Wednesday, December 30, 2009


The below URL explains the SHOW INNODB STATUS in detail

Suresh Kuna

Tuesday, December 29, 2009

What is Ajax ?

AJAX isn't a technology, or a language, and there's no recipe to implement it; it's just a combination of various components to achieve something you otherwise couldn't: asynchronous http requests. However, since early 2005, when Google and Flickr popularized the concept, its use has grown rapidly.

The name AJAX is short for Asynchronous JavaScript and XML. It uses the JavaScript XMLHttpRequest function to create a tunnel from the client's browser to the server and transmit information back and forth without having to refresh the page. The data travels in XML format because it transmits complex data types over clear text.

AJAX uses XHTML for the data presentation of the view layer, DOM, short for Document Object Model, which dynamically manipulates the presentation, XML for data exchange, and XMLHttpRequest as the exchange engine that ties everything together.

Because of these requirements, AJAX works on I.E. 5.0+, Mozilla 1.0+, Firefox 1.0+, Netscape 7.0+, and Apple added it to Safari 1.2+.

Traditional HTML sends a request to the server, which processes it and either returns a static HTML page or dispatches the request to some scripting language such as ColdFusion, which creates and returns an HTML page for the browser to render. When this method has to retrieve new data from the server it has to repost and reload another HTML file. In many cases perhaps only a small portion of the returned HTML code varies and the shell itself remains the same resulting in huge overhead because the data has to be downloaded every time.

Some classic examples of applications that would benefit from AJAX are searching for information and displaying it back in a table, related select dropdowns, or checking if a user exists before submitting an entire form.

The below url contains a detail implementation of how it works.

Sunday, December 27, 2009

DBConvert for Oracle and MySQL

Free tools for the Database conversion to Mysql.,39043052,39654405s,00.htm
The following are some of the key features of the MySQL Migration Toolkit:

* The MySQL Migration Toolkit supports a variety of source database systems, including the following:
o Oracle
o Microsoft SQL Server
o Microsoft Access
o Sybase

* The MySQL Migration Toolkit is fully customizable through its Java runtime interface. Advanced users can use Java to perform custom data and schema transformations.
* The MySQL Migration Toolkit supports agent-based data migrations, with the MySQL Migration Toolkit residing on a separate machine than the source and target database servers, through the use of a special migration agent. The agent-based data migration improves migration performance by allowing data to be transferred directly from the source machine to the target machine without being routed through the MySQL Migration Toolkit.

Wednesday, December 23, 2009

Feature enhancements to MySQL Cluster

How important / useful would the following potential enhancements to MySQL Cluster be ?

Running MySQL Cluster on Windows in a production environment
Running MySQL Cluster within virtual machines in a production environment
Improved performance for complex joins
Support for Foreign Keys
More than 128 columns per row
More than 8 Kbytes of data (excluding BLOBs) per row
Ability for indexes to be stored on disk rather than always in memory
Improved performance for asynchronous (Geographic) replication (This does *not* refer to the synchronous replication between data nodes within a single Cluster).
Disk-durable commits - the ability to specify that a transaction does not commit until the in-memory change has been persisted to disk (Latency would be impacted)
Integrate MySQL Cluster backups with Enterprise backup solutions (e.g. Tivoli, NetBackup, HP DataProtector)
XA Distributed commit
Support for application and data nodes to run on machines with different endian architectures
Allow MySQL Cluster to continue operations after a full node-group has been lost (Depending on configuration, a limited number of rows in each table would be unavailable when a full node group is lost)
Allow effective use of more than 8 cores/hardware threads for a single data node
On-line drop column
Meta data (views, privileges etc.) shared between MySQL Servers
Enhanced asynchronous (geographic) replication management
MySQL Enterprise Monitor support for MySQL Cluster (including data nodes)
Extend conflict resolution for asynchronous (geographic) replication to include deletes and inserts
Extend conflict resolution for asynchronous (geographic) replication to remove requirement for application to manage Timestamps.
Support for the Service Availability Framework (SAF)
NDB API thread contention
2 x Data Node (1 node group) configuration where application selects which data node should be responsible for each row (e.g. all rows active on the same data node)
Variable sized VARCHARS on disk
Improve OPTIMIZE TABLE command
Enhanced memory use reporting
Support Map Reduce
Increase security by allowing table data to be transparently encrypted and the key kept secure.
SNMP support for traps
SNMP support for management
Backup a single database
Filtering of NDB API events
Abort transactions when disks become overloaded in order to avoid data nodes crashing

MySQL Storage Engines

Custom Storage Engine

Tuesday, December 22, 2009

Most important MySQL Cluster features

High Availability
Distributed, shared-nothing architecture
Synchronous data replication
Fast Failover
On-line operations (i.e. add nodes, upgrades, schema changes, etc)
On-line back-up
Self-healing (i.e. automatic node recovery)
Geographic redundancy / replication
ACID Compliance / Transactional
Low latency / real-time operations
High write (UPDATE) performance
High read performance
Multiple interfaces / access methods to the data
Ability to scale out on commodity hardware
In-memory data storage
Disk-based data storage
Automatic data partitioning
User-defined data partitioning
Multi-platform support
Open source licensing / distribution
Low cost of acquisition
Low cost of operations