Hi Tim, All.
On 02/07/14 14:32, Allison, Timothy B. wrote:
Hi Sergey,
I'd take a look at what the DataImportHandler in Solr does. If you want to
store the field, you need to create the field with a String (as opposed to a
Reader); which means you have to have the whole thing in memory. Also, if
you're proposing adding a field entry in a multivalued field for a given SAX
event, I don't think that will help, because you still have to hold the entire
document in memory before calling addDocument() if you are storing the field.
If you aren't storing the field, then you could try a Reader.
I'd like to ask something about using Tika parser and a Reader (and
Lucene Store.NO)
Consider a case where we have a service which accepts a very large PDF
file. This file will be stored on the disk or may be in some DB. And
this service will also use Tika to extract content and populate a Lucene
Document.
Now, we already have the original PDF occupying some space, so
duplicating it (its content) with a Document with Store.YES fields may
not be the best idea in some cases.
So I wonder, is it possible somehow for a given Tika Parser, lets say a
PDF parser, report, via the Metadata, the start and end indexes of the
content ? So the consumer will create say InputStreamReader for a
content region and will use Store.NO and this Reader ?
Does it really make sense at all ? I can create a minor enhancement
request for parsers getting the access to a low level info like the
start/stop delimiters of the content to report it ?
Cheers, Sergey
Some thoughts:
At the least, you could create a separate Lucene document for each container
document and each of its embedded documents.
You could also break large documents into logical sections and index those
as separate documents; but that gets very use-case dependent.
In practice, for many, many use cases I've come across, you can index quite large documents
with no problems, e.g. "Moby Dick" or "Dream of the Red Chamber." There may be
a hit at highlighting time for large docs depending on which highlighter you use. In the old days,
there used to be a 10k default limit on the number of tokens, but that is now long gone.
For truly large docs (probably machine generated), yes, you could run into
problems if you need to hold the whole thing in memory.
Cheers,
Tim
-----Original Message-----
From: Sergey Beryozkin [mailto:sberyoz...@gmail.com]
Sent: Wednesday, July 02, 2014 8:27 AM
To: user@tika.apache.org
Subject: How to index the parsed content effectively
Hi All,
We've been experimenting with indexing the parsed content in Lucene and
our initial attempt was to index the output from
ToTextContentHandler.toString() as a Lucene Text field.
This is unlikely to be effective for large files. So I wonder what
strategies exist for a more effective indexing/tokenization of the
possibly large content.
Perhaps a custom ContentHandler can index content fragments in a unique
Lucene field every time its characters(...) method is called, something
I've been planning to experiment with.
The feedback will be appreciated
Cheers, Sergey
