EclipseStore And Postgres Demo Application

[snehal-pokharkar]

Hi Team,
I am currently trying to perform basic operations like create,update,fetch and delete using eclipsestore and postgres.
These basic operations working fine.
To connect to postgres and create storage every time using below:
SqlFileSystem fileSystem = SqlFileSystem.New(SqlConnector.Caching(SqlProviderpostgres.New(dataSource)));
EmbeddedStorageManager storageManager = EmbeddedStorage.start(fileSystem.ensureDirectoryPath(name));

However if I start java application in multiple instances and try to add or update records to root and perform storeroot operation,facing below issue:

Caused by: org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "Userdemo$channel_0_pk"
Detail: Key (identifier, start)=(channel_0_1.dat, 256280) already exists.
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2532)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2267)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:312)
at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:448)
at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:369)
at org.postgresql.jdbc.PgPreparedStatement.executeWithFlags(PgPreparedStatement.java:153)
at org.postgresql.jdbc.PgPreparedStatement.executeUpdate(PgPreparedStatement.java:119)
at org.eclipse.store.afs.sql.types.SqlConnector$Default.lambda$writeData$19(SqlConnector.java:902)
at org.eclipse.store.afs.sql.types.SqlProvider$Abstract.execute(SqlProvider.java:390)

I am unable to fetch latest storageManager and root content, before storing root. How to get latest storagemanger so that while storing data latest start and end values from User$channel_0 will be available and next offset value will be stored ?

[zdenek-jonas]

Hello, this is unfortunately not possible. It is embedded storage. One storage - one JVM. PostgreSQL only serves as storage instead of disk at the moment. You can solve it with for example Rest API, one JVM will be the writer and another will communicate with him during rest.

[snehal-pokharkar]

Hello,
Thank you for quick help.
Just to confirm again, accessing single storage via multiple instances on one JVM is not an option.
Am I right ?

[zdenek-jonas]

In one JVM, only one instance of EmbeddedStorageManager can exist for a single physical storage. You may have multiple instances that write to different locations on disk (or a database). You can create stoageManager as a singleton and utilize it from multiple locations in your code. However, you'll need to address concurrency, such as employing a reentrant lock.

[snehal-pokharkar]

Query has been answered.