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Subject: Re: hash aggregation
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> What I can not understand is why the seq scan's estimated cost is
> better the index scan's one. It depends on the number of pages in
> index/relation. May be the index is heavily bloated?
Mm i don't know how to see bloating level. But the index was created by 
create index on hashcheck using btree (name)
after the table population.

Sizes:
hashes=# select pg_total_relation_size('hashcheck');
 pg_total_relation_size 
------------------------
             2067701760
(1 row)

hashes=# select pg_total_relation_size('hashcheck_name_rev_idx');
 pg_total_relation_size 
------------------------
              629170176
(1 row)