[gdal-dev] Problems with OGROpen, OCI Driver (OGROCITableLayer::ReadTableDefinition) and Oracle Views in GDAL 1.8.1

[Ethan Alpert]

All,

 

I've run into some very serious problems (for me) with changes made to
the OCI driver for 1.8.1. Specifically lines the following lines
(270-274).

 

        oDimCmd.Append( "SELECT a." );

        oDimCmd.Append( pszGeomName  );

        oDimCmd.Append( ".GET_DIMS() DIM FROM " );

        oDimCmd.Append( pszTableName );

        oDimCmd.Append( " a WHERE ROWNUM = 1" );

 

 

 

Our schema has many large  tables and several views which use these
tables. The views are referenced in all_sdo_geom_metadata. When the
query "select a.geometry.get_dims() dim from <the_view> a  where rownum
= 1" is run it results in FULL Table accesses. This has result in
running sorted queries on very large tables and I managed to blow out
the temp table space on our oracle instance just calling OGROpen. To say
the least our DBA's are not happy with me.

 

 

I'm considering changing :

 

        oDimCmd.Append( "SELECT a." );

        oDimCmd.Append( pszGeomName  );

        oDimCmd.Append( ".GET_DIMS() DIM FROM " );

        oDimCmd.Append( pszTableName );

        oDimCmd.Append( " a WHERE ROWNUM = 1" );

 

to:

 

 

        oDimCmd.Append( "SELECT COUNT(t.SDO_DIMNAME) DIM FROM
ALL_SDO_GEOM_METADATA A, TABLE(A.DIMINFO) T WHERE a.TABLE_HAME='" );

        oDimCmd.Append( pszTableName );

        oDimCmd.Append( "'" );

 

 

The following code was not in 1.7.2.

 

"ogrocitablelayer.cpp" Lines 259-316

   /*
-------------------------------------------------------------------- */

    /*      Identify Geometry dimension
*/

    /*
-------------------------------------------------------------------- */

 

    if( pszGeomName != NULL && strlen(pszGeomName) > 0 )

    {

        OGROCIStringBuf oDimCmd;

        OGROCIStatement oDimStatement( poSession );

        char **papszResult;

        int iDim = -1;

 

        oDimCmd.Append( "SELECT a." );

        oDimCmd.Append( pszGeomName  );

        oDimCmd.Append( ".GET_DIMS() DIM FROM " );

        oDimCmd.Append( pszTableName );

        oDimCmd.Append( " a WHERE ROWNUM = 1" );

 

        oDimStatement.Execute( oDimCmd.GetString() );

 

        papszResult = oDimStatement.SimpleFetchRow();

 

        if( CSLCount(papszResult) < 1 )

        {

            OGROCIStringBuf oDimCmd2;

            OGROCIStatement oDimStatement2( poSession );

            char **papszResult2;

 

            oDimCmd2.Appendf( 1024,

                "select m.sdo_index_dims\n"

                "from   all_sdo_index_metadata m, all_sdo_index_info
i\n"

                "where  i.index_name = m.sdo_index_name\n"

                "   and i.sdo_index_owner = m.sdo_index_owner\n"

                "   and i.table_name = upper('%s')",

                pszTableName );

 

            oDimStatement2.Execute( oDimCmd2.GetString() );

 

            papszResult2 = oDimStatement2.SimpleFetchRow();

 

            if( CSLCount( papszResult2 ) > 0 )

            {

                iDim = atoi( papszResult2[0] );

            }

        }

        else

        {

            iDim = atoi( papszResult[0] );

        }

 

        if( iDim > 0 )

        {

            SetDimension( iDim );

        }

        else

        {

            CPLDebug( "OCI", "get dim based of existing data or index
failed." );

        }

    }


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