Re: pgsql: Add GUC to enable compression of full page images stored in WAL.

On 3/12/15 6:13 AM, Fujii Masao wrote:
> On Wed, Mar 11, 2015 at 11:30 PM, Michael Paquier
> <michael.paquier@gmail.com> wrote:
>> On Wed, Mar 11, 2015 at 11:18 PM, Andres Freund <andres@2ndquadrant.com> wrote:
>>> On 2015-03-11 06:54:16 +0000, Fujii Masao wrote:
>>>> Add GUC to enable compression of full page images stored in WAL.
>>>
>>> This triggers a couple warnings here (gcc 4.9 and 5):
>>>
>>> /home/andres/src/postgresql/src/backend/access/transam/xloginsert.c: In function 'XLogInsert':
>>> /home/andres/src/postgresql/src/backend/access/transam/xloginsert.c:670:5: warning: 'cbimg.hole_length' may be used
uninitializedin this function [-Wmaybe-uninitialized] 
>>>      memcpy(scratch, &cbimg,
>>>      ^
>>> /home/andres/src/postgresql/src/backend/access/transam/xloginsert.c:494:33: note: 'cbimg.hole_length' was declared
here
>>>    XLogRecordBlockCompressHeader cbimg;
>>>                                  ^
>>> /home/andres/src/postgresql/src/backend/access/transam/xloginsert.c:668:20: warning: 'hole_length' may be used
uninitializedin this function [-Wmaybe-uninitialized] 
>>>     if (hole_length != 0 && is_compressed)
>>>                     ^
>>> /home/andres/src/postgresql/src/backend/access/transam/xloginsert.c:497:10: note: 'hole_length' was declared here
>>>    uint16 hole_length;
>>>
>>> I've not checked whether they're spurious or not.
>
> Thanks for the report! We can suppress those warnings just by
> initializing cbimg.hole_length and hole_length. But I'd like to apply
> the attached patch which not only initializes the variable but also
> refactors the related code.

Could you please fix this compiler warning soon?