A database index is a data structure that improves the speed of operations in a table. Indexes can be created using one or more columns, providing the basis for both rapid random lookups and efficient ordering of access to records.
The best practices for using MySQL indexes are.
If a table is very large as a CSV, then using indexes will insert the records at the end.
The indexes create a sequence of rows of a table.
Indexes speed up certain select operations
The INSERT and UPDATE statements take more time on tables having indexes, whereas the SELECT statements become fast on those tables. The reason is that while doing insert or update, a database needs to insert or update the index values as well.
Example of MySQL indexes: If a CSV file is spread out, then indexes maintain the ordering of rows.
Let us see an example to create an index.
Create a table and indexes on a specific column.
mysql> create table IndexingDemo -> ( -> Id int, -> Name varchar(100) -> ); Query OK, 0 rows affected (0.86 sec)
The syntax to create an index on a table.
create index yourIndexName on yourTableName(column_name);
The following is the output.
mysql> create index indexName on IndexingDemo(Name); Query OK, 0 rows affected (0.75 sec) Records: 0 Duplicates: 0 Warnings: 0