Re: ON UPDATE CASCADE overhead?

Forest Wilkinson wrote:
> If I add ON UPDATE CASCADE to my foreign key definitions, how much will it
> affect performance for queries that don't trigger the cascade?

The trigger fired on the PK table does a check if the key
fields changed first. Therefore, at the first time of fireing
for this action during backend lifetime it'll do some
syscache lookups and remember the comparision functions to
call for this check. From then on it'll call the comparision
functions directly and return immediately without doing any
real work if the key effectively didn't change.

I expect it to not affect the performance significant. Would
be nice though if you'd run some tests and share the results
with us.

Jan

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