Re: found xmin from before relfrozenxid on pg_catalog.pg_authid

[Maxim Boguk <maxim.boguk@xxxxxxxxx>]

Hi Andres,

> ​
> Looking for possible course of action.
> Probably simplest fix - drop and recreate these 6 affected users, but so
> far I willing spent some time research into this issue.

Could you use pageinspect to get the infomasks for the affected tuples?

Greetings,

Andres Freund

​For sample:

postgres=# vacuum pg_catalog.pg_authid;
ERROR:  found xmin 2894889518 from before relfrozenxid 248712603

select ctid, xmin, xmax, cmin, cmax from pg_catalog.pg_authid where xmin::text::bigint=2894889518;
  ctid  |    xmin    | xmax | cmin | cmax
--------+------------+------+------+------
 (1,26) | 2894889518 |    0 |    0 |    0

postgres=# SELECT * FROM heap_page_items(get_raw_page('pg_authid', 1)) where t_ctid::text='(1,26)';
-[ RECORD 1 ]-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
lp          | 26
lp_off      | 4656
lp_flags    | 1
lp_len      | 144
t_xmin      | 2894889518
t_xmax      | 0
t_field3    | 0
t_ctid      | (1,26)
t_infomask2 | 32779
t_infomask  | 10507
t_hoff      | 32
t_bits      | 1111111111000000
t_oid       | 189787727

Any new role created in DB instantly affected by this issue.

In the same time:

 select relfrozenxid from pg_class where relname='pg_authid';
 relfrozenxid
--------------
   2863429136

So it's interesting where value of " from before relfrozenxid 248712603" come from.

​

​

--

Maxim Boguk
Senior Postgresql DBA
http://dataegret.com/

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