Hey
The more I think about the feature, the less I like it.
Here is what I have written in Hibernate Search in Action
Hibernate Search, by default, does not store null attributes into
the index.
Lucene does not have the notion of null fields, the field is simply
not
there. Hibernate Search could offer the ability (and most likely
will in the
future) to use a special string as a null marker to still be able
to search
by "null".
But before you jump at the Hibernate Search team throat, you need to
understand why they have not offered this feature so far. Null is
not a
value per se. Null means that the data is not known (or does not make
sense). Therefore, searching by null as if it was a value is
somewhat odd.
The authors are well aware that this is a raging debate especially
amongst
the relational model experts (see
http://en.wikipedia.org/wiki/Null_%28SQL%29).
Whenever you feel the need for searching by "null", you should ask
yourself
if storing a special marker value in the database would make more
sense. If
you store a special marker value in the database, a lot of the "null"
inconsistencies vanish. It also has the side effect of being
queriable in
Lucene and Hibernate Search.
So before we jump on the boat for this feature, I would like to
know if
people think it's still a good idea to offer this feature.
To answer your questions, the reason why I do not pass @Field but
the raw
set of data is because the @Field.index is translated into it's
Lucene
representation: some work is done.
Most people will write StringBridge implementation anyway where the
null
handling will be taken care of transparently (by
String2FieldBridgeAdaptor).
I think I like 1 or 3. Note that get should be changed as well.
Three is
interesting indeed, rename it IndexingStragegy.
On Apr 21, 2008, at 10:07, Hardy Ferentschik wrote:
Hi Emmanuel,
what's you take on this? Just adding another String parameter will
work, but
are we not getting too many parameters into the method? Wouldn't it
be nicer
to pass the actual @Field annotation. I think this might make
things also
clearer for the implementor of the interface.
I am also trying here to get a little into your head to understand
your
ideas behind the code design - hope
you don't mind ;-)
--Hardy
------- Forwarded message -------
From: "Hardy Ferentschik (JIRA)" <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Subject: [Hibernate-JIRA] Commented: (HSEARCH-115) Add a default
value for
indexing null value
Date: Mon, 21 Apr 2008 14:04:33 +0200
[
http://opensource.atlassian.com/projects/hibernate/browse/HSEARCH-115?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_30032
]
Hardy Ferentschik commented on HSEARCH-115:
-------------------------------------------
Ok, here are a few suggestions:
1. This is the simplest way. Basically just add a new property named
'indexNullAs' to @Field and @ClassBridge. Accordingly extend the
FieldBridge
interface to set(String name, Object value, Document document,
Field.Store
store, Field.Index index, Field.TermVector termVector, Float boost,
String
indexNullAs).
2. Alternatively one could change the FieldBridge API to actually
pass in
the Field annotation itself: set(String name, Object value, Document
document, Field fieldAnnotation, Float boost). This would reduce
the amount
of parameters and might actually be more transparent for users
implementing
custom bridges. Unfortunately, one would have to introduce a
ClassBridge
interface as well in this case. I am not sure whether it is a good
design
choice to pass annotation instances around.
3. We ccould also change the API into something like this:
set(String name,
Object value, Document document, IndexProperties props), where
IndexProperties is just a wrapper class for Field.Store,
Field.Index, ...
The drawback is that this just increases the number of classes.
Any comments?
Add a default value for indexing null value
-------------------------------------------
Key: HSEARCH-115
URL:
http://opensource.atlassian.com/projects/hibernate/browse/HSEARCH-115
Project: Hibernate Search
Issue Type: Improvement
Components: mapping
Reporter: Julien Brulin
Assignee: Hardy Ferentschik
Fix For: 3.1.0
Hi,
Null elements are not indexed by lucene then it's not easy to use a
nullable
property in lucene query.
I have a TagTranslation entity in my model with a nullable property
language. In this case null is used as default language for tag
translation.
Each translation may have many variations like synonyms.
Because I can specified a default value for null value in the @Field
annotation like this @Field(index=Index.UN_TOKENIZED,
store=Store.NO, default='null'), i can't search a cat tag with a
default
translation like this : +value:cat* +lang:null
<pre></code>
@Entity()
@Table(name="indexing_tag_trans")
@org
.hibernate
.annotations
.Cache
(usage=org.hibernate.annotations.CacheConcurrencyStrategy.READ_WRITE)
@Indexed
public class TagTranslation implements java.io.Serializable {
private static final long serialVersionUID = -1065316566731456110L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@DocumentId
private Integer id;
@Field(index=Index.UN_TOKENIZED, store=Store.NO)
private String language;
@Field(index=Index.TOKENIZED, store=Store.YES)
private String value;
@OneToMany(cascade=CascadeType.ALL,
fetch=FetchType.LAZY)
@org
.hibernate
.annotations.Fetch(org.hibernate.annotations.FetchMode.SUBSELECT)
@JoinColumn(name="translation_id")
@IndexedEmbedded
private List<TagVariation> variations = new
LinkedList<TagVariation>();
public TagTranslation() { }
...
</code>
</pre>
What do you think about that ?
Ps: sorry for english write, i am a french guy.
--
Hartmut Ferentschik
Ekholmsv.339 ,1, 127 45 Skärholmen, Sweden
Phone: +46 704 225 097 (m)
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