How to CREATE INDEX in MariaDB

How do I create indexes in MariaDB to speed up queries?

CREATE INDEX speeds up data retrieval by building an auxiliary data structure that allows MariaDB to locate rows without scanning the whole table.

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Description

Example H2

Example H3

Why use CREATE INDEX in MariaDB?

CREATE INDEX cuts query time by letting MariaDB seek rows directly rather than performing full table scans, especially on large ecommerce tables such as Orders or OrderItems.

What is the basic CREATE INDEX syntax?

The minimal pattern is CREATE [UNIQUE|FULLTEXT|SPATIAL] INDEX index_name ON table_name (column_list). Options control index type and storage engine behavior.

How do I choose columns to index?

Pick columns used in WHERE, JOIN, and ORDER BY clauses.Composite indexes should follow column order that matches the most selective leading columns.

Can I create an index on multiple columns?

Yes.Composite indexes accelerate queries that filter or sort by the same ordered set of columns, e.g., (customer_id, order_date) in Orders.

Example — speeding up recent orders lookup

CREATE INDEX idx_orders_customer_date ON Orders (customer_id, order_date);

This index benefits queries like SELECT * FROM Orders WHERE customer_id = 5 AND order_date > '2024-01-01';

How do I create a UNIQUE index?

UNIQUE prevents duplicate values, useful for enforcing business rules like unique emails.

CREATE UNIQUE INDEX idx_customers_email ON Customers (email);

What about indexing JSON or virtual columns?

MariaDB 10.2+ lets you index virtual columns extracted from JSON to speed up attribute searches while keeping raw JSON data intact.

Best practices for CREATE INDEX

1) Index only what you query.2) Prefer single or small composite indexes. 3) Re-evaluate after workload changes using EXPLAIN and slow query logs.

How do I remove or rename an index?

Drop with DROP INDEX index_name ON table; or rename via ALTER TABLE table RENAME INDEX old TO new; (MariaDB 10.5+).

Performance tip: cover queries

If all referenced columns are inside one composite index, MariaDB can use the index alone (covering), avoiding extra table reads and boosting speed.

Why How to CREATE INDEX in MariaDB is important

How to CREATE INDEX in MariaDB Example Usage


-- Speed up product search by name prefix and current stock level
CREATE INDEX idx_products_name_stock
ON Products (name(20), stock);

-- Composite index for order item lookups by order and product
CREATE INDEX idx_orderitems_order_product
ON OrderItems (order_id, product_id);

How to CREATE INDEX in MariaDB Syntax


CREATE [UNIQUE | FULLTEXT | SPATIAL] INDEX index_name
    [USING {BTREE | HASH}]
    ON table_name (col1 [ASC|DESC] [, col2 ...])
    [COMMENT 'text']
    [ALGORITHM {DEFAULT|INPLACE|COPY}]
    [LOCK {DEFAULT|NONE|SHARED|EXCLUSIVE}];

Common Mistakes

Indexing every column: adds write overhead and bloats storage. Fix by indexing only columns frequently used in WHERE, JOIN, or ORDER BY clauses.
Ignoring column order in composite indexes: wrong order prevents use of index. Place the most selective column first to maximize efficiency.