diff options
Diffstat (limited to 'src/backend/executor/nodeSeqscan.c')
| -rw-r--r-- | src/backend/executor/nodeSeqscan.c | 60 |
1 files changed, 29 insertions, 31 deletions
diff --git a/src/backend/executor/nodeSeqscan.c b/src/backend/executor/nodeSeqscan.c index fab526f399c..91e0c81e036 100644 --- a/src/backend/executor/nodeSeqscan.c +++ b/src/backend/executor/nodeSeqscan.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/executor/nodeSeqscan.c,v 1.53 2005/05/15 21:19:55 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/executor/nodeSeqscan.c,v 1.54 2005/10/15 02:49:17 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -62,11 +62,11 @@ SeqNext(SeqScanState *node) slot = node->ss_ScanTupleSlot; /* - * Clear any reference to the previously returned tuple. The idea - * here is to not have the tuple slot be the last holder of a pin on - * that tuple's buffer; if it is, we'll need a separate visit to the - * bufmgr to release the buffer. By clearing here, we get to have the - * release done by ReleaseAndReadBuffer inside heap_getnext. + * Clear any reference to the previously returned tuple. The idea here is + * to not have the tuple slot be the last holder of a pin on that tuple's + * buffer; if it is, we'll need a separate visit to the bufmgr to release + * the buffer. By clearing here, we get to have the release done by + * ReleaseAndReadBuffer inside heap_getnext. */ ExecClearTuple(slot); @@ -87,8 +87,8 @@ SeqNext(SeqScanState *node) /* * Note that unlike IndexScan, SeqScan never use keys in - * heap_beginscan (and this is very bad) - so, here we do not - * check are keys ok or not. + * heap_beginscan (and this is very bad) - so, here we do not check + * are keys ok or not. */ /* Flag for the next call that no more tuples */ @@ -102,20 +102,19 @@ SeqNext(SeqScanState *node) tuple = heap_getnext(scandesc, direction); /* - * save the tuple and the buffer returned to us by the access methods - * in our scan tuple slot and return the slot. Note: we pass 'false' - * because tuples returned by heap_getnext() are pointers onto disk - * pages and were not created with palloc() and so should not be - * pfree()'d. Note also that ExecStoreTuple will increment the - * refcount of the buffer; the refcount will not be dropped until the - * tuple table slot is cleared. + * save the tuple and the buffer returned to us by the access methods in + * our scan tuple slot and return the slot. Note: we pass 'false' because + * tuples returned by heap_getnext() are pointers onto disk pages and were + * not created with palloc() and so should not be pfree()'d. Note also + * that ExecStoreTuple will increment the refcount of the buffer; the + * refcount will not be dropped until the tuple table slot is cleared. */ if (tuple) - ExecStoreTuple(tuple, /* tuple to store */ - slot, /* slot to store in */ - scandesc->rs_cbuf, /* buffer associated with - * this tuple */ - false); /* don't pfree this pointer */ + ExecStoreTuple(tuple, /* tuple to store */ + slot, /* slot to store in */ + scandesc->rs_cbuf, /* buffer associated with this + * tuple */ + false); /* don't pfree this pointer */ return slot; } @@ -157,8 +156,8 @@ InitScanRelation(SeqScanState *node, EState *estate) HeapScanDesc currentScanDesc; /* - * get the relation object id from the relid'th entry in the range - * table, open that relation and initialize the scan state. + * get the relation object id from the relid'th entry in the range table, + * open that relation and initialize the scan state. * * We acquire AccessShareLock for the duration of the scan. */ @@ -191,8 +190,8 @@ ExecInitSeqScan(SeqScan *node, EState *estate) SeqScanState *scanstate; /* - * Once upon a time it was possible to have an outerPlan of a SeqScan, - * but not any more. + * Once upon a time it was possible to have an outerPlan of a SeqScan, but + * not any more. */ Assert(outerPlan(node) == NULL); Assert(innerPlan(node) == NULL); @@ -291,9 +290,8 @@ ExecEndSeqScan(SeqScanState *node) * close the heap relation. * * Currently, we do not release the AccessShareLock acquired by - * InitScanRelation. This lock should be held till end of - * transaction. (There is a faction that considers this too much - * locking, however.) + * InitScanRelation. This lock should be held till end of transaction. + * (There is a faction that considers this too much locking, however.) */ heap_close(relation, NoLock); } @@ -359,10 +357,10 @@ ExecSeqRestrPos(SeqScanState *node) HeapScanDesc scan = node->ss_currentScanDesc; /* - * Clear any reference to the previously returned tuple. This is - * needed because the slot is simply pointing at scan->rs_cbuf, which - * heap_restrpos will change; we'd have an internally inconsistent - * slot if we didn't do this. + * Clear any reference to the previously returned tuple. This is needed + * because the slot is simply pointing at scan->rs_cbuf, which + * heap_restrpos will change; we'd have an internally inconsistent slot if + * we didn't do this. */ ExecClearTuple(node->ss_ScanTupleSlot); |