Re: Wrong estimation of Rows in explain

[Rathi Rao]

Hi Rick,

Apologies for the delayed response.

That many a data is needed and unfortunately I do not have any where conditions to filter the data

Would you please help me understand how is the row estimate correct? Should'nt it show the total number of rows in the table?

Also, with the join such as a.col1 = b.col1 and a.col2 = b.col2, which one would be better?

Separate indexes on each of the columns a.col1, a.col2 , b.col2 and b.col1

or

composite indexes on (a.col1,a.col2) and (b.col1,b.col2) ??

Thanks in advance
Rathi