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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I had been thinking about our Range discussions when I was looking at this. You may have already thought through this problem, but “completeness” of the cached
sets has been on my mind. With both caching of ranges and caching of members in general, it seems like a big challenge is figuring out whether we have the complete set given a context. With a TupleConstraint in place, level.members (or a range) may be discontinuous,
so it could be tricky figuring out whether the cache contains all members needed given a new context.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">For example, if there’s a request for Customer.[Name].members with a SqlContextConstraint including [Store].[Store 1], we might end up with a limited and discontinuous
set of members, say<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">{ Customer.[A], Customer.[C] }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">A subsequent request for this range in the context of [Store 2] might then cache a different discontinuous set:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">{ Customer.[A], Customer.[B], Customer.[D] }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Ideally we’d have a way of merging these two sets, such that requests for single members can be fulfilled. It would further be useful to know whether the set
of level members is complete for a context (do we have all members?), as well as if the range { [A] : [E] } can safely be fulfilled in other contexts.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">With both caching of ranges and caching of members in general it seems like we need a way to update a combined cache when new members have been retrieved and
insert them in the correct places. But the real trick seems to be knowing whether we really have the complete set. Unless the members have ever been retrieved in the context of the DefaultTupleConstraint, I don’t see a simple way to know whether we have
all of them.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> mondrian-bounces@pentaho.org [mailto:mondrian-bounces@pentaho.org]
<b>On Behalf Of </b>Luc Boudreau<br>
<b>Sent:</b> Tuesday, October 28, 2014 4:14 PM<br>
<b>To:</b> Mondrian developer mailing list<br>
<b>Subject:</b> Re: [Mondrian] Retrieving child members from cache<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">This is a similar problem than what I'm facing while trying to optimize ranges of members in the cache. We use a hash to represent entries, while we should use something like a TreeSet. The TupleConstraints we have can all be represented
in terms of ranges (singletons are a range of 1). <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I had looked into the RangeSet class from Guava, but it didn't fit. I haven't had any spare time yet to look into Julian's proposal of using the TreeSet, but am planning to do it soon. Let me know if you find something useful before I do.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Luc<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Tue, Oct 28, 2014 at 3:36 PM, Matt Campbell <<a href="mailto:mcampbell@pentaho.com" target="_blank">mcampbell@pentaho.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">When a query like<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:#44546A"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas;color:#44546A"> SELECT Customer.[Name].members on 0 from [Sales]</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">is executed, MemberCacheHelper will helpfully cache the set of members from the [Name] level. Subsequent queries which require loading level.members can skip the SQL query and
grab from cache. Very good.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">If, however, the subsequent MDX is for specific members of that level, e.g.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas;color:#44546A"> SELECT {[Customer].[Customers].[USA].[OR].[Portland].[Jade Brandberry],
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas;color:#44546A"> [Customer].[Customers].[USA].[OR].[Portland].[James Solano]} on 0 from [Sales]</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">then each Customer member will be retrieved individually via separate SQL queries and cached, using the its corresponding ChildByNameConstraint in the key.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Given that we have already loaded these members, intuitively it seems like we should be able to find them in the level member cache and avoid the redundant SQL queries. Finding
the members in cache, however, is complicated by the fact that caching uses the TupleConstraint as part of the key, so it’s not obvious which (if any) item in the cache might actually contain the referenced member.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Have others thought about how we might improve member retrieval for enumerated sets?
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><br>
_______________________________________________<br>
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<a href="http://lists.pentaho.org/mailman/listinfo/mondrian" target="_blank">http://lists.pentaho.org/mailman/listinfo/mondrian</a><o:p></o:p></p>
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