Friday, December 21, 2007

Eraser - Free secure data removal tool

Eraser completely removes data from your system by overwriting it several times (sometimes referred to as shredding), which sanitizes the data, making it unrecoverable. Eraser permanently removes data from your PC, ensuring confidentiality. Similar to shredding a paper document, when you shred a file, it cannot be recovered.

Normally, when you delete a file, the operating system does not really remove the file from the disk; it only removes the reference of the file from the file system table. The file remains on the disk until another file is created over it, and even after that, it might be possible to recover data by studying the magnetic fields on the disk platter surface. Eraser works by overwriting it several times with carefully selected patterns. Follow the link to download Eraser.

Wednesday, December 19, 2007

Teradata - Table Type Specifications of Set VS Multiset

There are two different type tables in Teradata. They are SET and MULTISET. If we do not specify the table type when we creating a table in Teradata, SET is used as the default.

  • SET table - does not allow duplicate rows and Teradata will check to ensure that no two rows in a table is exactly the same
  • MULTISET table - allow duplicate rows