Re: Changeset Extraction v7.5

On February 7, 2014 9:58:14 PM CET, Thom Brown <thom@linux.com> wrote:
>On 7 February 2014 19:35, Andres Freund <andres@2ndquadrant.com> wrote:
>> 0004: wal_decoding: Documentation for replication slots and changeset
>extraction
>
>The usage of pg_create_decoding_replication_slot does show the "(1
>row)" line.
>
>The output of "SELECT * FROM pg_replication_slots;" is out-of-date.
>
>There appears to be a column named "slot_name" and "slottype".  Could
>one of these have or not have the underscore for consistency?
>
>The example also shows output from pg_decoding_slot_get_changes after
>inserting 2 rows, but when I run the same example, there are no rows
>returned:
>
># BEGIN;
>BEGIN
>
>*# INSERT INTO data(data) VALUES('1');
>INSERT 0 1
>
>*# INSERT INTO data(data) VALUES('1');
>INSERT 0 1
>
>*# COMMIT;
>COMMIT
>
># SELECT * FROM pg_decoding_slot_get_changes('regression_slot', 'now',
>'include-xids', '0');
> location | xid | data
>----------+-----+------
>(0 rows)
>
>
>I inserted a single row outside of a transaction, and got the expected
>output.  Then I ran the above again, and got an output, but an
>unexpected one:
>
>SELECT * FROM pg_decoding_slot_get_changes('regression_slot', 'now',
>'include-xids', '0');
> location  | xid |                     data
>-----------+-----+-----------------------------------------------
> 0/16C8B90 | 769 | BEGIN
> 0/16C8D50 | 769 | table "data": INSERT: id[int4]:3 data[text]:1
> 0/16C8D50 | 769 | COMMIT
>(3 rows)
>
>And running the transaction with inserts again, there's no output from
>that same function command.  I always get an output from isolated
>INSERT statements.  I should point out that in my .psqlrc file I have
>"\set ON_ERROR_ROLLBACK".  If I use psql -X, this symptom no longer
>occurs, so I think the automatic savepoints are interfering, and the
>effect appears to be inconsistent.

More complete answer later, but any chance you're using synchronous commit = off?

Thanks for looking,

Andres

-- 
Please excuse brevity and formatting - I am writing this on my mobile phone.

Andres Freund                       http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services