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From Ravikumar Govindarajan <ravikumar.govindara...@gmail.com>
Subject Re: Index Warmup in Blur
Date Tue, 01 Oct 2013 16:41:04 GMT
Thanks Aaron

General sampling and warming is fine and the code is really concise and
clear.

 The act of reading
brings the data into the block cache and the result is that the index is
"hot".

Will all the terms of a field be read and brought into the cache? If so,
then it has an obvious implication to avoid fields like, say
attachment-data from warming up, provided queries don't often include such
fields


On Tue, Oct 1, 2013 at 7:58 PM, Aaron McCurry <amccurry@gmail.com> wrote:

> Take a look at this package.
>
>
> https://git-wip-us.apache.org/repos/asf?p=incubator-blur.git;a=tree;f=blur-store/src/main/java/org/apache/blur/lucene/warmup;h=f4239b1947965dc7fe8218eaa16e3f39ecffdda0;hb=apache-blur-0.2
>
> Basically when the warmup process starts (which is asynchronous to the rest
> of the application) it flips a thread local switch to allow for tracing of
> the file accesses.  The sampler will sample each of the fields in each
> segment and create a sample file that attempts to detect the boundaries of
> each field within each file within each segment.  Then it stores the sample
> info into the directory beside each segment (so that way it doesn't have to
> re-sample the segment).  After the sampling is complete or loaded, the
> warmup just reads the binary data from each file.  The act of reading
> brings the data into the block cache and the result is that the index is
> "hot".
>
> Hope this helps.
>
> Aaron
>
>
>
>
> On Tue, Oct 1, 2013 at 10:09 AM, Ravikumar Govindarajan <
> ravikumar.govindarajan@gmail.com> wrote:
>
> > As I understand,
> >
> > Lucene will store the files in following way per-segment
> >
> > TIM file
> >      Field1 ---> Some byte[]
> >      Field2 ---> Some byte[]
> >
> > TIP file
> >      Field1 ---> Some byte[]
> >      Field2 ---> Some byte[]
> >
> >
> > Blur will "sample" this lucene-file in the following way
> >
> > Field1 --> <TIM, start-offset>, <TIP, start-offset>, ...
> >
> > Field 2 --> <TIM, start-offset>, <TIP, start-offset>, ...
> >
> > Is my understanding correct?
> >
> > How does Blur warm-up the fields, when it does not know the "end-offset"
> or
> > the "length" for each field to warm.
> >
> > Will it by default read all Terms of a field?
> >
> > --
> > Ravi
> >
>

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