// CopySchemaShard copies the schema from a source tablet to the
// specified shard. The schema is applied directly on the master of
// the destination shard, and is propogated to the replicas through
// binlogs.
func (wr *Wrangler) CopySchemaShard(ctx context.Context, sourceTabletAlias *topodatapb.TabletAlias, tables, excludeTables []string, includeViews bool, destKeyspace, destShard string) error {
destShardInfo, err := wr.ts.GetShard(ctx, destKeyspace, destShard)
if err != nil {
return err
}
sourceSd, err := wr.GetSchema(ctx, sourceTabletAlias, tables, excludeTables, includeViews)
if err != nil {
return err
}
destSd, err := wr.GetSchema(ctx, destShardInfo.MasterAlias, tables, excludeTables, includeViews)
if err != nil {
destSd = nil
}
if destSd != nil {
diffs := tmutils.DiffSchemaToArray("source", sourceSd, "dest", destSd)
if diffs == nil {
// Return early because dest has already the same schema as source.
return nil
}
}
createSQL := tmutils.SchemaDefinitionToSQLStrings(sourceSd)
destTabletInfo, err := wr.ts.GetTablet(ctx, destShardInfo.MasterAlias)
if err != nil {
return err
}
for i, sqlLine := range createSQL {
err = wr.applySQLShard(ctx, destTabletInfo, sqlLine, i == len(createSQL)-1)
if err != nil {
return err
}
}
return nil
}
// CopySchemaShard copies the schema from a source tablet to the
// specified shard. The schema is applied directly on the master of
// the destination shard, and is propogated to the replicas through
// binlogs.
func (wr *Wrangler) CopySchemaShard(ctx context.Context, sourceTabletAlias *topodatapb.TabletAlias, tables, excludeTables []string, includeViews bool, destKeyspace, destShard string, waitSlaveTimeout time.Duration) error {
destShardInfo, err := wr.ts.GetShard(ctx, destKeyspace, destShard)
if err != nil {
return err
}
diffs, err := wr.compareSchemas(ctx, sourceTabletAlias, destShardInfo.MasterAlias, tables, excludeTables, includeViews)
if err != nil {
return fmt.Errorf("CopySchemaShard failed because schemas could not be compared initially: %v", err)
}
if diffs == nil {
// Return early because dest has already the same schema as source.
return nil
}
sourceSd, err := wr.GetSchema(ctx, sourceTabletAlias, tables, excludeTables, includeViews)
if err != nil {
return err
}
createSQL := tmutils.SchemaDefinitionToSQLStrings(sourceSd)
destTabletInfo, err := wr.ts.GetTablet(ctx, destShardInfo.MasterAlias)
if err != nil {
return err
}
for i, sqlLine := range createSQL {
err = wr.applySQLShard(ctx, destTabletInfo, sqlLine, i == len(createSQL)-1)
if err != nil {
return err
}
}
// Remember the replication position after all the above were applied.
destMasterPos, err := wr.tmc.MasterPosition(ctx, destTabletInfo.Tablet)
if err != nil {
return fmt.Errorf("CopySchemaShard: can't get replication position after schema applied: %v", err)
}
// Although the copy was successful, we have to verify it to catch the case
// where the database already existed on the destination, but with different
// options e.g. a different character set.
// In that case, MySQL would have skipped our CREATE DATABASE IF NOT EXISTS
// statement. We want to fail early in this case because vtworker SplitDiff
// fails in case of such an inconsistency as well.
diffs, err = wr.compareSchemas(ctx, sourceTabletAlias, destShardInfo.MasterAlias, tables, excludeTables, includeViews)
if err != nil {
return fmt.Errorf("CopySchemaShard failed because schemas could not be compared finally: %v", err)
}
if diffs != nil {
return fmt.Errorf("CopySchemaShard was not successful because the schemas between the two tablets %v and %v differ: %v", sourceTabletAlias, destShardInfo.MasterAlias, diffs)
}
// Notify slaves to reload schema. This is best-effort.
reloadCtx, cancel := context.WithTimeout(ctx, waitSlaveTimeout)
defer cancel()
wr.ReloadSchemaShard(reloadCtx, destKeyspace, destShard, destMasterPos)
return nil
}