release-20.2: sql: disable interleaved joins by default #54162
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yuzefovich
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LGTM pending review in release meeting. There are also a bunch of logictests that need to be cleaned up. |
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Fixed the tests.
Reviewable status:
complete! 0 of 0 LGTMs obtained (waiting on @asubiotto)
pkg/sql/logictest/testdata/logic_test/select_for_update_nowait_interleaved, line 10 at r1 (raw file):
# logic of mapping a WriteIntentError back to the corresponding table. # Note that for some reason setting a session variable is not sufficient to
@nvanbenschoten do you know why SET enable_interleaved_joins = true; would work differently from the cluster setting change?
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pkg/sql/logictest/testdata/logic_test/select_for_update_nowait_interleaved, line 10 at r1 (raw file):
Previously, yuzefovich wrote…
@nvanbenschoten do you know why
SET enable_interleaved_joins = true;would work differently from the cluster setting change?
It could be because we're switching users down below, which I believe means that we're creating a new session. Setting a session variable only impacts the current session, while setting the cluster setting impacts the initial value of the session variables for all sessions.
This commit switches the default value of a cluster setting to disable planning the interleaved joins because they are under-tested and often are actually slower than the merge joins. In 21.1 release we will be removing the corresponding code entirely. Release note (sql change): Interleaved joins are now disabled by default and will be entirely removed in 21.1 release because they are often slower than the merge join.
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pkg/sql/logictest/testdata/logic_test/select_for_update_nowait_interleaved, line 10 at r1 (raw file):
Previously, nvanbenschoten (Nathan VanBenschoten) wrote…
It could be because we're switching users down below, which I believe means that we're creating a new session. Setting a session variable only impacts the current session, while setting the cluster setting impacts the initial value of the session variables for all sessions.
Oh, I didn't realize that switching the user starts a new session, makes sense, thanks.
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ok to merge this per latest guidance |
This commit switches the default value of a cluster setting to disable
planning the interleaved joins because they are under-tested and often
are actually slower than the merge joins. In 21.1 release we will be
removing the corresponding code entirely.
Release note (sql change): Interleaved joins are now disabled by default
and will be entirely removed in 21.1 release because they are often
slower than the merge join.