Re: Recommendation to run vacuum FULL in parallel

Perumal Raj wrote:
> We are planning to reclaim unused space from 9.2 Version postgres Cluster,
>
> Method : VACUUM FULL
> DB Size : 500 GB
> Expected space to reclaim 150 GB
> work_mem : 250 MB
> maintenance_work_mem : 20 GB
>
> Question :
>
> 1. vacuumdb --j option (Parallel) not available for version 9.2.
> How to run vacuum full in parallel ? At present its taking 8Hrs if i run sequential ( vacuum full verbose;)

Run several scripts in parallel, where each of them vacuums some bloated tables.
Be warned that VACUUM (FULL) is quite I/O intense, so too much parallelism
might overload your I/O system and harm performance.

> 2. If we run vacuum full, Do we need to run REINDEX/ANALYZE exclusively ?

You don't need to run REINDEX, because that happens automatically.
You can use VACUUM (FULL, ANALYZE) to also gather statistics.

> 3. What is the best way to run VACUUM FULL with less window.

Identify which tables really need it rather than VACUUMing everything.

Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com