Hello All:
I have a vexing problem where wildcard expressions in my mapfile return blank
maps (tested directly in the browser address bar) when queried against a
PostGIS database, but work perfectly against a shapefile.
There are no errors indicated in the log. In fact, the log indicates that it
finds all the data alright:
(snip)
[Wed Dec 02 11:02:28 2009].890000 msPostGISLayerWhichShapes got 20691 records
in result.
(snip)
[Wed Dec 02 11:02:28 2009].921000 msPostGISReadShape called.
[Wed Dec 02 11:02:28 2009].921000 msPostGISReadShape: [welluse] "P-R"
[Wed Dec 02 11:02:28 2009].921000 msPostGISReadShape: [newid] "001-1060"
[Wed Dec 02 11:02:28 2009].921000 msPostGISReadShape: [index] 4
[Wed Dec 02 11:02:28 2009].921000 msPostGISReadShape: [shape] POINT
(577278.4106000000600000 3355380.4495999999000000)
[Wed Dec 02 11:02:28 2009].921000 msPostGISLayerNextShape called.
(snip)
There are indeed 20691 records in the table. The "welluse" field contains
entries that start with one of the letters "P", "N", "T", "Z", or "O", and are
classified based on these letters.
The mapfile contains the following relevant lines:
(snip)
CLASSITEM "welluse"
CLASS
NAME "Public"
EXPRESSION /P^/
(snip)
Using
EXPRESSION /P^/
returns nothing from PostGIS, but the proper results from the shapefile (all
records that start with the letter "P" in the field "welluse"). There are no
errors returned from PostGIS, just a blank map and entries as shown in the log
snippet above.
Using
EXPRESSION /P-R/
returns the correct results (all records with "P-R" in the field "welluse")
from PostGIS and the shapefile.
I have tried crafting an expression using the SQL "LIKE" operator, e.g. various
forms of
EXPRESSION ([welluse] like 'P%')
which usually works in SQL, but appears to not be supported in this instance
based on all the syntax errors in the log after trying it, hence trying the
regex above.
I am certain I am missing something obvious, but I would nevertheless
appreciate your advice. I am trying to migrate the point data to PostGIS to
improve on the query performance which is too poor using shapefiles on our
humble server. Then I may be back to ask why php_cgi.exe crashes in ntdll.dll
every time I try to query a dataset in PostGIS but works fine (but too slow)
when using shapefiles, but I'll leave that for a later time.
I am currently using the MS4W beta from earlier this autumn, version 3 I think.
It shipped with MS 5.4.2, but I have updated the to the RC1 version of MS 5.6
while looking for a solution to the php crashes (no difference).
Thanks in advance,
Johan.
----------------------
Johan Forsman
Geologist
Safe Drinking Water Program
Louisiana Department of Health and Hospitals
Office of Public Health
Telephone: 225.342.7309
Telefax: 225.342.7303
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