Initialize pad bytes in GinFormTuple().

Every other core buffer page consumer initializes the bytes it furnishes
to PageAddItem().  For consistency, do the same here.  No back-patch;
regardless, we couldn't count on the fix so long as binary upgrade can
carry forward affected index builds.

diff --git a/src/backend/access/gin/ginentrypage.c b/src/backend/access/gin/ginentrypage.c
index 8ead38f234ab36e4920650775d2591e3df0ab4be..7733028fba8b8b6dab19441edd0e682670ede9ea 100644 (file)
--- a/src/backend/access/gin/ginentrypage.c
+++ b/src/backend/access/gin/ginentrypage.c
@@ -112,6 +112,12 @@ GinFormTuple(GinState *ginstate,
    if (newsize != IndexTupleSize(itup))
    {
        itup = repalloc(itup, newsize);
+       /*
+        * PostgreSQL 9.3 and earlier did not clear this new space, so we
+        * might find uninitialized padding when reading tuples from disk.
+        */
+       memset((char *) itup + IndexTupleSize(itup),
+              0, newsize - IndexTupleSize(itup));
 
        /* set new size in tuple header */
        itup->t_info &= ~INDEX_SIZE_MASK;