Index use on data query from BTrieve through HS ODBC

Hi

I'm working on integration system which periodically retrieves data to Oracle from BTrieve database using heterogeneous service and Pervasive ODBC. Queries from Oracle understand BTrieve indexes through ODBC, even composite, so everything goes well.

But now I got a problem: Oracle understands and uses NOT all indexes from BTrieve database. Some indexes are used, but some are not. I can't understand the reason why index 1 easily used if needed, but index 2 cannot be used in any way.

For example, here's the structure of some table and information about indexes. Key1 works good, but query against Key6 fields leads to fullscan.

SQL> select column_name, rpad(data_type,10), rpad(data_length,4) from all_tab_columns_at_lux where table_name = 'ininv1_dbt';

COLUMN_NAME                    RPAD(DATA_TYPE,10) RPAD(DATA_LENGTH,4)
------------------------------ ------------------ -------------------
Autokey                        NUMBER             4
Ndprt                          NUMBER             2
Invoice                        NUMBER             4
Source                         NUMBER             2
Target                         NUMBER             2
Date                           DATE               6
DateSend                       DATE               6
DebetSign                      NUMBER             2
iType                          NUMBER             2
Contract                       VARCHAR2           10
Receips                        VARCHAR2           10
Numb_Invoice                   VARCHAR2           10
RinvDprt                       NUMBER             2
Oper                           NUMBER             2
Prim                           VARCHAR2           79
iDoc_Dprt                      NUMBER             2
lDoc                           NUMBER             4
FormWHouse                     NUMBER             2
iTypeDoc                       NUMBER             2
Mail                           DATE               6
Reserve                        VARCHAR2           111

SQL> select index_name, column_name from all_ind_columns_at_lux where table_name = 'ininv1_dbt' order by index_name, column_position;

INDEX_NAME                     COLUMN_NAME
------------------------------ ----------------------
key0                           Autokey
key1                           Ndprt
key1                           Invoice
key2                           Date
key3                           DebetSign
key3                           Date
key4                           FormWHouse
key4                           Ndprt
key5                           iType
key5                           Date
key6                           iTypeDoc
key6                           iDoc_Dprt
key6                           lDoc

Please give me any idea of such behavior. Received on Sun Oct 08 2006 - 05:14:49 CDT