[seek-dev] EcoGrid Query and problems with pubDate

Matt Jones jones at nceas.ucsb.edu
Thu Oct 14 15:12:35 PDT 2004


My (educated) guess is that Metacat isn't casting the values properly to 
dates. THis is closely related to the casting problems you've been 
having with latitude and longitude values.  Somebody at NCEAS, probably 
Sid, will be looking into these issues for Metacat.  We'll be 
simultaneously trying to deal with the query performance issues which 
are closely related.


Steve Tekell wrote:
> There seems to be some potential problems with pubDate and maybe other
> dates.
> eml/dataset/pubDate 
> can be a year (2002) or a date (2002-06-21)
> (maybe year+month and no day is ok, too, but I'll ignore that case for now)
> So, for EML, the datatype of the field is ambiguous.
> (I haven't begun to look into the other schemas that I'll be searching yet).
> If a user enters for start date 2002-01-01, it generates the condition
> <condition operator="GREATER THAN OR EQUALS"
> concept="/eml/dataset/pubDate">2002-01-01</condition>
> which logically should return anything published in 2002 or later, but it
> doesn't.  Items with pubDate=2002 won't be returned.  I assume if an item
> had a pubDate of 2002-06-21 it would be returned, but I am only getting
> items where the pubDate is a Year instead of Date.
> I am guessing that it's doing a String compare on pubDate.  Whereas maybe
> collection date is actually comparing dates.  Collection date searches all
> time out like the geographic boundary searches since it's storing everything
> as strings and doing type conversions on the fly.
> I guess one solution is for me to cripple the app to only allow pubDate to
> be a Year instead of Date and treat it separately from collection dates.
> However, this is a EML/Metacat specific solution.  If other schemas store
> pubDate as a Date, then using only Year could cause other problems (invalid
> input).
> I put up a build, a snapshot of my work in progress, on my dev server so
> that you can see this problem as well as see the various performance
> problems.  
> http://lternet-163.lternet.edu:8080/ecogrid/query.jsp 
> Remember this is just an early stage test app.
> The results screen currently shows the execution time for the EcoGrid client
> query as well as the generated Query XML.  So you can grab the XML of
> queries that timeout and do other tests.
> Steve
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Matt Jones                                     jones at nceas.ucsb.edu
http://www.nceas.ucsb.edu/    Fax: 425-920-2439    Ph: 907-789-0496
National Center for Ecological Analysis and Synthesis (NCEAS)
University of California Santa Barbara
Interested in ecological informatics? http://www.ecoinformatics.org

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