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Set a transaction isolation level for MySQL connections (#1156)

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* Set transaction isolation in connections

* Revert load_map.go change

* Var rename

* Restore comment
This commit is contained in:
Tim Vaillancourt 2022-08-12 18:52:22 +02:00 committed by GitHub
parent 5de91c9f90
commit 3f44e04365
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4 changed files with 39 additions and 22 deletions
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2
doc/requirements-and-limitations.md
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@ -20,6 +20,8 @@ The `SUPER` privilege is required for `STOP SLAVE`, `START SLAVE` operations. Th
- Switching your `binlog_format` to `ROW`, in the case where it is _not_ `ROW` and you explicitly specified `--switch-to-rbr`
- If your replication is already in RBR (`binlog_format=ROW`) you can specify `--assume-rbr` to avoid the `STOP SLAVE/START SLAVE` operations, hence no need for `SUPER`.
- `gh-ost` uses the `REPEATABLE_READ` transaction isolation level for all MySQL connections, regardless of the server default.
- Running `--test-on-replica`: before the cut-over phase, `gh-ost` stops replication so that you can compare the two tables and satisfy that the migration is sound.
### Limitations

30
go/cmd/gh-ost/main.go
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@ -181,7 +181,7 @@ func main() {
}
if migrationContext.AlterStatement == "" {
log.Fatalf("--alter must be provided and statement must not be empty")
log.Fatal("--alter must be provided and statement must not be empty")
}
parser := sql.NewParserFromAlterStatement(migrationContext.AlterStatement)
migrationContext.AlterStatementOptions = parser.GetAlterStatementOptions()
@ -190,7 +190,7 @@ func main() {
if parser.HasExplicitSchema() {
migrationContext.DatabaseName = parser.GetExplicitSchema()
} else {
log.Fatalf("--database must be provided and database name must not be empty, or --alter must specify database name")
log.Fatal("--database must be provided and database name must not be empty, or --alter must specify database name")
}
}
@ -202,48 +202,48 @@ func main() {
if parser.HasExplicitTable() {
migrationContext.OriginalTableName = parser.GetExplicitTable()
} else {
log.Fatalf("--table must be provided and table name must not be empty, or --alter must specify table name")
log.Fatal("--table must be provided and table name must not be empty, or --alter must specify table name")
}
}
migrationContext.Noop = !(*executeFlag)
if migrationContext.AllowedRunningOnMaster && migrationContext.TestOnReplica {
migrationContext.Log.Fatalf("--allow-on-master and --test-on-replica are mutually exclusive")
migrationContext.Log.Fatal("--allow-on-master and --test-on-replica are mutually exclusive")
}
if migrationContext.AllowedRunningOnMaster && migrationContext.MigrateOnReplica {
migrationContext.Log.Fatalf("--allow-on-master and --migrate-on-replica are mutually exclusive")
migrationContext.Log.Fatal("--allow-on-master and --migrate-on-replica are mutually exclusive")
}
if migrationContext.MigrateOnReplica && migrationContext.TestOnReplica {
migrationContext.Log.Fatalf("--migrate-on-replica and --test-on-replica are mutually exclusive")
migrationContext.Log.Fatal("--migrate-on-replica and --test-on-replica are mutually exclusive")
}
if migrationContext.SwitchToRowBinlogFormat && migrationContext.AssumeRBR {
migrationContext.Log.Fatalf("--switch-to-rbr and --assume-rbr are mutually exclusive")
migrationContext.Log.Fatal("--switch-to-rbr and --assume-rbr are mutually exclusive")
}
if migrationContext.TestOnReplicaSkipReplicaStop {
if !migrationContext.TestOnReplica {
migrationContext.Log.Fatalf("--test-on-replica-skip-replica-stop requires --test-on-replica to be enabled")
migrationContext.Log.Fatal("--test-on-replica-skip-replica-stop requires --test-on-replica to be enabled")
}
migrationContext.Log.Warning("--test-on-replica-skip-replica-stop enabled. We will not stop replication before cut-over. Ensure you have a plugin that does this.")
}
if migrationContext.CliMasterUser != "" && migrationContext.AssumeMasterHostname == "" {
migrationContext.Log.Fatalf("--master-user requires --assume-master-host")
migrationContext.Log.Fatal("--master-user requires --assume-master-host")
}
if migrationContext.CliMasterPassword != "" && migrationContext.AssumeMasterHostname == "" {
migrationContext.Log.Fatalf("--master-password requires --assume-master-host")
migrationContext.Log.Fatal("--master-password requires --assume-master-host")
}
if migrationContext.TLSCACertificate != "" && !migrationContext.UseTLS {
migrationContext.Log.Fatalf("--ssl-ca requires --ssl")
migrationContext.Log.Fatal("--ssl-ca requires --ssl")
}
if migrationContext.TLSCertificate != "" && !migrationContext.UseTLS {
migrationContext.Log.Fatalf("--ssl-cert requires --ssl")
migrationContext.Log.Fatal("--ssl-cert requires --ssl")
}
if migrationContext.TLSKey != "" && !migrationContext.UseTLS {
migrationContext.Log.Fatalf("--ssl-key requires --ssl")
migrationContext.Log.Fatal("--ssl-key requires --ssl")
}
if migrationContext.TLSAllowInsecure && !migrationContext.UseTLS {
migrationContext.Log.Fatalf("--ssl-allow-insecure requires --ssl")
migrationContext.Log.Fatal("--ssl-allow-insecure requires --ssl")
}
if *replicationLagQuery != "" {
migrationContext.Log.Warningf("--replication-lag-query is deprecated")
migrationContext.Log.Warning("--replication-lag-query is deprecated")
}
switch *cutOver {

19
go/mysql/connection.go
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@ -1,5 +1,5 @@
/*
Copyright 2016 GitHub Inc.
Copyright 2022 GitHub Inc.
See https://github.com/github/gh-ost/blob/master/LICENSE
*/
@ -12,11 +12,13 @@ import (
"fmt"
"io/ioutil"
"net"
"strings"
"github.com/go-sql-driver/mysql"
)
const (
transactionIsolation = "REPEATABLE-READ"
TLS_CONFIG_KEY = "ghost"
)
@ -112,12 +114,23 @@ func (this *ConnectionConfig) GetDBUri(databaseName string) string {
// Wrap IPv6 literals in square brackets
hostname = fmt.Sprintf("[%s]", hostname)
}
interpolateParams := true
// go-mysql-driver defaults to false if tls param is not provided; explicitly setting here to
// simplify construction of the DSN below.
tlsOption := "false"
if this.tlsConfig != nil {
tlsOption = TLS_CONFIG_KEY
}
return fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?timeout=%fs&readTimeout=%fs&writeTimeout=%fs&interpolateParams=%t&autocommit=true&charset=utf8mb4,utf8,latin1&tls=%s", this.User, this.Password, hostname, this.Key.Port, databaseName, this.Timeout, this.Timeout, this.Timeout, interpolateParams, tlsOption)
connectionParams := []string{
"autocommit=true",
"charset=utf8mb4,utf8,latin1",
"interpolateParams=true",
fmt.Sprintf("tls=%s", tlsOption),
fmt.Sprintf("transaction_isolation=%q", transactionIsolation),
fmt.Sprintf("timeout=%fs", this.Timeout),
fmt.Sprintf("readTimeout=%fs", this.Timeout),
fmt.Sprintf("writeTimeout=%fs", this.Timeout),
}
return fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?%s", this.User, this.Password, hostname, this.Key.Port, databaseName, strings.Join(connectionParams, "&"))
}

8
go/mysql/connection_test.go
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@ -1,5 +1,5 @@
/*
Copyright 2016 GitHub Inc.
Copyright 2022 GitHub Inc.
See https://github.com/github/gh-ost/blob/master/LICENSE
*/
@ -67,9 +67,10 @@ func TestGetDBUri(t *testing.T) {
c.Key = InstanceKey{Hostname: "myhost", Port: 3306}
c.User = "gromit"
c.Password = "penguin"
c.Timeout = 1.2345
uri := c.GetDBUri("test")
test.S(t).ExpectEquals(uri, "gromit:penguin@tcp(myhost:3306)/test?timeout=0.000000s&readTimeout=0.000000s&writeTimeout=0.000000s&interpolateParams=true&autocommit=true&charset=utf8mb4,utf8,latin1&tls=false")
test.S(t).ExpectEquals(uri, `gromit:penguin@tcp(myhost:3306)/test?autocommit=true&charset=utf8mb4,utf8,latin1&interpolateParams=true&tls=false&transaction_isolation="REPEATABLE-READ"&timeout=1.234500s&readTimeout=1.234500s&writeTimeout=1.234500s`)
}
func TestGetDBUriWithTLSSetup(t *testing.T) {
@ -77,8 +78,9 @@ func TestGetDBUriWithTLSSetup(t *testing.T) {
c.Key = InstanceKey{Hostname: "myhost", Port: 3306}
c.User = "gromit"
c.Password = "penguin"
c.Timeout = 1.2345
c.tlsConfig = &tls.Config{}
uri := c.GetDBUri("test")
test.S(t).ExpectEquals(uri, "gromit:penguin@tcp(myhost:3306)/test?timeout=0.000000s&readTimeout=0.000000s&writeTimeout=0.000000s&interpolateParams=true&autocommit=true&charset=utf8mb4,utf8,latin1&tls=ghost")
test.S(t).ExpectEquals(uri, `gromit:penguin@tcp(myhost:3306)/test?autocommit=true&charset=utf8mb4,utf8,latin1&interpolateParams=true&tls=ghost&transaction_isolation="REPEATABLE-READ"&timeout=1.234500s&readTimeout=1.234500s&writeTimeout=1.234500s`)
}