At 8:23 PM +0300 6/14/1999, Mark Papadakis wrote:
>Say we have a table
>create table xx
> a1 smallint unsigned not null,
> a2 smallint unsigned not null,
> a3 smallint unsigned not null,
> primary key (a1,a2,a3)
>According the the manual:
>Keys are used to retreive values withotu consulting the data file, in some
>If all used columns for some table and numeric and form a leftmost prefix
>for some key, the values
>may be retrieved from the index tree from greater tree.
>So, will the above get the values from the index tree instead from the
There is no select query "above". ???
>select xx.a2, count(xx.a2) as mc, sum(a3) as mys from xx where xx.a1
>in(1,2,4,5,6) group by a2 having myc=5 order by mys;
>A query like this
>select xx.a2, count(xx.a2) as myc from xx where xx.a1 in(1,2,4,5,6) group by
>a2 having myc=5;
>gets all its values from the index tree and it's VERY fast. But, how about
>the previous one ?
Hard to say. Your first query doesn't look legal. You have "having myc=5"
but there is no column called myc. Do you mean mc or mys?
Paul DuBois, paul@stripped
Northern League Chronicles: http://www.snake.net/nl/
|• Indexes #2||Mark Papadakis||14 Jun|
| • Re: Indexes #2||Paul DuBois||14 Jun|