condense max and min bug

[Dirk Daems]

Doesn't seem to work in the pre-release of v9.0.
Got the following exception using the last WCPS query listed in this ticket:

WcpsError: Invalid coverage Expression, next node: condense - Invalid coverage Expression, next node: condense
        at petascope.wcps.server.core.CoverageExpr.<init>(CoverageExpr.java:171)
        at petascope.wcps.server.core.ConstructCoverageExpr.<init>(ConstructCoverageExpr.java:87)
        at petascope.wcps.server.core.CoverageExpr.<init>(CoverageExpr.java:94)
        at petascope.wcps.server.core.EncodeDataExpr.<init>(EncodeDataExpr.java:77)
        at petascope.wcps.server.core.XmlQuery.startParsing(XmlQuery.java:120)
        at petascope.wcps.server.core.ProcessCoveragesRequest.<init>(ProcessCoveragesRequest.java:102)
        at petascope.wcps.server.core.Wcps.pcPrepare(Wcps.java:118)
        at petascope.wcps.server.core.Wcps.pcPrepare(Wcps.java:112)
        at petascope.wcps.server.servlet.WcpsServlet.doPost(WcpsServlet.java:181)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
        at java.lang.Thread.run(Thread.java:722)

System tests involving condense min / max also fail.

[cj]

there is no such operator max or min (i.e. writing max(1,2) will also not be recognized). So the problem is not in the condenser per se but in the grammar. Closing the ticket.

[Peter Baumann]

the documentation in the QL Guide indeed lists these operations, so they should be supported.

[Piero Campalani]

Hi there,

in the meantime, a workaround for WCPS condense expressions with min and max — leading to this unsupported RasQL condense operations — is achieved by either using a direct min() operator call, or either, in case of a condense operation nested into a coverage constructor, replacing the nested condensation with a min(<coverageConstr>).
E.g.

for c in (mean_summer_airtemp)
  return encode(
     coverage mincov
     over     $px x (100:101)
     values   min(
        coverage mincov
        over     $py y (300:301)
        values   c[x:"CRS:1"($px), y:"CRS:1"($py)]
     )
  ), "csv")

Instead of:

for c in (mean_summer_airtemp)
  return encode(
     coverage mincov
     over     $px x (100:101)
     values   (
        condense min
        over     $py y (300:301)
        values   c[x:"CRS:1"($px), y:"CRS:1"($py)]
     )
  ), "csv")

[Dimitar Misev]

Seems like it was fixed in rasql but not yet in WCPS.

[Dimitar Misev]

Replying to pcampalani:

Instead of:

for c in (mean_summer_airtemp)
  return encode(
     coverage mincov
     over     $px x (100:101)
     values   (
        condense min
        over     $py y (300:301)
        values   c[x:"CRS:1"($px), y:"CRS:1"($py)]
     )
  ), "csv")

Actually it's working in WCPS too, note that condense should have using, not values. I've added a test in the WCPS tests.

for c in (mean_summer_airtemp)
  return encode(
     coverage mincov
     over     $px x (100:101)
     values   (
        condense min
        over     $py y (300:301)
        using    c[x:"CRS:1"($px), y:"CRS:1"($py)]
     )
  ), "csv")