> Portal Navigation:
> 
> - Append `.md` to any URL under `https://dev.wix.com/docs/` to get its markdown version.
> - Pages are either content pages (article or reference text) or menu pages (a list of links to child pages).
> - To get a menu page, truncate any URL to a parent path and append `.md` (e.g. `https://dev.wix.com/docs/sdk.md`, `https://dev.wix.com/docs/sdk/core-modules.md`).
> - Top-level index of all portals: https://dev.wix.com/docs/llms.txt
> - Full concatenated docs: https://dev.wix.com/docs/llms-full.txt

## Resource: Index Types

## Article: Index Types

## Article Link: https://dev.wix.com/docs/api-reference/business-solutions/cms/collection-management/indexes/index-types.md

## Article Content:

# Index Types

The Indexes API allows you to create 2 kinds of indexes:
- A regular index accelerates queries for up to 3 fields in a collection.
- A unique index enforces unique values for 1 field in a collection and also functions as a regular index for that field.

## Regular indexes

You can create up to 3 regular indexes for each collection. Most regular indexes can be created for up to 3 fields, with each field sorted either in ascending or descending order.

For example, consider a database containing information about many different products. Each data item contains `productName`, `category`, and `price` fields.

An index for the `productName` field in ascending order accelerates queries based on the `productName` field. Instead of searching through all of the data entries until one is found with the desired name, the index enables the query to jump based on alphabetical ordering.

An index for the `category` and `price` fields speeds up queries that include these fields. A general query for all products in a particular `category`, ordered by `price`, doesn't need to iterate through the entire collection to find all items in the specified `category`. The results of that search will already be ordered by `price` and thus won't need to be sorted again. For a large collection, this can save a significant amount of time.

## Unique indexes

A unique index enforces unique values for an indexed field. You can create 1 unique index for each collection, in addition to its regular indexes.

A unique index can only have 1 field. For that field, it functions like a regular index. For example, a unique index for the `productName` field in a product database enables faster queries based on that field.

In addition, a unique index enforces unique values for the indexed field in all data items across the collection. So if you created a unique index for the `productName` field, you won't be able to create more than 1 item with any given `productName` value.

## Index limits

Basic website plans and most premium plans support 4 indexes, 3 regular and 1 unique. Certain tier premium plans support 15 indexes, 5 regular (up to 3 fields),  2 unique, and 8 additional regular fields (1 field). If a Wix user needs more indexes than their current plan offers, they can [upgrade a site](https://www.wix.com/upgrade/website).

## Index sources

Indexes can be created in 3 ways:
+ **System:** Automatically created by Wix for all collections. System indexes are created for essential attributes, such as ID and creation date. You can't delete them and they don't count towards the index limit.
+ **User:** Manually created by a Wix user via the API or in the dashboard. They count towards the index limit.
+ **Automatic:** Automatically created by Wix based on a Wix user's queries. For large collections, Wix identifies slow-running queries and creates indexes to improve performance. They don't count towards the index limit.

> **Notes:** 
> + If you create a manual index with the same fields as an automatic index, the manual index takes priority and the automatic index is automatically removed.
> + Automatic indexes may be removed by the system if they're no longer necessary for query optimization. To keep an automatic index permanently, create an identical index manually.