[AccessD] Question about the TableDef.Fields collection
stuart at lexacorp.com.pg
Fri Aug 26 16:21:36 CDT 2022
On 26 Aug 2022 at 12:58, John Colby wrote:
> Autonumbers serve another purpose, speeding up joins. Joining strings
> between tables requires a visit to a library where the string is
> scanned and compared to the other field byte by byte. A long integer
> OTOH used a simple equal operator on a 32 bit number. One instruction
> vs potentially hundreds.
Don't conflate Primary Keys with Unique indexes, they serve different purposes.
You can impose constraints on a field or a group of fields with unique indexes. Keys are
designed to uniquely identify a row for edit/delete operations and there use optimises joins.
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