[Ovirt-devel] [PATCH] Update search index every half hour.

[Scott Seago]

Daniel P. Berrange wrote:
> On Wed, Jan 21, 2009 at 07:24:27PM +0000, Scott Seago wrote:
>   
>> Sets up a cron job to update the search index every half hour.
>>  With this in place it will be at most 30 minutes after new/
>> updated content is generated before it will show up in search results.
>>     
>
> 30 minutes seems like quite a long time.  Is there much CPU overhead
> from updating the search index ?  If not I think it'd be nicer to
> do it every 5 minutes or more frequently still. Shame it can't be
> done "on demand" really - eg triggered when an indexable table is
> updated - albeit it with a small delay, so if multiple updates arrive
> in a short time it can coalleasce into one index update.
>
> Daniel
>   
30 minutes was totally arbitrary. Overhead would depend mostly on how 
much content we've got -- and for now, we don't have a huge quantity -- 
just rows for VMs, storage volumes, hosts, and pools. 5 minutes is 
probably fine -- in any case, there's probably not much point in going 
longer than 5 minutes unless we have to.

Search index updates are triggered from outside the DB, so there isn't a 
direct way of doing an on-demand update, although you could probably 
simulate this with a daemon of some sort. There's already a db table 
that gets rows added for objects that need to be updated. Index updates 
(rather than the reindex operation) only work on objects with an update 
-- so we could have a daemon that polled this table and forked a process 
to do the update after it observed a new row added to this table -- but 
with no new rows added after a set period of time.

On my dev server it takes about 3 seconds to run the update index rake 
task when there's nothing to update -- so even running this task every 
minute might not have much of an impact on performance.

Scott