In sequential access, process reads long continuous blocks. Query that does full table scan (FTS), it reads several blocks in single IO operation. This is sequential access.
An indexed sql query uses random access to fulfill single block read.
Thursday, June 3, 2010
Sequential and random db reads
In case of batch operations with bulk data fetching, it is desirable to have sequential data access where as in OLTP, db queries are random.
Wednesday, May 26, 2010
Improving web service WS-Security performance using WS-SecureConversation and WS-Trust
Performance of web services using WS-Security is not good. Reason behind this is, WS-Security uses asymmetric encryption based on public private key. Asymmetric encryption requires large key size and more processing overhead compared to symmetric encryption.
Solution to this is to use WS-Trust and WS-SecureConversation to use symmetric tokens and to improve performance.
WS-SecureConversation allows symmetric encryption for conversation between client and server. WS-SecureConversation uses WS-Security and WS-Trust to support secure exchange of secret key. WS-Trust publishes an interface for webservice that creates and works with security tokens.
Read more details at
Thursday, May 20, 2010
A word on grid computing
Grid computing enables groups of networked computers to be pooled and provisioned on demand to meet the changing needs of business. Instead of dedicated servers and storage for each application, grid computing enables multiple applications to share computing infrastructure, resulting in much greater flexibility, cost, power efficiency, performance, scalability and availability, all at the same time.
Scale out computing capacity on demand in smaller units, instead of buying oversized systems for peak periods or uncertain growth. Remove unneeded or failed machines without interruptions in service, saving cost and ensuring business continuity. Manage all your systems end-to-end with integrated and automated administration and monitoring.
http://www.oracle.com/us/technologies/grid/index.htm
Grid:
- Coordinates resources that are not subject to centralized control. A grid integrates and coordinates resources and users that live within different control domains -- for example, different administrative units of the same company, or even different companies. A grid addresses the issues of security, policy, payment membership, and so forth that arise in these settings.
- Uses standard, open, general-purpose protocols and interfaces. A grid is built from multi-purpose protocols and interfaces that address such fundamental issues as authentication, authorization, resource discovery, and resource access. It is important that these protocols and interfaces be standard and open. Otherwise, we are dealing with application, hardware, or OS -specific systems.
- Delivers nontrivial qualities of service. A grid should be transparent to the end user, addressing issues of response time, throughput, availability, security, and/or co-allocation of multiple resource types to meet complex user demands. The goal is that the utility of the combined system is significantly greater than that of the sum of its parts.
Wednesday, May 19, 2010
Nurturing Creativity
Things that make our thought process dull:
- Habbit of thinking about past and worrying about present
- Feeling of jealousy, hate, egoism and selfishness
Things that make our thoug process creative and innovative
- those things that bring in feeling of unconditional love of doing something good without any expectations of getting something in return; name, fame or money
- thoughts of enjoyment along with others that promote community spririt and feeling of togetherness
Developing Portable Cloud Apps
Google and VMWare are developing development tools, using which developers will be able to build cloud ready apps and deploy them on any cloud environment such EC2, Google app engine, VM ware (vSphere, vCloud, VMForce)
Data Clouds
Data clouds provide a service in platform independent manner to store and retrieve data. User does not care what kind of system stores the data and does not bother about administration. The service grantees high availability, scalability and availability and low latency.
The requirements of data cloud solution are multi-tenancy, metering and health monitoring. Metering, would be crucial to appropriately apportion the shared cost of running the service, and would entail keeping track of CPU cycles consumed, disk and memory space consumed, and possibly even bandwidth.
Example is Amazon SimpleDB
Amazon SimpleDB is a highly available, scalable, and flexible non-relational data store that offloads the work of database administration. Developers simply store and query data items via web services requests, and Amazon SimpleDB does the rest.
Tuesday, May 18, 2010
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