analyze table before cutover - #1419
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wangzihuacool
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timvaillancourt
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May 23, 2024 12:42
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LGTM |
meiji163
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May 29, 2024
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When the modified table is a partition table, the execution time of the ANALYZE command will increase as the number of partitions increases. When the ANALYZE statement is synchronized to the replica, it may cause replication lag. |
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Maybe make this feature a optional flag then? What do you think @timvaillancourt ? |
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@meiji163 considering this (I didn't think of it) I suggest this is an optional flag for now and we can have opt-in users report on performance @wangzihuacool can you add an optional flag and |
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August 15, 2024 22:29
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This was referenced Jul 29, 2026
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Add --analyze-ghost-table-before-cutover. When set, cutOver() runs an explicit ANALYZE TABLE on the ghost table after the postpone gate releases — before atomicCutOver() takes the source lock and before --test-on-replica stops replication — logs the elapsed milliseconds on success, and aborts the migration (fatal) if the ANALYZE fails, rather than swap in a table with stale InnoDB statistics. The abort exits synchronously (Log.Fatale), not via a retriable return — a plain return re-runs cutOver() and the ANALYZE up to --default-retries. Because ANALYZE TABLE reports table-level failures (missing table, storage-engine errors) as Msg_type Error rows in its result set while succeeding at the protocol level, the result rows are inspected and cut-over is refused unless ANALYZE reports status OK with no Error rows; privilege-style failures surface as statement errors on the same abort path. Without this, a freshly swapped table can briefly serve traffic with a near-zero row estimate, which the optimizer may cost as a free full scan on hot query paths, flipping plans until statistics are recomputed. Issue #1418 / PR #1419 propose an ANALYZE for the same reason; this variant corrects two defects there — the ANALYZE runs after the postpone gate (so a postponed cut-over still gets fresh statistics) and a failed ANALYZE aborts instead of being ignored. Opt-in, matching the maintainers' ask on #1419 (ANALYZE cost grows with partition count, and the statement replicates). The result-row inspection is extracted as classifyAnalyzeTableResult, a pure, DB-free function, and covered by: - TestClassifyAnalyzeTableResult: a table test over status-OK, case folding, an error row (alone and alongside a status-OK row), a status-OK row followed by a later error row (rows are scanned fully, not short-circuited), a non-OK status, and an empty result. Each refusal asserts the underlying cause via ErrorContains. - ApplierTestSuite.TestAnalyzeGhostTable (real MySQL): happy path; the fail-open regression (dropping the ghost table makes ANALYZE return an Error row with no statement error, which the row inspection must refuse); and the statement-error branch (a closed connection is refused via the distinct error path). Also fixes a pre-existing suite bug surfaced while adding the test above: testify's suite runner calls TearDownSuite() (capital D), but the applier, migrator, and streamer suites all spelled it TeardownSuite(), so the method never matched the interface and the MySQL testcontainer was never terminated. Renamed in all three suites. Co-authored-by: wangzihuacool <wangzihuacool@163.com> Signed-off-by: Vandhana Selvaprakash <vandhana.selvaprakash@airtable.com>
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Related issue: #1418
Description:
analyze ghost table before cutover to avoid table statistics not timely updated.