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From "Andy Brown" <andy_br...@rhoworld.com>
Subject RE: Slow Highlighter Performance Even Using FastVectorHighlighter
Date Fri, 14 Jun 2013 20:52:22 GMT
Bryan,

For specifics, I'll refer you back to my original email where I
specified all the fields/field types/handlers I use. Here's a general
overview. 
 
I really only have 3 fields that I index and search against: "name",
"description", and "content". All of which are just general text
(string) fields. I have a catch-all field called "text" that is only
used for querying. It's indexed but not stored. The "name",
"description", and "content" fields are copied into the "text" field. 
 
For partial word matching, I have 4 more fields: "name_par",
"description_par", "content_par", and "text_par". The "text_par" field
has the same relationship to the "*_par" fields as "text" does to the
others (only used for querying). Those partial word matching fields are
of type "text_general_partial" which I created. That field type is
analyzed different than the regular text field in that it goes through
an EdgeNGramFilterFactory with the minGramSize="2" and maxGramSize="7"
at index time. 
 
I query against both "text" and "text_par" fields using edismax deftype
with my qf set to "text^2 text_par^1" to give full word matches a higher
score. This part returns back very fast as previously stated. It's when
I turn on highlighting that I take the huge performance hit. 
 
Again, I'm using the FastVectorHighlighting. The hl.fl is set to "name
name_par description description_par content content_par" so that it
returns highlights for full and partial word matches. All of those
fields have indexed, stored, termPositions, termVectors, and termOffsets
set to "true". 
 
It all seems redundant just to allow for partial word
matching/highlighting but I didn't know of a better way. Does anything
stand out to you that could be the culprit? Let me know if you need any
more clarification. 
 
Thanks! 
 
- Andy 

-----Original Message-----
From: Bryan Loofbourrow [mailto:bloofbourrow@knowledgemosaic.com] 
Sent: Wednesday, May 29, 2013 5:44 PM
To: solr-user@lucene.apache.org
Subject: RE: Slow Highlighter Performance Even Using
FastVectorHighlighter

Andy,

> I don't understand why it's taking 7 secs to return highlights. The
size
> of the index is only 20.93 MB. The JVM heap Xms and Xmx are both set
to
> 1024 for this verification purpose and that should be more than
enough.
> The processor is plenty powerful enough as well.
>
> Running VisualVM shows all my CPU time being taken by mainly these 3
> methods:
>
>
org.apache.lucene.search.vectorhighlight.FieldPhraseList$WeightedPhraseI
> nfo.getStartOffset()
>
org.apache.lucene.search.vectorhighlight.FieldPhraseList$WeightedPhraseI
> nfo.getStartOffset()
>
org.apache.lucene.search.vectorhighlight.FieldPhraseList.addIfNoOverlap(
> )

That is a strange and interesting set of things to be spending most of
your CPU time on. The implication, I think, is that the number of term
matches in the document for terms in your query (or, at least, terms
matching exact words or the beginning of phrases in your query) is
extremely high . Perhaps that's coming from this "partial word match"
you
mention -- how does that work?

-- Bryan

> My guess is that this has something to do with how I'm handling
partial
> word matches/highlighting. I have setup another request handler that
> only searches the whole word fields and it returns in 850 ms with
> highlighting.
>
> Any ideas?
>
> - Andy
>
>
> -----Original Message-----
> From: Bryan Loofbourrow [mailto:bloofbourrow@knowledgemosaic.com]
> Sent: Monday, May 20, 2013 1:39 PM
> To: solr-user@lucene.apache.org
> Subject: RE: Slow Highlighter Performance Even Using
> FastVectorHighlighter
>
> My guess is that the problem is those 200M documents.
> FastVectorHighlighter is fast at deciding whether a match, especially
a
> phrase, appears in a document, but it still starts out by walking the
> entire list of term vectors, and ends by breaking the document into
> candidate-snippet fragments, both processes that are proportional to
the
> length of the document.
>
> It's hard to do much about the first, but for the second you could
> choose
> to expose FastVectorHighlighter's FieldPhraseList representation, and
> return offsets to the caller rather than fragments, building up your
own
> snippets from a separate store of indexed files. This would also
permit
> you to set stored="false", improving your memory/core size ratio,
which
> I'm guessing could use some improving. It would require some work, and
> it
> would require you to store a representation of what was indexed
outside
> the Solr core, in some constant-bytes-to-character representation that
> you
> can use offsets with (e.g. UTF-16, or ASCII+entity references).
>
> However, you may not need to do this -- it may be that you just need
> more
> memory for your search machine. Not JVM memory, but memory that the
O/S
> can use as a file cache. What do you have now? That is, how much
memory
> do
> you have that is not used by the JVM or other apps, and how big is
your
> Solr core?
>
> One way to start getting a handle on where time is being spent is to
set
> up VisualVM. Turn on CPU sampling, send in a bunch of the slow
highlight
> queries, and look at where the time is being spent. If it's mostly in
> methods that are just reading from disk, buy more memory. If you're on
> Linux, look at what top is telling you. If the CPU usage is low and
the
> "wa" number is above 1% more often than not, buy more memory (I don't
> know
> why that wa number makes sense, I just know that it has been a good
rule
> of thumb for us).
>
> -- Bryan
>
> > -----Original Message-----
> > From: Andy Brown [mailto:andy_brown@rhoworld.com]
> > Sent: Monday, May 20, 2013 9:53 AM
> > To: solr-user@lucene.apache.org
> > Subject: Slow Highlighter Performance Even Using
FastVectorHighlighter
> >
> > I'm providing a search feature in a web app that searches for
> documents
> > that range in size from 1KB to 200MB of varying MIME types (PDF,
DOC,
> > etc). Currently there are about 3000 documents and this will
continue
> to
> > grow. I'm providing full word search and partial word search. For
each
> > document, there are three source fields that I'm interested in
> searching
> > and highlighting on: name, description, and content. Since I'm
> providing
> > both full and partial word search, I've created additional fields
that
> > get tokenized differently: name_par, description_par, and
content_par.
> > Those are indexed and stored as well for querying and highlighting.
As
> > suggested in the Solr wiki, I've got two catch all fields text and
> > text_par for faster querying.
> >
> > An average search results page displays 25 results and I provide
> paging.
> > I'm just returning the doc ID in my Solr search results and response
> > times have been quite good (1 to 10 ms). The problem in performance
> > occurs when I turn on highlighting. I'm already using the
> > FastVectorHighlighter and depending on the query, it has taken as
long
> > as 15 seconds to get the highlight snippets. However, this isn't
> always
> > the case. Certain query terms result in 1 sec or less response time.
> In
> > any case, 15 seconds is way too long.
> >
> > I'm fairly new to Solr but I've spent days coming up with what I've
> got
> > so far. Feel free to correct any misconceptions I have. Can anyone
> > advise me on what I'm doing wrong or offer a better way to setup my
> core
> > to improve highlighting performance?
> >
> > A typical query would look like:
> > /select?q=foo&start=0&rows=25&fl=id&hl=true
> >
> > I'm using Solr 4.1. Below the relevant core schema and config
details:
> >
> > <!-- Misc fields -->
> > <field name="_version_" type="long" indexed="true" stored="true"/>
> > <field name="id" type="string" indexed="true" stored="true"
> > required="true" multiValued="false"/>
> >
> >
> > <!-- Fields for whole word matches -->
> > <field name="name" type="text_general" indexed="true" stored="true"
> > multiValued="true" termPositions="true" termVectors="true"
> > termOffsets="true"/>
> > <field name="description" type="text_general" indexed="true"
> > stored="true" multiValued="true" termPositions="true"
> termVectors="true"
> > termOffsets="true"/>
> > <field name="content" type="text_general" indexed="true"
stored="true"
> > multiValued="true" termPositions="true" termVectors="true"
> > termOffsets="true"/>
> > <field name="text" type="text_general" indexed="true" stored="false"
> > multiValued="true"/>
> >
> > <!-- Fields for partial word matches -->
> > <field name="name_par" type="text_general_partial" indexed="true"
> > stored="true" multiValued="true" termPositions="true"
> termVectors="true"
> > termOffsets="true"/>
> > <field name="description_par" type="text_general_partial"
> indexed="true"
> > stored="true" multiValued="true" termPositions="true"
> termVectors="true"
> > termOffsets="true"/>
> > <field name="content_par" type="text_general_partial" indexed="true"
> > stored="true" multiValued="true" termPositions="true"
> termVectors="true"
> > termOffsets="true"/>
> > <field name="text_par" type="text_general_partial" indexed="true"
> > stored="false" multiValued="true"/>
> >
> >
> > <!-- Copy source name, description, and content fields to name_par,
> > description_par, and content_par for partial word searches -->
> > <copyField source="name" dest="name_par"/>
> > <copyField source="description" dest="description_par"/>
> > <copyField source="content" dest="content_par"/>
> >
> > <!-- Copy source name, description, and content fields to catch-all
> text
> > field for faster querying. -->
> > <copyField source="name" dest="text"/>
> > <copyField source="description" dest="text"/>
> > <copyField source="content" dest="text"/>
> >
> > <!-- Copy source name, description, and content fields to catch-all
> > text_par field for faster querying of partial word searches. -->
> > <copyField source="name" dest="text_par"/>
> > <copyField source="description" dest="text_par"/>
> > <copyField source="content" dest="text_par"/>
> >
> > <!-- A text field for whole word matches -->
> > <fieldType name="text_general" class="solr.TextField"
> > positionIncrementGap="100">
> >   <analyzer type="index">
> >     <tokenizer class="solr.StandardTokenizerFactory"/>
> >     <filter class="solr.StopFilterFactory" ignoreCase="true"
> > words="stopwords.txt" enablePositionIncrements="true" />
> >     <filter class="solr.LowerCaseFilterFactory"/>
> >   </analyzer>
> >   <analyzer type="query">
> >     <tokenizer class="solr.StandardTokenizerFactory"/>
> >     <filter class="solr.StopFilterFactory" ignoreCase="true"
> > words="stopwords.txt" enablePositionIncrements="true" />
> >     <filter class="solr.SynonymFilterFactory"
synonyms="synonyms.txt"
> > ignoreCase="true" expand="true"/>
> >     <filter class="solr.LowerCaseFilterFactory"/>
> >    </analyzer>
> >  </fieldType>
> >
> > <!-- A text field for parital matches -->
> > <fieldType name="text_general_partial" class="solr.TextField"
> > positionIncrementGap="100">
> >   <analyzer type="index">
> >     <tokenizer class="solr.StandardTokenizerFactory"/>
> >     <filter class="solr.StopFilterFactory" ignoreCase="true"
> > words="stopwords.txt" enablePositionIncrements="true" />
> >     <filter class="solr.LowerCaseFilterFactory"/>
> > 	<filter class="solr.EdgeNGramFilterFactory" minGramSize="2"
> > maxGramSize="7"/>
> >   </analyzer>
> >   <analyzer type="query">
> >     <tokenizer class="solr.StandardTokenizerFactory"/>
> >     <filter class="solr.StopFilterFactory" ignoreCase="true"
> > words="stopwords.txt" enablePositionIncrements="true" />
> >     <filter class="solr.SynonymFilterFactory"
synonyms="synonyms.txt"
> > ignoreCase="true" expand="true"/>
> >     <filter class="solr.LowerCaseFilterFactory"/>
> >   </analyzer>
> > </fieldType>
> >
> >
> >
> > <requestHandler name="/select" class="solr.SearchHandler">
> >     <!-- default values for query parameters can be specified, these
> > will be overridden by parameters in the request. -->
> >      <lst name="defaults">
> >        <str name="echoParams">explicit</str>
> >        <int name="rows">10</int>
> >        <str name="df">text</str>
> > 	   <str name="defType">edismax</str>
> > 	   <str name="qf">text^2 text_par^1</str>   <!-- Boost whole
> > word matches more than partial matches in the scroing. -->
> > 	   <bool name="termVectors">true</bool>
> >        <bool name="termPositions">true</bool>
> >        <bool name="termOffsets">true</bool>
> >        <bool name="hl.useFastVectorHighlighter">true</bool>
> >        <str name="hl.boundaryScanner">breakIterator</str>
> >        <str name="hl.snippets">2</str>
> > 	   <str name="hl.fl">name name_par description description_par
> > content content_par</str>
> >        <int name="hl.fragsize">162</int>
> > 	   <str name="hl.fragListBuilder">simple</str>
> >        <str name="hl.fragmentsBuilder">default</str>
> >        <str name="hl.simple.pre"><![CDATA[<strong>]]></str>
> >        <str name="hl.simple.post"><![CDATA[</strong>]]></str>
> > 	   <str name="hl.tag.pre"><![CDATA[<strong>]]></str>
> >        <str name="hl.tag.post"><![CDATA[</strong>]]></str>
> >      </lst>
> >  </requestHandler>
> >
> >
> > Cheers!
> >
> > - Andy

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