What was your coolest SQL optimization, on a slow performing query?

Question

Just speaking to a colleague of mine. He was walking with a hop in his step, on the way to the coffee machine.

I asked him \"what\'s with the \'swarmy\' walk?\", he said

Answer 1

I had a query that was originally written for SQL Server 6.5, which did not support the SQL 92 join syntax, i.e.

select foo.baz
from foo
  left outer join bar
  on foo.a = bar.a

was instead written as

select foo.baz
from foo, bar
where foo.a *= bar.a

The query had been around for a while, and the relevant data had accumulated to make the query run too slow, abut 90 seconds to complete. By the time this problem arose, we had upgraded to SQL Server 7.

After mucking about with indexes and other Easter-egging, I changed the join syntax to be SQL 92 compliant. The query time dropped to 3 seconds.

I don't think I'll ever have that feeling again. I was a f%$^ing hero.