server: prefetch point-get keys for multi-statement queries. #18155
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| continue | ||
| } | ||
| // Only support Update for now. | ||
| // TODO: support other point plans. |
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I think we could support select/delete. It won't be very complex.
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I'm trying to make the change as minimum as possible to make the review work easier.
server/conn.go
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| return nil, nil | ||
| } | ||
| vars := cc.ctx.GetSessionVars() | ||
| if vars.TxnCtx.IsPessimistic && vars.TxnCtx.Isolation == ast.ReadCommitted { |
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maybe it has a limited effect when IsPessimistic == true && vars.TxnCtx.Isolation == RR？ because it's still need lock per stmt(and lock request also can prefetch cache), but it's great for multi-stmt in side optimistic txn :D
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Yes, I should make it skip pessimistic transactions.
server/conn_test.go
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| query := "update prefetch set c = c + 1 where a = 1 and b = 1;" + | ||
| "update prefetch set c = c + 1 where a = 2 and b = 2;" + | ||
| "update prefetch set c = c + 1 where a = 3 and b = 3;" | ||
| err = cc.handleQuery(ctx, query) |
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will you add a union scan case?
Codecov Report
@@ Coverage Diff @@
## master #18155 +/- ##
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Coverage 79.6358% 79.6358%
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Files 526 526
Lines 144425 144425
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Hits 115014 115014
Misses 20158 20158
Partials 9253 9253 |
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LGTM |
tiancaiamao
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status/LGT3
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/merge |
ti-srebot
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status/can-merge
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/run-all-tests |
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@coocood merge failed. |
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/run-all-tests |
What problem does this PR solve?
Statements in a multi-statement query are executed one by one currently.
If there are many point plan statements, we can prefetch the point keys, cache them in the transaction snapshot cache. reduce RPC cost and latency.
What is changed and how it works?
Proposal: xxx
What's Changed:
How it works:
Check List
Tests
Release note