Re: DEALLOCATE ALL

Alvaro Herrera wrote:
> Marko Kreen escribió:
>> On 3/30/07, Alvaro Herrera <alvherre@commandprompt.com> wrote:
>
>>> In any case it's not likely that there are going to be thousands of
>>> prepared statements, so is this really an issue?
>> I think the issue is here that its very common thing to do,
>> so open-coding it everywhere is waste, there should be some
>> utility function for that.
>>
>> void hash_foreach(HTAB, void (*cb_func)(void *));
>
> Extra points if you can implement a map() function for hashes ;-) (I
> think it's called "mutator" in our sources for other kind of stuff)
>
> I think it would be
> void *hash_map(HTAB, void *(*map_func) (void *))
>
> Not sure what the return value would be though :-( (Maybe this is
> extra complication enough that it's not worth the hassle)

hash_map and hash_foreach seem like overkill to me, looping with
hash_seq_search and doing stuff is simple enough that it doesn't really
require any additional shorthands. Besides, to use them you'd always
have to have a separate function and often a struct to pass down to the
function, so it's not really any shorter or simpler.

What would be useful is a hash_seq_remove-function that removes the
previous item returned by hash_seq_search without the overhead of
recalculating the hash value.

While reviewing ITAGAKI's dead space map patch I noticed that he also
added a hash_truncate function that removes all entries in the hash
table, but unlike hash_destroy leaves the hash table intact. His
implementation also calls hash_search(REMOVE) in a loop, which isn't the
most efficient way to do it, but clearly there's need for more ways to
empty a hash table.

--
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com