Re: autovacuum

Autovacuum does not release space back to the OS. It only marks the tuples
avaiable for reuse. To give the space back to the OS, you would have to run
a vacuum full on the table.

Chris

On 6/1/06, Sriram Dandapani <sdandapani(at)counterpane(dot)com> wrote:
>
> Hi
>
>
>
> I have a table about 17G in size. I did a pg_relation_size before deleting
> 2 millions rows. I waited a few hours(actually overnight) and then checked
> the table size with pg_relation_size. The size reported was exactly the
> same.
>
>
>
> My autovacuum is set to run every 50 minutes.
>
>
>
> Settings:
>
>
>
> autovacuum = on # enable autovacuum subprocess?
>
> autovacuum_naptime = 3000 # time between autovacuum runs, in
> secs
>
> autovacuum_vacuum_threshold = 10000 # min # of tuple updates before
>
> # vacuum
>
> autovacuum_analyze_threshold = 1500 # min # of tuple updates before
>
> # analyze
>
> autovacuum_vacuum_scale_factor = 0.4 # fraction of rel size before
>
> # vacuum
>
> autovacuum_analyze_scale_factor = 0.2 # fraction of rel size before
>
> # analyze
>
> autovacuum_vacuum_cost_delay = -1
>
>
>
> vacuum_cost_delay = 200 # 0-1000 milliseconds
>
> #vacuum_cost_page_hit = 1 # 0-10000 credits
>
> #vacuum_cost_page_miss = 10 # 0-10000 credits
>
> #vacuum_cost_page_dirty = 20 # 0-10000 credits
>
> vacuum_cost_limit = 50
>
>
>
>
>
> work_mem = 802400 # min 64, size in KB
>
> maintenance_work_mem = 102400 # min 1024, size in KB
>
> #max_stack_depth = 2048 # min 100, size in KB
>
>
>
> # - Free Space Map -
>
> max_fsm_pages = 2000000
>
>
>
>
>
> Why doesn't pg_relation_size take the autovacuum maintenance into effect
>