diff options
Diffstat (limited to 'src/include/utils/snapmgr.h')
| -rw-r--r-- | src/include/utils/snapmgr.h | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index f8308e69259..c49aceadfb1 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -61,6 +61,45 @@ extern PGDLLIMPORT TransactionId RecentXmin; extern PGDLLIMPORT TransactionId RecentGlobalXmin; extern PGDLLIMPORT TransactionId RecentGlobalDataXmin; +/* Variables representing various special snapshot semantics */ +extern PGDLLIMPORT SnapshotData SnapshotSelfData; +extern PGDLLIMPORT SnapshotData SnapshotAnyData; +extern PGDLLIMPORT SnapshotData CatalogSnapshotData; + +#define SnapshotSelf (&SnapshotSelfData) +#define SnapshotAny (&SnapshotAnyData) + +/* + * We don't provide a static SnapshotDirty variable because it would be + * non-reentrant. Instead, users of that snapshot type should declare a + * local variable of type SnapshotData, and initialize it with this macro. + */ +#define InitDirtySnapshot(snapshotdata) \ + ((snapshotdata).snapshot_type = SNAPSHOT_DIRTY) + +/* + * Similarly, some initialization is required for a NonVacuumable snapshot. + * The caller must supply the xmin horizon to use (e.g., RecentGlobalXmin). + */ +#define InitNonVacuumableSnapshot(snapshotdata, xmin_horizon) \ + ((snapshotdata).snapshot_type = SNAPSHOT_NON_VACUUMABLE, \ + (snapshotdata).xmin = (xmin_horizon)) + +/* + * Similarly, some initialization is required for SnapshotToast. We need + * to set lsn and whenTaken correctly to support snapshot_too_old. + */ +#define InitToastSnapshot(snapshotdata, l, w) \ + ((snapshotdata).snapshot_type = SNAPSHOT_TOAST, \ + (snapshotdata).lsn = (l), \ + (snapshotdata).whenTaken = (w)) + +/* This macro encodes the knowledge of which snapshots are MVCC-safe */ +#define IsMVCCSnapshot(snapshot) \ + ((snapshot)->snapshot_type == SNAPSHOT_MVCC || \ + (snapshot)->snapshot_type == SNAPSHOT_HISTORIC_MVCC) + + extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); @@ -98,6 +137,11 @@ extern void MaintainOldSnapshotTimeMapping(TimestampTz whenTaken, extern char *ExportSnapshot(Snapshot snapshot); +/* + * Utility functions for implementing visibility routines in table AMs. + */ +extern bool XidInMVCCSnapshot(TransactionId xid, Snapshot snapshot); + /* Support for catalog timetravel for logical decoding */ struct HTAB; extern struct HTAB *HistoricSnapshotGetTupleCids(void); |