friendVU admin wrote: [...]d
Ex: A common thing I used to consult on before Java was Performance and Tuning SQL DBs. A client would have a slow querry, and they say make it fast. I can! I used to take things that take 15 minutes down to split second. One tecquique is to break a complex querry into 2 simpler querries with less joins; even using a temporary tables. This exponentialy increased peformance to sub second.
(also.. you avoid group by, distinct, order by... imagine sorting 30 million records BEFORE you start to returun... and that you have 10,000 concurent users each runing a variation on the querry. Lots of trick to get arround that).
I have experienced the same thing .V describes here. I had a query which would have subselects counting certain things in the same table several times with each subselect having joins to other tables. No amount of indexing/joining was able to make it fast so selecting two sets of rows and doing the operations manually speed it up dramatically.
Huy
All the best,
.V
Clinton Begin wrote:
With the N+1 selects solution, you can do this with one query, with one hit to the database -- no matter how many relationships you have or how much data.
Trust me bud, this is VERY good advice.
Cheers, Clinton
