[gdal-dev] OGR FileGDB driver: 'OBJECTID' not recognised as an available field

[Even Rouault]

On mercredi 4 septembre 2019 22:13:40 CEST Tamas Szekeres wrote:
> Hi,
> 
> It looks like  the sql queries with -dialect "OGRSQL" doesn't seem to work
> as expected. When I specify the FID in the where clause, it doesn't filter
> anything. The same query is also described as a solution in the following
> ticket https://trac.osgeo.org/gdal/ticket/4253 but I doubt if that works at
> all.
> 
> The code causing this problem is fairly generic (ogr_gensql.cpp)
> 
> if( psSelectInfo->where_expr && pszDialect != nullptr &&
>             EQUAL(pszDialect, "OGRSQL") )
>         {
>             int nMinIndexForSpecialField =
> poSrcLayer->GetLayerDefn()->GetFieldCount();
>             bForwardWhereToSourceLayer =
> !OGRGenSQLResultsLayerHasSpecialField
>                             (psSelectInfo->where_expr,
> nMinIndexForSpecialField);
>         }
>         if (bForwardWhereToSourceLayer)
>             pszWHERE = CPLStrdup(pszWHEREIn);
>         else
>             pszWHERE = nullptr;
> 
> In the "where" expression, the FID field is thanslated to OBJECTID and it
> is now treated as a special field, therefore the "where" expression is not
> being passed to the driver.
> 
> I'm also unsure if that is a correct action to omit passing "where" to the
> layer instead of providing an error message.

Actually the where isn't completely discarded. It is set on the 
OGRGenSQLResultsLayer per

    if( !bForwardWhereToSourceLayer )
        OGRGenSQLResultsLayer::SetAttributeFilter( pszWHEREIn );

around line 492

The issue is that the GenSQL layer has no FID column set, and thus this filter 
fails. One could potentially set the FID Column name on it from the source 
layer, but that wouldn't be really appropriate in the case of JOIN. That said 
I see a poDstFeat->SetFID( poSrcFeat->GetFID() ); at line 1332 of 
TranslateFeature(), so...

(there might have been other fixes since #4253 that have made this case 
broken)

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