Posts tagged Database
To be useful, data held and used in information systems has to live up to a number of expectations. The data should be an accurate representation of its source. It should be reliable. The data should have internal consistency. The data should adhere to rules based on the logic of the real world. This accuracy, internal quality, and reliability of data is frequently referred as data integrity.
Safeguarding the integrity of data is a challenge, one that increases in complexity when multiple users access and manipulate the data simultaneously , obviously a common situation. And that challenge reaches new heights when the data is managed in multiple independent data stores rather than a single database.
Earlier this month, the Oracle Technology Network published an article that I recently wrote on this subject: http://www.oracle.com/technetwork/articles/soa/jellema-data-integrity-1932181.html. I was triggered into writing it by two recent experiences.
One was at a customer of mine where we are designing a service oriented architecture, based on a number of distinct and independent data domains. These domains are exposed through elementary (entity) services. A second tier of More >
How Oracle Database uses internal locks to make statement level constraint validation robust at the transaction level0
Data Constraints are essential in protecting the integrity of the data in any relational database. The Oracle Database provides four types of declarative constraints that help implement various types of data rules. These are: Primary Key, Unique Key, Foreign Key and Check Constraint. Although these constraints can be configured to be enforced at transaction time (when the transaction is committed) by setting them to be deferred, the default behavior of the constraints is to enforce the integrity rule at statement level. That means that when a transaction performs multiple DML statements, the constraints are validated during execution of the statement. When the statement is done, the integrity is ensured (otherwise the statement would have failed) and additional statements can be executed.
In the multi session environment that is the Oracle Database, you could be wondering – as was I – how the Oracle Database ensures that other sessions executing DML operations can not undermine the integrity of the data touched by the current transaction. And how it can do so without needlessly preventing other sessions to perform data manipulation using various forms of locking.
It turns out that More >
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Database development in the Oracle Database is crucial for creating well balanced multi tier applications. This presentation describes a number of useful facilities and application architecture considerations around the database, taking into account some of the most recent insights.
The official slide deck from this presentation at Oracle Open World 2012:
Last night, Oracle Open World 2012 kicked off with the keynote session by Larry Ellison. In just under one hour, and with a novelty for Larry watchers (no more “next slide please”),
Oracle’s CEO had a number of interesting announcements.
Oracle will provide cloud services (no surprise) on all three tiers: SaaS, PaaS and (the surprise) IaaS.
On a recent project, I ran into a problem with an XML document, that had to be enclosed within another XML document, generated from a database query. The problem I ran into was the character encoding of the XMLElement function, which eventually was worked around with UPDATEXML.
In this blog post I would like to share with you several attempts to solve this problem, why they failed and the final solution to the problem.
Printing of official documents happened in a separate printing module. Whenever a document needed to be printed, an XML document was generated in a database query and sent to the printing module. Most of the data came from relational database tables, but pieces of standard text were supplied as XML documents by another party… and saved in our database in an XMLType column based on CLOB storage.
Our printing module expected to find these standard text XML documents within a tag in our generated XML document. Also both XML documents, our generated XML and the supplied XML, had different namespaces, this needed to maintained this way. The Oracle database version we were working with was 10.1.0.5.0.
In this post I will use a simplified version of the real XML More >