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evictAll() behavior

size before commit= " + pm.getManagedObjects().size()); pm.currentTransaction().commit(); pm.currentTransaction().begin(); System.out.println("Cache size after commit= " + pm.getManagedObjects().size()); pm.evictAll(); System.out.println("Cache size after pm.evict = " + pm.getManagedObjects().size

Out of memory

.OutOfMemoryError: GC overhead limit exceeded GC overhead limit exceeded Database size is only 67MB, heap size is set to 1536MB. Log files are empty. Database uptime was about 3 weeks. It's still version ... lot of data from other source). I didn't catch the size of record log file. For now I turned on heap

JPA Query Expressions (JPQL / Criteria)

, isMember, isNotMember, size). Comparison expressions (equal, notEqual, gt, ge, lt, le, between, isNull, ...) Logical expressions (and, or, not, isTrue).

Best practise loading big data

sizes of caches and how to configure them. Please clarify whether the RAM is released when you close the database (i.e. the EntityManagerFactory). If you need an advice regarding tuning cache sizes ... size and the number of weak references still grows. One could expect that the could be reused


Returns: simple case expression Since: JPA 2.0 Expression<Integer> size(C collection) Create an expression that tests the size of a collection. Create an expression that tests the size of a collection. Parameters: collection - collection Returns: size expression Since: JPA 2.0 Expression<Integer

Use temporary files to enable very large transactions

results), currently the size of a transaction (i.e. the total size of database pages that have to be replaced) is limited by the JVM heap size. Supporting huge transactions requires some major changes in ... situation. For this, we need more information: What is the total size of data in the transaction

[ODB1] Chapter 2 - A Quick Tour

list.add("Hello World " + list.size()); 30 31 // Display the content

[ODB1] Chapter 1 - About ObjectDB

ObjectDB for Java/JDO is a powerful Object Database Management System (ODBMS) written entirely in Java. It can efficiently handle a wide range of database sizes, from a few KBs to hundreds of GBs. It has a small footprint, high performance, and a flexible architecture (1-Tier, 2-Tier or N-Tier). 1


Method javax.jdo.FetchPlan FetchPlan setFetchSize( int fetchSize ) Set the fetch size for large result set support. Use FETCH_SIZE_OPTIMAL to unset, and FETCH_SIZE_GREEDY to force loading of everything. Parameters: fetchSize - the fetch size Returns: the FetchPlan Since: JDO 2.0


Method javax.jdo.FetchPlan int getFetchSize() Return the fetch size, or FETCH_SIZE_OPTIMAL if not set, or FETCH_SIZE_GREEDY to fetch all. Returns: the fetch size Since: JDO 2.0

Getting Started

ObjectDB is very easy to use. Follow the Getting Started Tutorial and the Quick Tour manual chapter and in minutes you may be able to write and run first Java programs against ObjectDB.

Prior knowledge or experience in database programming (SQL, JDBC, ORM, JPA, etc.) is not required, but some background in using the Java language is essential.

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