AW: AW: AW: Combining cursors

[Ruslan Zasukhin]

on 12/1/03 9:06 PM, Florian Bogeschdorfer at fb at memedia.de wrote:

> I don't think that is the same while you may go both ways to get the result.
> But I would like that very much too. In spite of searching the whole DB just
> search a cursor, kind of focussing in. Very nice Ruslan!

In fact all is not so easy.

When I search the whole table, I can easy use index of field.

If I have some SELECTIONS of records for this table,
Then I have 2 ways:

1) using this selection SCAN the table and check values

2) still use the same THE WHOLE index, execute search as usual,
And make additional step -- built intersections of 2 sets.

So it is not 100% speed up!

All depends on kind of query, number of records on table and number of
records in the cursor.

--------
Another case, when cursor build own RESULT table. Then it can have smaller
size than original. On the other hand it DO NOT have indexes. Of course I
can build indexes, but this is again time.

Measure what way is better is VERY HARD task. :-)


-- 
Best regards,
Ruslan Zasukhin      [ I feel the need...the need for speed ]
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e-mail: ruslan at paradigmasoft.com
web: http://www.paradigmasoft.com

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