![]() ![]() That means index data and complete data (here onward referred to as heap data) are stored in a separate storage. PostgreSQL supports only non-clustered index. There are various data structures used for implementing indexes, some of the widely adopted by the majority of databases are B-Tree and Hash. There can be as many indexes of this category as you want on a specified table. Non-Clustered Index – Index data gets stored separately and it has a pointer to the storage where other part of data is stored.At most there can be only one index in this category for a specified table. Clustered Index – Index data gets stored along with other part of data and data gets sorted based on index key.There are primarily two types of index architecture one or more columns of the specified table). Indexes are specific to the underlying table and consist of one or more keys (i.e. Index benefit comes at the cost of additional storage space in order to write additional data. In a more database terminology, the index allows fetching page containing indexed data in a very minimal traversal as data is sorted in specific order. What is a Database Index?ĭatabase Index, as the name suggests, maintains an index to the actual data and thereby improves performance to retrieve data from the actual table. One of the well known approaches adopted by most databases is to have an index on the table. There have been many successful inventions and implementations done to achieve the same. Considering the current major use-case of a database as to retrieve data, it becomes very important that its performance is very high and It can only be achieved if data is fetched in the most efficient possible way from storage. ![]()
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