Kei wrote: > Hi all, > > I have one performance question about select all and select all with limit > and offset. I do the test for measuring the time usage of the following > select statement. > > Task 1. select * from tablename order by name Task 2. select * from table > name order by name limit 8 offset 0 > > and I have 5000 records in arm-platform . > > The result in Task 1 and 2 is they use 2 seconds to preform the select > statement. > > I think the action in Task 1 and 2 are that they extract all records from the > table but Task 2 then limit 8 records, isn't it? Or what does the action in > task 2?Thanks! >
It depends. If there are no indices to work with, then both Task 1 and Task 2 extract all records from the database and sort them. But if you have an index on name: CREATE INDEX idx1 ON tablename(name); Then Task 2 only extracts the first 8 elements from the table. -- D. Richard Hipp -- [EMAIL PROTECTED] -- 704.948.4565 --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
