Re: Query execution time survey

Depends on many things:

    Length of row
    Complexity of WHERE clause
    Number of columns selected
    Number of rows to be returned
    Post-processing to be done to rows returned     Degree of parallelism
    Number of spindles
    Max I/O size known to Oracle/Hardware

As a very rough guideline:

    calculate the size of the table in MB     Divide by the maximium multiblock read size

        (usually 64K, but could be 512K)
        to get number of read requests needed
    Divide by the lower of (spindles, parallel query slaves)
        to get number of read request per stream
    Divide by 40 (ish) as that's probably the realistic max reads per second
        to get total number of elapsed seconds

--

Jonathan Lewis
Yet another Oracle-related web site: www.jlcomp.demon.co.uk Received on Mon Apr 19 1999 - 15:47:19 CDT