Thread: Avoid a potential unstable test case: xmlmap.sql

In the test case of  xmlmap.sql, we have the query below under schema_to_xml.

explain (costs off, verbose) 

SELECT oid FROM pg_catalog.pg_class 

WHERE  relnamespace = 28601 

AND relkind IN ('r','m','v') 

AND pg_catalog.has_table_privilege (oid, 'SELECT') 

ORDER BY relname;

based on current cost setting and algorithm.  With this plan,  

has_table_privilege(pg_class.oid, 'SELECT'::text)  may be executed

against all the relations (not just the given namespace), so if a

tuple in pg_class is scanned and before has_table_privilege is called,

the relation is dropped, then we will get error:

 Sort
   Output: oid, relname
   Sort Key: pg_class.relname
   ->  Seq Scan on pg_catalog.pg_class
         Output: oid, relname
         Filter: (has_table_privilege(pg_class.oid, 'SELECT'::text) AND (pg_class.relnamespace = '28601'::oid) AND (pg_class.relkind = ANY ('{r,m,v}'::"char"[])))                                                    QUERY PLAN                                                    
------------------------------------------------------------------------------------------------------------------
 Index Scan using pg_class_relname_nsp_index on pg_catalog.pg_class
   Output: oid, relname
   Index Cond: (pg_class.relnamespace = '28601'::oid)
   Filter: (has_table_privilege(pg_class.oid, 'SELECT'::text) AND (pg_class.relkind = ANY ('{r,m,v}'::"char"[])))

Patch is attached. 

I overlooked the fact even in the bitmap index scan loose mode,  the recheck