Quote:
Originally posted by mchih
Right now I have a few PL/SQL procedures that calculate count(*) and sum(*) values for different reports. So far it's a daily operation, with around 80000 records per day (seems to be increasing by 10000 records every week though)
it's not a complex procedure, just a lot of number crunching for each columns. Right now the basic logic is to use a separate SQL statement for each column(with different conditions, of course), and repeat it until all the reports are filled in.
So far it's taking about 20 secs for going thru every 10000 records. Add the time it takes to load the records in (about 25-30 secs per 80000 records), and it becomes about 3 minutes of operation each day.
I have been thinking about how I can improve the performance of the procedure. So far I am thinking about whether the performance would improve if I can change the logic by declaring a cursor for the records, and just go thru it one time, then put the value into different variables.
Any suggestion is appreciated
Mark
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Generally it is preferable to avoid procedural logic if you want best performance. Maybe you could combine all (or many of) your counts and sums into a single query using DECODE (or CASE) to filter the records:
SELECT SUM( DECODE( col1, 'x', 1, 0 )) as COUNT_WHERE_COL1_IS X
, COUNT(*) TOTAL_COUNT,
, SUM( DECODE( col3, 123, col4, 0 )) as SUM_COL4_WHERE_COL3_IS_123
...
FROM ...