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BugZero found this defect 34 days ago.
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MongoDB | 2642909
SBE-eligible queries with many predicates multi-plan every time even when SBE is off
Last update date:
4/15/2024
Affected products:
MongoDB Server
Affected releases:
8.0.0-rc0
8.1.0-rc0
Fixed releases:
No fixed releases provided.
Description:
Info
According to comments in the code, we do not use the SBE cache for queries that have more than a certain number of parameters (512). This has two issues: These queries now have to multi-plan every time, whereas in classic they would not. While it may be the case that parameterizing is not the right choice for queries like this, from a user's perspective, going from classic to SBE will cause the query to multi-plan every time and possibly regress performance. This is more of a design choice than a code-level issue. SERVER-89436 discusses this problem in detail. It seems like in master we've accidentally made it so queries like this are not cached even when SBE is completely disabled. This ticket is specifically about fixing the second issue.
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