add computeHashHook

src/gausskernel/storage/access/hash/hashfunc.cpp

@@ -708,6 +708,9 @@ Datum compute_hash(Oid type, Datum value, char locator)
             return DirectFunctionCall1(uuid_hash, value);
 
         default:
+            if (u_sess->hook_cxt.computeHashHook != NULL) {
+                return ((computeHashFunc)(u_sess->hook_cxt.computeHashHook))(type, value, locator);
+            }
             ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                             errmsg("Unhandled datatype for modulo or hash distribution\n")));
     }

src/include/access/hash.h

@@ -440,4 +440,6 @@ extern uint32 hash_multikey(MultiHashKey* mkeys);
 
 #define GetBucketID(hashval, hashmapsize)  (compute_modulo(abs((int)hashval), hashmapsize))
 
+typedef Datum (*computeHashFunc)(Oid type, Datum value, char locator);
+
 #endif   /* HASH_H */

src/include/knl/knl_session.h

@@ -2640,6 +2640,7 @@ typedef struct knl_u_hook_context {
     void *analyzerRoutineHook;
     void *transformStmtHook;
     void *execInitExprHook;
+    void *computeHashHook;
 } knl_u_hook_context;
 
 typedef struct knl_session_context {