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Table GC: disable binary logging on best effort basis #7588

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Merged
shlomi-noach merged 5 commits into from
Mar 9, 2021
Merged

Table GC: disable binary logging on best effort basis #7588

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b4f244f
Table GC: disable inary logging on best effort basis
shlomi-noach Mar 3, 2021
084a8c7
Fix minor comment nits
aquarapid Mar 3, 2021
91683e8
rewording per review
shlomi-noach Mar 7, 2021
a7f66e8
resolve conflict
shlomi-noach Mar 7, 2021
6023dab
typos per review
shlomi-noach Mar 9, 2021
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27 changes: 25 additions & 2 deletions go/vt/vttablet/tabletserver/gc/tablegc.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@ import (
"sync/atomic"
"time"

"vitess.io/vitess/go/mysql"
"vitess.io/vitess/go/timer"
"vitess.io/vitess/go/vt/dbconnpool"
"vitess.io/vitess/go/vt/log"
Expand Down Expand Up @@ -429,11 +430,33 @@ func (collector *TableGC) purge(ctx context.Context) (tableName string, err erro
// This saves a lot of load from the replication stream, avoiding excessive lags. It also
// avoids excessive IO on the replicas.
// (note that the user may skip the PURGE step if they want, but the step is on by default)
if _, err := conn.ExecuteFetch("SET sql_log_bin = OFF", 0, false); err != nil {

// However, disabling SQL_LOG_BIN requires SUPER privileges, and we don't know that we have that.
// e.g. on Amazon Aurora we do not have SUPER and cannot disable log bin.
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// We therefore disable log bin on best-effort base. The logic is still fine and sound if binary logging
// is left enabled. We just lose some optimization.
disableLogBin := func() (bool, error) {
_, err := conn.ExecuteFetch("SET sql_log_bin = OFF", 0, false)
if err == nil {
return true, nil
}
if merr, ok := err.(*mysql.SQLError); ok {
if merr.Num == mysql.ERSpecifiedAccessDenied {
// We do not have privileges to disable binary logging. That's fine, we're on best effort,
// so we're going to silently ignore this error.
return false, nil
}
}
// We do not tolerate other errors, though.
return false, err
}
sqlLogBinDisabled, err := disableLogBin()
if err != nil {
return tableName, err
}

defer func() {
if !conn.IsClosed() {
if sqlLogBinDisabled && !conn.IsClosed() {
if _, err := conn.ExecuteFetch("SET sql_log_bin = ON", 0, false); err != nil {
log.Errorf("TableGC: error setting sql_log_bin = ON: %+v", err)
// a followup defer() will run conn.Close() at any case.
Expand Down