SYSTEM CATALOG · System catalog

pg_cast

PostgreSQL documentation ↗Source definition ↗

The catalog pg_cast stores data type conversion paths, both built-in and user-defined. It should be noted that pg_cast does not represent every type conversion that the system knows how to perform; only those that cannot be deduced from some generic rule. For example, casting between a domain and its base type is not explicitly represented in pg_cast. Another important exception is that “automatic I/O conversion casts”, those performed using a data type's own I/O functions to convert to or from text or other string types, are not explicitly represented in pg_cast.

First seen PG 9.0Last seen PG 19Columns 6

9.0 9.1 9.2 9.3 9.4 9.5 9.6 10 11 12 13 14 15 16 17 18 19^β3

Checked column by column against a PostgreSQL 18.6 instance · Raw measurement record ↗

Columns PostgreSQL 18

pg_cast

COLUMN	TYPE	DESCRIPTION
`oid`	`oid`NOT NULL	Row identifier
`castsource`	`oid`NOT NULL	OID of the source data typeReferences:`pg_type.oid`
`casttarget`	`oid`NOT NULL	OID of the target data typeReferences:`pg_type.oid`
`castfunc`	`oid`NOT NULL	The OID of the function to use to perform this cast. Zero is stored if the cast method doesn't require a function.References:`pg_proc.oid`
`castcontext`	`"char"`NOT NULLDocumented as:`char`	Indicates what contexts the cast can be invoked in. e means only as an explicit cast (using CAST or :: syntax). a means implicitly in assignment to a target column, as well as explicitly. i means implicitly in expressions, as well as the other cases.
`castmethod`	`"char"`NOT NULLDocumented as:`char`	Indicates how the cast is performed. f means that the function specified in the castfunc field is used. i means that the input/output functions are used. b means that the types are binary-coercible, thus no conversion is required.

Columns marked "implicit" are not included in SELECT *; some early statistics views are completed from same-version source, and the extra provenance is shown in the column description.

Common system columns 6

System attributes PostgreSQL provides, normally not expanded by SELECT *. Kept separately so they are not mixed in with ordinary columns.

Columns	Type	attnum
`tableoid`	`oid`	-6
`cmax`	`cid`	-5
`xmax`	`xid`	-4
`cmin`	`cid`	-3
`xmin`	`xid`	-2
`ctid`	`tid`	-1

Column evolution matrix

Hover a cell for the column type

PresentAdded / type or attribute changeRemoved

COLUMN	9.0	9.1	9.2	9.3	9.4	9.5	9.6	10	11	12	13	14	15	16	17	18	19
`oid`
`castsource`
`casttarget`
`castfunc`
`castcontext`
`castmethod`

9.0 is the coverage baseline; a column already present in the baseline is not marked as added. The matrix aligns columns by name, so a rename appears as the old column removed and a new column added.

Evolution timeline

Changes between adjacent majors

PostgreSQL 12 ← 11

~ oid: implicit → ordinary1 column description updates

PostgreSQL 10 ← 9.6

Catalog description updated

PostgreSQL 9.3 ← 9.2

1 column description updates

PostgreSQL 9.2 ← 9.1

Catalog description updated

Compare any two versions

FROMTOInclude description updates

Pick two versions to see added, removed, and retyped columns. The interactive comparison needs JavaScript; the evolution timeline reads fine without it.