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Posted to dev@quickstep.apache.org by jianqiao <gi...@git.apache.org> on 2016/10/04 22:22:48 UTC
[GitHub] incubator-quickstep pull request #106: Improve StarSchemaSimpleCostModel to ...
GitHub user jianqiao opened a pull request:
https://github.com/apache/incubator-quickstep/pull/106
Improve StarSchemaSimpleCostModel to provide better group cardinality estimation for aggregations.
This PR revises `StarSchemaSimpleCostModel` to provide better group cardinality estimation for aggregations. This information will be used by a subsequent PR from Harshad to decide when to use _partitioned hash tables_.
The estimation relies on the _number of distinct values_ statistic of each group-by attribute, which can be gathered by running `\analyze` command on the corresponding table.
This PR does not affect the query plans for SSB queries. It changes some of the TPC-H query plans (and a subsequent `LIPFilter` PR will bring more changes to TPC-H query plans).
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/apache/incubator-quickstep estimate-num-distinct-values
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-quickstep/pull/106.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 #106
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commit ad1f8c406954778d332f02b680e08e0118727436
Author: Jianqiao Zhu <ji...@cs.wisc.edu>
Date: 2016-10-04T04:58:30Z
Improve StarSchemaSimpleCostModel to provide closer estimation of number of groups for hash aggregation.
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[GitHub] incubator-quickstep issue #106: Improve StarSchemaSimpleCostModel to provide...
Posted by jianqiao <gi...@git.apache.org>.
Github user jianqiao commented on the issue:
https://github.com/apache/incubator-quickstep/pull/106
@hbdeshmukh There is no need to reload the data or run \analyze again.
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[GitHub] incubator-quickstep issue #106: Improve StarSchemaSimpleCostModel to provide...
Posted by hbdeshmukh <gi...@git.apache.org>.
Github user hbdeshmukh commented on the issue:
https://github.com/apache/incubator-quickstep/pull/106
Hi @jianqiao
I have a dataset on which \analyze was ran already. Do I need to reload the data for the changes in this PR to be effective?
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[GitHub] incubator-quickstep issue #106: Improve StarSchemaSimpleCostModel to provide...
Posted by hbdeshmukh <gi...@git.apache.org>.
Github user hbdeshmukh commented on the issue:
https://github.com/apache/incubator-quickstep/pull/106
Looks good, merging. Thanks @jianqiao for the feature.
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[GitHub] incubator-quickstep pull request #106: Improve StarSchemaSimpleCostModel to ...
Posted by asfgit <gi...@git.apache.org>.
Github user asfgit closed the pull request at:
https://github.com/apache/incubator-quickstep/pull/106
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