[Mondrian] hierarchical sorting
Julian Hyde
jhyde at pentaho.com
Tue Jan 11 15:55:54 EST 2011
Joe,
Thinking about the sorting performance issues you are trying to solve.
Are a lot of your sorts hierarchical (i.e. use ASC or DESC flags, as opposed
to BASC and BDESC)? I am thinking that we have been doing hierarchical sorts
inefficiently. If two members in the list are not siblings, we should even
try to sort them; we should just leave them in the incoming order. But I
think the current algorithm spends a significant amount of our time figuring
out whether members are ancestors, siblings, cousins etc. and this is wasted
effort. Plus it leads to sorting one big list as opposed to a number of much
smaller lists.
If your sorts use BASC and BDESC (or indeed TopCount etc.) then ignore -- we
do have to compare all members.
Julian
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