planner: check schema stale for plan cache when forUpdateRead #22381
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Signed-off-by: you06 <[email protected]>
Signed-off-by: you06 <[email protected]>
Signed-off-by: you06 <[email protected]>
Signed-off-by: you06 <[email protected]>
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LGTM |
ti-srebot
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Jan 14, 2021
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Do not merge this PR now. |
Signed-off-by: you06 <[email protected]>
you06
commented
Jan 15, 2021
session/pessimistic_test.go
Outdated
| c.Assert(err, IsNil) | ||
| tk2.CheckExecResult(1, 0) | ||
| // FIXME: should hit plan cache here | ||
| tk2.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0")) |
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There still exist a problem, plan cache will not hit here.
Signed-off-by: you06 <[email protected]>
you06
commented
Jan 21, 2021
| delete(sessVars.IsolationReadEngines, kv.TiFlash) | ||
| cacheKey = NewPSTMTPlanCacheKey(sctx.GetSessionVars(), e.ExecID, prepared.SchemaVersion) | ||
| sessVars.IsolationReadEngines[kv.TiFlash] = struct{}{} | ||
| } |
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When use binary protocol and the plan cache is not hit, a new cache will generate inside getPhysicalPlan function, in which use the following codes to exclude TiFlash engine for write statement.
Lines 85 to 88 in 2364fec
After the plan is builing complete, the
TiFlash engine is set back and the it'll still write a plan-cache key with TiFlash engine. As a result, we cache a write plan for TiFlash engine, and it'll never be used correctly.
Signed-off-by: you06 <[email protected]>
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I think this bug is serious, @winoros can you help reviewing it? Thanks! |
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Signed-off-by: you06 <[email protected]>
Signed-off-by: you06 <[email protected]>
winoros
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Mar 19, 2021
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/merge |
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This pull request has been accepted and is ready to merge. Commit hash: 5702b0e
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Signed-off-by: ti-srebot <[email protected]>
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cherry pick to release-5.0 in PR #23435 |
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What problem does this PR solve?
Issue Number: #21498 will also affected plan cache.
Problem Summary:
What is changed and how it works?
What's Changed: when the plan is using forUpdateRead, we need to use the latest schema to check if plan is valid.
How it Works:
Update schema version when required.
Related changes
Check List
Tests
Release note