Mysql alter index

How do I drop Index in MySQL? How can I rename all the indexes in MySQL? Is it possible to make Index on Alias column in MySQL? In order to drop an index that is not a primary key, the name of index should be specified.

ALTER TABLE to rename an index (or key, which is a synonym). SQL Server: how to write an alter. The following code block is an example to add index in an existing table. Full-text index implementation is storage engine dependent.

Spatial indexes are implemented as R-tree indexes. CREATE INDEX enables you to add indexes to existing tables. Indexes are used to retrieve data from the database more quickly than otherwise. CREATE UNIQUE NONCLUSTERED INDEX (indexname) ON dbo.

ALTER INDEX PK_Employee_EmployeeID ON HumanResources. This algorithm allows for concurrent data manipulation statements. Note that the ALGORITHM clause is optional. Any help would be appreciated. To date ( mysql .18) there is no suitable function inside mysql to re-create indexes.

Sometimes after a table has been created in a database, we find that it is advantageous to add an index to that table to speed up queries involving this table (to understand what an index is and how it can help speed up SQL queries, please see the INDEX section). Create UNIQUE INDEX with index type. An index is a performance-tuning method of allowing faster retrieval of records. By default, indexes are visible.

You must have EXECUTE privileges on the index type and its implementation type. The spatial index to be altered is not marked in-progress. It allows renaming multiple tables in one statement. This can be useful when replacing a table with a new pre-populated version: RENAME.

You can generate index in such a way that the index is created without checking it the index exists ahead of time. MySQL offers two ways to rename tables. I witnessed over 4sessions trying to insert into the table and waiting over minute in updating event.

This is a really non online way of doing online DDL. Having the right indexes on tables are critical to making your queries performant, especially when your data grows. Not having the needed indexes will typically result in high CPU usage in your database server, slow response times, and ultimately unhappy users. Creating a dropping a clustered index , the old technique, is expensive since it has to update all the non-clustered indexes with the correct pointer, twice!

When you create a clustered index , it updates all the non-clustered indexes with a pointer to the clustering key. But because PRIMARY is a reserved keywor backticks are required when you use it in the DROP INDEX command. Thanks for your fast answer, So I try with version 5. I retry the test and I find that the problem come with sql-mode=TRADITIONAL (in my.cnf).

If another connection is using the table, a metadata lock is active, and this statement will wait until the lock is released.