= xmax. It can see * the effects of all older XIDs except those listed in the snapshot. xmin * is stored as an optimization to avoid needing to search the XID arrays * for most tuples. */ TransactionId xmin; /* all XID < xmin are visible to me */ TransactionId xmax; /* all XID >= xmax are invisible to me */ TransactionId *xip; /* array of xact IDs in progress */ uint32 xcnt; /* # of xact ids in xip[] */ /* note: all ids in xip[] satisfy xmin <= xip[i] < xmax */ int32 subxcnt; /* # of xact ids in subxip[] */ TransactionId *subxip; /* array of subxact IDs in progress */ bool suboverflowed; /* has the subxip array overflowed? */ bool takenDuringRecovery; /* recovery-shaped snapshot? */ bool copied; /* false if it's a static snapshot */ /* * note: all ids in subxip[] are >= xmin, but we don't bother filtering * out any that are >= xmax */ CommandId curcid; /* in my xact, CID < curcid are visible */ uint32 active_count; /* refcount on ActiveSnapshot stack */ uint32 regd_count; /* refcount on RegisteredSnapshotList */ } SnapshotData; /* * Result codes for HeapTupleSatisfiesUpdate. This should really be in * tqual.h, but we want to avoid including that file elsewhere. */ typedef enum { HeapTupleMayBeUpdated, HeapTupleInvisible, HeapTupleSelfUpdated, HeapTupleUpdated, HeapTupleBeingUpdated } HTSU_Result; #endif /* SNAPSHOT_H */