CODEWITHSUNDEEP
postgresqlchange-data-capture
Bala
Bala

Reputation: 139

could not access file wal2json no such file or directory

I am new to PostgreSQL. I am trying to implement logical replication in PostgreSQL installed in my laptop.

When I run the following query to create a replication slot, I am getting

could not access file wal2json: no such file or directory 

SELECT * FROM pg_create_logical_replication_slot('test_slot', 'wal2json');

After a search in google, I understand that wal2json is an additional extension kind of thing which needs to be setup separately.

Does anyone have an idea how to setup "wal2json" in PostgreSQL installed on a local laptop (Windows OS)?

Upvotes: 1

Views: 4288

Answers (2)

Venryx
Venryx

Reputation: 18059

You can find the binaries for wal2json here: https://www.striim.com/docs/smsgc/en/smsgc-how-to-guides/postgresql-to-google-cloud-postgresql-migration-guide/set-up-the-postgresql-source.html

(They're provided by a third-party, Striim, but the company appears legit, so I'm not concerned by it.)

After downloading, copy the dll file into the C:\Program Files\PostgreSQL\VERSION\lib folder, and restart PostgreSQL.

EDIT: Actually, on attempting to use the wal2json extension from NodeJS, it appears something is incompatible between the prebuilt Windows 10 binary above, and my Postgres install. I get the following error in Postgraphile:

Could not Initiate PgLDSSourcePlugin, continuing without LDS live queries. Error: Couldn't create replication slot, seems you don't have wal2json installed? Error: could not load library "C:/Program Files/PostgreSQL/13/lib/wal2json.dll": The specified procedure could not be found.

So in the end I had to compile the dll myself, as the wal2json readme specifies. (I was getting a compilation error, so I tried upgrading Visual Studio from 2015 to 2019. Once I did so, the build completed easily however. I just opened the wal2json.vcxproj file, pressed Build->Build wal2json, then copied the dll file it produced into the PostgreSQL lib folder.)

Upvotes: 0

Jonathan Jacobson
Jonathan Jacobson

Reputation: 1518

wal2json is a plugin (not an extension) that needs to be installed separately. The README.md file has some info about installing it for Windows. I think that you will have an easier time installing and managing PostgreSQL and the plugin inside a Linux virtual machine.

Upvotes: 1

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