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Posted to dev@quickstep.apache.org by jianqiao <gi...@git.apache.org> on 2017/08/04 19:58:29 UTC
[GitHub] incubator-quickstep pull request #277: Fix a bug with min/max aggregation.
GitHub user jianqiao opened a pull request:
https://github.com/apache/incubator-quickstep/pull/277
Fix a bug with min/max aggregation.
This PR fixes the bug with min/max aggregation (that produces incorrect results) when the aggregated column is stored with **leading-zero-truncation compression**.
The bug happens because the untyped value (i.e. a `const void *` pointer) obtained from the leading-zero-truncation compressed column's corresponding `ValueAccessor` is [the address of a temporary buffer](https://github.com/apache/incubator-quickstep/blob/master/storage/CompressedColumnStoreValueAccessor.hpp#L112) -- i.e. the value pointer becomes invalid when the next `accessor->next()` gets called. [Keeping the value pointer](https://github.com/apache/incubator-quickstep/blob/master/types/operations/comparisons/LiteralComparators-inl.hpp#L546) across [multiple iterations of](https://github.com/apache/incubator-quickstep/blob/master/types/operations/comparisons/LiteralComparators-inl.hpp#L568) accessor->next() causes the problem.
The fix is to copy the value pointer's underlying value to a local variable (so that the value remains valid across iterations of accessor->next()).
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/apache/incubator-quickstep fix-compare-aggregate
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-quickstep/pull/277.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 #277
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commit f3b792bf532aad41724b91cf88c97fcfbbdc1ea9
Author: Jianqiao Zhu <ji...@cs.wisc.edu>
Date: 2017-08-02T20:47:30Z
Fix the bug with min/max aggregation.
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[GitHub] incubator-quickstep issue #277: Fix a bug with min/max aggregation.
Posted by zuyu <gi...@git.apache.org>.
Github user zuyu commented on the issue:
https://github.com/apache/incubator-quickstep/pull/277
LGTM.
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[GitHub] incubator-quickstep pull request #277: Fix a bug with min/max aggregation.
Posted by asfgit <gi...@git.apache.org>.
Github user asfgit closed the pull request at:
https://github.com/apache/incubator-quickstep/pull/277
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