Re: Recommendation to run vacuum FULL in parallel

On 4/3/19 12:50 AM, Perumal Raj wrote:

Hi ALL

We are  planning to reclaim unused space from 9.2 Version postgres Cluster,

Method : VACUUM FULL

Does every table have so much free space that it's impractical to just let the files just get refilled by normal usage?

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;)

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

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

A good way to run any task like this in parallel is to generate X lists of objects, and then process each list in parallel.