Mark correctly initial slot snapshots with MVCC type when built

michaelpq · michaelpq · commit 56fadbedbd2f · 2019-02-20T12:31:07.000+09:00
When building an initial slot snapshot, snapshots are marked with historic MVCC snapshots as type with the marker field being set in SnapBuildBuildSnapshot() but not overriden in SnapBuildInitialSnapshot(). Existing callers of SnapBuildBuildSnapshot() do not care about the type of snapshot used, but extensions calling it actually may, as reported. While on it, mark correctly the snapshot type when importing one. This is cosmetic as the field is enforced to 0. Author: Antonin Houska Reviewed-by: Álvaro Herrera, Michael Paquier Discussion: https://postgr.es/m/23215.1527665193@localhost Backpatch-through: 9.4
diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
@@ -616,6 +616,8 @@ SnapBuildInitialSnapshot(SnapBuild *builder)
 		TransactionIdAdvance(xid);
 	}
 
+	/* adjust remaining snapshot fields as needed */
+	snap->snapshot_type = SNAPSHOT_MVCC;
 	snap->xcnt = newxcnt;
 	snap->xip = newxip;
 
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
@@ -1509,6 +1509,8 @@ ImportSnapshot(const char *idstr)
 	src_isolevel = parseIntFromText("iso:", &filebuf, path);
 	src_readonly = parseIntFromText("ro:", &filebuf, path);
 
+	snapshot.snapshot_type = SNAPSHOT_MVCC;
+
 	snapshot.xmin = parseXidFromText("xmin:", &filebuf, path);
 	snapshot.xmax = parseXidFromText("xmax:", &filebuf, path);
 

Original file line number	Diff line number	Diff line change
`@@ -616,6 +616,8 @@ SnapBuildInitialSnapshot(SnapBuild *builder)`
`616`	`616`	`TransactionIdAdvance(xid);`
`617`	`617`	`}`
`618`	`618`
	`619`	`+ /* adjust remaining snapshot fields as needed */`
	`620`	`+ snap->snapshot_type = SNAPSHOT_MVCC;`
`619`	`621`	`snap->xcnt = newxcnt;`
`620`	`622`	`snap->xip = newxip;`
`621`	`623`