[mapserver-users] Mapfile - filter by parameter - full scan

[Lime, Steve D (MNIT)]

You can just put the where clause in the data statement using a sub select using the native SQL of the underlying database. The substitution will work there to and you avoid the translation step from MapServer expressions to native SQL. --Steve

________________________________________
From: mapserver-users [mapserver-users-bounces at lists.osgeo.org] on behalf of Steve.Toutant at inspq.qc.ca [Steve.Toutant at inspq.qc.ca]
Sent: Thursday, January 26, 2017 8:28 AM
To: Lane, Michael
Cc: 'mapserver-users at lists.osgeo.org'
Subject: Re: [mapserver-users] Mapfile - filter by parameter - full scan

How using (), [], "", '' is still a great mystery to me in filters. Every time I do many tries to got it right
Your expression seems to be ok so I don't know why you need extra ()

You can try without '' and [] like this
FILTER  ((no_diag=%no_diag%) or (%no_diag% = 0))

Or try using processing instead of FILTER

PROCESSING 'NATIVE_FILTER=((%no_diag% = 0 OR no_diag=%no_diag%))'

Steve

-----"mapserver-users" <mapserver-users-bounces at lists.osgeo.org> a écrit : -----
A : "'mapserver-users at lists.osgeo.org'" <mapserver-users at lists.osgeo.org>
De : "Lane, Michael"
Envoyé par : "mapserver-users"
Date : 25/01/2017 16:13
Objet : [mapserver-users] Mapfile - filter by parameter - full scan

Hi,

Experiencing something not expected with the filter condition in mapfile.

I add this code in my mapFile to have the possibility to void the filter if no parameter is given:

VALIDATION
       no_diag '^[0-9]{1,2}$'
       default_no_diag '0'
 END
 DATA "geom_surf from LOCTS_PARC_AGRI_AN_COUR using srid 4326"
  FILTER  (([no_diag]='%no_diag%') or ('%no_diag%' = '0'))
I compare my execution time without parameter and it’s going to an execution time of 3 seconds before filter to one of 3 minutes with the filter.

After debugging, I realize that the « where clause » generated by MapServe were bad with the filter and that generate a full table scan :
WHERE   ( '0' = '0' ) OR ( no_diag = '0' )  AND …
I was expecting something more like :
WHERE   (( '0' = '0' ) OR ( no_diag = '0' ))  AND …
So I had to add more parenthesis to the filter to get it correct
((('%no_diag%' = '0') or ([no_diag]='%no_diag%')))
Is it normal that I have to do that? The examples I found on the internet, have always single parenthesis. Do I code it right?

I use Mapserver 7 with database Oracle 12c. My parameter no_diag is a number.

Thanks

Michael Lane
Technicien en informatique

Direction des solutions d'affaires
La Financière agricole du Québec
1400, boul. Guillaume-Couture
Lévis (Québec) G6W 8K7
Tél. : 418 838-5614, poste 6034
michael.lane at fadq.qc.ca<mailto:Michael.Lane at fadq.qc.ca>

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