I'm Very New to Infinispan Framework.I want To Know can Infinispan Use For Cashed Entities Data Syncronization with Oracle database tables. Simple scenario is This When I Put an Entity into Cache I want to Persist That entity into Database without persisting It in to the Database(only puting to Cache) .what I am looking for is a slightly different cache store. The idea behind it is to have the data stored as if we used Hibernate JPA . So the cache store needs to update the right table/row depending on the information of the map key and/or information gained from the JPA annotationsPlease let me know Infinispan Supports this scenario or not?If Supports Please share some sample code with me.
Maybe what you're looking for is Hibernate OGM which allows you to store data into a data grid, such as Infinispan, instead of the database, while using the JPA API?
Related
I just recently switch from MySQL to MongoDB, I'm wondering with MySQL I stored the player data inside a hashmap and retrieved name, coins etc; like that so I don't have to constantly query the database to retrieve the data.
Now with MongoDB would I need to do the same thing store the values inside a hashmap and retrieve it the same way I did with MySQL?
It depends on your requirement. You have migrated to mongodb from mysql, this doesnt means that your reads would be superfast. If there would have been any significant I/O improvement in mongodb, mysql developers would have adopted it as well. MongoDB provide flexibility over mysql and there are some more advantages there. So If your load remains the same, you should have a caching layer before mongodb layer. Both Mysql and mongodb come with in-built caching which caches results on the basis of query just like a hashmap, but rest data is on disk and as mentioned mongodb doesnt have any technical advantage over mysql in terms of I/O. So have a caching layer to avoid excessive querying to db.
I have 2 applications, which using the same database. The first app can write and read from database. The second app only read from database.
I include second-level hibernate cache with read-write strategy. And now, when I change data from the first app, I don't see this changes at the second app.
How to resolve this issue?
Disclaimer: I am not an hibernate expert, maybe somebody else can give a more cripsy answer...
This is the same question on SO:
Hibernate 2nd level cache invalidation when another process modifies the database However it seems fairly outdated.
You need to look for a distributed or replicated cache and follow the documentation of the respective product. Examples:
Using Infinispan as JPA second level cache provider
Using EHCache and hibernate
Some blog articles about it:
http://codespot.net/2014/02/03/hibernate-caching-strategies
http://vladmihalcea.com/how-does-hibernate-store-second-level-cache-entries
If one application directly writes to the database you need to properly invalidate the second level caches by yourself.
I am using Hibernate's multi-tenancy feature via JPA, with a database per tenant strategy. One of my requirements is to be able to run a query against a table that exists in each database but obviously with different data. Is this possible?
Thanks in advance for your time.
Nope. this is not possible because when hibernate runs queries it is already initialized with a connection. MT support in Hibernate is basically done a little "outside of Hibernate" itself. It's kind of feeding hibernate with a proper connection and when it's fed :) it's bound to that connection.
If you need cross-tenant queries you might want to reconsider multitenancy or change JPA provider to the one that support "shared schema approach" e.g. EclipseLink. With shared shema approach you have two choices:
run native query agains table containing mt-aware entities
create additional entity - dont mark it as multitenant - map it to the table containing mt-ware entities and run JPQL query in standard manner
I need some clarification with the Hibernate second level cache.
How does the hibernate second level cache works?
Does it loads all the data from the tables for which there is #Cacheable annotation (with respect to hibernate annotation) in the entity classes on server start up in the Java EE environment?
Will the cache gets sync up when there is an update on those tables and how?
Last one is there any ways for my DAO code to get notified when there is an updated on some table which i am interested upon? (Looking for any listener which can intimate abt the updates of the tables).
How does the hibernate second level cache works?
When your entity is marked as cacheable and if you have configured the second level cache then hibernate will cache the entity to the second level cache after the first read.
Hibernate provides the flexibility to plugin any cache implementation that follows hibernates specification. Refer Hibernate Manual for more details on second level cache and configurations options.
Does it loads all the data from the tables for which there is #Cacheable annotation (with respect to hibernate annotation) in the entity classes on server start up in the Java EE environment?
I don't think there is any configuration for achieving this. Indirectly you can achieve this by reading the entire table in startup, this can adversely affect the system startup time. (i don't prefer this). If the entity is modified externally, then hibernate can't sync it and you will end up getting stale data.
Will the cache gets sync up when there is an update on those tables and how?
The cache won't get updated instantly after the table update. The subsequent call to fetch the updated record will go the database, hibernate achieves this internally by using session timestamps.
Last one is there any ways for my DAO code to get notified when there is an updated on some table which i am interested upon? (Looking for any listener which can intimate abt the updates of the tables).
No, hibernate doesn't support this.
That's a too broad question to be answered here.
No. It populates the cache lazily. Each time you get a cachable entity from the database, using the hibernate API or a query, this entity is stored in the cache. Later, when session.get() is called with an ID of an entity that is in the cache, no database query is necessary.
If the update is made through Hibernate, then the cache is updated. If it's done using an external application, or a SQL query, or even a bulk update HQL query, then the cache is unaware of the update. That's why you need to be careful about which entities you make cachable, which time-to-live you choose, etc. Sometimes, returning stale values is not problematic, and sometimes it is unacceptable.
No.
I have an application that uses hibernate and JPA to handle the database. I know that hibernate can create the database tables for me, however, I've found that I must first create the database files and the database user account before hibernate can create the tables. Is there a way for hibernate to do create the database and user account for me?
If this was possible, it would mean that an external process can create accounts, databases and tables in the database without any access rights. I think we don't want this.
Unfortunately not.
For one, Hibernate/JPA relies on the persistence.xml and specifically the JDBC connection URL required -- which contain the name and user of your database.
Hibernate/JPA are ORM frameworks: Object Relational mapping frameworks designed to map Java code to database objects.
What are your reasons for wanting this? I can only think for testing purposes, in that case you can use an in memory database (such as HSQLDB).