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Posted to issues@trafodion.apache.org by "ASF GitHub Bot (JIRA)" <ji...@apache.org> on 2016/06/02 22:11:59 UTC
[jira] [Commented] (TRAFODION-1585) MDAM plan is not chosen unless
NJ is turned off
[ https://issues.apache.org/jira/browse/TRAFODION-1585?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15313182#comment-15313182 ]
ASF GitHub Bot commented on TRAFODION-1585:
-------------------------------------------
GitHub user DaveBirdsall opened a pull request:
https://github.com/apache/incubator-trafodion/pull/519
[TRAFODION-1585] Allow MDAM on inner child of NJ sometimes
If it is known that there will be exactly one probe of the inner child of a nested join, this change enables consideration of MDAM for that inner child.
This is a replacement of https://github.com/apache/incubator-trafodion/pull/174. It takes the suggestion from @zellerh to use the input logical properties instead of adding constraint information to the input physical properties. The result is a much simpler code change. I will close the older pull request shortly.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/DaveBirdsall/incubator-trafodion Trafodion1585
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-trafodion/pull/519.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #519
----
commit e2ffd9e096a841b8e57fc68776c981c3a98816e1
Author: Dave Birdsall <db...@apache.org>
Date: 2016-06-02T22:07:37Z
[TRAFODION-1585] Allow MDAM on inner child of NJ if there is only one NJ probe
----
> MDAM plan is not chosen unless NJ is turned off
> -----------------------------------------------
>
> Key: TRAFODION-1585
> URL: https://issues.apache.org/jira/browse/TRAFODION-1585
> Project: Apache Trafodion
> Issue Type: Bug
> Components: sql-cmp
> Reporter: Qifan Chen
> Assignee: David Wayne Birdsall
>
> MDAM is used in scan node #8 in the following plan.
> >explain options 'f' xx;
> LC RC OP OPERATOR OPT DESCRIPTION CARD
> ---- ---- ---- -------------------- -------- -------------------- ---------
> 15 . 16 root 1.00E+000
> 14 7 15 hybrid_hash_join 1.00E+000
> 13 . 14 hash_partial_groupby 1.00E+000
> 12 . 13 esp_exchange 1:21(hash2) 1.00E+000
> 11 . 12 sort_partial_groupby 1.00E+000
> 10 . 11 hash_groupby 6.60E+004
> 9 . 10 hash_groupby 1.35E+005
> 8 . 9 esp_exchange 21(hash2):16(hash2) 1.40E+006
> . . 8 trafodion_scan OP 1.40E+006
> 6 . 7 sort_groupby 1.00E+000
> 5 . 6 hash_partial_groupby 3.09E+001
> 4 . 5 esp_exchange 1:21(hash2) 3.09E+001
> 3 . 4 hash_partial_groupby 3.09E+001
> 2 . 3 hash_groupby 1.35E+005
> 1 . 2 esp_exchange 21(hash2):16(hash2) 1.40E+006
> . . 1 trafodion_scan OP 1.40E+006
> The same MDAM scan is absent if CQD NESTED_JOINS 'off' is not used.
> TRAFODION_SCAN ============================ SEQ_NO 8 NO CHILDREN
> TABLE_NAME ............... P
> REQUESTS_IN .............. 1
> ROWS_OUT ......... 1,401,802
> EST_OPER_COST ............ 0.21
> EST_TOTAL_COST ........... 0.21
> DESCRIPTION
> max_card_est ........... 1.4018e+06
> fragment_id ............ 5
> parent_frag ............ 4
> fragment_type .......... esp
> scan_type .............. subset scan limited by mdam of table
> OP
> object_type ............ Trafodion
> cache_size ........ 10,000
> probes ................. 1
> rows_accessed .......... 1.4018e+06
> key_columns ............ _SALT_, SITE_ID, PANEL, DWD_ID
> executor_predicates .... (PANEL = '1') and (SITE_ID = 450)
> mdam_disjunct .......... (PANEL = '1') and (SITE_ID = 450) and (_SALT_
> >= (\:_sys_HostVarLoHashPart Hash2Distrib 64)) and
> (_SALT_ <= (\:_sys_HostVarHiHashPart Hash2Distrib
> 64))
> part_key_predicates .... (PANEL = '1' = PANEL) and (SITE_ID = 450
> = SITE_ID)
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