I am aware of how we create POJO classes (Java) and map them to the schema of the data in MongoDB, and create a connection with spring data. But if I don't have a specific schema and I want to have MongoDB as a back end for my cache in Hazelcast, how do I do that? In my use-case specifically, I have a cache which needs to keep mongodb updated with whatever updates it comes across.
Check this out:
https://github.com/hazelcast/hazelcast-code-samples/tree/master/hazelcast-integration/mongodb
Do note that this is a sample code that is meant for referential purposes only, do not copy paste into your production system.
Related
My requirement is to utilize 2 different database sources(persistent) and serve to frontend. To make api response faster can I utilize in-memory database like H2 or gemfire, to store data that is known to be frequently accessed (like a cron job at some time does that) and for other calls go to the databases. Here, the challenge for me is transferring the data from persistent to in-memory as Spring needs same 2 POJO's with different annotation(For e.g #Document for mongo, for h2,gemfire #Entity). as of now it does not make sense manually go through each record from an array received from mongo and save it in in-mem.
You can utilize the Spring Framework's Cache Abstraction and different forms of caching patterns when using Apache Geode (or alternatively, VMware Tanzu GemFire). See a more general description about caching starting here.
NOTE: VMware Tanzu GemFire, up to 9.15, is built on Apache Geode and are virtually interchangeable by swapping the bits.
I also provide many Samples of the different caching patterns in action, Guide and Source included, which are reference in the relevant section in the reference documentation.
Finally, in the Spring Boot for Apache Geode project, I also have 2 test classes testing the Inline Caching Pattern, which you may refer to:
The first test class uses Apache Geode as a caching provider in Spring's Cache Abstraction to cache data from a database, HSQLDB (predecessor of H2) in this case.
The second test class is similar in that Apache Geode caches data from Apache Cassandra.
The primary, backend data store used in Inline Caching is made irrelevant since it uses the Spring Data Repository abstraction to interface with any data store (referred to as "modules" in the Spring Data portfolio; see here) supported by the SD Repository abstraction.
Caching is but 1 technique to keep relevant data in-memory in order to improve response times in a Spring (Boot) application using a backing data store, such as an RDBMS, as the primary System of Record (SOR). Of course, there are other approaches, too.
Apache Geode can even be configured for durability (persistence) and redundancy. In some cases, it might even completely replace your database for some function. So, you have a lot of options.
Hopefully this will get you started and give you more ideas.
I have a Spring Batch application with two databases: one SQL DB for the Spring Batch meta data, and another which is a MongoDB where all the business data is stored. The relation DB still uses DataSourceTransactionManager.
However I dont think the Mongo writes are done within an active transaction with rollbacks. Here is the excerpt from the official Spring Batch documentation on MongoItemWriter:
A ItemWriter implementation that writes to a MongoDB store using an implementation of Spring Data's MongoOperations. Since MongoDB is not a transactional store, a best effort is made to persist written data at the last moment, yet still honor job status contracts. No attempt to roll back is made if an error occurs during writing.
However this is not the case any more; MongoDB introduced ACID transactions in version 4.
How do I go about adding transactions to my writes? I could use #Transactional on my service methods when I use ItemWriterAdapter. But still dont know what to do with MongoItemWriter... What is the right configuration here? Thank you.
I have a Spring Batch application with two databases: one SQL DB for the Spring Batch meta data, and another which is a MongoDB where all the business data is stored.
I invite you to take a look at the following posts to understand the implications of this design choice:
How to java-configure separate datasources for spring batch data and business data? Should I even do it?
How does Spring Batch transaction management work?
In your case, you have a distributed transaction across two data sources:
SQL datasource for the job repository, which is managed by a DataSourceTransactionManager
MongoDB for your step (using the MongoItemWriter), which is managed by a MongoTransactionManager
If you want technical meta-data and business data to be committed/rolled back in the scope of the same distributed transaction, you need to use a JtaTransactionManager that coordinates the DataSourceTransactionManager and MongoTransactionManager. You can find some resources about the matter here: https://stackoverflow.com/a/56547839/5019386.
BTW, there is a feature request to use MongoDB as a job repository in Spring Batch: https://github.com/spring-projects/spring-batch/issues/877. When this is implemented, you could store both business data and technical meta-data in the same datasource (so no need for a distributed transaction anymore) and you would be able to use the same MongoTransactionManager for both the job repository and your step.
I have a production dataset in my MongoDB which I use to run my application, I would like to give my devs access to the data in this database but the database contains sensitive data which I don't want exposed to devs poking around in the database. I would also prefer that the devs don't have access directly to the prod database, but rather have access to a replica of it stored somewhere else.
Ideally, I would prefer to use some tool to maintain a perfect replica of my MongoDB database in another MongoDB database, however, with the replica being redacted so no sensitive data is present.
As a plus, it would be nice if the data could also be transformed and aggregated in different ways before it lands in the second database.
What would be the best way to go about doing this?
Set up a change stream. In the change stream listener, redact the new/updated documents and write them to the analytics instance.
My SpringBoot API is supposed to read data from a collection of one database and before returning response back, it is supposed to insert a document in a collection of another database.
I am looking for a quick and efficient way to do this. I searched and found that I can make two entries in my application.properties and create two different Mongo template connection using those. But I am looking for a more clean and compact way to do this (if any).
Refer
https://github.com/Mohit-Hurkat/spring-boot-multi-mongo
it's by using two templates (but a clean way and simple to do this)
https://github.com/Mohit-Hurkat/multi-tenant-spring-mongodb
You can use change stream concept in mongodb..
If you have any change in database it automatically drop the changes in another database
I'm trying to store configuration in MongoDB. I want the document schema to be dynamic so as to store different type of configuration in the collection. The configuration may consist of more than just simple string key-value pairs. While using spring-data-mongodb, I see that I need to define a class which is usually mapped to a mongodb. So, when I need to add more configuration to the collection, I need to make changes to the class. I don't really want to do this as I want to be able to modify configuration without code changes (and ideally without restarting long-running applications). Also, what I'm eventually storing is configuration which should be consumed by different services, so I can't really have a well-defined schema. Instead, I would want the services to pull configuration from the store (i.e. provide key, get value). This makes me doubt where spring-data-mongodb is the right choice for such a use-case. Is there any obvious solution or alternative to my use-case?
Thanks in advance.
The obvious solution is use just the Java driver for MongoDB. The Java driver has an implementation of BSON's spec and you can work with BSON/JSON objects instead classes.