Re: [GENERAL] pglogical vs. built-in logical replication in pg-10

På torsdag 22. juni 2017 kl. 11:43:02, skrev Achilleas Mantzios <achill@matrix.gatewaynet.com>:

On 22/06/2017 11:21, Andreas Joseph Krogh wrote:

Hi.

 

1. Why should one prefer built-in logical replication in pg-10 to pglogical, does it do anything pglogical doesn't?

It seems pglogical is more feature-rich...

2. As I understand built-in logical replication in pg-10 doesn't support large-objects, which we use a lot. Does pglogical replicate large objects? I cannot find any notes about large-objects under "Limitations and Restrictions": https://www.2ndquadrant.com/en/resources/pglogical/pglogical-docs/

You may do a simple test, create a table with a largeobject and try to read the logical stream, if it cannot represent the lo_import, lo_open, lowrite, lo_close (and I 'd bet they can't be encoded) then neither pglogical (being based on the same logical decoding technology) will support them
 

 

The point of email-lists like this is that one may share knowledge so one doesn't have to test everything one self, and can build on knowledge from others. I'm looking for an answer from someone who's not betting, but knows.

I gave you enough knowledge already. Here's some more :
- go and install 10
- create a table containing one col with type oid (large object) and one bytea
- follow the simple setup here : https://www.postgresql.org/docs/10/static/logicaldecoding-example.html
- insert a row
- Do again : SELECT * FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL);

Do you see any of your oid image data in the output? Do you see any of the bytea ? (the answer here in 9.5 is  "no"/"yes").
If in 10.0 is still the case, then you should think about moving to bytea.

 

Thanks.

 

--

Andreas Joseph Krogh

CTO / Partner - Visena AS

Mobile: +47 909 56 963

andreas@visena.com

www.visena.com

 

-- 
Achilleas Mantzios
IT DEV Lead
IT DEPT
Dynacom Tankers Mgmt