SYSXTDTYPES (IDS)

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SYSXTDTYPES (IDS)

The sysxtdtype system catalog table has an entry for each UDT (user-defined data type), including opaque and distinct data types and complex data types (named ROW type, unnamed ROW type, and COLLECTION type), that is defined in the database. The sysxtdtypes table has the following columns.

Column	Type	Explanation
extended_id	SERIAL	Unique identifying code for extended data type
domain	CHAR(1)	Code for the domain of the UDT
mode	CHAR(1)	Code classifying the UDT: B = Base (opaque) type C = Collection type or unnamed ROW type D = Distinct type R = Named ROW type ' ' (blank) = Built-in type
owner	VARCHAR(32)	Name of the owner of the UDT
name	VARCHAR(128)	Name of the UDT
type	SMALLINT	Code classifying the UDT
source	INTEGER	The sysxtdtypes reference (for distinct types only) Zero (0) indicates that a distinct UDT was created from a built-in data type.
maxlen	INTEGER	The maximum length for variable-length data types Zero indicates a fixed-length UDT.
length	INTEGER	The length in bytes for fixed-length data types Zero indicates a variable-length UDT.
byvalue	CHAR(1)	'`T`' = UDT is passed by value '`F`' = UDT is not passed by value
cannothash	CHAR(1)	'`T`' = UDT is hashable by default hash function '`F`' = UDT is not hashable by default function
align	SMALLINT	Alignment ( = 1, 2, 4, or 8) for this UDT
locator	INTEGER	Locator key for unnamed ROW type

Each extended data type is characterized by a unique identifier, called an extended identifier (extended_id), a data type identifier (type), and the length and description of the data type.

For distinct types created from built-in data types, the type column codes correspond to the value of the syscolumns.coltype column (indicating the source type) as listed on page ***, but incremented by the hexadecimal value 0x0000800. The file $INFORMIXDIR/incl/esql/sqltypes.h contains information about sysxtdtypes.type and syscolumns.coltype codes.

An index on the extended_id column allows only unique values. An index on the locator column allows duplicate values, as does a composite indexes on the name and owner columns. A composite index on the type and source columns also allows duplicate values.