I posted to -sql the other day about an atrociously slow DELETE on a table
that has two FKs to a 'parent' table ... if the # of records in the table
that match the condition is 1, its fast ... in the sample I'm working
with, there are 1639 records in the table ...
Now, I'm making a guess that for each row that needs to be DELETEd, the FK
forces a 'SELECT * FROM fk_table WHERE fk = value', to check for its
existence ... so, in this case, we're talking about 1639*2 SELECTs to the
backend ... is this correct?
If this is correct ... is 7.4/8.0 any smarter when it comes to
'duplicates'? Somehow keeping a list of 'fk = value's that have already
been checked, instead of re-issuing a new SELECT for each row? In the
case of the table I'm working on, all row DELETEs would have the same
result, as the delete is *on* the FK value itself, so the first check of
the fk_table should be all that is required ...
Not sure if this is even possible ... or is already done ...
Note that I'm working on a 7.3 database right now, so if this is something
that is improved with 7.4, please let me know ..
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Marc G. Fournier Hub.Org Networking Services (http://www.hub.org)
Email: scrappy@hub.org Yahoo!: yscrappy ICQ: 7615664
