Separate multixact freezing parameters from xid's

Previously we were piggybacking on transaction ID parameters to freeze
multixacts; but since there isn't necessarily any relationship between
rates of Xid and multixact consumption, this turns out not to be a good
idea.

Therefore, we now have multixact-specific freezing parameters:

vacuum_multixact_freeze_min_age: when to remove multis as we come across
them in vacuum (default to 5 million, i.e. early in comparison to Xid's
default of 50 million)

vacuum_multixact_freeze_table_age: when to force whole-table scans
instead of scanning only the pages marked as not all visible in
visibility map (default to 150 million, same as for Xids).  Whichever of
both which reaches the 150 million mark earlier will cause a whole-table
scan.

autovacuum_multixact_freeze_max_age: when for cause emergency,
uninterruptible whole-table scans (default to 400 million, double as
that for Xids).  This means there shouldn't be more frequent emergency
vacuuming than previously, unless multixacts are being used very
rapidly.

Backpatch to 9.3 where multixacts were made to persist enough to require
freezing.  To avoid an ABI break in 9.3, VacuumStmt has a couple of
fields in an unnatural place, and StdRdOptions is split in two so that
the newly added fields can go at the end.

Patch by me, reviewed by Robert Haas, with additional input from Andres
Freund and Tom Lane.

1 files changed, 21 insertions, 8 deletions

diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index 1cdb22048a4..c903f0eba7c 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -64,9 +64,13 @@ typedef struct
 
 
 static void rebuild_relation(Relation OldHeap, Oid indexOid,
-				 int freeze_min_age, int freeze_table_age, bool verbose);
+				 int freeze_min_age, int freeze_table_age,
+				 int multixact_freeze_min_age, int multixact_freeze_table_age,
+				 bool verbose);
 static void copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex,
-			   int freeze_min_age, int freeze_table_age, bool verbose,
+			   int freeze_min_age, int freeze_table_age,
+			   int multixact_freeze_min_age, int multixact_freeze_table_age,
+			   bool verbose,
 			   bool *pSwapToastByContent, TransactionId *pFreezeXid,
 			   MultiXactId *pCutoffMulti);
 static List *get_tables_to_cluster(MemoryContext cluster_context);
@@ -179,7 +183,7 @@ cluster(ClusterStmt *stmt, bool isTopLevel)
 		 * Do the job.  We use a -1 freeze_min_age to avoid having CLUSTER
 		 * freeze tuples earlier than a plain VACUUM would.
 		 */
-		cluster_rel(tableOid, indexOid, false, stmt->verbose, -1, -1);
+		cluster_rel(tableOid, indexOid, false, stmt->verbose, -1, -1, -1, -1);
 	}
 	else
 	{
@@ -230,7 +234,7 @@ cluster(ClusterStmt *stmt, bool isTopLevel)
 			PushActiveSnapshot(GetTransactionSnapshot());
 			/* Do the job.  As above, use a -1 freeze_min_age. */
 			cluster_rel(rvtc->tableOid, rvtc->indexOid, true, stmt->verbose,
-						-1, -1);
+						-1, -1, -1, -1);
 			PopActiveSnapshot();
 			CommitTransactionCommand();
 		}
@@ -262,7 +266,8 @@ cluster(ClusterStmt *stmt, bool isTopLevel)
  */
 void
 cluster_rel(Oid tableOid, Oid indexOid, bool recheck, bool verbose,
-			int freeze_min_age, int freeze_table_age)
+			int freeze_min_age, int freeze_table_age,
+			int multixact_freeze_min_age, int multixact_freeze_table_age)
 {
 	Relation	OldHeap;
 
@@ -407,6 +412,7 @@ cluster_rel(Oid tableOid, Oid indexOid, bool recheck, bool verbose,
 
 	/* rebuild_relation does all the dirty work */
 	rebuild_relation(OldHeap, indexOid, freeze_min_age, freeze_table_age,
+					 multixact_freeze_min_age, multixact_freeze_table_age,
 					 verbose);
 
 	/* NB: rebuild_relation does heap_close() on OldHeap */
@@ -566,7 +572,9 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal)
  */
 static void
 rebuild_relation(Relation OldHeap, Oid indexOid,
-				 int freeze_min_age, int freeze_table_age, bool verbose)
+				 int freeze_min_age, int freeze_table_age,
+				 int multixact_freeze_min_age, int multixact_freeze_table_age,
+				 bool verbose)
 {
 	Oid			tableOid = RelationGetRelid(OldHeap);
 	Oid			tableSpace = OldHeap->rd_rel->reltablespace;
@@ -591,7 +599,9 @@ rebuild_relation(Relation OldHeap, Oid indexOid,
 
 	/* Copy the heap data into the new table in the desired order */
 	copy_heap_data(OIDNewHeap, tableOid, indexOid,
-				   freeze_min_age, freeze_table_age, verbose,
+				   freeze_min_age, freeze_table_age,
+				   multixact_freeze_min_age, multixact_freeze_table_age,
+				   verbose,
 				   &swap_toast_by_content, &frozenXid, &cutoffMulti);
 
 	/*
@@ -733,7 +743,9 @@ make_new_heap(Oid OIDOldHeap, Oid NewTableSpace)
  */
 static void
 copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex,
-			   int freeze_min_age, int freeze_table_age, bool verbose,
+			   int freeze_min_age, int freeze_table_age,
+			   int multixact_freeze_min_age, int multixact_freeze_table_age,
+			   bool verbose,
 			   bool *pSwapToastByContent, TransactionId *pFreezeXid,
 			   MultiXactId *pCutoffMulti)
 {
@@ -849,6 +861,7 @@ copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex,
 	 * compute xids used to freeze and weed out dead tuples.
 	 */
 	vacuum_set_xid_limits(freeze_min_age, freeze_table_age,
+						  multixact_freeze_min_age, multixact_freeze_table_age,
 						  OldHeap->rd_rel->relisshared,
 						  &OldestXmin, &FreezeXid, NULL, &MultiXactCutoff,
 						  NULL);