diff options
Diffstat (limited to 'src/backend/access/heap/hio.c')
| -rw-r--r-- | src/backend/access/heap/hio.c | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/src/backend/access/heap/hio.c b/src/backend/access/heap/hio.c index 583bb209336..fc1b0afd21e 100644 --- a/src/backend/access/heap/hio.c +++ b/src/backend/access/heap/hio.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/heap/hio.c,v 1.56 2005/05/07 21:32:23 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/access/heap/hio.c,v 1.57 2005/06/20 18:37:01 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -79,12 +79,26 @@ RelationPutHeapTuple(Relation relation, * happen if space is freed in that page after heap_update finds there's not * enough there). In that case, the page will be pinned and locked only once. * + * If use_fsm is true (the normal case), we use FSM to help us find free + * space. If use_fsm is false, we always append a new empty page to the + * end of the relation if the tuple won't fit on the current target page. + * This can save some cycles when we know the relation is new and doesn't + * contain useful amounts of free space. + * + * The use_fsm = false case is also useful for non-WAL-logged additions to a + * relation, if the caller holds exclusive lock and is careful to invalidate + * relation->rd_targblock before the first insertion --- that ensures that + * all insertions will occur into newly added pages and not be intermixed + * with tuples from other transactions. That way, a crash can't risk losing + * any committed data of other transactions. (See heap_insert's comments + * for additional constraints needed for safe usage of this behavior.) + * * ereport(ERROR) is allowed here, so this routine *must* be called * before any (unlogged) changes are made in buffer pool. */ Buffer RelationGetBufferForTuple(Relation relation, Size len, - Buffer otherBuffer) + Buffer otherBuffer, bool use_fsm) { Buffer buffer = InvalidBuffer; Page pageHeader; @@ -121,11 +135,14 @@ RelationGetBufferForTuple(Relation relation, Size len, * on each page that proves not to be suitable.) If the FSM has no * record of a page with enough free space, we give up and extend the * relation. + * + * When use_fsm is false, we either put the tuple onto the existing + * target page or extend the relation. */ targetBlock = relation->rd_targblock; - if (targetBlock == InvalidBlockNumber) + if (targetBlock == InvalidBlockNumber && use_fsm) { /* * We have no cached target page, so ask the FSM for an initial @@ -209,6 +226,10 @@ RelationGetBufferForTuple(Relation relation, Size len, ReleaseBuffer(buffer); } + /* Without FSM, always fall out of the loop and extend */ + if (!use_fsm) + break; + /* * Update FSM as to condition of this page, and ask for another * page to try. |