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From Mark Miller <>
Subject Re: lucene 2.9 sorting algorithm
Date Fri, 23 Oct 2009 13:04:35 GMT
>>I still think we should if performance is no
>>better with the new one.

Where is there any indication performance is not better with the new one?

The benchmarks are clearly against switching back. At best they could argue for two API's
- even then it depends - a loss of 10% on Java 1.5
with the most recent linux for a topn:10 ? I'm all for more results, but its not looking like
a good switch to me. What API do I use? Well, it depends - how many docs will you ask for
back, what OS are running, how hard is it for you to grok one API over the other?

And then as we make changes in the future we have to manage both APIs.

bq. digging in deep and running thorough perf tests makes sense

Again - no one is arguing against - dig all year - I'll help - but I don't see the treasure
yet, and the hole is starting to look deep. 

bq. removing that if from the Multi PQ patch makes sense

I didn't have a problem with that either - or other code changes - but
jeeze, mention what you are seeing with the switch. I'll tell you what I
saw it - not that much - a bit of improvement, but take a look at the
Java 1.5 run - it ended up being a blade of grass holding up a boulder
on Linux.

Michael McCandless wrote:
> Sheesh I go to bed and so much all of a sudden happens!!
> Sorry Mark; I should've called out "PATCH IS ON 2.9 BRANCH" more
> clearly ;)
> There's no question in my mind that the new comparator API is more
> complex than the old one, and I really don't like that.  I had to
> rewrite the section of LIA that gives an example of a [simple] custom
> sort and it wasn't pleasant!  Two compare methods (compare,
> compareBottom)?  Two copy methods (copy, setBottom)?  Sure, you can
> grok it and get through it if you have to, but it is more complex
> because it's conflated with the PQ API.
> Ease on consumption of our APIs is very important, so, only when
> performance clearly warrants it should we adopt a more complex API.
> Also, yeah, it would suck to have to switch back to the old API at
> this point, but net/net I still think we should if performance is no
> better with the new one.
> The old API also fits cleanly with per-segment searching (John's
> initial patch shows that -- it's simply another per-segment Colletor).
> The two APIs (collection, comparator) are well decoupled.
> So, digging in deep and running thorough perf tests makes sense; we
> need to understand the performance to make the API switch decision.
> And definitely we should tune both approaches as much as possible
> (removing that if from the Multi PQ patch makes sense).
> But... Multi PQ's performance isn't better in many cases... though,
> we're clearly still iterating.  I'll run a 1.5 (32 & 64 bit) test,
> with the if statement removed.
> Mike
> On Fri, Oct 23, 2009 at 3:53 AM, Earwin Burrfoot <> wrote:
>> I did.
>> On Fri, Oct 23, 2009 at 09:05, Jake Mannix <> wrote:
>>> On Thu, Oct 22, 2009 at 9:58 PM, Mark Miller <> wrote:
>>>> Yes - I've seen a handful of non core devs report back that they
>>>> upgraded with no complaints on the difficulty. Its in the mailing list
>>>> archives. The only core dev I've seen say its easy is Uwe. He's super
>>>> sharp though, so I wasn't banking my comment on him ;)
>>> Upgrade custom sorting?  Where has anyone talked about this?
>>> 2.9 is great, I like the new apis, they're great in general.  It's just this
>>> multi-segment sorting we're talking about here.
>>>   -jake
>> --
>> Kirill Zakharenko/Кирилл Захаренко (
>> Home / Mobile: +7 (495) 683-567-4 / +7 (903) 5-888-423
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- Mark

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