Re: Deletion from large table

Is this a one time thing, or a regularly occurring thing? (A one time data cleanup versus a nightly routine)

If it's a one time data cleanup (or rarely needed), I'd recommend saving off the rows you want to keep into another table, truncate the big_table and reload the rows from the temporary table you created to save the rows you wanted.

Delete is one of the (if not THE) single most expensive operation you can run in a database (but I'm sure you're aware of that but wanted to mention it).

Chris

On Tue, Aug 23, 2016 at 5:17 AM, John Dunn <JDunn_at_sefas.com> wrote:

> I need to delete large numbers of rows from a large table based upon
> whether a record exists in a small table.
>
>
>
> I am currently using :
>
> delete from big_table where not exists (select 1 from
> small_table s where s.id = b.id)"
>
>
>
> big_table may have up to 100,000 rows for the same id value.
>
> small_table will only have one row per id value
>
>
>
> Is there a better way to code this?
>
>
>
>
>
> *John *
>
>
>

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