diff options
Diffstat (limited to 'src/backend/utils/adt/selfuncs.c')
| -rw-r--r-- | src/backend/utils/adt/selfuncs.c | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index 53d974125fd..00c7afc66fc 100644 --- a/src/backend/utils/adt/selfuncs.c +++ b/src/backend/utils/adt/selfuncs.c @@ -5786,14 +5786,15 @@ get_actual_variable_endpoint(Relation heapRel, * recent); that case motivates not using SnapshotAny here. * * A crucial point here is that SnapshotNonVacuumable, with - * RecentGlobalXmin as horizon, yields the inverse of the condition that - * the indexscan will use to decide that index entries are killable (see - * heap_hot_search_buffer()). Therefore, if the snapshot rejects a tuple - * (or more precisely, all tuples of a HOT chain) and we have to continue - * scanning past it, we know that the indexscan will mark that index entry - * killed. That means that the next get_actual_variable_endpoint() call - * will not have to re-consider that index entry. In this way we avoid - * repetitive work when this function is used a lot during planning. + * GlobalVisTestFor(heapRel) as horizon, yields the inverse of the + * condition that the indexscan will use to decide that index entries are + * killable (see heap_hot_search_buffer()). Therefore, if the snapshot + * rejects a tuple (or more precisely, all tuples of a HOT chain) and we + * have to continue scanning past it, we know that the indexscan will mark + * that index entry killed. That means that the next + * get_actual_variable_endpoint() call will not have to re-consider that + * index entry. In this way we avoid repetitive work when this function + * is used a lot during planning. * * But using SnapshotNonVacuumable creates a hazard of its own. In a * recently-created index, some index entries may point at "broken" HOT @@ -5805,7 +5806,8 @@ get_actual_variable_endpoint(Relation heapRel, * or could even be NULL. We avoid this hazard because we take the data * from the index entry not the heap. */ - InitNonVacuumableSnapshot(SnapshotNonVacuumable, RecentGlobalXmin); + InitNonVacuumableSnapshot(SnapshotNonVacuumable, + GlobalVisTestFor(heapRel)); index_scan = index_beginscan(heapRel, indexRel, &SnapshotNonVacuumable, |