[Xapian-tickets] [Xapian] #653: OP_PHRASE seems to sometimes match terms in wrong order

[Xapian]

#653: OP_PHRASE seems to sometimes match terms in wrong order
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        Reporter:  medoc          |      Owner:  olly
            Type:  defect         |     Status:  new
        Priority:  normal         |  Milestone:
       Component:  Backend-Chert  |    Version:
        Severity:  normal         |   Keywords:
      Blocked By:                 |   Blocking:
Operating System:  Linux          |
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 It seems that OP_PHRASE will sometimes match terms in the wrong order.
 This was reported by a Recoll user on Xapian 1.2.12, and I seem to be able
 to reproduce it on Xapian 1.2.16:

 {{{
 jfmac$ delve -t hurricane  xapiandb/
 Posting List for term `hurricane' (termfreq 1, collfreq 2, wdf_max 2): 4

 jfmac$ delve -t katrina  xapiandb/
 Posting List for term `katrina' (termfreq 1, collfreq 3, wdf_max 3): 4

 jfmac$ delve -t hurricane  -r 4 xapiandb/
 Position List for term `hurricane', record #4: 199881 203084

 jfmac$ delve -t katrina  -r 4 xapiandb/
 Position List for term `katrina', record #4: 199882 202473 203085

 jfmac$ xadump -q katrina hurricane
 q argc 2
 DB: ndocs 8 lastdocid 8 avglength 135233
 DB: terms are stripped
 Performing query `Xapian::Query((katrina PHRASE 5 hurricane))'
 Estimated results: 1
 Document ID 4   100% [url=file:///home/dockes/Downloads/[Mehdi_Khosrow-
 Pour,_Mehdi_Khosrow-Pour]_Encyclope(BookZZ.org).txt
 ...
 }}}

 (xadump is a tool in the recoll source which performs low level Xapian
 operations much like delve. Unlike delve it has a primitive query
 capability, normally performing AND queries, here modified to do
 OP_PHRASE, which a compiled-in phrase window (here 5). The window has to
 be at least 4 for the problem to appear (no match with a window of 2 or
 3).

 The index is not that big (3.6 MB compressed), I'll try to attach it to
 the ticket. If this fails, I can upload it wherever convenient.
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Ticket URL: <http://trac.xapian.org/ticket/653>
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