Fix problems in pg_autovacuum:

1) temp table crash

2) Check send_query() function call return value.

Backpatch to 7.4.X.

contrib/pg_autovacuum/pg_autovacuum.c

@@ -225,6 +225,8 @@ update_table_list(db_info * dbi)
 		 * tables to the list that are new
 		 */
 		res = send_query((char *) TABLE_STATS_QUERY, dbi);
+		if (res != NULL)
+		{
 			t = PQntuples(res);
 			
 			/*
@@ -289,6 +291,7 @@ update_table_list(db_info * dbi)
 					}
 				}
 			}						/* end of for loop that adds tables */
+		}
 		fflush(LOGOUTPUT);
 		PQclear(res);
 		res = NULL;
@@ -410,6 +413,8 @@ init_db_list()
 	if (dbs->conn != NULL)
 	{
 		res = send_query(FROZENOID_QUERY, dbs);
+		if (res != NULL)
+		{
 			dbs->oid = atooid(PQgetvalue(res, 0, PQfnumber(res, "oid")));
 			dbs->age = atol(PQgetvalue(res, 0, PQfnumber(res, "age")));
 			if (res)
@@ -418,6 +423,9 @@ init_db_list()
 			if (args->debug >= 2)
 				print_db_list(db_list, 0);
 		}
+		else
+			return NULL;
+	}
 	return db_list;
 }
 
@@ -488,6 +496,8 @@ update_db_list(Dllist *db_list)
 		 * add databases to the list that are new
 		 */
 		res = send_query(FROZENOID_QUERY2, dbi_template1);
+		if (res != NULL)
+		{
 			t = PQntuples(res);
 	
 			/*
@@ -560,6 +570,7 @@ update_db_list(Dllist *db_list)
 					}
 				}
 			}						/* end of for loop that adds tables */
+		}
 		fflush(LOGOUTPUT);
 		PQclear(res);
 		res = NULL;
@@ -599,7 +610,10 @@ xid_wraparound_check(db_info * dbi)
 
 		res = send_query("VACUUM", dbi);
 		/* FIXME: Perhaps should add a check for PQ_COMMAND_OK */
+		if (res != NULL)
+		{
 			PQclear(res);
+		}
 		return 1;
 	}
 	return 0;
@@ -750,7 +764,7 @@ check_stats_enabled(db_info * dbi)
 	int			ret = 0;
 
 	res = send_query("SHOW stats_row_level", dbi);
-	if (res)
+	if (res != NULL)
 	{
 		ret = strcmp("on", PQgetvalue(res, 0, PQfnumber(res, "stats_row_level")));
 		PQclear(res);
@@ -1079,6 +1093,8 @@ main(int argc, char *argv[])
 					res = send_query(TABLE_STATS_QUERY, dbs);	/* Get an updated
 																 * snapshot of this dbs
 																 * table stats */
+					if (res != NULL)
+					{
 						for (j = 0; j < PQntuples(res); j++)
 						{			/* loop through result set */
 							tbl_elem = DLGetHead(dbs->table_list);	/* Reset tbl_elem to top
@@ -1154,6 +1170,7 @@ main(int argc, char *argv[])
 								
 							}		/* end for table while loop */
 						}			/* end for j loop (tuples in PGresult) */
+					}			/* end if (res != NULL) */
 				}				/* close of if(xid_wraparound_check()) */
 				/* Done working on this db, Clean up, then advance cur_db */
 				PQclear(res);

contrib/pg_autovacuum/pg_autovacuum.h

@@ -34,7 +34,7 @@
 #define VACUUM_ANALYZE		0
 #define ANALYZE_ONLY		1
 
-#define TABLE_STATS_QUERY	"select a.oid,a.relname,a.relnamespace,a.relpages,a.relisshared,a.reltuples,b.schemaname,b.n_tup_ins,b.n_tup_upd,b.n_tup_del from pg_class a, pg_stat_all_tables b where a.oid=b.relid and a.relkind = 'r'"
+#define TABLE_STATS_QUERY	"select a.oid,a.relname,a.relnamespace,a.relpages,a.relisshared,a.reltuples,b.schemaname,b.n_tup_ins,b.n_tup_upd,b.n_tup_del from pg_class a, pg_stat_all_tables b where a.oid=b.relid and a.relkind = 'r' and schemaname not like 'pg_temp_%'"
 
 #define FRONTEND
 #define PAGES_QUERY "select oid,reltuples,relpages from pg_class where oid=%u"