StateDeleteOnly means we can only delete items for this schema element.

StateDeleteReorganization means we are re-organizing whole data after delete only state.

StateNone means this schema element is absent and can't be used.

StatePublic means this schema element is ok for all write and read operations.

StateWriteOnly means we can use any write operation on this schema element, but outer can't read the changed data.

StateWriteReorganization means we are re-organizing whole data after write only state.

CIStr is case insensitive string.

DBInfo provides meta data describing a DB.

IndexInfo provides meta data describing a DB index.

PartitionDefinition defines a single partition.

PartitionInfo provides table partition info.

TableInfo provides meta data describing a DB table.

Key represents high-level TiDB Key type.

KeyInfoBuffer can obtain the meta information of the TiDB Key.

SchemaState is the state for schema elements.