Set transaction isolation in connections

Author: timvaillancourt

.github/workflows/golangci-lint.yml

@@ -19,3 +19,5 @@ jobs:
       - uses: actions/checkout@v3
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v3
+        with:
+          version: v1.46.2

doc/command-line-flags.md

@@ -6,6 +6,10 @@ A more in-depth discussion of various `gh-ost` command line flags: implementatio
 
 Add this flag when executing on Aliyun RDS.
 
+### allow-zero-in-date
+
+Allows the user to make schema changes that include a zero date or zero in date (e.g. adding a `datetime default '0000-00-00 00:00:00'` column), even if global `sql_mode` on MySQL has `NO_ZERO_IN_DATE,NO_ZERO_DATE`.
+
 ###  azure
 
 Add this flag when executing on Azure Database for MySQL.

doc/requirements-and-limitations.md

@@ -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

go/base/context.go

@@ -92,6 +92,7 @@ type MigrationContext struct {
 	AssumeRBR                bool
 	SkipForeignKeyChecks     bool
 	SkipStrictMode           bool
+	AllowZeroInDate          bool
 	NullableUniqueKeyAllowed bool
 	ApproveRenamedColumns    bool
 	SkipRenamedColumns       bool

go/base/load_map.go

@@ -23,7 +23,7 @@ func NewLoadMap() LoadMap {
 
 // NewLoadMap parses a `--*-load` flag (e.g. `--max-load`), which is in multiple
 // key-value format, such as:
-//   'Threads_running=100,Threads_connected=500'
+// 'Threads_running=100,Threads_connected=500'
 func ParseLoadMap(loadList string) (LoadMap, error) {
 	result := NewLoadMap()
 	if loadList == "" {

go/cmd/gh-ost/main.go

@@ -78,6 +78,7 @@ func main() {
 	flag.BoolVar(&migrationContext.DiscardForeignKeys, "discard-foreign-keys", false, "DANGER! This flag will migrate a table that has foreign keys and will NOT create foreign keys on the ghost table, thus your altered table will have NO foreign keys. This is useful for intentional dropping of foreign keys")
 	flag.BoolVar(&migrationContext.SkipForeignKeyChecks, "skip-foreign-key-checks", false, "set to 'true' when you know for certain there are no foreign keys on your table, and wish to skip the time it takes for gh-ost to verify that")
 	flag.BoolVar(&migrationContext.SkipStrictMode, "skip-strict-mode", false, "explicitly tell gh-ost binlog applier not to enforce strict sql mode")
+	flag.BoolVar(&migrationContext.AllowZeroInDate, "allow-zero-in-date", false, "explicitly tell gh-ost binlog applier to ignore NO_ZERO_IN_DATE,NO_ZERO_DATE in sql_mode")
 	flag.BoolVar(&migrationContext.AliyunRDS, "aliyun-rds", false, "set to 'true' when you execute on Aliyun RDS.")
 	flag.BoolVar(&migrationContext.GoogleCloudPlatform, "gcp", false, "set to 'true' when you execute on a 1st generation Google Cloud Platform (GCP).")
 	flag.BoolVar(&migrationContext.AzureMySQL, "azure", false, "set to 'true' when you execute on Azure Database on MySQL.")
@@ -180,7 +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()
@@ -189,7 +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")
 		}
 	}
 
@@ -201,48 +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 {

go/logic/applier.go

@@ -117,6 +117,24 @@ func (this *Applier) validateAndReadTimeZone() error {
 	return nil
 }
 
+// generateSqlModeQuery return a `sql_mode = ...` query, to be wrapped with a `set session` or `set global`,
+// based on gh-ost configuration:
+// - User may skip strict mode
+// - User may allow zero dats or zero in dates
+func (this *Applier) generateSqlModeQuery() string {
+	sqlModeAddendum := `,NO_AUTO_VALUE_ON_ZERO`
+	if !this.migrationContext.SkipStrictMode {
+		sqlModeAddendum = fmt.Sprintf("%s,STRICT_ALL_TABLES", sqlModeAddendum)
+	}
+	sqlModeQuery := fmt.Sprintf("CONCAT(@@session.sql_mode, ',%s')", sqlModeAddendum)
+	if this.migrationContext.AllowZeroInDate {
+		sqlModeQuery = fmt.Sprintf("REPLACE(REPLACE(%s, 'NO_ZERO_IN_DATE', ''), 'NO_ZERO_DATE', '')", sqlModeQuery)
+	}
+	sqlModeQuery = fmt.Sprintf("sql_mode = %s", sqlModeQuery)
+
+	return sqlModeQuery
+}
+
 // readTableColumns reads table columns on applier
 func (this *Applier) readTableColumns() (err error) {
 	this.migrationContext.Log.Infof("Examining table structure on applier")
@@ -182,11 +200,33 @@ func (this *Applier) CreateGhostTable() error {
 		sql.EscapeName(this.migrationContext.DatabaseName),
 		sql.EscapeName(this.migrationContext.GetGhostTableName()),
 	)
-	if _, err := sqlutils.ExecNoPrepare(this.db, query); err != nil {
-		return err
-	}
-	this.migrationContext.Log.Infof("Ghost table created")
-	return nil
+
+	err := func() error {
+		tx, err := this.db.Begin()
+		if err != nil {
+			return err
+		}
+		defer tx.Rollback()
+
+		sessionQuery := fmt.Sprintf(`SET SESSION time_zone = '%s'`, this.migrationContext.ApplierTimeZone)
+		sessionQuery = fmt.Sprintf("%s, %s", sessionQuery, this.generateSqlModeQuery())
+
+		if _, err := tx.Exec(sessionQuery); err != nil {
+			return err
+		}
+		if _, err := tx.Exec(query); err != nil {
+			return err
+		}
+		this.migrationContext.Log.Infof("Ghost table created")
+		if err := tx.Commit(); err != nil {
+			// Neither SET SESSION nor ALTER are really transactional, so strictly speaking
+			// there's no need to commit; but let's do this the legit way anyway.
+			return err
+		}
+		return nil
+	}()
+
+	return err
 }
 
 // AlterGhost applies `alter` statement on ghost table
@@ -201,11 +241,33 @@ func (this *Applier) AlterGhost() error {
 		sql.EscapeName(this.migrationContext.GetGhostTableName()),
 	)
 	this.migrationContext.Log.Debugf("ALTER statement: %s", query)
-	if _, err := sqlutils.ExecNoPrepare(this.db, query); err != nil {
-		return err
-	}
-	this.migrationContext.Log.Infof("Ghost table altered")
-	return nil
+
+	err := func() error {
+		tx, err := this.db.Begin()
+		if err != nil {
+			return err
+		}
+		defer tx.Rollback()
+
+		sessionQuery := fmt.Sprintf(`SET SESSION time_zone = '%s'`, this.migrationContext.ApplierTimeZone)
+		sessionQuery = fmt.Sprintf("%s, %s", sessionQuery, this.generateSqlModeQuery())
+
+		if _, err := tx.Exec(sessionQuery); err != nil {
+			return err
+		}
+		if _, err := tx.Exec(query); err != nil {
+			return err
+		}
+		this.migrationContext.Log.Infof("Ghost table altered")
+		if err := tx.Commit(); err != nil {
+			// Neither SET SESSION nor ALTER are really transactional, so strictly speaking
+			// there's no need to commit; but let's do this the legit way anyway.
+			return err
+		}
+		return nil
+	}()
+
+	return err
 }
 
 // AlterGhost applies `alter` statement on ghost table
@@ -539,12 +601,9 @@ func (this *Applier) ApplyIterationInsertQuery() (chunkSize int64, rowsAffected
 			return nil, err
 		}
 		defer tx.Rollback()
+
 		sessionQuery := fmt.Sprintf(`SET SESSION time_zone = '%s'`, this.migrationContext.ApplierTimeZone)
-		sqlModeAddendum := `,NO_AUTO_VALUE_ON_ZERO`
-		if !this.migrationContext.SkipStrictMode {
-			sqlModeAddendum = fmt.Sprintf("%s,STRICT_ALL_TABLES", sqlModeAddendum)
-		}
-		sessionQuery = fmt.Sprintf("%s, sql_mode = CONCAT(@@session.sql_mode, ',%s')", sessionQuery, sqlModeAddendum)
+		sessionQuery = fmt.Sprintf("%s, %s", sessionQuery, this.generateSqlModeQuery())
 
 		if _, err := tx.Exec(sessionQuery); err != nil {
 			return nil, err
@@ -1056,12 +1115,7 @@ func (this *Applier) ApplyDMLEventQueries(dmlEvents [](*binlog.BinlogDMLEvent))
 		}
 
 		sessionQuery := "SET SESSION time_zone = '+00:00'"
-
-		sqlModeAddendum := `,NO_AUTO_VALUE_ON_ZERO`
-		if !this.migrationContext.SkipStrictMode {
-			sqlModeAddendum = fmt.Sprintf("%s,STRICT_ALL_TABLES", sqlModeAddendum)
-		}
-		sessionQuery = fmt.Sprintf("%s, sql_mode = CONCAT(@@session.sql_mode, ',%s')", sessionQuery, sqlModeAddendum)
+		sessionQuery = fmt.Sprintf("%s, %s", sessionQuery, this.generateSqlModeQuery())
 
 		if _, err := tx.Exec(sessionQuery); err != nil {
 			return rollback(err)

go/mysql/connection.go

@@ -1,5 +1,5 @@
 /*
-   Copyright 2016 GitHub Inc.
+   Copyright 2022 GitHub Inc.
 	 See https://github.com/github/gh-ost/blob/master/LICENSE
 */
 
@@ -12,12 +12,14 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net"
+	"strings"
 
 	"github.com/go-sql-driver/mysql"
 )
 
 const (
-	TLS_CONFIG_KEY = "ghost"
+	transactionIsolation = "REPEATABLE-READ"
+	TLS_CONFIG_KEY       = "ghost"
 )
 
 // ConnectionConfig is the minimal configuration required to connect to a MySQL server
@@ -112,12 +114,21 @@ 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"
+
+	tls := "false"
 	if this.tlsConfig != nil {
-		tlsOption = TLS_CONFIG_KEY
+		tls = TLS_CONFIG_KEY
+	}
+	connectionParams := []string{
+		"autocommit=true",
+		"charset=utf8mb4,utf8,latin1",
+		"interpolateParams=true",
+		fmt.Sprintf("tls=%s", tls),
+		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?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)
+
+	return fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?%s", this.User, this.Password, hostname, this.Key.Port, databaseName, strings.Join(connectionParams, "&"))
 }

go/mysql/connection_test.go

@@ -1,5 +1,5 @@
 /*
-   Copyright 2016 GitHub Inc.
+   Copyright 2022 GitHub Inc.
 	 See https://github.com/github/gh-ost/blob/master/LICENSE
 */
 
@@ -67,18 +67,20 @@ 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) {
 	c := NewConnectionConfig()
 	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`)
 }

localtests/datetime-with-zero/create.sql

@@ -0,0 +1,20 @@
+drop table if exists gh_ost_test;
+create table gh_ost_test (
+  id int unsigned auto_increment,
+  i int not null,
+  dt datetime,
+  primary key(id)
+) auto_increment=1;
+
+drop event if exists gh_ost_test;
+delimiter ;;
+create event gh_ost_test
+  on schedule every 1 second
+  starts current_timestamp
+  ends current_timestamp + interval 60 second
+  on completion not preserve
+  enable
+  do
+begin
+  insert into gh_ost_test values (null, 7, '2010-10-20 10:20:30');
+end ;;