Revert "Remove CopySchemaShard"

This reverts commit a091042.

go/cmd/vtctldclient/command/schema.go

@@ -58,6 +58,13 @@ For --sql, semi-colons and repeated values may be mixed, for example:
 		Args:                  cobra.ExactArgs(1),
 		RunE:                  commandApplySchema,
 	}
+	CopySchemaShard = &cobra.Command{
+		Use:                   "CopySchemaShard [--tables=<table1>,<table2>,...] [--exclude-tables=<table1>,<table2>,...] [--include-views] [--skip-verify] [--wait-replicas-timeout=10s] {<source keyspace/shard> || <source tablet alias>} <destination keyspace/shard>",
+		Short:                 "Copies the schema from a source shard's primary (or a specific tablet) to a destination shard. The schema is applied directly on the primary of the destination shard, and it is propagated to the replicas through binlogs.",
+		DisableFlagsInUseLine: true,
+		Args:                  cobra.ExactArgs(2),
+		RunE:                  commandCopySchemaShard,
+	}
 	// GetSchema makes a GetSchema gRPC call to a vtctld.
 	GetSchema = &cobra.Command{
 		Use:                   "GetSchema [--tables TABLES ...] [--exclude-tables EXCLUDE_TABLES ...] [{--table-names-only | --table-sizes-only}] [--include-views] alias",
@@ -173,6 +180,47 @@ func commandApplySchema(cmd *cobra.Command, args []string) error {
 	return nil
 }
 
+func commandCopySchemaShard(cmd *cobra.Command, args []string) error {
+	/*
+		tables := subFlags.String("tables", "", "Specifies a comma-separated list of tables to copy. Each is either an exact match, or a regular expression of the form /regexp/")
+		excludeTables := subFlags.String("exclude_tables", "", "Specifies a comma-separated list of tables to exclude. Each is either an exact match, or a regular expression of the form /regexp/")
+		includeViews := subFlags.Bool("include-views", true, "Includes views in the output")
+		skipVerify := subFlags.Bool("skip-verify", false, "Skip verification of source and target schema after copy")
+		// for backwards compatibility
+		waitReplicasTimeout := subFlags.Duration("wait_replicas_timeout", grpcvtctldserver.DefaultWaitReplicasTimeout, "The amount of time to wait for replicas to receive the schema change via replication.")
+		if err := subFlags.Parse(args); err != nil {
+			return err
+		}
+
+		if subFlags.NArg() != 2 {
+			return fmt.Errorf("the <source keyspace/shard> and <destination keyspace/shard> arguments are both required for the CopySchemaShard command. Instead of the <source keyspace/shard> argument, you can also specify <tablet alias> which refers to a specific tablet of the shard in the source keyspace")
+		}
+		var tableArray []string
+		if *tables != "" {
+			tableArray = strings.Split(*tables, ",")
+		}
+		var excludeTableArray []string
+		if *excludeTables != "" {
+			excludeTableArray = strings.Split(*excludeTables, ",")
+		}
+		destKeyspace, destShard, err := topoproto.ParseKeyspaceShard(subFlags.Arg(1))
+		if err != nil {
+			return err
+		}
+
+		sourceKeyspace, sourceShard, err := topoproto.ParseKeyspaceShard(subFlags.Arg(0))
+		if err == nil {
+			return wr.CopySchemaShardFromShard(ctx, tableArray, excludeTableArray, *includeViews, sourceKeyspace, sourceShard, destKeyspace, destShard, *waitReplicasTimeout, *skipVerify)
+		}
+		sourceTabletAlias, err := topoproto.ParseTabletAlias(subFlags.Arg(0))
+		if err == nil {
+			return wr.CopySchemaShard(ctx, sourceTabletAlias, tableArray, excludeTableArray, *includeViews, destKeyspace, destShard, *waitReplicasTimeout, *skipVerify)
+		}
+		return err
+	*/
+	return nil
+}
+
 var getSchemaOptions = struct {
 	Tables          []string
 	ExcludeTables   []string
@@ -375,6 +423,7 @@ func init() {
 	ApplySchema.Flags().StringArrayVar(&applySchemaOptions.SQL, "sql", nil, "Semicolon-delimited, repeatable SQL commands to apply. Exactly one of --sql|--sql-file is required.")
 	ApplySchema.Flags().StringVar(&applySchemaOptions.SQLFile, "sql-file", "", "Path to a file containing semicolon-delimited SQL commands to apply. Exactly one of --sql|--sql-file is required.")
 	ApplySchema.Flags().Int64Var(&applySchemaOptions.BatchSize, "batch-size", 0, "How many queries to batch together. Only applicable when all queries are CREATE TABLE|VIEW")
+
 	Root.AddCommand(ApplySchema)
 
 	GetSchema.Flags().StringSliceVar(&getSchemaOptions.Tables, "tables", nil, "List of tables to display the schema for. Each is either an exact match, or a regular expression of the form `/regexp/`.")

go/test/endtoend/vtgate/schema/schema_test.go

@@ -17,10 +17,12 @@ limitations under the License.
 package schema
 
 import (
+	"encoding/json"
 	"flag"
 	"fmt"
 	"os"
 	"path"
+	"reflect"
 	"strings"
 	"testing"
 	"time"
@@ -106,6 +108,9 @@ func TestSchemaChange(t *testing.T) {
 	testApplySchemaBatch(t)
 	testUnsafeAllowForeignKeys(t)
 	testCreateInvalidView(t)
+	testCopySchemaShards(t, clusterInstance.Keyspaces[0].Shards[0].Vttablets[0].VttabletProcess.TabletPath, 2)
+	testCopySchemaShards(t, fmt.Sprintf("%s/0", keyspaceName), 3)
+	testCopySchemaShardWithDifferentDB(t, 4)
 	testWithAutoSchemaFromChangeDir(t)
 }
 
@@ -281,6 +286,58 @@ func checkTablesCount(t *testing.T, tablet *cluster.Vttablet, count int) {
 	assert.Equal(t, len(queryResult.Rows), count)
 }
 
+// testCopySchemaShards tests that schema from source is correctly applied to destination
+func testCopySchemaShards(t *testing.T, source string, shard int) {
+	addNewShard(t, shard)
+	// InitShardPrimary creates the db, but there shouldn't be any tables yet.
+	checkTablesCount(t, clusterInstance.Keyspaces[0].Shards[shard].Vttablets[0], 0)
+	checkTablesCount(t, clusterInstance.Keyspaces[0].Shards[shard].Vttablets[1], 0)
+	// Run the command twice to make sure it's idempotent.
+	for i := 0; i < 2; i++ {
+		err := clusterInstance.VtctlclientProcess.ExecuteCommand("CopySchemaShard", source, fmt.Sprintf("%s/%d", keyspaceName, shard))
+		require.Nil(t, err)
+	}
+	// shard2 primary should look the same as the replica we copied from
+	checkTablesCount(t, clusterInstance.Keyspaces[0].Shards[shard].Vttablets[0], totalTableCount)
+	checkTablesCount(t, clusterInstance.Keyspaces[0].Shards[shard].Vttablets[1], totalTableCount)
+
+	matchSchema(t, clusterInstance.Keyspaces[0].Shards[0].Vttablets[0].VttabletProcess.TabletPath, clusterInstance.Keyspaces[0].Shards[shard].Vttablets[0].VttabletProcess.TabletPath)
+}
+
+// testCopySchemaShardWithDifferentDB if we apply different schema to new shard, it should throw error
+func testCopySchemaShardWithDifferentDB(t *testing.T, shard int) {
+	addNewShard(t, shard)
+	checkTablesCount(t, clusterInstance.Keyspaces[0].Shards[shard].Vttablets[0], 0)
+	checkTablesCount(t, clusterInstance.Keyspaces[0].Shards[shard].Vttablets[1], 0)
+	source := fmt.Sprintf("%s/0", keyspaceName)
+
+	tabletAlias := clusterInstance.Keyspaces[0].Shards[shard].Vttablets[0].VttabletProcess.TabletPath
+	schema, err := clusterInstance.VtctldClientProcess.ExecuteCommandWithOutput("GetSchema", tabletAlias)
+	require.Nil(t, err)
+
+	resultMap := make(map[string]any)
+	err = json.Unmarshal([]byte(schema), &resultMap)
+	require.Nil(t, err)
+	dbSchema := reflect.ValueOf(resultMap["database_schema"])
+	assert.True(t, strings.Contains(dbSchema.String(), "utf8"))
+
+	// Change the db charset on the destination shard from utf8 to latin1.
+	// This will make CopySchemaShard fail during its final diff.
+	// (The different charset won't be corrected on the destination shard
+	//  because we use "CREATE DATABASE IF NOT EXISTS" and this doesn't fail if
+	//  there are differences in the options e.g. the character set.)
+	err = clusterInstance.VtctldClientProcess.ExecuteCommand("ExecuteFetchAsDBA", "--json", tabletAlias, "ALTER DATABASE vt_ks CHARACTER SET latin1")
+	require.Nil(t, err)
+
+	output, err := clusterInstance.VtctlclientProcess.ExecuteCommandWithOutput("CopySchemaShard", source, fmt.Sprintf("%s/%d", keyspaceName, shard))
+	require.Error(t, err)
+	assert.True(t, strings.Contains(output, "schemas are different"))
+
+	// shard2 primary should have the same number of tables. Only the db
+	// character set is different.
+	checkTablesCount(t, clusterInstance.Keyspaces[0].Shards[shard].Vttablets[0], totalTableCount)
+}
+
 // addNewShard adds a new shard dynamically
 func addNewShard(t *testing.T, shard int) {
 	keyspace := &cluster.Keyspace{