I don't think you can have much, if any, influence on the docid that Lucene
assigns. When you add a document, it's guaranteed to have an ID greater than
any already in the index. I just think (but don't depend) on it being N + 1
where N is the largest docid already in the index.
But here's the really critical part. A document ID can change. If you delete
a document and re-optimize the index (I'm pretty sure the optimization is
necessary), all the documents with docids greater than the one you deleted
will be re-assigned.
People have recommended instead, that you store things like ROWID in a new
field in the Lucene document and leave the docid alone......
Or something like that <G>...
BTW, I commend your efforts and contributions to the Lucene corpus with
this, keep up the good work!
Best
Erick
On 11/23/06, Marcelo Ochoa <[EMAIL PROTECTED]> wrote:
Otis:
I am new to Lucene API and searching technologies :)
doc.add(new Field("rowid", rowid, Field.Store.YES,
Field.Index.UN_TOKENIZED));
Done!!.
Also the Oracle ROWID format has a portion which can be used as the
document id into the Lucene document, this will simplify the delete
operation, for example, because with the rowid we can use
reader.deleteDocument(idFromRowIDValue).
http://download-east.oracle.com/docs/cd/B19306_01/server.102/b14220/datatype.htm#sthref3899
But I don't know how to add documents with an specific id.
Somebody can help me showing a code snipped with an adding operation
using a predefined ID?
Rowid number start with 0 and are sequentially assigned.
Best regards, Marcelo.
On 11/23/06, Otis Gospodnetic <[EMAIL PROTECTED]> wrote:
> Wow, very cool, even though I don't use Oracle anywhere at the moment.
> You probably don't want that rowid field tokenized, by the way.
>
> Otis
>
> ----- Original Message ----
> From: Marcelo Ochoa <[EMAIL PROTECTED]>
> To: [email protected]
> Sent: Wednesday, November 22, 2006 8:44:58 AM
> Subject: Re: Oracle and Lucene Integration
>
> Hi Mark:
> > Very interesting.
> >
> > So how does this solution manage mapping Oracle primary keys to and
from Lucene doc ids?
> I am storing the rowid value as a Document field, here a code sniped
> Document doc = new Document();
> doc.add(new Field("rowid", rowid, Field.Store.YES,
> Field.Index.TOKENIZED));
> Object value = rs.getObject(2);
> String valueStr = null;
> if (value!=null) { // Sanity checks
> if (value instanceof CLOB)
> valueStr =
> ((CLOB)value).getSubString(1,(int)((CLOB)value).length());
> else if (value instanceof XMLType)
> valueStr =
> ((XMLType)value).extract("//text()","").getStringVal();
> else
> valueStr = value.toString();
> doc.add(new
> Field(col,valueStr,Field.Store.NO,Field.Index.TOKENIZED));
> writer.addDocument(doc);
>
> So when I am querying I can get the rowid back using:
> if (iterator.hasNext()) {
> // append rowid to collection
> Hit hit = (Hit) iterator.next();
> try {
> rid = hit.get("rowid");
> score = hit.getScore();
> } catch (IOException e) {
> e.printStackTrace();
> throw new SQLException(e.getMessage());
> }
> rlist[i] = new String(rid);
> slist.put(rid,new Float(score));
> idx++;
> } else {.............
> and passing the rowid to the Oracle execution plan which is
> collecting in bacth of 2000 rowids.
> >
> > >> Another benefits of using the Data Cartridge API is that if the
> > >>table T1 has insert, update or delete rows operations a
corresponding
> > >>Java method will be called to automatically update the Lucene Index.
> >
> > I suspect the tricky bit is optimizing the opening/closing of Lucene
IndexReaders/Writers especially in the event of large batches of database
updates.
> > Does this API pass the transactional info which would help organize
the batching of the Lucene reader.delete and writer.add calls?
> Well, I think that Oracle Text uses a Queue to store large batches,
> because it use a ctx_sys.sync procedure to update the index ;)
> We can make the same solution using Oracle AQ.
> >
> > Cheers
> > Mark
> Best regards, Marcelo.
> --
> Marcelo F. Ochoa
> http://marcelo.ochoa.googlepages.com/home
> ______________
> Do you Know DBPrism? Look @ DB Prism's Web Site
> http://www.dbprism.com.ar/index.html
> More info?
> Chapter 17 of the book "Programming the Oracle Database using Java &
> Web Services"
> http://www.amazon.com/gp/product/1555583296/
> Chapter 21 of the book "Professional XML Databases" - Wrox Press
> http://www.amazon.com/gp/product/1861003587/
> Chapter 8 of the book "Oracle & Open Source" - O'Reilly
> http://www.oreilly.com/catalog/oracleopen/
>
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--
Marcelo F. Ochoa
http://marcelo.ochoa.googlepages.com/home
______________
Do you Know DBPrism? Look @ DB Prism's Web Site
http://www.dbprism.com.ar/index.html
More info?
Chapter 17 of the book "Programming the Oracle Database using Java &
Web Services"
http://www.amazon.com/gp/product/1555583296/
Chapter 21 of the book "Professional XML Databases" - Wrox Press
http://www.amazon.com/gp/product/1861003587/
Chapter 8 of the book "Oracle & Open Source" - O'Reilly
http://www.oreilly.com/catalog/oracleopen/
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