SQLite CREATE INDEX is a SQL command that creates an index on one or more columns of a table in a SQLite database. An index is a data structure that allows for faster retrieval of data from a table by storing a copy of a portion of the table’s data in a smaller, more easily searchable format. Indexes are typically used to improve the performance of queries that involve searching or sorting large amounts of data.
When to use index?
When querying large tables with frequent searches on specific columns.
When sorting the data in a specific column of a large table.
When joining multiple tables on a specific column.
Advantages of using SQLite CREATE INDEX
Faster search and retrieval of data from a table.
Improved performance of queries that involve searching or sorting large amounts of data.
Reduced disk I/O and CPU usage, which can lead to improved application performance.
Indexes can be used to enforce unique constraints, which can help to ensure data integrity.
Disadvantages of using SQLite CREATE INDEX
Indexes can take up disk space and can slow down write operations.
Creating and updating indexes can take time and resources, especially on large tables.
Too many indexes on a table can cause the database to slow down and use more disk space.
Syntax
CREATE INDEX index_name ON table_name (column_name);
Example
CREATE INDEX myindex ON mytable (mycolumn);
This would create an index called “myindex” on the column “mycolumn” in the table “mytable”.
The SQLite CREATE INDEX statement creates an index on a single column of a table. If you want to create an index on multiple columns of a table, you need to use the SQLite CREATE INDEX statement as follows:
CREATE INDEX index_name ON table_name (column1, column2, column3);
In the above SQLite CREATE INDEX syntax, the index_name is the name of the index to be created. The table_name is the name of the table on which the index is to be created. The column1, column2 and column3 are the names of the columns on which the index is to be created. SQLite allows indexes to be created on multiple columns.
In general, SQLite CREATE INDEX should be used judiciously, and indexes should be created only when they are needed to improve the performance of queries. Indexes should be periodically reviewed and removed if they are no longer necessary or if they are causing performance issues.