diff options
Diffstat (limited to 'src/backend/access/index/indexam.c')
| -rw-r--r-- | src/backend/access/index/indexam.c | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/src/backend/access/index/indexam.c b/src/backend/access/index/indexam.c index 493e9f0ad00..6d60f461784 100644 --- a/src/backend/access/index/indexam.c +++ b/src/backend/access/index/indexam.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.95 2006/10/04 00:29:48 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.96 2006/12/23 00:43:08 tgl Exp $ * * INTERFACE ROUTINES * index_open - open an index relation by relation OID @@ -608,17 +608,27 @@ index_vacuum_cleanup(IndexVacuumInfo *info, /* ---------------- * index_getprocid * - * Some indexed access methods may require support routines that are - * not in the operator class/operator model imposed by pg_am. These - * access methods may store the OIDs of registered procedures they - * need in pg_amproc. These registered procedure OIDs are ordered in - * a way that makes sense to the access method, and used only by the - * access method. The general index code doesn't know anything about - * the routines involved; it just builds an ordered list of them for + * Index access methods typically require support routines that are + * not directly the implementation of any WHERE-clause query operator + * and so cannot be kept in pg_amop. Instead, such routines are kept + * in pg_amproc. These registered procedure OIDs are assigned numbers + * according to a convention established by the access method. + * The general index code doesn't know anything about the routines + * involved; it just builds an ordered list of them for * each attribute on which an index is defined. * - * This routine returns the requested procedure OID for a particular - * indexed attribute. + * As of Postgres 8.3, support routines within an operator family + * are further subdivided by the "left type" and "right type" of the + * query operator(s) that they support. The "default" functions for a + * particular indexed attribute are those with both types equal to + * the index opclass' opcintype (note that this is subtly different + * from the indexed attribute's own type: it may be a binary-compatible + * type instead). Only the default functions are stored in relcache + * entries --- access methods can use the syscache to look up non-default + * functions. + * + * This routine returns the requested default procedure OID for a + * particular indexed attribute. * ---------------- */ RegProcedure @@ -647,7 +657,8 @@ index_getprocid(Relation irel, * index_getprocinfo * * This routine allows index AMs to keep fmgr lookup info for - * support procs in the relcache. + * support procs in the relcache. As above, only the "default" + * functions for any particular indexed attribute are cached. * * Note: the return value points into cached data that will be lost during * any relcache rebuild! Therefore, either use the callinfo right away, |