Query to check index on a table

sql

database-optimization

indexing-strategy

performance-tuning

byAnton Shumikhin·Sep 11, 2024

To find indexes on a table, use the system views particular to your database. In MySQL, type:

SELECT INDEX_NAME FROM INFORMATION_SCHEMA.STATISTICS WHERE TABLE_SCHEMA = 'YourDB' AND TABLE_NAME = 'YourTable';

For SQL Server, type:

SELECT i.name FROM sys.indexes i JOIN sys.tables t ON t.object_id = i.object_id WHERE t.name = 'YourTable';

Remember to replace YourDB and YourTable with your database and table names to fetch a list of index names for that table.

Deep Dive into Indexes

Indexes are vital for database optimization. They function like a book index, speeding up data fetching and making it more efficient. Without them, the database must sieve through the whole table to fetch the necessary data, leading to performance decline.

Index Types in a nutshell

Clustered Indexes: These dictate the physical order of the table data.
Non-Clustered Indexes: These maintain the physical location references of the data but don't affect their order.

Spotting the missing treasures

Identifying tables without indexes is as important as knowing the present ones. Use this SQL Server query to list such tables:

SELECT name FROM sys.tables WHERE OBJECTPROPERTY(object_id,'IsIndexed') = 0; -- "You can't hide from me, Index!"

Breakdown of Index Columns and Types

Taking a deep dive into the structure of indexes shows the type of data organization used:

EXEC sp_helpindex 'YourTableName'; -- "Tell me more about yourself, Index."

For a more comprehensive view of the indexed columns, it's best to look into INFORMATION_SCHEMA.KEY_COLUMN_USAGE, regardless of your database management system (DBMS).

Monitoring and Performance Tuning

To ensure efficient querying, continually review and tune indexes. Like a well-oiled machine, indexes need maintenance. Index fragmentation can occur over time, and maintenance tasks such as REORGANIZE or REBUILD in SQL Server can help.

Remember this!

Regular check-ups of your indexes and keeping them optimized are essential
Your indexing strategy must evolve as your application does for optimized performance