Re: Transition Tables doesn´t have OID - Mailing list pgsql-general

On 12/01/2018 06:22 AM, PegoraroF10 wrote:
> I´m trying to use transition tables for auditing purposes.
>
> create trigger MyTableAudit_UPD after update on MyTable referencing old
> table as Transition_old new table as Transition_new for each statement
> execute procedure AuditTable();
>
> create or replace function AuditTable() returns trigger language plpgsql as
> $$
> if (TG_OP = 'UPDATE') then
>    insert into audittable(table_name, oid, audit_action, user_id,
> table_schema, values_old, values_new)
>    select TG_TABLE_NAME, Transition_new.oid, TG_OP, CURRENT_USER,
> TG_TABLE_SCHEMA,  row_to_json(Transition_old.*)::jsonb,
> row_to_json(Transition_new.*)::jsonb from Transition_new inner join
> Transition_old on Transition_new.OID = Transition_old.OID;
> elsif (TG_OP = 'DELETE') then
>    insert into audittable(table_name, oid, audit_action, user_id,
> table_schema, values_old)
>    select TG_TABLE_NAME, Transition_old.oid, TG_OP, CURRENT_USER,
> TG_TABLE_SCHEMA, row_to_json(Transition_old.*)::jsonb from Transition_old;
> end if;
>
> [42703] ERROR: column transition_new.oid does not exist Where: função
> PL/pgSQL audittable() linha 14 em comando SQL
>
> I would like to user OID value because we change our primary keys,
> sometimes, OID doesn´t.
>
> So, there is a way to get OID on transition tables ?

Did you create MyTable WITH OIDS (or set default_with_oids on in 
postgresql.conf)? https://www.postgresql.org/docs/9.6/datatype-oid.html

Also, 
https://www.postgresql.org/docs/9.6/runtime-config-compatible.html#GUC-DEFAULT-WITH-OIDS
"The use of OIDs in user tables is considered deprecated, so most 
installations should leave this variable disabled. Applications that require 
OIDs for a particular table should specify WITH OIDS when creating the table."

More importantly, https://wiki.postgresql.org/wiki/FAQ#What_is_an_OID.3F
"OIDs are sequentially assigned 4-byte integers. Initially they are unique 
across the entire installation. However, the OID counter wraps around at 4 
billion, and after that OIDs may be duplicated.

It is possible to prevent duplication of OIDs within a single table by 
creating a unique index on the OID column (but note that the WITH OIDS 
clause doesn't by itself create such an index). The system checks the index 
to see if a newly generated OID is already present, and if so generates a 
new OID and repeats. This works well so long as no OID-containing table has 
more than a small fraction of 4 billion rows."


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