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51.26. pg_index
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51.26. pg_index#

The catalogpg_index contains part of the information about indexes. The rest is mostly inpg_class.

Table 51.26. pg_index Columns

Column Type

Description

indexrelidoid (referencespg_class.oid)

The OID of thepg_class entry for this index

indrelidoid (referencespg_class.oid)

The OID of thepg_class entry for the table this index is for

indnattsint2

The total number of columns in the index (duplicatespg_class.relnatts); this number includes both key and included attributes

indnkeyattsint2

The number ofkey columns in the index, not counting anyincluded columns, which are merely stored and do not participate in the index semantics

indisuniquebool

If true, this is a unique index

indnullsnotdistinctbool

This value is only used for unique indexes. If false, this unique index will consider null values distinct (so the index can contain multiple null values in a column, the default PostgreSQL behavior). If it is true, it will consider null values to be equal (so the index can only contain one null value in a column).

indisprimarybool

If true, this index represents the primary key of the table (indisunique should always be true when this is true)

indisexclusionbool

If true, this index supports an exclusion constraint

indimmediatebool

If true, the uniqueness check is enforced immediately on insertion (irrelevant ifindisunique is not true)

indisclusteredbool

If true, the table was last clustered on this index

indisvalidbool

If true, the index is currently valid for queries. False means the index is possibly incomplete: it must still be modified byINSERT/UPDATE operations, but it cannot safely be used for queries. If it is unique, the uniqueness property is not guaranteed true either.

indcheckxminbool

If true, queries must not use the index until thexmin of thispg_index row is below theirTransactionXmin event horizon, because the table may contain brokenHOT chains with incompatible rows that they can see

indisreadybool

If true, the index is currently ready for inserts. False means the index must be ignored byINSERT/UPDATE operations.

indislivebool

If false, the index is in process of being dropped, and should be ignored for all purposes (including HOT-safety decisions)

indisreplidentbool

If true this index has been chosen asreplica identity usingALTER TABLE ... REPLICA IDENTITY USING INDEX ...

indkeyint2vector (referencespg_attribute.attnum)

This is an array ofindnatts values that indicate which table columns this index indexes. For example, a value of1 3 would mean that the first and the third table columns make up the index entries. Key columns come before non-key (included) columns. A zero in this array indicates that the corresponding index attribute is an expression over the table columns, rather than a simple column reference.

indcollationoidvector (referencespg_collation.oid)

For each column in the index key (indnkeyatts values), this contains the OID of the collation to use for the index, or zero if the column is not of a collatable data type.

indclassoidvector (referencespg_opclass.oid)

For each column in the index key (indnkeyatts values), this contains the OID of the operator class to use. Seepg_opclass for details.

indoptionint2vector

This is an array ofindnkeyatts values that store per-column flag bits. The meaning of the bits is defined by the index's access method.

indexprspg_node_tree

Expression trees (innodeToString() representation) for index attributes that are not simple column references. This is a list with one element for each zero entry inindkey. Null if all index attributes are simple references.

indpredpg_node_tree

Expression tree (innodeToString() representation) for partial index predicate. Null if not a partial index.



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