Indexes
Introduction:
- An index is a data structure that improves the speed of operations in a table.
- We can create an index using one or more columns, providing the basis for both rapid random lookups and efficient ordering of access to records.
- Without an index, SQL must begin with the first row and then read the entire table to find the relevant rows.
- The larger the table, the more the cost. If a table has an index for the column in question, SQL can quickly determine the position to seek to in the middle of the data file without having to look at all the data.
- If a table has 10000 rows, this is the least 1000 times faster than reading sequentially. Learn More Visit http://blog.devitpl.com/advanced-sql-indexing-stored-procedures-and-triggers/
