Re: pg_dump -Fd and compression level

On 07/25/2015 03:07 PM, Marc Mamin wrote:
>>> I propose to tighten pg_dump's rules so that only 0..9 are accepted as
>>> arguments for -Z, and in compress_io.c:cfopen(), if compression is
>>> equal to Z_DEFAULT_COMPRESSION, not add any explicit compression value
>>> to the mode, thus using the zlib default.
>>>
>>>
>>
>> As per attached patch.
>>
>> Comments?
>
> It seems that the first test on the compression in pg_backup_tar.c is now obsolete.
> It didn't make much sense anyway.
>
>
>
>    211         if (AH->compression < 0 || AH->compression > 9)
>    212             AH->compression = Z_DEFAULT_COMPRESSION;
>    213
>    214         /* Don't compress into tar files unless asked to do so */
>    215         if (AH->compression == Z_DEFAULT_COMPRESSION)
>    216             AH->compression = 0;
>    217
>    218         /*
>    219          * We don't support compression because reading the files back is not
>    220          * possible since gzdopen uses buffered IO which totally screws file
>    221          * positioning.
>    222          */
>    223         if (AH->compression != 0)
>    224             exit_horribly(modulename,
>    225                      "compression is not supported by tar archive format\n");
>    226     }
>    
>    

In fact, the first two tests look unnecessary. Neither condition should 
be possible now.

cheers

andrew