PG-1532 Rewrite seqeunces using lower level functions

By using SPI and a SQL language function to force the rewrite of
sequences we made life unnecessarily hard for ourselves and also
intoduced a bug where ALTER TABLE could break if the pg_tde extension's
functions were not in the search path.

Instead we re-use the code for updating sequence persistence whe table
persistance is changed. And we only need to look at the table's
presistance since it is always the same as the one of the sequences.

Author: jeltz

contrib/pg_tde/pg_tde--1.0-rc.sql

@@ -414,43 +414,6 @@ BEGIN ATOMIC
                             'certPath' VALUE kmip_cert_path));
 END;
 
-
-CREATE FUNCTION pg_tde_internal_refresh_sequences(table_oid OID)
-RETURNS VOID
-AS
-$BODY$
-DECLARE
-    rec RECORD;
-BEGIN
-    FOR rec IN
-            SELECT s.relname AS sequence_name,
-                ns.nspname AS sequence_namespace,
-                se.seqstart AS sequence_start
-            FROM pg_class AS t
-            JOIN pg_attribute AS a
-                ON a.attrelid = t.oid
-            JOIN pg_depend AS d
-                ON d.refobjid = t.oid
-                AND d.refobjsubid = a.attnum
-            JOIN pg_class AS s
-                ON s.oid = d.objid
-            JOIN pg_sequence AS se
-                ON se.seqrelid = d.objid
-            JOIN pg_namespace AS ns
-                ON ns.oid = s.relnamespace
-            WHERE d.classid = 'pg_catalog.pg_class'::regclass
-            AND d.refclassid = 'pg_catalog.pg_class'::regclass
-            AND d.deptype IN ('i', 'a')
-            AND t.relkind IN ('r', 'P')
-            AND s.relkind = 'S'
-            AND t.oid = table_oid
-    LOOP
-        EXECUTE format('ALTER SEQUENCE %s.%s START %s', rec.sequence_namespace, rec.sequence_name, rec.sequence_start);
-    END LOOP;
-END
-$BODY$
-LANGUAGE plpgsql;
-
 CREATE FUNCTION pg_tde_is_encrypted(relation regclass)
 RETURNS boolean
 STRICT

contrib/pg_tde/src/pg_tde_event_capture.c

@@ -16,6 +16,7 @@
 #include "utils/builtins.h"
 #include "catalog/pg_class.h"
 #include "commands/defrem.h"
+#include "commands/sequence.h"
 #include "access/table.h"
 #include "access/relation.h"
 #include "catalog/pg_event_trigger.h"
@@ -28,7 +29,6 @@
 #include "miscadmin.h"
 #include "access/tableam.h"
 #include "catalog/tde_global_space.h"
-#include "executor/spi.h"
 
 /* Global variable that gets set at ddl start and cleard out at ddl end*/
 static TdeCreateEvent tdeCurrentCreateEvent = {.tid = {.value = 0},.relation = NULL};
@@ -273,35 +273,24 @@ pg_tde_ddl_command_end_capture(PG_FUNCTION_ARGS)
 	if (IsA(parsetree, AlterTableStmt) && tdeCurrentCreateEvent.alterAccessMethodMode)
 	{
 		/*
-		 * sequences are not updated automatically call a helper function that
-		 * automatically alters all of them, forcing an update on the
-		 * encryption status int ret;
+		 * sequences are not updated automatically so force rewrite by
+		 * updating their persistence to be the same as before.
 		 */
-		char	   *sql = "SELECT pg_tde_internal_refresh_sequences($1);";
-		Oid			argtypes[1];
-		SPIPlanPtr	plan;
-		Datum		args[1];
-		char		nulls[1];
-		int			ret;
+		List	   *seqlist = getOwnedSequences(tdeCurrentCreateEvent.baseTableOid);
+		ListCell   *lc;
+		Relation	rel = relation_open(tdeCurrentCreateEvent.baseTableOid, NoLock);
+		char		persistence = rel->rd_rel->relpersistence;
 
-		SPI_connect();
+		relation_close(rel, NoLock);
 
-		argtypes[0] = OIDOID;
-		plan = SPI_prepare(sql, 1, argtypes);
-
-		args[0] = ObjectIdGetDatum(tdeCurrentCreateEvent.baseTableOid);
-		nulls[0] = ' ';
+		foreach(lc, seqlist)
+		{
+			Oid			seq_relid = lfirst_oid(lc);
 
-		ret = SPI_execute_plan(plan, args, nulls, false, 0);
+			SequenceChangePersistence(seq_relid, persistence);
+		}
 
 		tdeCurrentCreateEvent.alterAccessMethodMode = false;
-
-		SPI_finish();
-
-		if (ret != SPI_OK_SELECT)
-		{
-			elog(ERROR, "Failed to update encryption status of sequences.");
-		}
 	}
 
 	/*