I wanted to move my test db2 installation based on a Fedora Core 23 to a RHEL7 virtual machine without having to reinstall everything and not lose any data. This is in fact cloning my test environment database. This is not an easy task as is not officially supported by IBM but the beauty of… Read More »
Sometimes working with Hibernate you get the following error in case a persist is executed on an object with dependencies. com.ibm.db2.jcc.am.SqlIntegrityConstraintViolationException: Error for batch element #1: The insert or update value of the FOREIGN KEY “INST1.MESSAGE.FK_1FUTL48XT47HPPGH0YXQM1MIJ” is not equal to any value of the parent key of the parent table.. SQLCODE=-530, SQLSTATE=23503, DRIVER=4.13.127 From IBM… Read More »
Sometimes things go slow in the database even if the original setup was done with a lot of care. The data traffic the usage of the application can sometimes impose the need of extra indices in addition to the original indices added by the enterprise application client that uses the Oracle database. The following procedure… Read More »
Microsoft SQL Server Standard Edition has a great feature present in this basic license: Database Replication in Synchronous mode. To activate the database replication of a database from Primary Site (PR) to Disaster Recovery Site (DR) where the database to be replicated is called myDB the following simple steps must be performed: On PR site… Read More »
Snapshot isolation is a guarantee that all reads made in a transaction will see a consistent snapshot of the database. The transaction itself will successfully commit only if no updates it has made, conflicts with any concurrent updates made since that snapshot. By using it, deadlock situations when a read operation (intense resource consuming operation)… Read More »
This error is the DB2 cryptic way of informing you that a value which an insert query tries to insert in a table is too large. Usually when using java + hibernate we can define a member of an EJB as: @Column(length = 10) protected String receiver; If somehow when the object is created we… Read More »
From a very strange reason after updating the hibernate4 from version 4.1.4 to 4.2.5 there was suddenly a weird behaviour of the EJB3.1 enterprise application I am working on. A piece of code that commits to the database an object (ProcessingStatus) containing a BLOB was throwing the following: [1/31/16 23:37:15:922 EET] 000000eb AbstractBatch Z org.hibernate.engine.jdbc.batch.internal.AbstractBatchImpl… Read More »
This is an annoying issues of hibernate with DB2. Trying to add a new primitive type to an already existing entity will result in an error when updating the associated database table. As a result no update of the schema is done. Why is that ? When adding to an entity a new primitive type… Read More »
As we now in case of a table with BLOBs in the actual table row only a reference to the BLOB is stored. In order to get the real table size of my table ‘MY_BLOB_TABLE’ including the refereed BLOBs the following query holds in Oracle: SELECT sum( bytes)/1024/1024 size_in_MB FROM user_segments WHERE (segment_name = ‘MY_BLOB_TABLE’… Read More »
Sometimes an oracle query goes nuts and blocks the DB. To find the blocked processes started by user MYUSER execute: SELECT s.inst_id, s.sid, s.serial#, p.spid, s.username, s.program FROM gv$session s JOIN gv$process p ON p.addr = s.paddr AND p.inst_id = s.inst_id where s.username like ‘MYUSER’; To kill the blocking process: ALTER SYSTEM KILL SESSION ‘sid,serial#’