Bug #101985 | cost planner doesn't know when DuplicateWeedout Strategy creates disk table | ||
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Submitted: | 13 Dec 2020 15:03 | Modified: | 14 Dec 2020 14:11 |
Reporter: | Vinieth S S | Email Updates: | |
Status: | Not a Bug | Impact on me: | |
Category: | MySQL Server: Optimizer | Severity: | S3 (Non-critical) |
Version: | Mysql 5.7 | OS: | Any |
Assigned to: | CPU Architecture: | Any |
[13 Dec 2020 15:03]
Vinieth S S
[14 Dec 2020 14:11]
MySQL Verification Team
Hi Mr. S S, Thank you for your bug report. However, this is not a bug. Simply, there are two reasons why it is not a bug. First of all, in the optimising stage, our server does not know how big will the temporary table be. It is known only at the moment when its size becomes larger then the limit for the in-memory temporary tables. Second, it is possible to change this limit, so even that would require constant reading of the variables. Third, you can work around this problem by setting the session limit before running the query and resetting it thereafter. Not a bug.
[14 Dec 2020 14:16]
MySQL Verification Team
Hi Mr. S S, On second thought, your idea could be a good feature request. However, you filed this as a bug. Would you agree to make it a fully verified feature request for 8.0 ????