Re: Create Index (Hash) on a Large Table Taking Days...

>I have a very large table (~5GB, 100mm rows) on which I am creating an
>index on an int4 column:

>CREATE INDEX CONCURRENTLY rums_idx2
> ON rums
> USING hash
> (user_id);

Why are you using a hash index on an int4 column?

as you have 100mm (mm= Million?) rows, only 1 GIG ram and the
column_name is "user_id", I suspect:
- you have far less then 100*10E6 Users
- there are less distince user_ids than rows

I just know "hash" from general programming, thatfor my belly is
announcing "hash collisions, hash collisions" ...

(within PostgreSQL I once read that hash indices are only for some
cases I could not match to something that happens in my world; since
then I am using default btree and am VERY happy.)

Best wishes,

Harald

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