Lookup the Oid for int8eq using the parser

kudos @edongashi for the parser suggestion

Author: pdobacz

pg_diffix/oid_cache.h

@@ -56,6 +56,8 @@ typedef struct Oids
 
   /* Internal functions */
   Oid internal_qual_wrapper; /* diffix.internal_qual_wrapper(boolean) */
+
+  Oid op_int8eq;
 } Oids;
 
 /*

src/oid_cache.c

@@ -3,6 +3,7 @@
 #include "catalog/pg_type.h"
 #include "lib/stringinfo.h"
 #include "parser/parse_func.h"
+#include "parser/parse_oper.h"
 #include "utils/lsyscache.h"
 
 #include "pg_diffix/oid_cache.h"
@@ -66,6 +67,10 @@ void oid_cache_init(void)
 
   g_oid_cache.internal_qual_wrapper = lookup_function("diffix", "internal_qual_wrapper", 1, (Oid[]){BOOLOID});
 
+  List *eq_op_name = list_make1(makeString("="));
+  g_oid_cache.op_int8eq = LookupOperName(NULL, eq_op_name, INT8OID, INT8OID, false, -1);
+  list_free_deep(eq_op_name);
+
   g_loaded = true;
 }
 

src/query/anonymization.c

@@ -202,7 +202,7 @@ static Expr *make_safe_anon_count_value(const Aggref *source_aggref)
   count_aggref->aggdistinct = false;
 
   NullIfExpr *nullif = makeNode(NullIfExpr);
-  nullif->opno = 410; /* = for int8eq. */
+  nullif->opno = g_oid_cache.op_int8eq;
   nullif->opfuncid = F_INT8EQ;
   nullif->opresulttype = count_aggref->aggtype;
   nullif->opretset = false;