About database

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Forum
15

Performance with large databases

When populating a large database (10s of GBs) performance drops suddenly at a certain time whenever I run the populating application.  Is there typically a database size when indexes can no longer ... the database size and the available RAM. As long as the available RAM is larger than the database
Forum
15

Shrinking Database Files

would be with Database Doctor. Is there a way to reclaim database file space? Is it worth trying to reclaim ... context to propose an answer.) ObjectDB reuses space of deleted objects but the database is never resized to a smaller file. Currently the only way to make the database file smaller is to run
Forum
15

Using the wrong class to access a database

the Point database described in the Getting Started section: package com.objectdb.tutorial ... if I can access the database from here. This program is almost the same as the first; it only calls ... are working fine, but the third ruins the database: - The number of entries is zero. - running the app
Tutorial
15

Step 4: Add a Servlet Class

response) throws ServletException, IOException { // Obtain a database connection ... , response); } finally { // Close the database connection: if (em ... (representing a database connection) is constructed. If a new guest has registered (using a JSP form
Tutorial
15

Step 4: Add a Servlet Class

, IOException { // Obtain a database connection: EntityManagerFactory emf ... { // Close the database connection: if (em.getTransaction().isActive ... the application scope attribute, and then an EntityManager (representing a database connection
FAQ
15

What is the Java Persistence API (JPA)?

The Java Persistence API (JPA) is a standard API for accessing databases from within Java applications. The main advantage of JPA over JDBC (the older Java API for interacting with databases ... . Using plain old Java objects (POJO) to represent persistent data can significantly simplify database
FAQ
15

Which API should I use - JPA or JDO?

code. When to prefer JDO JDO might be preferred when portability to other object databases is more important than general portability to both object and relational databases. JPA is designated to be used mainly with relational databases. ObjectDB is the only object database that supports JPA
FAQ
15

Is ObjectDB scalable? What are its limitations?

ObjectDB is highly scalable and can manage efficiently databases in a wide range of sizes, from ... supports: Database file size up to 128 TB (= 131,072 GB = 134,217,728 MB). Up to 2,147,483,648 entity classes per database file. Up to 2,147,483,648 indexes per database file
Manual
15

Deleting JPA Entity Objects

Existing entity objects can be deleted from the database either explicitly by invoking the remove ... from the database it has to first be retrieved (no matter which way) and then in an active ... (); The entity object is physically deleted from the database when the transaction is committed. Embedded
Forum
15

can't get HashMap out of the database

I'm trying to persist an Entity containing a HashMap. It stores the data in the database OK, but the map is always empty when I get the entity out of the database again. I've reproduced this problem ... stored in the database. The updated project attached. Regards, Natalia. You are right