public class ParallelReader
extends IndexReader
An IndexReader which reads multiple, parallel
indexes. Each index added
must have the same number of documents, but
typically each contains
different fields. Each document contains the union
of the fields of all
documents with the same document number. When
searching, matches for a
query term are from the first index added that has
the field.
This is useful, e.g., with collections that have
large fields which
change rarely and small fields that change more
frequently. The smaller
fields may be re-indexed in a new index and both
indexes may be searched
together.
Warning: It is up to you to make sure all indexes
are created and
modified the same way. For example, if you add
documents to one index,
you need to add the same documents in the same order
to the other
indexes. Failure to do so will result in undefined
behavior.
karl
Rajesh parab skrev:
Hi,
We are using Lucene 2.0 to index data stored
inside
relational database. Like any relational database,
our
database has quite a few one-to-one and
one-to-many
relationships. For example, let’s say an Object A
has
one-to-many relationship with Object X and Object
Y.
As we need to de-normalize relational data as
key-value pairs before storing it inside Lucene
index,
we have de-normalized these relationships (Object
X
and Object Y) while building an index on Object A.
We have large no of such object relationships and
most
of the times, the related objects are modified
more
frequently than the base objects. For example, in
our
above case, objects X and Y are updated in the
system
very frequently, whereas Object A is not updated
that
often. Still, we will need to update Object A
entries
inside the index, every time its related objects X
and/or Y are modified.
To avoid the above situation, we were thinking of
having 2 separate indexes – first index will only
index data of base objects (Object A in above
example)
and second index will contain data about its
relationship objects (Object X and Y above), which
are
updated more frequently. This way, the more
frequent
updates to Object X and Y will only impact second
index that stores relationship information and
reduce
the cost to re-index object A. However, I don’t
think,
MultiSearcher will be helpful if we want to search
for
data which spans across both indexes (e.g. some
fields
of Object A in first index and some fields of
Object X
or Y in second index).
Do we have any option in Lucene to handle such
scenario? Can we search across multiple indexes
which
have some relationships between them and search
for
fields that span across these indexes?
Regards,
Rajesh
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