GS_LOGICAL_TYPE

GS_LOGICAL_TYPE stores information about data types.

**Table 1** GS_LOGICAL_TYPE columns
Column	Type	Description
typname	name	Type name.
typnamespace	oid	OID of the namespace that contains this type.
typlen	smallint	Number of bytes used by a value of this type.
typbyval	boolean	Specifies whether the value of this type is passed by value or by reference.
typtype	"char"	Row type of the catalog.
typisdefined	boolean	Specifies whether a type is completely defined.
typreceive	regproc	Receiving function in binary format.
typsend	regproc	Sending function.
typmodin	regproc	Input function for optional type modifiers.
typmodout	regproc	Output function.
typid	oid	Type OID.
dbnode	oid	Database OID.
originid	integer	Source identifier of a tuple.
createtime	timestamp with time zone	Timestamp when a tuple is inserted.
csnmin	bigint	CSN when a tuple is inserted.
csnmax	bigint	CSN when a tuple is updated or deleted.
typstorage	"char"	Data storage mode of a specified column, including the following types: p: plain storage. Numbers are always stored in a simple way. e: external storage. Data is stored outside the main table (for example, in the TOAST table). The main table stores references to data form external storage. m: main storage. Data can be stored compressed inline, which is similar to plain storage. This method is usually used to store types that require customized storage, for example, customized composite types. x: extended storage. Values may be compressed and/or moved into a level-2 relational table. x is usually the storage mode of the TOAST type.
typelem	oid	If typelem is not zero, it represents another row in the gs_logical_type table that defines the type (such as array) obtained by index. If typsubscript is zero, typelem should be zero. If the handler does not need typelem to determine the index type, typelem can also be zero when typsubscript is not zero. Note that typelem dependencies represent physical constraints on element types in this type; therefore, using DDL to modify of a type may be restricted by the existence of this type.
typinput	regproc	Input conversion function (text format).
typoutput	regproc	Output conversion function (text format).
typrelid	oid	If this is a composite type (see typtype), then this column points to the GS_LOGICAL_CLASS entry that defines the corresponding table. For a composite type, the type of GS_LOGICAL_CLASS is not a table. It is 0 for non-composite type.