difference between count(*) and count(1)

[ratnababunarne]

difference between count(*) and count(1)

[debasisdas]

Please dont post questions in Article section

I am moving it to Oracle Forum

[frozenmist]

Hi,

Both perform the same function, to get the number of rows returned by the query.
But performance wise count(1) is better as count(*) retrieves all columns and counts the rows, where as count(1) retrieves 1's whenever a row is there.

Cheers

[Medhatithi]

Hi,

Both perform the same function, to get the number of rows returned by the query.
But performance wise count(1) is better as count(*) retrieves all columns and counts the rows, where as count(1) retrieves 1's whenever a row is there.

Cheers

Tom Kyte said about it correctly, there was a version where it did make a difference (6, early 7 maybe) and thus a myth was born. According to Tom, the parser is now coded so that count(1) and count(*) use exactly the same code path so any differences you see between the two would occur on multiple runs of the same statement, i.e. they are caused by external events.