in reply to Re: SQL question: Insertion with FK constraint
in thread SQL question: Insertion with FK constraint

psini, thank you very much for your reply.. this is actually an example, so there are probably more fields in table2.:)

In fact, even with just two fields, using a separate table sometimes save me lot of disk spaces and time, i.e. if 'property' varchar(20) becomes varchar(250) or text. In fact, I just refactored one of my big table from 4GB to 2.2GB yesterday by such process(normalization). the new table took 4 hours instead of 2 days to build a huge Unique key constraint. :-)

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Re^3: SQL question: Insertion with FK constraint
by psini (Deacon) on Jun 26, 2008 at 15:38 UTC

    Ah, OK. If data grouped in table2 is significantly complex I'd expect a little performance gain. But with an efficient DBMS I'd believe that the overhead added by joining the tables should lose the gain from memory saving.

    BTW, 4 days to build a unique index seems to me really too much! I have a table with about 10 million rows (but only 6 columns, I've to admit) that build its primary key (on two columns) in about an hour. And last time I had to restore it from a backup I grumbled for it was too slow... :)

    Rule One: "Do not act incautiously when confronting a little bald wrinkly smiling man."

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