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@xxxxxxxxx> 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 *
