I have a memory HSQLDB database with this connection URL:
jdbc:hsqldb:mem:test_database
It runs fine with my application but I need to configure this database in a SQL Client.
I can't because every clients complain that no host was found or there's no database.
I'm not sure if I'm filling all the information correctly in "host" and "database" fields or if it is a HSQLDB memory restriction.
Has anyone got the same error?? Thanks a lot.
With :mem: you define a database which is only accessible within the running java vm. This database resides in memory and cannot be accessed externally via host/port jdbc access.
Please read:
Running and Using Hsqldb
Advanced Topics
You can use the Database Manager provided by HSQLDB, just run in console
java -cp hsqldb.jar org.hsqldb.util.DatabaseManagerSwing
and connect to the jdbc:hsqldb:mem:test_database
Related
We have Oracle SQL, and SQL Server. Both runs on different servers. We would like to make a database triggers that will call a Java method. The Java web server which is running in another server in the Docker container environment. After reading some online docs as follows I found it is possible.
Oracle SQL : https://docs.oracle.com/en/database/oracle/oracle-database/12.2/jjdev/calling-Java-from-database-triggers.html#GUID-5C498DEF-0348-484D-AA26-2A88EF348D5C
SQL Server: https://learn.microsoft.com/en-us/sql/language-extensions/how-to/call-java-from-sql?view=sqlallproducts-allversions
So I am not sure which way to go ahead with this distributed system. Is it RMI or something else? Please suggest to me what to do?
I am fairly new to H2 Database. As a part of a PoC, I am using H2 database(version : 1.4.187) for mocking the MS SQL Server DB. I have one application, say app1 which generates the data and save into H2. Another application, app2, needs to read from the H2 database and process the data it reads. I am trying to use Auto Server mode so that even if one of the application is down, other one is able to read/write to/from the database.
After reading multiple examples, i found how to build the h2 url and shown as below:
jdbc:h2:~/datafactory;MODE=MSSQLServer;AUTO_SERVER=TRUE;
Enabled the tcp and remote access as Below:
org.h2.tools.Server.createTcpServer("-tcpAllowOthers","-webAllowOthers").start()
With this, I am able to write to the database. Now, I want to read the data using the h2-web-console application. I am able to do that from my local machine. However, I am not able to understand how I can connect to this database remotely from another machine.
My plant is to run these two apps in an ubuntu machine and I can monitor the data using the web console from my machine. Is it not possible with this approach?
How can I solve this ?
Or do I need to use server mode and explicitly start the h2 server? Any help would be appreciated.
By default, remote connections are disabled for H2 database for protection. To enable remote access to the TCP server, you need to start the TCP server using the option -tcpAllowOthers or the other flags -webAllowOthers, -pgAllowOthers
.
To start both the Web Console server (the H2 Console tool) and the TCP server with remote connections enabled, you will have to use something like below
java -jar /path/to/h2.jar -web -webAllowOthers -tcp -tcpAllowOthers -browser
More information can be found in the docs here and console settings can be configured from here
Not entirely sure but looking at the documentation and other questions answered previously regarding the same topic the url should be something like this:
jdbc:h2:tcp://<host>:<port>/~/datafactory;MODE=MSSQLServer;AUTO_SERVER=TRUE;
It seems that the host may not be localhost and the database may not be in memory
Is there a need for the H2 web console?
You can use a different SQL tool using the TCP server you have already started. I use SQuirreL SQL Client (http://squirrel-sql.sourceforge.net/) to connect to different databases.
If you need a web interface you could use Adminer (https://www.adminer.org/) which can connect to different database vendors, including MS SQL, which happens to be mode you're running H2. There is an Adminer Debian package that should work for Ubuntu.
I have two independent Java apps which I would like to communicate with each other through an in-memory H2-DB. In theory very straight forward, but I cannot get the connection to work.
What I am trying to do:
I create an in-memory DB executing jdbc:h2:mem:test.
With the client(s), I try connecting to it. I tried jdbc:h2:tcp://localhost/~/test and similar connection strings, but all without success.
Is it possible to connect to an in-memory DB? What should the connection strings look like to make this work? Thanks a bunch.
After a ton of reading and trial-and-error with H2 options (http://h2database.com/html/features.html and http://h2database.com/html/advanced.html), I found that it is possible to access an in-memory database from multiple processes on the same machine (or remotely) using TCP/IP or SSL/TLS. The connection string for an in-memory database test is jdbc:h2:tcp://localhost/mem:test.
H2 database can be shared but not in memory, Your may please refer to official documentation:
http://h2database.com/html/features.html#auto_mixed_mode
First application with open it in embedded mode and other application will use server mode.
Background:
I am about to enhance an existing application. This application uses already derby.
For an other use case I want to use derby, too.
Is it possible to run embedded AND client server derby database at the same time?
Yes, you can do this. We call this "Embedded Server", and you can find more details here: http://db.apache.org/derby/docs/10.10/adminguide/cadminov17524.html
Not it is not possible to run the derby in both the modes at the same time. But if you run derby in the network or client/server mode then both your local and remote applications can access the databse. Remote applications means, applications running in different JVMs on the same machine or on remote machines.
I am having a problem with Java DB that I just don't know how to resolve. I am creating a DB and connecting to it using Java DB's native JDBC driver. If I relocate that database physically and try to connect to it using its new path, I consistently get XJ004 errors:
ERROR XJ004: Database 'blahblah' not found.
I am sure I am using the correct connection string. Is there any possibility the DB is somehow getting corrupted? Or is there some encoding of the DB path in the DB such that if you relocate a Java DB it gets confused?
I'm really at a loss here. :( Please help!
Jim
Have you verified that this error message isn't also used when there's no listener on the host machine ... and were you using JavaDB on your local machine before the relocation? Many database systems (and I'm not that familiar with JavaDB) ship set-up to only allow connections from localhost for security reasons. On PostgreSQL for instance, you have to allow TCP connections and bounce the daemon to obtain a remote connection.
Anyway ... since the problem started when you when remote, look for issues related to that first! (And if you can run your application on the remote machine, does that work?)
There must be a file named derby.log somewhere. Check the error there. If it is not detailed enough, try setting derby.stream.error.logSeverityLevel to a lower value. See the manual for more information.