code: func (b *Builder) InitWithOldInfoSchema() *Builder {
  	oldIS := b.handle.Get().(*infoSchema)
  	b.is.schemaMetaVersion = oldIS.schemaMetaVersion
  	b.copySchemasMap(oldIS)
  	copy(b.is.sortedTablesBuckets, oldIS.sortedTablesBuckets)
  	return b
  }
docs: // InitWithOldInfoSchema initializes an empty new InfoSchema by copies all the data from old InfoSchema.