fri, 06 Oct 2017 21:53:46 +0000
Gerrit-HasComments: Yes

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