Re: Changeset Extraction v7.5

On 7 February 2014 19:35, Andres Freund <andres(at)2ndquadrant(dot)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The output of "SELECT * FROM pg_replication_slots;" is out-of-date.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.

--
Thom