Re: Multicolumn index including tsvector.

On 24 Nov 2009, at 24:08, Kris Gale wrote:

> Table "public.example"
> Column | Type | Modifiers
> ---------+----------+-----------
> body | text |
> vectors | tsvector |
> user_id | bigint |
>
> I've got btree_gin and btree_gist installed, so I can make a composite index on vectors and user_id (which is a bigint).

A bigint for userid? How many billions of users do you expect to get?

A bigint is 8 bytes or 64 bits. I think a normal int (32-bits) would be quite sufficient; it allows up to 2 billion users. It uses less storage space for both the data and the indices too.

And as Tom already said casting can be a problem with bigints, not only if certain operators aren't defined for comparison between int and bigint, but you'll also see a performance hit if table data you compare to needs to be upcasted to a bigint; joins come to mind.

Alban Hertroys

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