Compound indexes

[Bryan McCormack]

Thanks for the advice, Ruslan.  I thought that was how I was going to
have to construct a "compound index" with Valentina.  One last question,
though.  You mentioned:

> A BaseObject method can have TYPE the same as normal fields.
> In your case you join 4 ULONG values. So you get 12 bytes key.
> As you know there is no such numeric type, so you need to use String
for
> such key.

> In case you'd need join only 4 ULONG fields you could use method of
type
> ULLONG and build its value using bit operations:   (v1 << 32) + v2

> In your case you need do:
> (btw, in ValentinaSQL.pdf you can see that Valentina for command
CREATE
> TABLE have extension METHOD )

>  CREATE TABLE tblCustomerInvoices (
>  CustomerInvoiceID ULONG NOT NULL UNIQUE INDEXED,
>  CustomerID ULONG INDEXED,
>  SalespersonID ULONG INDEXED,
>  InvoiceID ULONG INDEXED,
>  Notes TEXT(255)
 
>  idxCustomerSalespersonInvoice STRING(12) INDEXED
>                   METHOD('concat(CustomerID, SalespersonID,
InvoiceID)')
>  );

Would making this field a numeric type of field, for instance ULONG, and
performing a numeric operation as the method, for instance adding the
values of the 3 fields together, speed up the performance of the index?
For example, would defining the field as:

idxCustomerSalespersonInvoice ULONG INDEXED
	METHOD(CustomerID + SalespersonID + InvoiceID)

boost the performance of the index?  Or would there be no noticable
increase in performance in Valentina over an indexed string field as in
the example you've given?  Furthermore, how would such a field, either
defined as a string or an integer datatype, be calculated if the value
in any one of those fields for a particular record was null?  For
example, if a particular record had a CustomerID = 2, SalespersonID =
NULL, InvoiceID = 678, would the idxCustomerSalespersonInvoice calculate
to null?

Thanks.