Merge pull request #31 from openark/zero-date

Support zero date and zero in date, via dedicated command line flag

Author: shlomi-noach

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.

go/base/context.go

@@ -15,7 +15,7 @@ import (
 	"sync/atomic"
 	"time"
 
-	"github.com/satori/go.uuid"
+	uuid "github.com/satori/go.uuid"
 
 	"github.com/github/gh-ost/go/mysql"
 	"github.com/github/gh-ost/go/sql"
@@ -90,6 +90,7 @@ type MigrationContext struct {
 	AssumeRBR                bool
 	SkipForeignKeyChecks     bool
 	SkipStrictMode           bool
+	AllowZeroInDate          bool
 	NullableUniqueKeyAllowed bool
 	ApproveRenamedColumns    bool
 	SkipRenamedColumns       bool

go/cmd/gh-ost/main.go

@@ -77,6 +77,7 @@ 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.")

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")
@@ -201,11 +219,33 @@ 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
@@ -511,12 +551,9 @@ 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
@@ -1029,12 +1066,7 @@ 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)

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 ;;

localtests/datetime-with-zero/extra_args

@@ -0,0 +1 @@
+--allow-zero-in-date --alter="change column dt dt datetime not null default '1970-00-00 00:00:00'"

localtests/fail-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 ;;

localtests/fail-datetime-with-zero/expect_failure

@@ -0,0 +1 @@
+Invalid default value for 'dt'

localtests/fail-datetime-with-zero/extra_args

@@ -0,0 +1 @@
+--alter="change column dt dt datetime not null default '1970-00-00 00:00:00'"

localtests/fail-datetime-with-zero/ignore_versions

@@ -0,0 +1 @@
+(5.5|5.6)