Problem with Numerics multiplication in C-function - Mailing list pgsql-general

Hi, I have a strange problem with Numeric multiplication in C-function.

There are 2 functions getRate and getVAT which return Numeric. In 3rd function calculateService I try to multiply the results of getRate and getVAT. After execution I have two types of error, some time without messages and with message "Invalid memory alloc ... ".
If I initialize the Numeric variables inside calculateService and multiply, function numeric_mul works fine.

PostgreSQL 8.3.7

Datum getRate(PG_FUNCTION_ARGS) {
    int32 accountId = PG_GETARG_INT32(0);
    int16 serviceId = PG_GETARG_INT16(1);
    DateADT date = PG_GETARG_DATEADT(2);

    bool isNull;
    char command[QUERY_MAX_SIZE];
    char message[MESSAGE_MAX_SIZE];

    Numeric rate = DatumGetNumeric(DirectFunctionCall3(numeric_in,
            CStringGetDatum(RATE_ERROR_CSTRING_VALUE), 0, -1));

    //Build SQL query
    snprintf(command, sizeof (command), "...");

    SPI_connect();
    SPI_execute(command, true, 0);
    rate = DatumGetNumeric(SPI_getbinval(SPI_tuptable->vals[0],
                     SPI_tuptable->tupdesc,
                     1,
                     &isNull));

#ifdef PR_DEBUG
    snprintf(message, sizeof (message), "<DEBUG> getRate: Returns rate = %s.",
            DatumGetCString(DirectFunctionCall1(numeric_out, NumericGetDatum(rate))));
    elog(INFO, message);
#endif
    SPI_finish();
    PG_RETURN_NUMERIC(rate);
}

Datum calculateService(PG_FUNCTION_ARGS) {
    // Like the getRate
}

Datum calculateService(PG_FUNCTION_ARGS) {
    int32   accountId = PG_GETARG_INT32(0);
    int16   serviceId = PG_GETARG_INT16(1);
    DateADT date = PG_GETARG_DATEADT(2);
    int32   transactionRegisterId = PG_GETARG_INT32(3);

    Numeric rate;
    Numeric vat;
    Numeric amount;

    rate = DatumGetNumeric(DirectFunctionCall3(getRate,
            Int32GetDatum(accountId),
            Int16GetDatum(serviceId),
            DateADTGetDatum(date)));
    vat = DatumGetNumeric(DirectFunctionCall1(getVAT, DateADTGetDatum(date)));

#ifdef PR_DEBUG
    snprintf(message, sizeof (message), "<DEBUG> calculateService: rate = %s, vat",
            DatumGetCString(DirectFunctionCall1(numeric_out, NumericGetDatum(rate))));
    elog(INFO, message);
#endif

    amount = DatumGetNumeric(DirectFunctionCall2(numeric_mul,
            NumericGetDatum(rate),
            NumericGetDatum(vat)));

    // ERROR
    ...
}


Best regards,
Ilya Urikh.