Re: "Indexer is busy" problem

Bob Harner schrieb:
> On 5/24/07, Andreas Hartmann <andreasapache.org> wrote:
>> Hi Lenya devs,
>>
>> what should we do about this issue?
>>
>> http://issues.apache.org/bugzilla/show_bug.cgi?id=42510
>>
>> I wouldn't like to implement a queue for
incremental indexing
>> events before 1.4 is out, because I think it's
quite a lot of
>> work (especially in the testing department), and I
can't predict
>> the consequences without giving it some thought.
Maybe someone
>> has a solution at the ready (crossing my fingers
...).
>>
>> Should we silently ignore the error and just don't
trigger
>> the indexing, or should we continue to throw the
exception?
>>
>> I hope someone comes up with a better idea 

[...]

> A better interrim solution might be to display a
helpful warning
> message rather than an exception:
> 
> "Warning:  this document can't be added to the
search index yet
> because the indexer is currently busy with another
document.  Please
> re-publish this document in a moment to ensure that it
is indexed."

The problem with this approach is that we can't determine if
the
indexer will be busy before we apply the change to the
document.
Since the indexer is a shared resource, we'd have to lock it
to
prevent concurrent tasks from starting an indexing process
while
the publishing (or any other action which changes the
document
content) is in progress.

I'd be interested how other systems handle this. Maybe the
indexing
has to be part of the transaction, so the transaction can be
rolled
back if the indexing fails. But maybe we shouldn't invest
too much
research in this issue but rather choose a powerful back-end
which
supports indexing for the next major version.

-- Andreas


-- 
Andreas Hartmann, CTO
BeCompany GmbH
http://www.becompany.ch


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