Insert performance (OT?)

Hi,


Suppose I have a table with 4 fields (f1, f2, f3, f4)

I define 2 unique indexes u1 (f1, f2, f3) and u2 (f1, f2, f4)


I have 3 records

A, B, C, D (this will be inserted)

A, B, C, E (this will pass u2, but not u1, thus  not inserted)

A, B, F, D (this will pass u1, but not u2, thus not inserted)


Now, for performance ...


I have tables like this with 500.000 records where there's a new
upload of approx. 20.000 records.

It is only now that we say index u2 to be necessary.  So, until now, I
did something like insert into ... select f1, f2, f2, max(f4) group by
f1, f2, f3

That is ok ... and also logically ok because of the data definition


I cannot do this with 2 group by's.  I tried this on paper and I'm not
succeeding.


So, I must use a function that will check against u1 and u2, and then
insert if it is ok.

I know that such a function is way slower that my insert query.


So, my question ...

How can I keep the same performance, but also with the new index in
mind ???



Met vriendelijke groeten,

Bien à vous,

Kind regards,


<bold>Yves Vindevogel</bold>

<bold>Implements</bold>

<smaller>

</smaller>Hi,

Suppose I have a table with 4 fields (f1, f2, f3, f4)
I define 2 unique indexes u1 (f1, f2, f3) and u2 (f1, f2, f4)

I have 3 records
A, B, C, D (this will be inserted)
A, B, C, E (this will pass u2, but not u1, thus  not inserted)
A, B, F, D (this will pass u1, but not u2, thus not inserted)

Now, for performance ...

I have tables like this with 500.000 records where there's a new upload
of approx. 20.000 records.
It is only now that we say index u2 to be necessary.  So, until now, I
did something like insert into ... select f1, f2, f2, max(f4) group by
f1, f2, f3
That is ok ... and also logically ok because of the data definition

I cannot do this with 2 group by's.  I tried this on paper and I'm not
succeeding.

So, I must use a function that will check against u1 and u2, and then
insert if it is ok.
I know that such a function is way slower that my insert query.

So, my question ...
How can I keep the same performance, but also with the new index in
mind ???


Met vriendelijke groeten,
Bien à vous,
Kind regards,

Yves Vindevogel
Implements

<smaller>


Mail: yves.vindevogel@implements.be  - Mobile: +32 (478) 80 82 91


Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76


Web: http://www.implements.be

<italic><x-tad-smaller>

First they ignore you.  Then they laugh at you.  Then they fight you.
Then you win.

Mahatma Ghandi.</x-tad-smaller></italic></smaller>


Mail: yves.vindevogel@implements.be  - Mobile: +32 (478) 80 82 91

Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76

Web: http://www.implements.be

First they ignore you.  Then they laugh at you.  Then they fight you.
Then you win.
Mahatma Ghandi.