Small optimization with expanding dynamic hash table

Hi, hackers

If I understand correctly, we only need to check the specific bit to determine whether a hash element needs relocation:

diff --git a/src/backend/utils/hash/dynahash.c b/src/backend/utils/hash/dynahash.c
index 1ad155d446e..32fbae71995 100644
--- a/src/backend/utils/hash/dynahash.c
+++ b/src/backend/utils/hash/dynahash.c
@@ -1626,7 +1626,7 @@ expand_table(HTAB *hashp)
                 currElement = nextElement)
        {
                nextElement = currElement->link;
-               if ((long) calc_bucket(hctl, currElement->hashvalue) == old_bucket)
+               if (!(currElement->hashvalue & (hctl->low_mask + 1)))
                {
                        *oldlink = currElement;
                        oldlink = &currElement->link;

--
Regards,
ChangAo Chen