diff options
| -rw-r--r-- | src/backend/access/nbtree/README | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/src/backend/access/nbtree/README b/src/backend/access/nbtree/README index 067d15c8039..a3f11da8d5a 100644 --- a/src/backend/access/nbtree/README +++ b/src/backend/access/nbtree/README @@ -521,11 +521,12 @@ because it allows running applications to continue while the standby changes state into a normally running server. The interlocking required to avoid returning incorrect results from -MVCC scans is not required on standby nodes. That is because +non-MVCC scans is not required on standby nodes. That is because HeapTupleSatisfiesUpdate(), HeapTupleSatisfiesSelf(), HeapTupleSatisfiesDirty() and HeapTupleSatisfiesVacuum() are only ever used during write transactions, which cannot exist on the standby. -This leaves HeapTupleSatisfiesMVCC() and HeapTupleSatisfiesToast(). +MVCC scans are already protected by definition, so HeapTupleSatisfiesMVCC() +is not a problem. That leaves concern only for HeapTupleSatisfiesToast(). HeapTupleSatisfiesToast() doesn't use MVCC semantics, though that's because it doesn't need to - if the main heap row is visible then the toast rows will also be visible. So as long as we follow a toast |