Desktop Search - Technologies

Technologies

Most desktop search engines build and maintain an index database to achieve reasonable performance when searching several gigabytes of data. Indexing usually takes place when the computer is idle and most search applications can be set to suspend it if a portable computer is running on batteries, in order to save power. (One exception would be tools which only search filenames — not the files' contents — e.g. Search Everything does this for NTFS volumes only, enabling it to build its index from scratch in just a few seconds.)

Desktop search tools typically collect three types of information about files:

• file and folder names
• metadata, such as titles, authors, comments in file types such as MP3, PDF and JPEG
• file content (for supported types of documents only)

Besides programs that use indexing, there are many programs that open and search files on the fly. Their disadvantage is that they can only feasibly search a certain folder tree, not the entire computer, but their great advantage is that they do not burden the computer's resources with indexing. Also, they are less likely to give incorrect results due to the index lagging behind.

To search effectively within documents, the tools need to be able to parse many different types of documents. This is achieved by using filters that interpret selected file formats. For example, a Microsoft Office Filter might be used to search inside Microsoft Office documents.

Long-term goals for desktop search include the ability to search the contents of image files, sound files and video by context.

The sector attracted considerable attention from the struggle between Microsoft and Google. According to market analysts, both companies are attempting to leverage their monopolies (of web browsers and search engines, respectively) to strengthen their dominance. Due to Google's complaint that users of Windows Vista can not choose any competitor's desktop search program over the built-in one, an agreement was reached between US Justice Department and Microsoft that Windows Vista Service Pack 1 would enable users to choose between the built-in and other desktop search programs, and select which one is to be the default.