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#’
LOBS is the DB2 way of dealing with big data. In db2 you can have a table that contains a column defined as LOB where one can dump large binary data (images, compressed text files, video or audio). The problem is the way this LOBS are stored by DB2. By default they are stored “offline”… Read More »
There are times when a simple UPDATE or DELETE cannot be used directly on the database due to the huge amount of data stored in the table. We already covered the topic of increasing the transaction log, see post, but sometimes this is not enough. In the cases when too much data is going to… Read More »
In a setup having an enterprise application depending on a database instance where some tables are defined as nicknames to tables from a federated database, it can happen to get this very cryptic DB2 error. [12/10/15 18:06:54:895 IST] 00000073 SqlExceptionH Z org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions SQL Error: -4229, SQLState: null [12/10/15 18:06:54:903 IST] 00000073 SqlExceptionH Z org.hibernate.engine.jdbc.spi.SqlExceptionHelper… Read More »