mlw <[EMAIL PROTECTED]> writes: > It took a bike ride to think about this one. The supposed advantage of a > sequential read over an random read, in an active multitasking system, is a > myth.
Disagree. > Execute a number of queries at the same time, the expected benefit of a > sequential scan goes out the window. The OS will be fetching blocks, more or > less, at random. If readahead is active (and it should be for sequential reads) there is still a pretty good chance that the next few disk blocks will be in cache next time you get scheduled. If your disk is thrashing that badly, you need more RAM and/or more spindles; using an index will just put even more load on the i/o system. -Doug -- Doug McNaught Wireboard Industries http://www.wireboard.com/ Custom software development, systems and network consulting. Java PostgreSQL Enhydra Python Zope Perl Apache Linux BSD... ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
