diff options
Diffstat (limited to 'src/backend/access/heap/pruneheap.c')
| -rw-r--r-- | src/backend/access/heap/pruneheap.c | 120 |
1 files changed, 4 insertions, 116 deletions
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c index 47b9e209154..18193efa238 100644 --- a/src/backend/access/heap/pruneheap.c +++ b/src/backend/access/heap/pruneheap.c @@ -36,18 +36,6 @@ typedef struct /* tuple visibility test, initialized for the relation */ GlobalVisState *vistest; - /* - * Thresholds set by TransactionIdLimitedForOldSnapshots() if they have - * been computed (done on demand, and only if - * OldSnapshotThresholdActive()). The first time a tuple is about to be - * removed based on the limited horizon, old_snap_used is set to true, and - * SetOldSnapshotThresholdTimestamp() is called. See - * heap_prune_satisfies_vacuum(). - */ - TimestampTz old_snap_ts; - TransactionId old_snap_xmin; - bool old_snap_used; - TransactionId new_prune_xid; /* new prune hint value for page */ TransactionId snapshotConflictHorizon; /* latest xid removed */ int nredirected; /* numbers of entries in arrays below */ @@ -110,8 +98,6 @@ heap_page_prune_opt(Relation relation, Buffer buffer) Page page = BufferGetPage(buffer); TransactionId prune_xid; GlobalVisState *vistest; - TransactionId limited_xmin = InvalidTransactionId; - TimestampTz limited_ts = 0; Size minfree; /* @@ -123,15 +109,6 @@ heap_page_prune_opt(Relation relation, Buffer buffer) return; /* - * XXX: Magic to keep old_snapshot_threshold tests appear "working". They - * currently are broken, and discussion of what to do about them is - * ongoing. See - * https://www.postgresql.org/message-id/20200403001235.e6jfdll3gh2ygbuc%40alap3.anarazel.de - */ - if (old_snapshot_threshold == 0) - SnapshotTooOldMagicForTest(); - - /* * First check whether there's any chance there's something to prune, * determining the appropriate horizon is a waste if there's no prune_xid * (i.e. no updates/deletes left potentially dead tuples around). @@ -143,35 +120,11 @@ heap_page_prune_opt(Relation relation, Buffer buffer) /* * Check whether prune_xid indicates that there may be dead rows that can * be cleaned up. - * - * It is OK to check the old snapshot limit before acquiring the cleanup - * lock because the worst that can happen is that we are not quite as - * aggressive about the cleanup (by however many transaction IDs are - * consumed between this point and acquiring the lock). This allows us to - * save significant overhead in the case where the page is found not to be - * prunable. - * - * Even if old_snapshot_threshold is set, we first check whether the page - * can be pruned without. Both because - * TransactionIdLimitedForOldSnapshots() is not cheap, and because not - * unnecessarily relying on old_snapshot_threshold avoids causing - * conflicts. */ vistest = GlobalVisTestFor(relation); if (!GlobalVisTestIsRemovableXid(vistest, prune_xid)) - { - if (!OldSnapshotThresholdActive()) - return; - - if (!TransactionIdLimitedForOldSnapshots(GlobalVisTestNonRemovableHorizon(vistest), - relation, - &limited_xmin, &limited_ts)) - return; - - if (!TransactionIdPrecedes(prune_xid, limited_xmin)) - return; - } + return; /* * We prune when a previous UPDATE failed to find enough space on the page @@ -205,8 +158,8 @@ heap_page_prune_opt(Relation relation, Buffer buffer) int ndeleted, nnewlpdead; - ndeleted = heap_page_prune(relation, buffer, vistest, limited_xmin, - limited_ts, &nnewlpdead, NULL); + ndeleted = heap_page_prune(relation, buffer, vistest, + &nnewlpdead, NULL); /* * Report the number of tuples reclaimed to pgstats. This is @@ -249,9 +202,7 @@ heap_page_prune_opt(Relation relation, Buffer buffer) * * vistest is used to distinguish whether tuples are DEAD or RECENTLY_DEAD * (see heap_prune_satisfies_vacuum and - * HeapTupleSatisfiesVacuum). old_snap_xmin / old_snap_ts need to - * either have been set by TransactionIdLimitedForOldSnapshots, or - * InvalidTransactionId/0 respectively. + * HeapTupleSatisfiesVacuum). * * Sets *nnewlpdead for caller, indicating the number of items that were * newly set LP_DEAD during prune operation. @@ -264,8 +215,6 @@ heap_page_prune_opt(Relation relation, Buffer buffer) int heap_page_prune(Relation relation, Buffer buffer, GlobalVisState *vistest, - TransactionId old_snap_xmin, - TimestampTz old_snap_ts, int *nnewlpdead, OffsetNumber *off_loc) { @@ -291,9 +240,6 @@ heap_page_prune(Relation relation, Buffer buffer, prstate.new_prune_xid = InvalidTransactionId; prstate.rel = relation; prstate.vistest = vistest; - prstate.old_snap_xmin = old_snap_xmin; - prstate.old_snap_ts = old_snap_ts; - prstate.old_snap_used = false; prstate.snapshotConflictHorizon = InvalidTransactionId; prstate.nredirected = prstate.ndead = prstate.nunused = 0; memset(prstate.marked, 0, sizeof(prstate.marked)); @@ -481,19 +427,6 @@ heap_page_prune(Relation relation, Buffer buffer, /* * Perform visibility checks for heap pruning. - * - * This is more complicated than just using GlobalVisTestIsRemovableXid() - * because of old_snapshot_threshold. We only want to increase the threshold - * that triggers errors for old snapshots when we actually decide to remove a - * row based on the limited horizon. - * - * Due to its cost we also only want to call - * TransactionIdLimitedForOldSnapshots() if necessary, i.e. we might not have - * done so in heap_page_prune_opt() if pd_prune_xid was old enough. But we - * still want to be able to remove rows that are too new to be removed - * according to prstate->vistest, but that can be removed based on - * old_snapshot_threshold. So we call TransactionIdLimitedForOldSnapshots() on - * demand in here, if appropriate. */ static HTSV_Result heap_prune_satisfies_vacuum(PruneState *prstate, HeapTuple tup, Buffer buffer) @@ -506,53 +439,8 @@ heap_prune_satisfies_vacuum(PruneState *prstate, HeapTuple tup, Buffer buffer) if (res != HEAPTUPLE_RECENTLY_DEAD) return res; - /* - * If we are already relying on the limited xmin, there is no need to - * delay doing so anymore. - */ - if (prstate->old_snap_used) - { - Assert(TransactionIdIsValid(prstate->old_snap_xmin)); - - if (TransactionIdPrecedes(dead_after, prstate->old_snap_xmin)) - res = HEAPTUPLE_DEAD; - return res; - } - - /* - * First check if GlobalVisTestIsRemovableXid() is sufficient to find the - * row dead. If not, and old_snapshot_threshold is enabled, try to use the - * lowered horizon. - */ if (GlobalVisTestIsRemovableXid(prstate->vistest, dead_after)) res = HEAPTUPLE_DEAD; - else if (OldSnapshotThresholdActive()) - { - /* haven't determined limited horizon yet, requests */ - if (!TransactionIdIsValid(prstate->old_snap_xmin)) - { - TransactionId horizon = - GlobalVisTestNonRemovableHorizon(prstate->vistest); - - TransactionIdLimitedForOldSnapshots(horizon, prstate->rel, - &prstate->old_snap_xmin, - &prstate->old_snap_ts); - } - - if (TransactionIdIsValid(prstate->old_snap_xmin) && - TransactionIdPrecedes(dead_after, prstate->old_snap_xmin)) - { - /* - * About to remove row based on snapshot_too_old. Need to raise - * the threshold so problematic accesses would error. - */ - Assert(!prstate->old_snap_used); - SetOldSnapshotThresholdTimestamp(prstate->old_snap_ts, - prstate->old_snap_xmin); - prstate->old_snap_used = true; - res = HEAPTUPLE_DEAD; - } - } return res; } |