Re: Largeobject Access Controls (r2460)

(2010/02/04 17:30), KaiGai Kohei wrote:
> (2010/02/04 0:20), Robert Haas wrote:
>> 2010/2/1 KaiGai Kohei<kaigai(at)ak(dot)jp(dot)nec(dot)com>:
>>> I again wonder whether we are on the right direction.
>>
>> I believe the proposed approach is to dump blob metadata if and only
>> if you are also dumping blob contents, and to do all of this for data
>> dumps but not schema dumps. That seems about right to me.
>
> In other words:
>
> <default> -> blob contents and metadata (owner, acl, comments) shall
> be dumped
> --data-only -> only blob contents shall be dumped
> --schema-only -> neither blob contents and metadata are dumped.
>
> Can I understand correctly?

The attached patch enables not to dump "BLOB ITEM" section and corresponding
metadata when --data-only is specified. In addition, it does not output
both "BLOB DATA" and "BLOB ITEM" section when --schema-only is specified.

When --data-only is given to pg_dump, it does not construct any DO_BLOB_ITEM
entries in getBlobs(), so all the metadata (owner, acls, comment) are not
dumped. And it writes legacy "BLOBS" section instead of the new "BLOB DATA"
section to inform pg_restore this archive does not create large objects in
"BLOB ITEM" section.
If --schema-only is given, getBlobs() is simply skipped.

When --data-only is given to pg_restore, it skips all the "BLOB ITEM" sections.
Large objects are created in _LoadBlobs() instead of the section, like as we
have done until now.
The _LoadBlobs() takes the third argument which specifies whether we should
create large object here, or not. Its condition is a bit modified from the
previous patch.

if (strcmp(te->desc, "BLOBS") == 0 || ropt->dataOnly)
_LoadBlobs(AH, ropt, true); ^^^^^^^^^^^^^^^^^
else if (strcmp(te->desc, "BLOB DATA") == 0)
_LoadBlobs(AH, ropt, false);

When --data-only is given to pg_restore, "BLOB ITEM" secition is skipped,
so we need to create large objects at _LoadBlobs() stage, even if the
archive has "BLOB DATA" section.

In addition, --schema-only kills all the "BLOB ITEM" section using a special
condition that was added to _tocEntryRequired().

It might be a bit different from what Itagaki-san suggested, because
"BLOB ITEM" section is still in SECTION_PRE_DATA section.
However, it minimizes special treatments in the code, and no differences
from the viewpoint of end-users.

Or, is it necessary to pack them into SECTION_DATA section anyway?

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