[Qgis-developer] Spatial index - what about having it automatically created and updated ?

[Andrea Peri]

Create or updte a spatial index in a table is a danger operation ..
So in postgis it is availabale only to user with write grant.

QGIS is unable to understand if a connection is readonly or write enable so
try to do an automatic update
is a trouble-matic operation if a table was open from a read-only user.

Another question is why it should be complex for an user to create an index
?

A second question is what kind of index ?
On postgis is possible to do more than one index.

A table could have more than one geometry and every one could have a
spatial index or not.
But an index is a space consuming and often the index is needed on 1 only
geometry field menawhile the other
geometry field are only for special uses.
To do always automatically a spatial index on every geometry filed is
really a not useful operation in these use-case.

A.



2014-02-27 15:04 GMT+01:00 Etienne Tourigny <etourigny.dev at gmail.com>:

>
>
>
> On Thu, Feb 27, 2014 at 10:56 AM, Etienne Tourigny <
> etourigny.dev at gmail.com> wrote:
>
>> That's a python plugin (ftools), so it may not be available to everyone.
>>
>> Better to do it natively (in the data provider) doing something like
>> OGR_DS_ExecuteSQL("CREATE SPATIAL INDEX ON tablename [DEPTH N]") -
>> untested
>>
>
> there is already a function QgsOgrProvider::createSpatialIndex() (for
> shapefiles only) which  is called by QgsOgrProvider::syncToDisc() if the
> spatial index already exists.
>
>
>>
>> I think it's a great idea to do this automatically with large ogr data
>> sources
>>
>> as you said you should probably ask the gdal-dev list about which drivers
>> support spatial index creation an automatic update.
>>
>> cheers
>> Etienne
>>
>>
>> On Thu, Feb 27, 2014 at 7:51 AM, kimaidou <kimaidou at gmail.com> wrote:
>>
>>> Hi
>>>
>>> 2014-02-27 11:14 GMT+01:00 Andrea Peri <aperi2007 at gmail.com>:
>>>
>>> I guess more better is to use this extremely simple batch and create all
>>>> the index in one step only.
>>>> sing the gdal/ogr from osgeo4w.
>>>>
>>>> http://trac.osgeo.org/gdal/wiki/BatchCreationIndexesForShapefilesOnDOS
>>>>
>>>> Regards,
>>>>
>>>>
>>>
>>>  As I said, I am thinking of non power users. They surely won't create
>>> nor use such a batch file, even if it is simple. I know there is also the
>>> great tool Vector / Data management tools / Create Spatial Index, which can
>>> create one for all layers in one step. But users do not use it : they do no
>>> know it exists, or they know but forget to use it.
>>>
>>>
>>> _______________________________________________
>>> Qgis-developer mailing list
>>> Qgis-developer at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/qgis-developer
>>>
>>
>>
>


-- 
-----------------
Andrea Peri
. . . . . . . . .
qwerty àèìòù
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