Thread: Re: Small optimization with expanding dynamic hash table

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;