Re: Largeobject Access Controls (r2460)

(2010/02/05 13:53), Takahiro Itagaki wrote:
>
> KaiGai Kohei<kaigai(at)kaigai(dot)gr(dot)jp> wrote:
>
>>> default: both contents and metadata
>>> --data-only: same
>>> --schema-only: neither
>>
>> However, it means only large object performs an exceptional object class
>> that dumps its owner, acl and comment even if --data-only is given.
>> Is it really what you suggested, isn't it?
>
> I wonder we still need to have both "BLOB ITEM" and "BLOB DATA"
> even if we will take the all-or-nothing behavior. Can we handle
> BLOB's owner, acl, comment and data with one entry kind?

I looked at the corresponding code.

Currently, we have three _LoadBlobs() variations in pg_backup_tar.c,
pg_backup_files.c and pg_backup_custom.c.

In the _tar.c and _files.c case, we can reasonably fetch data contents
of the blob to be restored. All we need to do is to provide an explicit
filename to the tarOpen() function, and a blob is not necessary to be
restored sequentially.
It means pg_restore can restore an arbitrary file when it found a new
unified blob entry.

In the _custom.c case, its _LoadBlobs() is called from _PrintTocData()
when the given TocEntry is "BLOBS", and it tries to load the following
multiple blobs. However, I could not find any restriction that custom
format cannot have multiple "BLOBS" section. In other word, we can
write out multiple sections with a blob for each a new unified blob entry.

Right now, it seems to me it is feasible to implement what you suggested.

The matter is whether we should do it, or not.
At least, it seems to me better than some of exceptional treatments in
pg_dump and pg_restore from the perspective of design.

What is your opinion?

Thanks,
--
OSS Platform Development Division, NEC
KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>