Yeah, unfortunately, they are two distinct things, completely
unrelated in terms of storage, access, etc. I've often felt the
access to position/offset information is hard in Lucene, which makes
it harder to do things like highlighting, co-occurrence analysis, etc.
LUCENE-1001 (which Mark Miller has revived a bit after I lost time on
it: https://issues.apache.org/jira/browse/LUCENE-1001) is one step
towards remedying this. By using Span Queries and (a working
version) of that patch, one should be able to get at payload info
related to the matches. Still not perfect, but better.
Purely wondering out loud here, but it may be possible to use the
TermVectorMapper in conjunction with TermPositions to correlate the
too, but I am not sure. The tricky part is you somehow need to
optimize access to the TermPositions.
Another thought is to add payloads storage to TermVectors. Now we
have offsets and positions, it's conceivable to also store payloads in
a doc. centric way. The tradeoff being more storage space required.
Still, if it's what you need, then it's what you need.
-Grant
On Aug 8, 2008, at 10:39 PM, Tricia Williams wrote:
Hi,
Following the history of Payloads from its beginnings (https://issues.apache.org/jira/browse/LUCENE-755
, https://issues.apache.org/jira/browse/LUCENE-761, https://issues.apache.org/jira/browse/LUCENE-834
, http://wiki.apache.org/lucene-java/Payload_Planning) it looks like
TermPostionsVector was never considered as part of the Payload
functionality. I think this is based on the underlying index file
structure??? I don't see any way to get at a Payload other than
through a TermPositions object. I don't think there is a way to
translate code which uses TermPositions to using TermPositionVector
with regards to payloads -- but I welcome someone to show me how
they could.
It looks like this conversation has happened at least twice
before: http://www.nabble.com/Best-Practices-for-getting-Strings-from-a-position-range-td11608273.html#a11609245
and http://www.nabble.com/Best-way-to-get-payloads-td17399361.html#a17399361
. Unfortunately it doesn't look like anything came of it.
Maybe there is some other work around. What are you trying to
accomplish "historically" with TermPositionsVectors instead of
TermPositions?
Tricia
Martin Owens wrote:
Dear Lucene Users and Tricia Williams,
The way we're operating our lucene index is one where we index all
the
terms but not store the text. From your SOLR-380 patch example
Tricia I
was able to get a very good idea of how to set things up.
Historically I
have used TermPositionsVector instead of TermPositions because of
that
data is available without storing the text in the index.
Is it possible to translate code which uses TermPositions to using
TermPositionsVector with regards to payloads?
Best Regards, Martin Owens
On Tue, 2008-08-05 at 11:14 -0600, Tricia Williams wrote:
Hi Martin,
Take a look at what I've done with SOLR-380 (https://issues.apache.org/jira/browse/SOLR-380
). It might solve your problem, or at least give you a good
starting point.
Tricia
Michael McCandless wrote:
I think you could use payloads (= arbitrary/opaque byte[]) for
this?
You can attach a payload to each term occurrence during
tokenization (indexing), and then retrieve the payload during
searching.
Mike
Martin Owens wrote:
Hello Users,
I'm working on a project which attempts to store data that comes
from an
OCR process which describes the pixel co-ordinates of each term
in the
document. It's used for hit highlighting.
What I would like to do is store this co-ordinate information
alongside
the terms. I know there is existing meta data stored per term
(Word
Offset and Char Offsets) the problem is that If I create a
separate
index and try and use the word offset or char offsets not only
is it
slower but it doesn't match because of the way the terms are
processed
both inside of lucene and the OCR program.
So, is it possible to store the data alongside the terms in
lucene and
then recall them when doing certain searches? and how much
custom code
needs to be written to do it?
Best Regards, Martin Owens
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Grant Ingersoll
http://www.lucidimagination.com
Lucene Helpful Hints:
http://wiki.apache.org/lucene-java/BasicsOfPerformance
http://wiki.apache.org/lucene-java/LuceneFAQ
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