Re: Partitioning option for COPY

Tom Lane wrote:
> Emmanuel Cecchet <manu(at)asterdata(dot)com> writes:
>
>> Tom Lane wrote:
>>
>>> This looks like the patch is trying to create a data structure in a
>>> memory context that's not sufficiently long-lived for the use of the
>>> structure. If you do this in a non-cassert build, it will seem to
>>> work, some of the time, if the memory in question happens to not
>>> get reallocated to something else.
>>>
>>>
>> I was using the CacheMemoryContext. Could someone tell me why this is
>> wrong and what should have been the appropriate context to use?
>>
>
> Well, (a) I doubt you really were creating the list in
> CacheMemoryContext, else it'd have not gotten clobbered; (b) creating
> statement-local data structures in CacheMemoryContext is entirely
> unacceptable anyway, because then they represent a permanent memory
> leak.
>
Well I thought that this code would do it:

child_table_lru = (OidLinkedList *)MemoryContextAlloc(
+ CacheMemoryContext, sizeof(OidLinkedList));
...
+ /* Add the new entry in head of the list */
+ new_head = (OidCell *) MemoryContextAlloc(
+ CacheMemoryContext, sizeof(OidCell));

> The right context for statement-lifetime data structures is generally
> the CurrentMemoryContext the statement code is called with.
>
Actually the list is supposed to stay around between statement
executions. You don't want to restart with a cold cache at every
statement so I really want this structure to stay in memory at a more
global level.

Emmanuel

--
Emmanuel Cecchet
Aster Data
Web: http://www.asterdata.com