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v1.1

Documentation:v1.1

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PG_AM

PG_AM records information about index access methods. There is one row for each index access method supported by the system.

Table 1 PG_AM columns

Name Type Reference Description
amname name - Name of the access method
amstrategies smallint - Number of operator strategies for the access method (0 if the access method does not have a fixed set of operator strategies)
amsupport smallint - Number of support routines for the access method
amcanorder Boolean - Whether the access method supports ordered scans sorted by the indexed column's value
amcanorderbyop Boolean - Whether the access method supports ordered scans sorted by the result of an operator on the indexed column
amcanbackward Boolean - Whether the access method supports backward scanning
amcanunique Boolean - Whether the access method supports unique indexes
amcanmulticol Boolean - Whether the access method supports multi-column indexes
amoptionalkey Boolean - Whether the access method supports scanning without any constraint for the first index column
amsearcharray Boolean - Whether the access method supports ScalarArrayOpExpr searches
amsearchnulls Boolean - Whether the access method supports IS NULL/NOT NULL searches
amstorage Boolean - Whether the index storage data type can differ from the column data type
amclusterable Boolean - Whether an index of this type can be clustered on
ampredlocks Boolean - Whether an index of this type manages fine-grained predicate locks
amkeytype oid PG_TYPE.oid Type of data stored in index (0 if it is not a fixed type)
aminsert regproc PG_PROC.proname "Insert this tuple" function
ambeginscan regproc PG_PROC.proname "Prepare for index scan" function
amgettuple regproc PG_PROC.proname "Next valid tuple" function (0 if none)
amgetbitmap regproc PG_PROC.proname "Fetch all valid tuples" function (0 if none)
amrescan regproc PG_PROC.proname "(Re)start index scan" function
amendscan regproc PG_PROC.proname "Clean up after index scan" function
ammarkpos regproc PG_PROC.proname "Mark current scan position" function
amrestrpos regproc PG_PROC.proname "Restore marked scan position" function
ammerge regproc PG_PROC.proname "Merge multiple indexes" function
ambuild regproc PG_PROC.proname "Build new index" function
ambuildempty regproc PG_PROC.proname "Build empty index" function
ambulkdelete regproc PG_PROC.proname Bulk-delete function
amvacuumcleanup regproc PG_PROC.proname Post-VACUUM cleanup function
amcanreturn regproc PG_PROC.proname Function to check whether the index supports index-only scans (0 if none)
amcostestimate regproc PG_PROC.proname Function to estimate cost of an index scan
amoptions regproc PG_PROC.proname Function to parse and validate reloptions for an index
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