{"id":827,"date":"2026-08-13T06:56:43","date_gmt":"2026-08-13T06:56:43","guid":{"rendered":"https:\/\/online.jnujaipur.ac.in\/blogs\/?p=827"},"modified":"2026-08-14T07:55:36","modified_gmt":"2026-08-14T07:55:36","slug":"types-of-indexes-in-sql-server","status":"publish","type":"post","link":"https:\/\/online.jnujaipur.ac.in\/blogs\/types-of-indexes-in-sql-server\/","title":{"rendered":"Types of Indexes in SQL Server: All 12 Types Explained with Syntax (2026)"},"content":{"rendered":"

SQL Server supports twelve distinct index types: clustered, non-clustered, unique, filtered, clustered columnstore, non-clustered column store, hash, memory-optimized non-clustered, XML, spatial, full-text and vector. Each one solves a different retrieval problem. Choosing correctly is the difference between a query that returns in eight milliseconds and the same query returning in eight seconds.<\/span><\/p>\n

Most articles on the types of indexes in SQL Server stop at six. They list clustered, non-clustered, unique, columnstore, filtered and full-text, then close with a paragraph about how indexes are like the index in a book. That was a complete answer in 2019. It is not a complete answer now. SQL Server 2025, released to general availability on 18 November 2025, added a native vector index built on Microsoft\u2019s DiskANN algorithm \u2014 the index type that makes semantic search and retrieval-augmented generation possible inside the database engine itself. Any guide that omits it is describing a product that no longer exists.<\/span><\/p>\n

This guide covers all twelve, with working T-SQL syntax, the workload each one is designed for, the trade-off each one imposes, and a decision matrix you can apply to a real schema. It is written for BCA, MCA and Diploma in Data Science students who need this for a semester examination, and for working professionals who need it for a technical interview on Monday morning.<\/span><\/p>\n

All 12 types of indexes in SQL Server at a glance<\/b><\/h2>\n

Before the detail, here is the complete taxonomy in one view. Bookmark this table \u2014 it is the answer to the exam question “list the types of indexes in SQL Server.”
\n<\/span><\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
#<\/th>\nIndex Type<\/th>\nStorage Model<\/th>\nPrimary Use Case<\/th>\nLimit per Table<\/th>\n<\/tr>\n<\/thead>\n
1<\/td>\nClustered<\/td>\nRowstore B-tree<\/td>\nRange queries, ORDER BY, physical row order<\/td>\nExactly 1<\/td>\n<\/tr>\n
2<\/td>\nNon-clustered<\/td>\nRowstore B-tree<\/td>\nPoint lookups on non-key columns<\/td>\nUp to 999<\/td>\n<\/tr>\n
3<\/td>\nUnique<\/td>\nRowstore B-tree<\/td>\nEnforcing uniqueness plus fast lookup<\/td>\nMultiple<\/td>\n<\/tr>\n
4<\/td>\nFiltered<\/td>\nRowstore B-tree<\/td>\nSkewed columns, sparse or status subsets<\/td>\nMultiple<\/td>\n<\/tr>\n
5<\/td>\nClustered columnstore<\/td>\nColumn segments<\/td>\nData warehouse fact tables<\/td>\nExactly 1<\/td>\n<\/tr>\n
6<\/td>\nNon-clustered
\ncolumnstore<\/td>\n		Column segments<\/td>\nReal-time analytics over OLTP tables<\/td>\nExactly 1<\/td>\n<\/tr>\n
7<\/td>\nHash<\/td>\nIn-memory
\nbuckets<\/td>\n		Equality-only lookups, In-Memory OLTP<\/td>\nMultiple<\/td>\n<\/tr>\n
8<\/td>\nMemory-optimized
\nnon-clustered<\/td>\n		In-memory
\nBw-tree<\/td>\n		Range scans on memory-optimized tables<\/td>\nMultiple<\/td>\n<\/tr>\n
9<\/td>\nXML<\/td>\nShredded node
\ntable<\/td>\n		XQuery over XML columns<\/td>\n1 primary + 3
\nsecondary<\/td>\n<\/tr>\n
10<\/td>\nSpatial<\/td>\nTessellated grid<\/td>\nGeometry and geography proximity queries<\/td>\nMultiple<\/td>\n<\/tr>\n
11<\/td>\nFull-text<\/td>\nInverted word
\nindex<\/td>\n		Linguistic search with CONTAINS \/ FREETEXT<\/td>\nExactly 1<\/td>\n<\/tr>\n
12<\/td>\nVector (SQL Server
\n2025)<\/td>\n		DiskANN graph<\/td>\nSemantic search, RAG, nearest-neighbour<\/td>\nMultiple<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Know More: <\/span>Best BCA Online Colleges in India (2026): The 7-Point Checklist to Choose the Right One<\/a><\/strong><\/p>\n

What is an index in SQL Server, and why does it change everything?<\/b><\/h2>\n

An index is a separate, ordered data structure that lets the SQL Server query optimizer locate rows without reading every page in the table.<\/span><\/p>\n

Without an index, SQL Server performs a <\/span>table scan: it reads all 8 KB data pages belonging to the table and discards the rows that do not match. On a 50-million-row orders table, that is millions of page reads for a query that returns four rows.<\/p>\n

With a suitable index, SQL Server performs an index seek: it navigates a B-tree from the root page down through intermediate levels to the exact leaf page holding the matching rows. Three or four page reads instead of millions.<\/span><\/p>\n

A table with no clustered index is called a <\/span>heap. Rows sit in no guaranteed order, and the only way to find anything is to scan. A table with a clustered index is called a clustered table, and its rows are stored in the logical order of the index key.<\/p>\n

Two terms you must be able to distinguish in any interview:<\/p>\n