On Monday, June 27, 2011 7:04:09 PM UTC-7, Jim D. wrote:
So that caveat aside, I will try later to find a large data set I can run
> the query on to get an idea of what kind of performance hit the check
> entails. If anyone else has a large data set with two related tables, you
> can try it out as well and report your results.
Okay, I just ran this on an InnoDB with 228k rows that's about 8.5MB in size
("REFERRING"), with a related table of 248 rows to join on ("REFERRED"),
with no invalid records:
SELECT REFERRING.`id`, REFERRING.`id_pointing_to_some_related_table ` FROM
`some_table` as REFERRING
LEFT JOIN `some_related_table` as REFERRED
ON (REFERRING.`id_pointing_to_some_related_table` = REFERRED.`id`)
WHERE REFERRING.`id_pointing_to_some_related_table ` IS NOT NULL
AND REFERRED.`id` IS NULL
I'm getting this consistently under 1 second, around 700 or 800 ms
generally. Not great but not horrible. I didn't do any sophisticated
profiling or setup for this or anything.
I'm not sure what kind of performance we might think is acceptable, but for
the dominant use cases of load data I think it's fine.
My thinking at this point would be the performance is "good enough" for the
scope of the current ticket, and that if better performance were required or
desired, that could be facilitated under a separate ticket, assuming there
was community demand for it.
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