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fix: use cut-over-lock-timeout for instant DDL #1468

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fix: use cut-over-lock-timeout for instant DDL #1468

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8f8e5af
fix: use cut-over-lock-timeout for instant DDL
artemvovk Nov 7, 2024
b74154d
add new usage to the arg description
artemvovk Nov 7, 2024
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2 changes: 1 addition & 1 deletion go/cmd/gh-ost/main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -107,7 +107,7 @@ func main() {
chunkSize := flag.Int64("chunk-size", 1000, "amount of rows to handle in each iteration (allowed range: 10-100,000)")
dmlBatchSize := flag.Int64("dml-batch-size", 10, "batch size for DML events to apply in a single transaction (range 1-100)")
defaultRetries := flag.Int64("default-retries", 60, "Default number of retries for various operations before panicking")
cutOverLockTimeoutSeconds := flag.Int64("cut-over-lock-timeout-seconds", 3, "Max number of seconds to hold locks on tables while attempting to cut-over (retry attempted when lock exceeds timeout)")
cutOverLockTimeoutSeconds := flag.Int64("cut-over-lock-timeout-seconds", 3, "Max number of seconds to hold locks on tables while attempting to cut-over (retry attempted when lock exceeds timeout) or attempting instant DDL")
niceRatio := flag.Float64("nice-ratio", 0, "force being 'nice', imply sleep time per chunk time; range: [0.0..100.0]. Example values: 0 is aggressive. 1: for every 1ms spent copying rows, sleep additional 1ms (effectively doubling runtime); 0.7: for every 10ms spend in a rowcopy chunk, spend 7ms sleeping immediately after")

maxLagMillis := flag.Int64("max-lag-millis", 1500, "replication lag at which to throttle operation")
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9 changes: 9 additions & 0 deletions go/logic/applier.go
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Expand Up @@ -255,6 +255,15 @@ func (this *Applier) ValidateOrDropExistingTables() error {
func (this *Applier) AttemptInstantDDL() error {
query := this.generateInstantDDLQuery()
this.migrationContext.Log.Infof("INSTANT DDL query is: %s", query)

// Reuse cut-over-lock-timeout from regular migration process to reduce risk
// in situations where there may be long-running transactions.
tableLockTimeoutSeconds := this.migrationContext.CutOverLockTimeoutSeconds * 2
this.migrationContext.Log.Infof("Setting LOCK timeout as %d seconds", tableLockTimeoutSeconds)
query = fmt.Sprintf(`set /* gh-ost */ session lock_wait_timeout:=%d`, tableLockTimeoutSeconds)
if _, err := this.db.Exec(query); err != nil {
return err
}
// We don't need a trx, because for instant DDL the SQL mode doesn't matter.
_, err := this.db.Exec(query)
return err
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