how to change database connection without restarting server when using AbstractRoutingDataSource - spring

I am using AbstractRoutingDataSource to store data sources which are stored in database during spring boot application startup.
System can switch to correct database during program running.
When end users manual change database connection information from UI (like change password every 6 months), then sysem need to reload data sources information.
According to testing, even sytem reset target data sources, the old jdbc connection is used.

Related

Informatica Workflow Cannot create proper Relational connection object to connect to SQL Server

On my Infa server PC, in Informatica Administration I created a repository service giving Oracle Database information. Once in Informatica I connect to this repository and there I want to create a mapping importing a table from a remote sql server pc (on my home network domain) and then create a workflow to put the data into an oracle target table.
Using ODBC admin console I created and tested the connection and I am also able to telnet the linked sql server and port.
Within informatica I created a relational connection for sql server and when I run the workflow I get the error reason (14007) failed to create and inituiate OLE DB instance and datatabase driven error, failed to connect to database using user I use in SSMS for windows authentication and connection string(). I would like to know, first of of all, if I am doing something wrong, willing to connect me to a repository with oracle database information and then use a sql server table on remote pc. Do I have to create another repository for Sql server and there use sql server tables or I can mix them? secondly I would like to know how to create a relational connection object in informatica for my linked sql server so that it will be the same of relatonal connection created with ODBC admin consolle. Last but not least I would like to understand why gives an error out saying I left connection string empty, when I cannot see a place where I can put it by creating the relational connection object
I might not be able to solve the problem completely, but here's few remarks that might be helpful:
PowerCenter Repository database is where PowerCenter will store all the metadata about the processes you create. It may be Oracle - that's perfectly fine. And as it is not releated to your data sources or targets, you do not need to create another one for different sources/targets. One is enough for all ot them.
Using PowerCenter Workflow Manager create the appropriate connections to all the systems you need. Here you create the connections that indicate ODBC/other connections that will be used by Integration Service to actually connect to your data sources and targets, hence
Make sure the ODBC / other data sources are specified on Intergration Service. It is the IS that will run the process, connect to systems specified in the process with the defined connections.
When you build the mappings, you create them in a client app (Mapping Designer) and you can connect to DB engines to create source and target definitions. Mark, that in such case you use the connection (eg. ODBC data source) defined on the client. Once you will try to actually run the workflow with the given mapping, it is executed on IS (mentioned above) where appropriate connections need to be defined - and that's completely separate.
When editing a session in a workflow, for each source and target you need to pick a connection defined in Informatica Repository, created as described in point 2 above (or use a variable to indicate one - but that's another story)
So the error you mention seems to be related to connection created in Workflow Manager - it probably does not specify the connection string that should refer the data source defined on IS.

Datasource changes to secondary on run time if primary is offline

I have to deal with the following scenario for spring application with Oracle database:
Spring application uses the primary database. In the meantime the secondary database stores data for disaster recovery (from primary).
The first step is currently provided. At this moment I have to implement:
When the primary database gets offline application should change the connection to the secondary database).
The implementation should be programmatically. How can I achieve that without changing the code that currently exists? Is there any working solution (library)?
I think about AbstractRoutingDataSource and ping databases (e.g. every 5 seconds) but I'm not sure about this solution.
So, let's to summarize the issue. I was unable to use Oracle RAC (Real Application Cluster). If the implementation should be programmatically you can try AbstractRoutingDataSource approche.
I have implemented timer that pings current database every 1 second (you can use validation query and check if you can read from database... if no we assume there is no connection and we can switch a datasource).
Thanks to that I was able to change datasource on runtime when current datasource is offline. What is more important it was automatic.
On the other hand, there are disadvantages:
For short time user can see the errors if the database is not
switched yet.
Some part of application may stop working if it is not properly
secured against the lack of connection to the database.

Can't find tables and data of my H2 database

A webapp is using following configuration to store some data in DB:
spring.datasource.continueOnError=true
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.url=jdbc:h2:mem:mydb
I was trying to reach this DB using H2 Console, but something is wrong. There are no tables even though I know they were created. I can also access any made up JDBC:URL like jdbc:h2:mem:fakeXYZ just as well with same result. What is goning on here? How can I see this DB tables and data?
Your JDBC URL specifies a named in-memory database which by default only will be available for connections from within the same virtual machine.
You can either change the URL to use a file-based database, or you will have to start a TCP server to allow for connections from other processes.

Can I connect the jdbc connected static Derby data file in remote repository?

I have to load two Derby instances that reference same data Derby file in a remote repository.
Is it possible? How can I achieve this? Would you give detailed information?
Two different connections in the same Derby app is ok because Derby uses Java synchronization features to coordinate their access to the db.
Two different apps cannot use Java synchronization because that only works inside a single Jvm class loader so instead Derby locks the db and only allows one app at a time to access the db.
That is the benefit of the Derby network server because many apps can access the db simultaneously via the network server.
There is a hybrid mode by which one embedded app can also serve as the network server for other apps but it is complex and usually not the best choice.
Update: You can find more information about embedded servers in these docs: http://db.apache.org/derby/docs/10.11/adminguide/cadminov825149.html and http://db.apache.org/derby/docs/10.11/adminguide/radminembeddedserverex.html
or by searching the Internet for "Derby embedded server".

H2 Database multiple connections

I have the following issue:
Two instances of an application on two different systems should share a small database.
The main problem is that both systems can only exchange data through a network-folder.
I don't have the possibilty to setup a database-server somewhere.
Is it possible to place a H2 database on the network-folder and let both instances connect to the database (also concurrently)?
I could connect with both instances to the db using the embedded mode if I disable the file-locking, right?
The instances can perfom either READ or INSERT operations on the db. Do I risk data corruptions using multiple concurrent embedded connections?
As the documentation says; ( http://h2database.com/html/features.html#auto_mixed_mode
)
Multiple processes can access the same database without having to start the server manually. To do that, append ;AUTO_SERVER=TRUE to the database URL. You can use the same database URL independent of whether the database is already open or not. This feature doesn't work with in-memory databases.
// Application 1:
DriverManager.getConnection("jdbc:h2:/data/test;AUTO_SERVER=TRUE");
// Application 2:
DriverManager.getConnection("jdbc:h2:/data/test;AUTO_SERVER=TRUE");
From H2 documentation:
It is also possible to open the database without file locking; in this
case it is up to the application to protect the database files.
Failing to do so will result in a corrupted database.
I think that if your application use always the same configuration (shared file database on network folder), you need to create an application layer that manages concurrency

Resources