BUG #13978: xmin,xmax not current for foreign table

Started by 德哥about 10 years ago2 messagesbugs
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#1德哥
digoal@126.com

The following bug has been logged on the website:

Bug reference: 13978
Logged by: digoal
Email address: digoal@126.com
PostgreSQL version: 9.5.0
Operating system: CentOS 6.x x64
Description:

tbl0 is a foreign table with postgres_fdw
master=# select tableoid,ctid,xmin,xmax,* from tbl0;
tableoid | ctid | xmin | xmax | id | info | crt_time

----------+--------+------+------------+----+------+----------------------------
20304 | (0,11) | 192 | 4294967295 | 4 | test | 2016-02-23
11:25:20.440349
20304 | (0,12) | 192 | 4294967295 | 8 | test | 2016-02-23
11:25:20.440349
(2 rows)

but the right values is:
db0=# select tableoid,ctid,xmin,xmax,* from tbl0;
tableoid | ctid | xmin | xmax | id | info | crt_time

----------+--------+----------+----------+----+------+----------------------------
20280 | (0,11) | 38232587 | 38232588 | 4 | test | 2016-02-23
11:25:20.440349
20280 | (0,12) | 38232587 | 38232588 | 8 | test | 2016-02-23
11:25:20.440349
(2 rows)

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#2Tom Lane
tgl@sss.pgh.pa.us
In reply to: 德哥 (#1)
Re: BUG #13978: xmin,xmax not current for foreign table

digoal@126.com writes:

tbl0 is a foreign table with postgres_fdw
master=# select tableoid,ctid,xmin,xmax,* from tbl0;
...
but the right values is:

xmin/xmax are not meaningful in foreign tables. Even in the case of a
postgres_fdw foreign table, they cannot be useful because there's no way
to map between the remote server's XID numbering and local XIDs. So I do
not believe your claim that there's a "right" value for them to have.

Ideally, those columns wouldn't even exist in foreign tables; but fixing
that has so far not seemed worth the trouble it would require.

regards, tom lane

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