Question

I am using a Cursor in my stored procedure. It works on a database that has a huge number of data. for every item in the cursor i do a update operation. This is taking a huge amount of time to complete. Almost 25min. 🙁 .. Is there anyway i can reduce the time consumed for this?

Answer 1

When you need to do a more complex operation to each row than what a simple update would allow you, you can try:

• Write a User Defined Function and use that in the update (probably still slow)
• Put data in a temporary table and use that in an UPDATE … FROM:

Did you know about the UPDATE … FROM syntax? It is quite powerful when things get more complex:

UPDATE   MyTable SET   Col1 = CASE WHEN b.Foo = 'Bar' THEN LOWER(b.Baz) ELSE '' END,   Col2 = ISNULL(c.Bling, 0) * 100 / Col3 FROM   MyTable    INNER JOIN MySecondTable AS b ON b.Id = MyTable.SecondId   LEFT  JOIN ##MyTempTable AS c ON c.Id = b.ThirdId WHERE   MyTabe.Col3 > 0   AND b.Foo NOT IS NULL   AND MyTable.TheDate > GETDATE() - 10 

The example is completely made-up and may not make much sense, but you get the picture of how to do a more complex update without having to use a cursor. Of course, a temp table would not necessarily be required for it to work. 🙂