Can one table have multiple indexes?

Can one table have multiple indexes?

It is possible for an index to have two or more columns. Multi column indexes are also known as compound or concatenated indexes. Let us look at a query that could use two different indexes on the table based on the WHERE clause restrictions. We first create these indexes.

Can SQL Server use multiple indexes?

SQL Server may decide to seek both indexes and join the result. Yes, two indexes may be used when 1st WHERE condition is covered by Index1 and 2nd WHERE condition is covered by Index2. In this case SQL may decide to use Index Seek for both indexes and then do Hash Match (Inner Join).

How many indexes can be created on a column in Oracle?

You can also create an index for a cluster. You can create a composite index on multiple columns up to a maximum of 32 columns.

Which server can join the indexes when only multiple indexes combined can cover the query?

Discussion Forum

Can a two column index be used as a single column index?

A two column index can also be used as a single column index, but only for the column listed first. Sometimes it can be useful to have an index on (A,B) and another index on (B).

Is it possible to use multiple indexes in MySQL?

Yes, MySQL can use multiple index for a single query. The optimizer will determine which indexes will benefit the query. You can use EXPLAIN to obtain information about how MySQL executes a statement. You can add or ignore indexes using hints like so:

Can a query have more than one index?

Classically, MySQL can use one index per table reference in a given query. However, in more recent versions of MySQL, an operation called an index merge can take place and allow MySQL to use more than one index per table. http://openquery.com/blog/mysql-50-index-merge-using-multiple-indexes.