indexing - What is an index in SQL? - Stack Overflow
2010年6月2日 · In SQL Server, a clustered index determines the physical order of data in a table. There can be only one clustered index per table (the clustered index IS the table). All other indexes on a table are termed non-clustered. SQL Server Index Basics. SQL Server Indexes: The Basics. SQL Server Indexes. Index Basics. Index (wiki)
What is the ideal indexing strategy for SQL Server?
2011年3月1日 · Use indexes on tables with numerous rows, on columns that are used in the WHERE clause of queries or in table joins, and on columns used in ORDER BY and GROUP BY queries. Avoid infrequently used indexes on frequently updated columns. In addition, avoid having many indexes on a table that is frequently updated.
sql - What are indexes and how can I use them to optimize queries …
2014年3月9日 · As previously stated, you can have a clustered index and multiple non-clustered indexes. In SQL 2005, you can also add additional columns to a non-clustered index, which can improve performance where a few commonly retrieved columns are included with the index but not part of the key, which eliminates a trip to the table altogether.
sql - How does database indexing work? - Stack Overflow
the second database - to which mirroring or replicating is done, the slave - would experience all the data manipulation as the first one does. with each dml-operation the indexes on that second database would experience "these indexing issues". i don't see the gain in that, where ever the indexes are needed and built for quick analysis they ...
List of all index & index columns in SQL Server DB
2009年4月20日 · Just note that if you are going to use any of the working queries in the answers here to script your indexes, you need to incorporate filter_definition column from sys.indexes table in your queries to get the filter definition of non-clustered indexes in SQL 2008+ AM –
sql - How to decide when use index on table column - Stack …
2012年8月16日 · Over-indexing in SQL Server can be worse than not having any indexes. Don't start out with too many indices to begin with! Don't start out with too many indices to begin with! Only establish good clustered PK and foreign key nonclustered indices - that's all - then observe, measure, optimize & repeat that cycle.
sql - Is there a downside to adding numerous indexes to tables?
2010年2月3日 · add indexes to columns that are foreign keys; add indexes to columns that are often used in where clauses; add indexes to columns that are used in order by clauses. Another -and perhaps better- approach, is to use SQL Profiler: use SQL Profiler to trace your application / database for a while; save the trace results
sql server - Multiple Indexes vs Multi-Column Indexes - Stack …
Indexes in SQL Server 2005/2008 – Best Practices, Part 1; Indexes in SQL Server 2005/2008 – Part 2 – Internals; One thing to note, clustered indexes should have a unique key (an identity column I would recommend) as the first column. Basically it helps your data insert at the end of the index and not cause lots of disk IO and Page splits.
What are Covering Indexes and Covered Queries in SQL Server?
A query is made into a covered query by the judicious arrangement of indexes. A covered query is often more performant than a non-covered query in part because non-clustered indexes have more rows per page than clustered indexes or heap indexes, so fewer pages need to be brought into memory in order to satisfy the query.
sql - Creating an index on a table variable - Stack Overflow
2009年5月20日 · The question is tagged SQL Server 2000 but for the benefit of people developing on the latest version I'll address that first. SQL Server 2014. In addition to the methods of adding constraint based indexes discussed below SQL Server 2014 also allows non unique indexes to be specified directly with inline syntax on table variable declarations.