[webservices] caching in dataselect and tracedsp

[John D. West]

That's very helpful and just what I needed to know. Thanks, Bruce!

     -- John


On Tue, Sep 25, 2012 at 11:41 AM, Bruce Weertman
<bruce at iris.washington.edu>wrote:

> John:
>
> Good to hear from you.
>
> A few points about caching:
>
> * Yes ws-dataselect and ws-tracedsp do cache the data.
>
> * The cache is very specific to the request that you make.
>
> If you asked for some time period from some  channel and then asked for
> exactly the same
> time period from the same  channel, you would hit the cache and it should
> return much faster.
> If the second request's time range was just a fraction of a second
> different than there first's, you would not
> as there would then be two objects in the cache. This is because the
> 'token' to the cached objects
> are generated from  hashes of request parameters. Changing a request in
> just the slightest
> way will generate a completely different hash.
>
> * ws-bulkdataselect does not cache data.
>
> * The underlying NFS filesystem which holds the archive and everything
> else we do here and the DMC
> does some caching of it's own. Going to datasets that are close to each
> other can result in sped up
> requests as a result. Performance may vary depending on many different
> factors including
> system load and  how close to each other subsequent queries are.
>
>
> Hope that helps.
>
> Cheers,
> -Bruce
>
>
>
> On Sep 25, 2012, at 11:17 AM, John D. West wrote:
>
> > Hello.
> >
> > I am working on code that retrieves corrected traces from the DMC using
> the dataselect and tracedsp web services. I notice that a second retrieval
> of the same data is much, much faster, presumably because the data is being
> cached by the DMC web services. I am retrieving broadband 40Hz data in
> 60-hour increments.
> >
> > Do these web services cache more data than I ask for? Can I speed up my
> requests by either sequentially asking for data for the same channel (i.e.,
> ask for 60 hours of BHZ for a station, then ask for the next 60 hours,
> etc.) or by asking for multiple traces for the same time period (i.e., 60
> hours of BHZ, then 60 hours of BHE & BHN for the same station & time span)?
> >
> > Thanks!
> >
> >      -- John
> > _______________________________________________
> > webservices mailing list
> > webservices at iris.washington.edu
> > http://www.iris.washington.edu/mailman/listinfo/webservices
>
>
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