[hibernate-dev] Search: how to define hints for batch indexing

[Sanne Grinovero]

Hi everyone,

I am working on batch indexing for Hibernate Search, I would like to define
a new annotation
to set the needed "hints" for the process "@BatchIndexingHints"; one of the
hint parameters is "which HQL query should I use?"
The query is optional and I can fallback to a simple scrolling criteria,
also this query should
not affect the functionality, only a performance hint to define join fetch
collections needed for indexing.

The options we found (speaking with Emmanuel) are 4:

1)don't ask for a query but for the name of a named query.
I don't like this one as the definition of a named query is too flexible,
e.g. I know for sure the
"readonly=true" is preferable for my purpose. Also this query is going to be
created only once per
thread during an indexing process, so I don't foresee a considerable
performance boost.
Additionally the name of the NamedQuery would be redundant as I would be the
only user (probably).

2)define the HQL to load all entities in @BatchIndexingHints.

3)Let the user only define a list of Strings, naming the properties to be
eagerly loaded;
I would add these using .setFetchMode("prop1", FetchMode.EAGER) on the base
Criteria.
This would be nice as we could be sure the users can't add some restriction
or load
the wrong entity, making it more safe.
But I wonder if we are loosing too much flexibility in this case.

4)don't tell anything at class level put add a boolean to desired fields,
something like
@Field(eagerInBatch=true) or @Field(InBatch=FetchType.EAGER)
(adding a property to existing annotation)

Besides the eagerly loading query the other parameters are 3 ints needed to
set the size
of 3 different ThreadPools which do the job at different stages; they are
here to provide
a nice per-entity default, but if I move them to a configuration property
and we
select option 4) I could avoid the new annotation.

some comments?

Sanne
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