Multithreaded replication WIP #1454
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Multiple `TableMap` events can happen inside of a single transaction, so we can't really use them to filter out events early or anything like that. Instead, we'll just skip them. Also adds some basic test cases for the transaction streaming.
Co-authored-by: Daniel Joos <[email protected]>
This reverts commit 2e78f6f.
arthurschreiber
previously approved these changes
Oct 23, 2024
arthurschreiber
previously approved these changes
Oct 23, 2024
…63/parallel-repl
arthurschreiber
previously approved these changes
Oct 25, 2024
arthurschreiber
previously approved these changes
Oct 25, 2024
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Description
This PR introduces multi-threaded replication for applying DML queries to the ghost table. The goal is to be able to migrate tables with high rate of DML queries (e.g. >5k rows/s). Currently gh-ost lags behind in these situations, taking a very long time to complete or not completing at all.
Similar to MySQL replication threads, gh-ost will stream binlog events from the source and group them into transactions. It then submits the transactions to a pool of workers to apply the transactions concurrently on the ghost table. We ensure that dependent transactions are applied in a consistent order (equivalent to MySQL multi-threaded replication with
replica_preserve_commit_order=0).With
WRITESETenabled on the source, this enables a great amount of parallelism in the transaction applier.Changes
TODO
Performance tests
TODO
script/cibuildreturns with no formatting errors, build errors or unit test errors.