update too slow

[news.tele.dk]

Hi,

I need to update 25 * 5000 records, if I do one at the time it takes too
long time, do any one have a good proposal ?

regards

Johnny

[Aggro]

news.tele.dk wrote:

Hi,

I need to update 25 * 5000 records, if I do one at the time it takes too
long time, do any one have a good proposal ?

If all columns are supposed to have the same value, then just:

update tablename set columnname = newvalue;

If not, then the solution depends on the details, which you didn't yet
tell.

[news.tele.dk]

Hi,

This is my sql....

UPDATE BurTabel SET BurOnsketMaengd e = :pOns WHERE BurHalID = :pHID AND
BurFarmID = :pFID AND BurID = :pID;

where the vaules pOns is different and pID i different.

regards
Johnny
"Aggro" <sp**********@y ahoo.com> skrev i en meddelelse
news:J5******** *******@read3.i net.fi...

news.tele.dk wrote:

Hi,

I need to update 25 * 5000 records, if I do one at the time it takes too
long time, do any one have a good proposal ?

If all columns are supposed to have the same value, then just:

update tablename set columnname = newvalue;

If not, then the solution depends on the details, which you didn't yet
tell.

[Aggro]

news.tele.dk wrote:

UPDATE BurTabel SET BurOnsketMaengd e = :pOns WHERE BurHalID = :pHID AND
BurFarmID = :pFID AND BurID = :pID;

where the vaules pOns is different and pID i different.

I assume you are running the query from some program.

If so, the options are quite low. But if you got same value for several
rows, you should get some speed gain, if you use

UPDATE BurTabel SET BurOnsketMaengd e = :pOns WHERE BurHalID = :pHID AND
BurFarmID = :pFID AND BurID IN( id1, id2, id2, ... );

Also, if you got same value for majority of rows, you could first update
the value for all rows, and then use single updates to correct the value
from the rest of the rows.

[news.tele.dk]

Hi,

your are right, I run the query from Delphi - just for your information.

The problem is, that I must update nearly all the records, so your
suggestion will not work - don't your know some trick to help my speeding
this process up, perhaps a different way to do the same work ?.

"Aggro" <sp**********@y ahoo.com> skrev i en meddelelse
news:6s******** *******@read3.i net.fi...

news.tele.dk wrote:

UPDATE BurTabel SET BurOnsketMaengd e = :pOns WHERE BurHalID = :pHID AND
BurFarmID = :pFID AND BurID = :pID;

where the vaules pOns is different and pID i different.

I assume you are running the query from some program.

If so, the options are quite low. But if you got same value for several
rows, you should get some speed gain, if you use

UPDATE BurTabel SET BurOnsketMaengd e = :pOns WHERE BurHalID = :pHID AND
BurFarmID = :pFID AND BurID IN( id1, id2, id2, ... );

Also, if you got same value for majority of rows, you could first update
the value for all rows, and then use single updates to correct the value
from the rest of the rows.

[Aggro]

news.tele.dk wrote:

The problem is, that I must update nearly all the records, so your
suggestion will not work - don't your know some trick to help my speeding
this process up, perhaps a different way to do the same work ?.

Well besides the one I told about, there are two more trics.

First helps if it is possible to get the new value from some other field
or fields. But I guess that is not the case here.

Second requires a bit more work, and your database needs to be offline
while doing it. Dump the content of the whole table into a file or
select all from the table (which would propably be slower) and then
delete all data from your table and create insert queries. Depending how
much data you have, you could perhaps add 500 rows in each query and
then insert 500 rows in each query. Adding 500 rows in one query is much
faster than adding 1 row 500 times, so I assume it would be faster than
updating 1 row at a time.

[news.tele.dk]

I think I will try your second suggestion - it will work for my in this
project so that will be fine.

Thx for the help.

Have a nice weekend.

Johnny
"Aggro" <sp**********@y ahoo.com> skrev i en meddelelse
news:6q******** ********@read3. inet.fi...

news.tele.dk wrote:

The problem is, that I must update nearly all the records, so your
suggestion will not work - don't your know some trick to help my speeding
this process up, perhaps a different way to do the same work ?.

Well besides the one I told about, there are two more trics.

First helps if it is possible to get the new value from some other field
or fields. But I guess that is not the case here.

Second requires a bit more work, and your database needs to be offline
while doing it. Dump the content of the whole table into a file or select
all from the table (which would propably be slower) and then delete all
data from your table and create insert queries. Depending how much data
you have, you could perhaps add 500 rows in each query and then insert 500
rows in each query. Adding 500 rows in one query is much faster than
adding 1 row 500 times, so I assume it would be faster than updating 1 row
at a time.

[Bill Karwin]

news.tele.dk wrote:

I think I will try your second suggestion - it will work for my in this
project so that will be fine.

Sounds like you have a good solution for this project, and that's good,
but for the record I can think of one more possible solution: use the
CASE function.

UPDATE BurTabel SET BurOnsketMaengd e =
CASE
WHEN :pId BETWEEN 'lowvalue1' AND 'highvalue1' THEN :pOns1
WHEN :pId BETWEEN 'lowvalue2' AND 'highvalue2' THEN :pOns2
WHEN :pId BETWEEN 'lowvalue3' AND 'highvalue3' THEN :pOns3
ELSE :pOnsElse
END CASE
WHERE BurHalID = :pHID AND BurFarmID = :pFID;

This is best if there are a short list of distinct :pOns values, and
that they can be inferred from the :pId values.

Regards,
Bill K.