/* tuple visibility test, initialized for the relation */
GlobalVisState *vistest;
+ /* whether or not dead items can be set LP_UNUSED during pruning */
+ bool mark_unused_now;
TransactionId new_prune_xid; /* new prune hint value for page */
TransactionId snapshotConflictHorizon; /* latest xid removed */
static void heap_prune_record_redirect(PruneState *prstate,
OffsetNumber offnum, OffsetNumber rdoffnum);
static void heap_prune_record_dead(PruneState *prstate, OffsetNumber offnum);
+static void heap_prune_record_dead_or_unused(PruneState *prstate, OffsetNumber offnum);
static void heap_prune_record_unused(PruneState *prstate, OffsetNumber offnum);
static void page_verify_redirects(Page page);
{
PruneResult presult;
- heap_page_prune(relation, buffer, vistest, &presult, NULL);
+ /*
+ * For now, pass mark_unused_now as false regardless of whether or
+ * not the relation has indexes, since we cannot safely determine
+ * that during on-access pruning with the current implementation.
+ */
+ heap_page_prune(relation, buffer, vistest, false,
+ &presult, NULL);
/*
* Report the number of tuples reclaimed to pgstats. This is
* (see heap_prune_satisfies_vacuum and
* HeapTupleSatisfiesVacuum).
*
+ * mark_unused_now indicates whether or not dead items can be set LP_UNUSED during
+ * pruning.
+ *
* off_loc is the offset location required by the caller to use in error
* callback.
*
void
heap_page_prune(Relation relation, Buffer buffer,
GlobalVisState *vistest,
+ bool mark_unused_now,
PruneResult *presult,
OffsetNumber *off_loc)
{
prstate.new_prune_xid = InvalidTransactionId;
prstate.rel = relation;
prstate.vistest = vistest;
+ prstate.mark_unused_now = mark_unused_now;
prstate.snapshotConflictHorizon = InvalidTransactionId;
prstate.nredirected = prstate.ndead = prstate.nunused = 0;
memset(prstate.marked, 0, sizeof(prstate.marked));
if (off_loc)
*off_loc = offnum;
- /* Nothing to do if slot is empty or already dead */
+ /* Nothing to do if slot is empty */
itemid = PageGetItemId(page, offnum);
- if (!ItemIdIsUsed(itemid) || ItemIdIsDead(itemid))
+ if (!ItemIdIsUsed(itemid))
continue;
/* Process this item or chain of items */
* function.)
*/
if (ItemIdIsDead(lp))
+ {
+ /*
+ * If the caller set mark_unused_now true, we can set dead line
+ * pointers LP_UNUSED now. We don't increment ndeleted here since
+ * the LP was already marked dead.
+ */
+ if (unlikely(prstate->mark_unused_now))
+ heap_prune_record_unused(prstate, offnum);
+
break;
+ }
Assert(ItemIdIsNormal(lp));
htup = (HeapTupleHeader) PageGetItem(dp, lp);
* redirect the root to the correct chain member.
*/
if (i >= nchain)
- heap_prune_record_dead(prstate, rootoffnum);
+ heap_prune_record_dead_or_unused(prstate, rootoffnum);
else
heap_prune_record_redirect(prstate, rootoffnum, chainitems[i]);
}
* item. This can happen if the loop in heap_page_prune caused us to
* visit the dead successor of a redirect item before visiting the
* redirect item. We can clean up by setting the redirect item to
- * DEAD state.
+ * DEAD state or LP_UNUSED if the caller indicated.
*/
- heap_prune_record_dead(prstate, rootoffnum);
+ heap_prune_record_dead_or_unused(prstate, rootoffnum);
}
return ndeleted;
prstate->marked[offnum] = true;
}
+/*
+ * Depending on whether or not the caller set mark_unused_now to true, record that a
+ * line pointer should be marked LP_DEAD or LP_UNUSED. There are other cases in
+ * which we will mark line pointers LP_UNUSED, but we will not mark line
+ * pointers LP_DEAD if mark_unused_now is true.
+ */
+static void
+heap_prune_record_dead_or_unused(PruneState *prstate, OffsetNumber offnum)
+{
+ /*
+ * If the caller set mark_unused_now to true, we can remove dead tuples
+ * during pruning instead of marking their line pointers dead. Set this
+ * tuple's line pointer LP_UNUSED. We hint that this option is less
+ * likely.
+ */
+ if (unlikely(prstate->mark_unused_now))
+ heap_prune_record_unused(prstate, offnum);
+ else
+ heap_prune_record_dead(prstate, offnum);
+}
+
/* Record line pointer to be marked unused */
static void
heap_prune_record_unused(PruneState *prstate, OffsetNumber offnum)
#ifdef USE_ASSERT_CHECKING
/*
- * Only heap-only tuples can become LP_UNUSED during pruning. They
- * don't need to be left in place as LP_DEAD items until VACUUM gets
- * around to doing index vacuuming.
+ * When heap_page_prune() was called, mark_unused_now may have been
+ * passed as true, which allows would-be LP_DEAD items to be made
+ * LP_UNUSED instead. This is only possible if the relation has no
+ * indexes. If there are any dead items, then mark_unused_now was not
+ * true and every item being marked LP_UNUSED must refer to a
+ * heap-only tuple.
*/
- Assert(ItemIdHasStorage(lp) && ItemIdIsNormal(lp));
- htup = (HeapTupleHeader) PageGetItem(page, lp);
- Assert(HeapTupleHeaderIsHeapOnly(htup));
+ if (ndead > 0)
+ {
+ Assert(ItemIdHasStorage(lp) && ItemIdIsNormal(lp));
+ htup = (HeapTupleHeader) PageGetItem(page, lp);
+ Assert(HeapTupleHeaderIsHeapOnly(htup));
+ }
+ else
+ {
+ Assert(ItemIdIsUsed(lp));
+ }
+
#endif
ItemIdSetUnused(lp);
Assert(!prunestate.all_visible || !prunestate.has_lpdead_items);
- if (vacrel->nindexes == 0)
- {
- /*
- * Consider the need to do page-at-a-time heap vacuuming when
- * using the one-pass strategy now.
- *
- * The one-pass strategy will never call lazy_vacuum(). The steps
- * performed here can be thought of as the one-pass equivalent of
- * a call to lazy_vacuum().
- */
- if (prunestate.has_lpdead_items)
- {
- Size freespace;
-
- lazy_vacuum_heap_page(vacrel, blkno, buf, 0, vmbuffer);
-
- /* Forget the LP_DEAD items that we just vacuumed */
- dead_items->num_items = 0;
-
- /*
- * Now perform FSM processing for blkno, and move on to next
- * page.
- *
- * Our call to lazy_vacuum_heap_page() will have considered if
- * it's possible to set all_visible/all_frozen independently
- * of lazy_scan_prune(). Note that prunestate was invalidated
- * by lazy_vacuum_heap_page() call.
- */
- freespace = PageGetHeapFreeSpace(page);
-
- UnlockReleaseBuffer(buf);
- RecordPageWithFreeSpace(vacrel->rel, blkno, freespace);
-
- /*
- * Periodically perform FSM vacuuming to make newly-freed
- * space visible on upper FSM pages. FreeSpaceMapVacuumRange()
- * vacuums the portion of the freespace map covering heap
- * pages from start to end - 1. Include the block we just
- * vacuumed by passing it blkno + 1. Overflow isn't an issue
- * because MaxBlockNumber + 1 is InvalidBlockNumber which
- * causes FreeSpaceMapVacuumRange() to vacuum freespace map
- * pages covering the remainder of the relation.
- */
- if (blkno - next_fsm_block_to_vacuum >= VACUUM_FSM_EVERY_PAGES)
- {
- FreeSpaceMapVacuumRange(vacrel->rel, next_fsm_block_to_vacuum,
- blkno + 1);
- next_fsm_block_to_vacuum = blkno + 1;
- }
-
- continue;
- }
-
- /*
- * There was no call to lazy_vacuum_heap_page() because pruning
- * didn't encounter/create any LP_DEAD items that needed to be
- * vacuumed. Prune state has not been invalidated, so proceed
- * with prunestate-driven visibility map and FSM steps (just like
- * the two-pass strategy).
- */
- Assert(dead_items->num_items == 0);
- }
-
/*
* Handle setting visibility map bit based on information from the VM
* (as of last lazy_scan_skip() call), and from prunestate
/*
* Final steps for block: drop cleanup lock, record free space in the
- * FSM
+ * FSM.
+ *
+ * If we will likely do index vacuuming, wait until
+ * lazy_vacuum_heap_rel() to save free space. This doesn't just save
+ * us some cycles; it also allows us to record any additional free
+ * space that lazy_vacuum_heap_page() will make available in cases
+ * where it's possible to truncate the page's line pointer array.
+ *
+ * Note: It's not in fact 100% certain that we really will call
+ * lazy_vacuum_heap_rel() -- lazy_vacuum() might yet opt to skip index
+ * vacuuming (and so must skip heap vacuuming). This is deemed okay
+ * because it only happens in emergencies, or when there is very
+ * little free space anyway. (Besides, we start recording free space
+ * in the FSM once index vacuuming has been abandoned.)
*/
- if (prunestate.has_lpdead_items && vacrel->do_index_vacuuming)
- {
- /*
- * Wait until lazy_vacuum_heap_rel() to save free space. This
- * doesn't just save us some cycles; it also allows us to record
- * any additional free space that lazy_vacuum_heap_page() will
- * make available in cases where it's possible to truncate the
- * page's line pointer array.
- *
- * Note: It's not in fact 100% certain that we really will call
- * lazy_vacuum_heap_rel() -- lazy_vacuum() might yet opt to skip
- * index vacuuming (and so must skip heap vacuuming). This is
- * deemed okay because it only happens in emergencies, or when
- * there is very little free space anyway. (Besides, we start
- * recording free space in the FSM once index vacuuming has been
- * abandoned.)
- *
- * Note: The one-pass (no indexes) case is only supposed to make
- * it this far when there were no LP_DEAD items during pruning.
- */
- Assert(vacrel->nindexes > 0);
- UnlockReleaseBuffer(buf);
- }
- else
+ if (vacrel->nindexes == 0
+ || !vacrel->do_index_vacuuming
+ || !prunestate.has_lpdead_items)
{
Size freespace = PageGetHeapFreeSpace(page);
UnlockReleaseBuffer(buf);
RecordPageWithFreeSpace(vacrel->rel, blkno, freespace);
+
+ /*
+ * Periodically perform FSM vacuuming to make newly-freed space
+ * visible on upper FSM pages. This is done after vacuuming if the
+ * table has indexes.
+ */
+ if (vacrel->nindexes == 0 && prunestate.has_lpdead_items &&
+ blkno - next_fsm_block_to_vacuum >= VACUUM_FSM_EVERY_PAGES)
+ {
+ FreeSpaceMapVacuumRange(vacrel->rel, next_fsm_block_to_vacuum,
+ blkno);
+ next_fsm_block_to_vacuum = blkno;
+ }
}
+ else
+ UnlockReleaseBuffer(buf);
}
vacrel->blkno = InvalidBlockNumber;
* in presult.ndeleted. It should not be confused with lpdead_items;
* lpdead_items's final value can be thought of as the number of tuples
* that were deleted from indexes.
+ *
+ * If the relation has no indexes, we can immediately mark would-be dead
+ * items LP_UNUSED, so mark_unused_now should be true if no indexes and
+ * false otherwise.
*/
- heap_page_prune(rel, buf, vacrel->vistest, &presult, &vacrel->offnum);
+ heap_page_prune(rel, buf, vacrel->vistest, vacrel->nindexes == 0,
+ &presult, &vacrel->offnum);
/*
* Now scan the page to collect LP_DEAD items and check for tuples
bool all_frozen;
LVSavedErrInfo saved_err_info;
- Assert(vacrel->nindexes == 0 || vacrel->do_index_vacuuming);
+ Assert(vacrel->do_index_vacuuming);
pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_VACUUMED, blkno);
projects / users / c2main / postgres.git / commitdiff