Indexing overview

Indexing is how Magento transforms data such as products and categories, to improve the performance of your storefront. As data changes, the transformed data must be updated or reindexed. Magento has a very sophisticated architecture that stores lots of merchant data (including catalog data, prices, users, and stores) in many database tables. To optimize storefront performance, Magento accumulates data into special tables using indexers.

For example, if you change the price of an item from $4.99 to $3.99. Magento must reindex the price change to display it on your storefront.

Without indexing, Magento would have to calculate the price of every product on the fly, taking into account shopping cart price rules, bundle pricing, discounts, tier pricing, etc. Loading the price for a product would take a long time, possibly resulting in cart abandonment.

Indexing terminology

Dictionary

Original data entered to the system. Dictionaries are organized in normal form to facilitate maintenance (updating the data).

Index

Representation of the original data for optimized reading and searching. Indexes can contain results of aggregations and various calculations. Index data can be always re-created from a dictionary using a certain algorithm.

Indexer

Object that creates an index.

Create custom indexers

Magento contains several indexers out of the box, but you might want to add your own if your customization requires data searches, which are not optimized by the Magento default indexers.

This topic provides a high level description of how indexing is implemented from a developer’s point of view, and practical advice for how to add your own indexer.

How Magento implements indexing

The following components are involved in the indexing process:

Magento_Indexer replaces the Magento 1.x Magento_Index module. Use Magento_Indexer for all new development.

Indexing types

Each index can perform the following types of reindex operations:

• Full reindex, which means rebuilding all the indexing-related database tables

  Full reindexing can be caused by a variety of things, including creating a new web store or new customer group.

  You can optionally fully reindex at any time using the command line.

• Partial reindex, which means rebuilding the database tables only for the things that changed (like changing a single product attribute or price)

The type of reindex performed in each particular case depends on the type of changes made in the dictionary or in the system. This dependency is specific for each indexer.

The following figure shows the logic for partial reindexing.

Indexer status

Depending on whether an index data is up to date, an indexer status value is one of the following:

• valid - data is synchronized, no reindex required
• invalid - the original data was changed, the index should be updated
• working - indexing is in progress

The Magento indexing mechanism uses the status value in reindex triggering process. You can check the status of an indexer in the Admin panel in System > Tools > Index Management or manually using the command line.

Indexing modes

Reindexing can be performed in two modes:

• Update on Save - index tables are updated immediately after the dictionary data is changed.
• Update by Schedule - index tables are updated by cron job according to the configured schedule.

To set these options:

1. Log in to the Magento Admin.
2. Click System > Tools > Index Management.
3. Select the checkbox next to each type of indexer to change.
4. From the Actions list, click the indexing mode.
5. Click Submit.

You can also reindex from the command line

The following figure shows an example of setting indexers to Update by Schedule:

How to reindex

You can reindex by:

• Using a cron job, which is preferred because indexing runs every minute.
• Using the magento indexer:reindex [indexer] command, which reindexes selected indexers, or all indexers, one time only.

Magento indexers

The Magento application implements the following indexers: