Arno Brinkman wrote:

> Hi Ann,
>
>
>> Err, actually, Jim and I just talked about the way sort works,
>> and unless something has changed, nothing is "moved around on
>> disk". When a sort run is larger than the memory allowed, it
>> is written out in sorted order. When all records have been
>> sorted, the runs are merged. If that's right, then runs are
>> both read and written sequentially, which seems like the best
>> of both worlds... given that you've got a world where the
>> sorted set doesn't fit in memory.
>>
>
> When does the merging (of multiple runs) happen? [By fetch, on first execute, ..?]
> Is the final merge only in memory or also written to disk?
>
>

The way it originally worked was that records we sucked from a tree of
merge objects. I think Borland tweaked it to do full intermediate
merges. I never quite figured out what they did or why the did it.

--

Jim Starkey, Senior Software Architect
MySQL AB, www.mysql.com
978 526-1376