What are Indexes

Indexes are database data structures that improve the speed of data retrieval operations on tables by organizing and sorting the data based on specific columns.

They function similarly to the index in a book, which enables readers to quickly locate relevant information without reading through the entire text.

In databases, indexes serve a similar purpose by allowing the database to swiftly locate specific rows within a table based on the indexed columns, thus significantly reducing the time required for query execution.

Key points

• Structure: Indexes consist of keys built from one or more columns in a table, along with pointers to the corresponding rows in the table;
• Speed: By using indexes, the database can quickly locate rows based on the values in the indexed columns, reducing the need for full table scans and improving query performance;
• Types: There are different types of indexes, including B-tree indexes, hash indexes, and bitmap indexes, each suitable for different types of queries and data;
• Maintenance: Indexes need to be maintained as data in the table changes. This includes updates, inserts, and deletes, which may require the index to be updated or rebuilt;
• Trade-offs: While indexes improve query performance, they also have trade-offs. They consume additional storage space and may slow down data modification operations due to the overhead of index maintenance.