SQL and Indexes
- Details
- Category: SQL Tips
- Published: Thursday, 28 April 2016 21:55
- Written by Super User
- Hits: 1155
SQL (Structured Query Language) is the language that almost every DBMS system knows and has its functionality built around with some variations. The language has been around since 1970 and became a DBMS Query Standard (ANSI SQL) in 1986 and since then used in almost every DBMS system available.
An index is a data structure, often a tree structure, that improves the searching and retrieval speed of a data in a table. The index is in fact a copy of some part or all ( called full index) of the tables data. Indexes are created using one or more columns of a table and organized to make random access lookups and sequential accees lookups as efficient as possible.
The sql query that is built do retrieve data is often not designed the optimal way, either by the user or query-builiding tools, or tables that is queried lacks good and vital indexes to gain optimal peformance.