FerretDB · AlekSi · Jun 2, 2023 · May 19, 2023 · May 19, 2023 · May 23, 2023
diff --git a/website/docs/aggregation operations/_category_.yml b/website/docs/aggregation operations/_category_.yml
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+---
+label: Aggregation operations
+position: 6
+link:
+  description: >
+    This section details aggregation operations in FerretDB, including aggregation commands, stages, and operators
diff --git a/website/docs/aggregation operations/aggregation-pipeline-and-commands.md b/website/docs/aggregation operations/aggregation-pipeline-and-commands.md
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+---
+sidebar_position: 1
+slug: /aggregation-pipeline-and-commands/
+---
+
+# Aggregation pipeline and commands
+
+Aggregation operations involve performing various operations on a large number of data records, such as data grouping, sorting, restructuring, or modifying.
+These operations pass through one or more stages, which make up a pipeline.
+
+![aggregation stages](../../static/img/docs/aggregation-stages.jpg)
+
+Each stage acts upon the returned documents of the previous stage, starting with the input documents.
+As shown above, the documents pass through the pipeline with the result of the previous stage acting as input for the next stage, going from `$count` => `$group` => `$sort` stage.
+
+In the pipeline, a complex query is broken down into separate stages where the record goes through a series of transformations until it finally produces the desired result.
+
+This section of the documentation will focus on [aggregation commands](#aggregation-commands), [aggregation stages](../aggregation-stages), and aggregation operators.
+
+## Aggregation commands
+
+Aggregation commands are top-level commands used for aggregating data, and are typically either via the `aggregate`, `count`, or `distinct` command.
+
+:::note
+Aggregation pipeline stages are only available for the `aggregate` command, and not for the `count` or `distinct` command.
+:::
+
+### `aggregate`
+
+The `aggregate` command is used for performing aggregation operations on a collection.
+It lets you specify aggregation operations in a pipeline consisting of one or more stages and operators for transforming and analyzing data, such as grouping, filtering, sorting, projecting, and calculating aggregates.
+
+```js
+// Aggregation pipeline to perform aggregation operations on a collection
+db.collection.aggregate([
+  // Stage 1: Matching documents based on a specific field and value
+  { $match: { field: value } },
+  // Stage 2: Grouping documents by the "category" field and calculating the sum of the "quantity" field
+  { $group: { _id: "$category", total: { $sum: "$quantity" } } }
+])
+```
+
+### `count`
+
+The `count` command displays the number of documents returned by a specific query.
+Returns a `count` as the result.
+
+```js
+db.collection.count({ field: value })
+```
+
+### `distinct`
+
+The `distinct` command returns unique values for a specified field in a collection.
+Returns an array of distinct values for the specified field.
+
+```js
+db.collection.distinct("field")
+```
diff --git a/website/docs/aggregation operations/aggregation-stages.md b/website/docs/aggregation operations/aggregation-stages.md
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+---
+sidebar_position: 2
+slug: /aggregation-stages/
+---
+
+# Aggregation stages
+
+Aggregation stages are a series of one or more processes in a pipeline that acts upon the returned result of the previous stage, starting with the input documents.
+
+| Supported aggregation stages | Description                                                                                           |
+| ---------------------------- | ----------------------------------------------------------------------------------------------------- |
+| `$count`                     | Returns the count of all matched documents in a specified query                                       |
+| `$group`                     | Groups documents based on specific value or expression and returns a single document for each group   |
+| `$limit`                     | Passes a limit on the documents passed to the next stage                                              |
+| `$match`                     | Acts as a `find` operation by only returning documents that match a specified query to the next stage |
+| `$skip`                      | Skips a specified `n` number of documents and passes the rest to the next stage                       |
+| `$sort`                      | Sorts and returns all the documents based on a specified order                                        |
+| `$unwind`                    | Deconstructs and returns a document for every element in an array field                               |
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 label: Configuration
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+position: 9
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   type: generated-index
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 label: Contributing to FerretDB
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   type: generated-index
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 slug: /diff/ # referenced in README.md and beacon
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 # Indexes

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 hide_table_of_contents: true
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 label: Reference
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+position: 13
 link:
   type: generated-index
   description: >

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-sidebar_position: 11
+sidebar_position: 12
 slug: /security/ # referenced in README.md
 description: TLS and authentication
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-sidebar_position: 10
+sidebar_position: 11
 slug: /telemetry/ # referenced in many places; must not change
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