----- Original Message -----
> From: "Rik Wasmus" <rik@stripped>
> Depends on the data and usage, but probably I'd go for a index(a,b) &
> index(b,a) if reads heavily outnumber writes. As index(a) is covered
> by index(a,b), and index(b) by index(b,a), we don't need to add those,
> which saves time on modifications.
I'm trying to think of a scenario where index(a) would be beneficial in the presence of
index(a,b). If both are available, and all else being equal, it's likely that the parser
will pick the simplest index; but I can't see it having a major impact.
Any full prefix of a combined index may be used; so afaik a separate index on any full
prefix is a waste of diskspace and cycles.
The net conclusion, Neil, is that you actually have to know what you're doing :-) Take the
time to read the online documentation on mysql.com, it's pretty good.
Bier met grenadyn
Is als mosterd by den wyn
Sy die't drinkt, is eene kwezel
Hy die't drinkt, is ras een ezel