diff options
Diffstat (limited to 'src/backend/access/index/indexam.c')
| -rw-r--r-- | src/backend/access/index/indexam.c | 85 |
1 files changed, 41 insertions, 44 deletions
diff --git a/src/backend/access/index/indexam.c b/src/backend/access/index/indexam.c index 7bf7fcd22f0..bd2e3bdd06e 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 1.85 2005/10/06 02:29:11 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.86 2005/10/15 02:49:09 momjian Exp $ * * INTERFACE ROUTINES * index_open - open an index relation by relation OID @@ -111,7 +111,7 @@ do { \ } while(0) static IndexScanDesc index_beginscan_internal(Relation indexRelation, - int nkeys, ScanKey key); + int nkeys, ScanKey key); /* ---------------------------------------------------------------- @@ -122,14 +122,14 @@ static IndexScanDesc index_beginscan_internal(Relation indexRelation, /* ---------------- * index_open - open an index relation by relation OID * - * Note: we acquire no lock on the index. A lock is not needed when + * Note: we acquire no lock on the index. A lock is not needed when * simply examining the index reldesc; the index's schema information * is considered to be protected by the lock that the caller had better - * be holding on the parent relation. Some type of lock should be + * be holding on the parent relation. Some type of lock should be * obtained on the index before physically accessing it, however. * This is handled automatically for most uses by index_beginscan * and index_endscan for scan cases, or by ExecOpenIndices and - * ExecCloseIndices for update cases. Other callers will need to + * ExecCloseIndices for update cases. Other callers will need to * obtain their own locks. * * This is a convenience routine adapted for indexscan use. @@ -241,8 +241,8 @@ index_beginscan(Relation heapRelation, scan = index_beginscan_internal(indexRelation, nkeys, key); /* - * Save additional parameters into the scandesc. Everything else was - * set up by RelationGetIndexScan. + * Save additional parameters into the scandesc. Everything else was set + * up by RelationGetIndexScan. */ scan->is_multiscan = false; scan->heapRelation = heapRelation; @@ -267,8 +267,8 @@ index_beginscan_multi(Relation indexRelation, scan = index_beginscan_internal(indexRelation, nkeys, key); /* - * Save additional parameters into the scandesc. Everything else was - * set up by RelationGetIndexScan. + * Save additional parameters into the scandesc. Everything else was set + * up by RelationGetIndexScan. */ scan->is_multiscan = true; scan->xs_snapshot = snapshot; @@ -294,14 +294,14 @@ index_beginscan_internal(Relation indexRelation, * Acquire AccessShareLock for the duration of the scan * * Note: we could get an SI inval message here and consequently have to - * rebuild the relcache entry. The refcount increment above ensures - * that we will rebuild it and not just flush it... + * rebuild the relcache entry. The refcount increment above ensures that + * we will rebuild it and not just flush it... */ LockRelation(indexRelation, AccessShareLock); /* - * LockRelation can clean rd_aminfo structure, so fill procedure - * after LockRelation + * LockRelation can clean rd_aminfo structure, so fill procedure after + * LockRelation */ GET_REL_PROCEDURE(ambeginscan); @@ -425,8 +425,8 @@ index_restrpos(IndexScanDesc scan) /* * We do not reset got_tuple; so if the scan is actually being - * short-circuited by index_getnext, the effective position - * restoration is done by restoring unique_tuple_pos. + * short-circuited by index_getnext, the effective position restoration is + * done by restoring unique_tuple_pos. */ scan->unique_tuple_pos = scan->unique_tuple_mark; @@ -454,19 +454,19 @@ index_getnext(IndexScanDesc scan, ScanDirection direction) /* * If we already got a tuple and it must be unique, there's no need to - * make the index AM look through any additional tuples. (This can - * save a useful amount of work in scenarios where there are many dead - * tuples due to heavy update activity.) + * make the index AM look through any additional tuples. (This can save a + * useful amount of work in scenarios where there are many dead tuples due + * to heavy update activity.) * * To do this we must keep track of the logical scan position * (before/on/after tuple). Also, we have to be sure to release scan - * resources before returning NULL; if we fail to do so then a - * multi-index scan can easily run the system out of free buffers. We - * can release index-level resources fairly cheaply by calling - * index_rescan. This means there are two persistent states as far as - * the index AM is concerned: on-tuple and rescanned. If we are - * actually asked to re-fetch the single tuple, we have to go through - * a fresh indexscan startup, which penalizes that (infrequent) case. + * resources before returning NULL; if we fail to do so then a multi-index + * scan can easily run the system out of free buffers. We can release + * index-level resources fairly cheaply by calling index_rescan. This + * means there are two persistent states as far as the index AM is + * concerned: on-tuple and rescanned. If we are actually asked to + * re-fetch the single tuple, we have to go through a fresh indexscan + * startup, which penalizes that (infrequent) case. */ if (scan->keys_are_unique && scan->got_tuple) { @@ -485,19 +485,18 @@ index_getnext(IndexScanDesc scan, ScanDirection direction) if (new_tuple_pos == 0) { /* - * We are moving onto the unique tuple from having been off - * it. We just fall through and let the index AM do the work. - * Note we should get the right answer regardless of scan - * direction. + * We are moving onto the unique tuple from having been off it. We + * just fall through and let the index AM do the work. Note we + * should get the right answer regardless of scan direction. */ scan->unique_tuple_pos = 0; /* need to update position */ } else { /* - * Moving off the tuple; must do amrescan to release - * index-level pins before we return NULL. Since index_rescan - * will reset my state, must save and restore... + * Moving off the tuple; must do amrescan to release index-level + * pins before we return NULL. Since index_rescan will reset my + * state, must save and restore... */ int unique_tuple_mark = scan->unique_tuple_mark; @@ -520,8 +519,7 @@ index_getnext(IndexScanDesc scan, ScanDirection direction) bool found; /* - * The AM's gettuple proc finds the next tuple matching the scan - * keys. + * The AM's gettuple proc finds the next tuple matching the scan keys. */ found = DatumGetBool(FunctionCall2(procedure, PointerGetDatum(scan), @@ -556,9 +554,9 @@ index_getnext(IndexScanDesc scan, ScanDirection direction) continue; /* - * If we can't see it, maybe no one else can either. Check to see - * if the tuple is dead to all transactions. If so, signal the - * index AM to not return it on future indexscans. + * If we can't see it, maybe no one else can either. Check to see if + * the tuple is dead to all transactions. If so, signal the index AM + * to not return it on future indexscans. * * We told heap_release_fetch to keep a pin on the buffer, so we can * re-access the tuple here. But we must re-lock the buffer first. @@ -576,8 +574,8 @@ index_getnext(IndexScanDesc scan, ScanDirection direction) scan->got_tuple = true; /* - * If we just fetched a known-unique tuple, then subsequent calls will - * go through the short-circuit code above. unique_tuple_pos has been + * If we just fetched a known-unique tuple, then subsequent calls will go + * through the short-circuit code above. unique_tuple_pos has been * initialized to 0, which is the correct state ("on row"). */ @@ -805,11 +803,10 @@ index_getprocinfo(Relation irel, procId = loc[procindex]; /* - * Complain if function was not found during - * IndexSupportInitialize. This should not happen unless the - * system tables contain bogus entries for the index opclass. (If - * an AM wants to allow a support function to be optional, it can - * use index_getprocid.) + * Complain if function was not found during IndexSupportInitialize. + * This should not happen unless the system tables contain bogus + * entries for the index opclass. (If an AM wants to allow a support + * function to be optional, it can use index_getprocid.) */ if (!RegProcedureIsValid(procId)) elog(ERROR, "missing support function %d for attribute %d of index \"%s\"", |