[gdal-dev] double delay getting feature count

[Chaitanya kumar CH]

Bruce,

The GetFeatureCount function gets the value with an SQL query to the data
server. The bottleneck may be at the connection.

On Wed, Oct 14, 2009 at 9:28 PM, Clay, Bruce <bclay at ball.com> wrote:

>  I have tried several different arrangements trying to get the feature
> count from a user selection and I am getting a delay two times for each
> query.
>
>
>
> My current arrangement is
>
>
>
> OGRLayer *queryLayer = dataSource->ExecuteSQL(fullQueryString, NULL,
> "generic");
>
>
>
> if (queryLayer != NULL)
>
> {
>
>       queryLayer->ResetReading();
>
>       OGRFeature *feature = queryLayer->GetNextFeature();
>
>
>
>       int numFeatures = queryLayer->GetFeatureCount();
>
>
>
> . . .Display progress meter then loop reading the features from Oracle
>
>
>
>
>
>
>
>
>
> I have tried putting the call to GetFeatureCount first and there is no
> apparent difference.
>
>
>
> I am reading data from an Oracle database and using GDAL version 1.6.2 on
> Windows XP
>
>
>
> The call to ExecuteSql returns right away but the call to the first
> GetNextFeature and the call to GetFeatureCount both have a long delay
> depending on the size of the dataset.
>
>
>
> I need the feature count to use in a progress popup window to let the user
> know what is happening.
>
>
>
> Is there a way to only pay for the query time once and still get the
> feature count?
>
>
>
>
>
> Bruce
>
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-- 
Best regards,
Chaitanya kumar CH.
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