Add an option to AlterTableCreateToastTable() to allow its caller to force

a toast table to be built, even if the sum-of-column-widths calculation
indicates one isn't needed.  This is needed by pg_migrator because if the
old table has a toast table, we have to migrate over the toast table since
it might contain some live data, even though subsequent column drops could
mean that no recently-added rows could require toasting.

6 files changed, 25 insertions, 13 deletions

diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index e87cc2e84b..bca0c450a8 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -33,21 +33,25 @@
 
 
 static bool create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
-				   Datum reloptions);
+				   Datum reloptions, bool force);
 static bool needs_toast_table(Relation rel);
 
 
 /*
  * AlterTableCreateToastTable
  *		If the table needs a toast table, and doesn't already have one,
- *		then create a toast table for it.
+ *		then create a toast table for it.  (With the force option, make
+ *		a toast table even if it appears unnecessary.)
+ *
+ * reloptions for the toast table can be passed, too.  Pass (Datum) 0
+ * for default reloptions.
  *
  * We expect the caller to have verified that the relation is a table and have
  * already done any necessary permission checks.  Callers expect this function
  * to end with CommandCounterIncrement if it makes any changes.
  */
 void
-AlterTableCreateToastTable(Oid relOid, Datum reloptions)
+AlterTableCreateToastTable(Oid relOid, Datum reloptions, bool force)
 {
 	Relation	rel;
 
@@ -59,7 +63,7 @@ AlterTableCreateToastTable(Oid relOid, Datum reloptions)
 	rel = heap_open(relOid, AccessExclusiveLock);
 
 	/* create_toast_table does all the work */
-	(void) create_toast_table(rel, InvalidOid, InvalidOid, reloptions);
+	(void) create_toast_table(rel, InvalidOid, InvalidOid, reloptions, force);
 
 	heap_close(rel, NoLock);
 }
@@ -85,7 +89,7 @@ BootstrapToastTable(char *relName, Oid toastOid, Oid toastIndexOid)
 						relName)));
 
 	/* create_toast_table does all the work */
-	if (!create_toast_table(rel, toastOid, toastIndexOid, (Datum) 0))
+	if (!create_toast_table(rel, toastOid, toastIndexOid, (Datum) 0, false))
 		elog(ERROR, "\"%s\" does not require a toast table",
 			 relName);
 
@@ -101,7 +105,8 @@ BootstrapToastTable(char *relName, Oid toastOid, Oid toastIndexOid)
  * bootstrap they can be nonzero to specify hand-assigned OIDs
  */
 static bool
-create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid, Datum reloptions)
+create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
+				   Datum reloptions, bool force)
 {
 	Oid			relOid = RelationGetRelid(rel);
 	HeapTuple	reltup;
@@ -139,8 +144,12 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid, Datum reloptio
 
 	/*
 	 * Check to see whether the table actually needs a TOAST table.
+	 *
+	 * Caller can optionally override this check.  (Note: at present
+	 * no callers in core Postgres do so, but this option is needed by
+	 * pg_migrator.)
 	 */
-	if (!needs_toast_table(rel))
+	if (!force && !needs_toast_table(rel))
 		return false;
 
 	/*
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index ba1cda6a63..215bbb3e69 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -741,7 +741,7 @@ make_new_heap(Oid OIDOldHeap, const char *NewName, Oid NewTableSpace)
 		if (isNull)
 			reloptions = (Datum) 0;
 	}
-	AlterTableCreateToastTable(OIDNewHeap, reloptions);
+	AlterTableCreateToastTable(OIDNewHeap, reloptions, false);
 
 	if (OidIsValid(toastid))
 		ReleaseSysCache(tuple);
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 0ba4c2c983..13b30d419b 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2584,7 +2584,7 @@ ATRewriteCatalogs(List **wqueue)
 			(tab->subcmds[AT_PASS_ADD_COL] ||
 			 tab->subcmds[AT_PASS_ALTER_TYPE] ||
 			 tab->subcmds[AT_PASS_COL_ATTRS]))
-			AlterTableCreateToastTable(tab->relid, (Datum) 0);
+			AlterTableCreateToastTable(tab->relid, (Datum) 0, false);
 	}
 }
 
diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 7931926a34..60ec27ccde 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -2953,7 +2953,7 @@ OpenIntoRel(QueryDesc *queryDesc)
 
 	(void) heap_reloptions(RELKIND_TOASTVALUE, reloptions, true);
 
-	AlterTableCreateToastTable(intoRelationId, reloptions);
+	AlterTableCreateToastTable(intoRelationId, reloptions, false);
 
 	/*
 	 * And open the constructed table for writing.
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 80070e39b2..c302c950e8 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -442,10 +442,13 @@ ProcessUtility(Node *parsetree,
 															"toast",
 															validnsps,
 															true, false);
-						(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options,
+						(void) heap_reloptions(RELKIND_TOASTVALUE,
+											   toast_options,
 											   true);
 
-						AlterTableCreateToastTable(relOid, toast_options);
+						AlterTableCreateToastTable(relOid,
+												   toast_options,
+												   false);
 					}
 					else
 					{
diff --git a/src/include/catalog/toasting.h b/src/include/catalog/toasting.h
index 4024103a5f..765ca98236 100644
--- a/src/include/catalog/toasting.h
+++ b/src/include/catalog/toasting.h
@@ -17,7 +17,7 @@
 /*
  * toasting.c prototypes
  */
-extern void AlterTableCreateToastTable(Oid relOid, Datum reloptions);
+extern void AlterTableCreateToastTable(Oid relOid, Datum reloptions, bool force);
 extern void BootstrapToastTable(char *relName,
 					Oid toastOid, Oid toastIndexOid);