life

how to deal with the struggle and fight the good fight

1. Don’t hide or fall into silence thinking you are alone. When something bad happens, we tend to close off and not to talk to anyone because,”they don’t understand me, ” or “they haven’t been through this.” But, as harsh as it might sound when you are struggling, the reality is that nothing you are […] Read more»

Query Processing

high level user query —–> query processor ——-> low level data manipulation commands Query processing: A 3-step process that transforms a high-level query (of relational calculus/SQL) into an equivalent and more efficient lower-level query (of relational algebra). 1. Parsing and translation – Check syntax and verify relations. – Translate the query into an equivalent relational algebra expression. 2. Optimization […] Read more»

Semantic Data Control

Semantic data control typically includes view management, security control, and semantic integrity control. views, security constraints, and semantic integrity constraints can be defined as rules that the system automatically enforces. Views enable full logical data independence. All views can be queried as base relations, but not all view can be updated as such – Updates through […] Read more»

Distributed Database Design

Design problem • Design strategies(top-down, bottom-up) • Fragmentation (horizontal and vertical) • Allocation and replication of fragments, optimality, heuristics   Top-down approach – Designing systems from scratch – Homogeneous systems Bottom-up approach – The databases already exist at a number of sites – The databases should be connected to solve common tasks   Distribution design […] Read more»

What is Distributed Database System

A distributed database is a collection of databases which are distributed over different computers of a computer network. Advantages: Local Autonomy: permits setting and enforcing local policies regarding the use of local data (suitable for organization that are inherently decentralized). Improved Performance: The regularly used data is proximate to the users and given the parallelism […] Read more»

Distributed Database Architecture

Architecture: The architecture of a system defines its structure: – the components of the system are identified; – the function of each component is specified; – the interrelationships and interactions among the components are defined.   Motivation for standardization of DDBMS architecture: a. Homogeneous DDBMS b. Heterogeneous DDBMS   Reference Model: A conceptual framework whose […] Read more»

odoo

How to install Odoo on Ubuntu 14.04

After certain features added to OpenERP version 7, it has been renamed to Odoo in version 8. So, to install and run Odoo in Ubuntu 14.04, it did this way, First of all, i downloaded Odoo source code from GitHUB. [crayon-5a35d3a71e636770121574/] Then, i created postgresql database user as, [crayon-5a35d3a71e63f837618592/] After that, i installed the dependencies […] Read more»

linux

TCP DUMP

  [crayon-5a35d3a71e875000834687/] TCP Flags (9 bits) (aka Control bits)contains 9 1-bit flags NS (1 bit) – ECN-nonce concealment protection (experimental: see RFC 3540). CWR (1 bit) – Congestion Window Reduced (CWR) flag is set by the sending host to indicate that it received a TCP segment with the ECE flag set and had responded in […] Read more»