commit 32efa598196c4f5da01910f576304312c7bfae41
author Orhan Kislal <okislal@apache.org> Tue Mar 03 19:04:19 2020 -0500
committer Orhan Kislal <okislal@pivotal.io> Wed Mar 04 19:19:09 2020 -0500
tree cac4eddd5c4d52253a33214ab15dba29922fd9ef
parent d165e84a27a98c6df75688ee37fdabbdf6422caa

MFVSketch: Use datumIsEqual for comparing datums

mfvsketch used memcmp() for comparing two Datums to check for
equality. There is a note in the postgres/gpdb source saying
this is unsafe, so we converted it over to calling the postgres
function datumIsEqual() which can handle either little-endian
or big-endian byte order, making it more portable.

Co-authored-by: Domino Valdano <dvaldano@pivotal.io>

methods/sketch/src/pg_gp/mfvsketch.c

diff --git a/methods/sketch/src/pg_gp/mfvsketch.c b/methods/sketch/src/pg_gp/mfvsketch.c
index 0b954cc..f1853e7 100644
--- a/methods/sketch/src/pg_gp/mfvsketch.c
+++ b/methods/sketch/src/pg_gp/mfvsketch.c
@@ -35,6 +35,7 @@
 #include <utils/lsyscache.h>
 #include <utils/numeric.h>
 #include <utils/typcache.h>
+#include <utils/datum.h>
 #include <nodes/execnodes.h>
 #include <fmgr.h>
 #include <catalog/pg_type.h>
@@ -179,10 +180,8 @@
 {
     mfvtransval *transval = (mfvtransval *)VARDATA(blob);
     unsigned     i;
-    uint32       len;
-    void *       datp;
+    void *datp;
     Datum        iDat;
-    void        *valp = DatumExtractPointer(val, transval->typByVal);
 
     /* look for existing entry for this value */
     for (i = 0; i < transval->next_mfv; i++) {
@@ -190,11 +189,9 @@
         datp = mfv_transval_getval(blob,i);
         iDat = PointerExtractDatum(datp, transval->typByVal);
 
-        if ((len = ExtractDatumLen(iDat, transval->typLen, transval->typByVal, -1))
-            == ExtractDatumLen(val, transval->typLen, transval->typByVal, -1)) {
-            if (!memcmp(datp, valp, len))
-                /* arg is an mfv */
-                return(i);
+        if (datumIsEqual(iDat, val, transval->typByVal, transval->typLen)) {
+            /* arg is an mfv */
+            return(i);
         }
     }
     return(-1);