Use multiStatement to apply DML#1462
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arthurschreiber merged 6 commits intomasterfrom Oct 25, 2024
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arthurschreiber
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Oct 24, 2024
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| tx, err := conn.BeginTx(ctx, nil) | ||
| if err != nil { | ||
| return err | ||
| } |
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We could have the BEGIN statement be the first in the list of the multistatement and avoid the network roundtrip for this.
SET SESSION can happen before the BEGIN now. The reason why it was done inside of the transaction was to ensure that it happens on the same connection, but we're now explicitly checking out the connection out of the database pool.
go/logic/applier.go
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| // each DML is either a single insert (delta +1), update (delta +0) or delete (delta -1). | ||
| // multiplying by the rows actually affected (either 0 or 1) will give an accurate row delta for this DML event | ||
| for i, rowsAffected := range mysqlRes.AllRowsAffected() { | ||
| totalDelta += rowDeltas[i] * rowsAffected |
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if we add BEGIN to the multi statement, this calculation here will need to be updated accordingly.
arthurschreiber
approved these changes
Oct 25, 2024
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Another screenshot showing the improvement over a longer time period. @meiji163 Great work! |
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Description
This PR changes the Applier to batch together DML statements into multi-statements in order to reduce the number of network trips in
ApplyDMLEventQueries.During testing on our
--test-on-replicasetup this provided around 10% increase in rows/second throughputRows Modified (rate);
dml-batch-size=10script/cibuildreturns with no formatting errors, build errors or unit test errors.