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From Jan Lehnardt <>
Subject Re: Lazy Fulltext Search
Date Fri, 11 Apr 2008 10:37:30 GMT

On Apr 11, 2008, at 12:23, Noah Slater wrote:
> On Thu, Apr 10, 2008 at 11:32:21PM +0200, Jan Lehnardt wrote:
>> My proposed architectural change would be to trigger the Indexer from
>> the Searcher module when a request comes in, just like views work.  
>> This
>> would delay the creation of fulltext indexes until they are
>> actually needed.
> I thought that the advantage of full text search systems is that you  
> can perform
> a lot of work up front in exchange for very fast queries later on.  
> This proposal
> would seem to make the trade-off in performance without the  
> associated benefit.

The associated benefit is that you delay the costs of generation of  
indexes until you actually need them.

>> The possible drawback though is, that when building the fulltext  
>> index
>> is rather slow, old-style pre-calculation might be more feasible.  
>> View
>> deal with that by requiring frequent requests (possibly cron-ed).
> My understanding is that the KEY element of CouchDB Wiews is that  
> they are
> generated in advance, and incrementally, before you use them.

And why not use the same principle fot fulltext indexes? Also, view  
indexes are not necessarily built in advance, though for online apps,  
you're likely to do that.

> What you're proposing for the full text indexing sounds like quite  
> the opposite
> to me, though I may be totally wrong.

I'm not proposing, I just thought I shared my idea here :) It is about  
trade-offs, you're right.


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