fsm and vacuum - Mailing list pgadmin-support

We’re new to Greenplum, based on PG (8.2.13).  we weren’t advised to increase the max_fsm_relations switch as our db has grown.

Currently we’re nearly 14k tables/indexes and the switch is set to 1000.

We’ve got it updated now, but wondering about the effect & recovery.

We’ve regularly been reloading tables with CTAS.

I’ve done some experiments and want to confirm my understanding.

1. Vacuum full only compacted the  oldest? tables (reducing pages from 109 to 5)

2.  vacuum full frees pages, but doesn’t reduce the file size (newer tables).  Table needed to be recreated to reduce size

I’ve searched the archives and haven’t found what I’m looking for.  I hope someone would just dash off a simple explanation.

1.  when are relations added to the fsm? (at create, or some other time)

2.  will vacuum (full) add a relation to the fsm - ? 

3.  if bloated table is vacuum full’d,  will the free space pages be use?

My assumptions are:

1. relation added to fsm list at create time.

2. fsm_pages keep track of free space for the relations being tracked in the fsm_relation list

3. table recreate is the only way to have a relation tracked.

Thanks in advance.

Doug Little

Sr. Data Warehouse Architect | Enterprise Data Management | Orbitz Worldwide

500 W. Madison, Suite 1000  Chicago IL 60661| Office 312.260.2588 | Fax 312.894.5164 | Cell 847-997-5741

Douglas.Little@orbitz.com

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