SYSTEM CATALOG · System catalog

pg_opclass

PostgreSQL documentation ↗Source definition ↗

The catalog pg_opclass defines index access method operator classes. Each operator class defines semantics for index columns of a particular data type and a particular index access method. An operator class essentially specifies that a particular operator family is applicable to a particular indexable column data type. The set of operators from the family that are actually usable with the indexed column are whichever ones accept the column's data type as their left-hand input. Operator classes are described at length in Section 36.16.

First seen PG 9.0Last seen PG 19Columns 9

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_opclass

COLUMN	TYPE	DESCRIPTION
`oid`	`oid`NOT NULL	Row identifier
`opcmethod`	`oid`NOT NULL	Index access method operator class is forReferences:`pg_am.oid`
`opcname`	`name`NOT NULL	Name of this operator class
`opcnamespace`	`oid`NOT NULL	Namespace of this operator classReferences:`pg_namespace.oid`
`opcowner`	`oid`NOT NULL	Owner of the operator classReferences:`pg_authid.oid`
`opcfamily`	`oid`NOT NULL	Operator family containing the operator classReferences:`pg_opfamily.oid`
`opcintype`	`oid`NOT NULL	Data type that the operator class indexesReferences:`pg_type.oid`
`opcdefault`	`boolean`NOT NULLDocumented as:`bool`	True if this operator class is the default for opcintype
`opckeytype`	`oid`NOT NULL	Type of data stored in index, or zero if same as opcintypeReferences:`pg_type.oid`

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`
`opcmethod`
`opcname`
`opcnamespace`
`opcowner`
`opcfamily`
`opcintype`
`opcdefault`
`opckeytype`

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 17 ← 16

Catalog description updated

PostgreSQL 14 ← 13

Catalog description updated

PostgreSQL 12 ← 11

~ oid: implicit → ordinary1 column description updatesCatalog description updated

PostgreSQL 11 ← 10

Catalog description updated

PostgreSQL 10 ← 9.6

Catalog description updated

PostgreSQL 9.6 ← 9.5

Catalog description updated

PostgreSQL 9.3 ← 9.2

1 column description updates

PostgreSQL 9.2 ← 9.1

Catalog description updated

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