planner: disable SQL_CALC_FOUND_ROWS/LOCK IN SHARE MODE by default #19506
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ghost
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I noticed after I wrote this, that I could also implement this in |
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I have updated this PR to fix |
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/run-all-tests |
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This was referenced Sep 10, 2020
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/run-all-tests tidb-test=pr/1087 |
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/run-all-tests tidb-test=pr/1087 |
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/run-integration-ddl-test tidb-test=pr/1087 |
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Thanks! Should be fixed now. |
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/merge |
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@nullnotnil merge failed. |
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/merge |
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Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
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cherry pick to release-4.0 in PR #21005 |
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What problem does this PR solve?
Issue Number: Fixes #14448 but leaves #8235 open to (eventually) add the functionality
Also fixes #19383
Problem Summary:
Unless you are reading every page of the TiDB manual, you may not notice that a query using
SQL_CALC_FOUND_ROWSwill return wrong results without a warning or error. This is unsafe, as described why in #14448.Similarly,
SELECT LOCK IN SHARE MODEis also described in the manual as a noop. But that's not obvious to new users.This protects against incorrect usage via the enable_noop_functions flag; meaning that applications that want to execute the query and receive broken results have a way out.
What is changed and how it works?
What's Changed:
Queries using SQL_CALC_FOUND_ROWS or LOCK IN SHARE MODE now get an error by default.
Related changes
Docs PR pingcap/docs#3898
Check List
Tests
Side effects
Release note
SQL_CALC_FOUND_ROWSorLOCK IN SHARE MODE. This helps alert users that this feature is not implemented by TiDB, but a workaround to restore the previous behavior is available by settingtidb_enable_noop_functions=1.