Thanks Jörn and Erick for your explanations.
What I do so far is the following:
* I have a RDBMS with one totally flatten table holding all the data
and the id.
* The data is unstructured. Fields can vary from document to document.
I have no fixed schema. A dataset is represented by a Hashmap.
* Lucene (7.5) is perfect to index the data - with analysed-fulltext
and also with non-analysed-fields.
The whole system is highly transactional as it runs on Java EE with JPA
and Session EJBs.
I can easily rebuild my index on any time as I have all the data in a
RDBMS. And of course it was necessary in the past to rebuild the index
for many projects after upgrading lucene (e.g. from 4.x to 7.x).
So, as far as I understand, you recommend to leave the data in the RDBMS?
The problem with RDBMS is that you can not easily scale over many nodes
with a master less cluster. This was why I thought Solr can solve this
problem easily. On the other hand my Lucene index also did not scale
over multiple nodes. Maybe Solr would be a solution to scale just the
index?
Another solution I am working on is to store all my data in a HA
Cassandra cluster because I do not need the SQL-Core functionallity. But
in this case I only replace the RDBMS with Cassandra and Lucene/Solr
holds again only the index.
So Solr can't improve my architecture, with the exception of the fact
that the search index could be distributed across multiple nodes with
Solr. Did I get that right?
===
Ralph
On 02.06.19 16:35, Erick Erickson wrote:
You must be able to rebuild your index completely when, at some point, you
change your schema in incompatible ways. For that reason, either you have to
play tricks with Solr (i.e. store all fields or the original document or….) or
somehow have access to the original document.
Furthermore, starting with Lucene 8, Lucene will not even open an index _ever_
touched with Lucene 6. In general you can’t even open an index with Lucene X
that was ever worked on with Lucene X-2 (starting where X = 8).
That said, it’s a common pattern to put enough information into Solr that a
user can identify documents that they need then go to the system-of-record for
the full document, whether that is an RDBMS or file system or whatever. I’ve
seen lots of hybrid systems that store additional data besides the id and let
the user get to the document she wants and only when she clicks on a single
document go to the system-of-record and fetch it. Think of a Google search
where the information you see as the result of a search is stored in Solr, but
when the user clicks on a link the original doc is fetched from someplace other
than Solr.
FWIW,
Erick
On Jun 2, 2019, at 7:05 AM, Jörn Franke <jornfra...@gmail.com> wrote:
It depends what you want to do with it. You can store all fields in Solr and
filter on them. However, as soon as it comes to Acid guarantees or if you need
to join the data you will be probably needing something else than Solr (or have
other workarounds eg flatten the table ).
Maybe you can describe more what the users do in Solr or in the database.
Am 02.06.2019 um 15:28 schrieb Ralph Soika <ralph.so...@imixs.com>:
Inspired by an article in the last german JavaMagazin written by Uwe Schindler
I wonder if Solr can also be used as a database?
In our open source project Imixs-Workflow we use Lucene
<https://imixs.org/doc/engine/queries.html> since several years with great
success. We have unstructured document-like data generated by the workflow engine. We
store all the data in a transactional RDBMS into a blob column and index the data
with lucene. This works great and is impressive fast also when we use complex queries.
The thing is that we do not store any fields into lucene - only the primary key
of our dataset is stored in lucene. The document data is stored in the SQL
database.
Now as far as I understand is solr a cluster enabled datastore which can be
used to store also all the data form our document.
The problem with relational databases was always the lack of cloud/cluster
support to get more stable data by using redundancy over serveral nodes.
What do you think? Is solr an alternative to store and index data instead of
useing Lucene in combination with RDBMS?
===
Ralph
