opensearch-docs-cn/_opensearch/rest-api/create-index.md

---
layout: default
title: Create index
parent: REST API reference
nav_order: 3
---

# Create index
Introduced 1.0
{: .label .label-purple }

While you can create an index by using a document as a base, you can also just create an empty index for use later.

## Example

The following example demonstrates how to create an index with a non-default number of primary and replica shards, specifies that `age` is of type `integer`, and assigns a `sample-alias1` alias to the index.

```json
PUT /sample-index1

{
  "settings": {
    "index": {
      "number_of_shards": 2,
      "number_of_replicas": 1
    }
  },
  "mappings": {
    "properties": {
      "age": {
        "type": "integer"
      }
    }
  },
  "aliases": {
    "sample-alias1": {}
  }
}
```

## Path and HTTP methods

```
PUT <index-name>
```

## Index naming restrictions

OpenSearch indices have the following naming restrictions:

- All letters must be lowercase.
- Index names can't begin with underscores (`_`) or hyphens (`-`).
- Index names can't contain spaces, commas, or the following characters:

  `:`, `"`, `*`, `+`, `/`, `\`, `|`, `?`, `#`, `>`, or `<`

## URL parameters

You can include the following URL parameters in your request. All parameters are optional.

Parameter | Type | Description
:--- | :--- | :---
include_type_name | Boolean | If `true`, the request expects a type in the body of mappings. Because OpenSearch indices all have a type of `_doc`, we recommend that this parameter is left as the default of `false.`
wait_for_active_shards | String | Specifies the number of active shards that must be available before OpenSearch processes the request. Default is 1 (only the primary shard). Set to `all` or a positive integer. Values greater than 1 require replicas. For example, if you specify a value of 3, the index must have two replicas distributed across two additional nodes for the request to succeed.
master_timeout | Time | How long to wait for a connection to the master node. Default is `30s`.
timeout | Time | How long to wait for the request to return. Default is `30s`.

## Request body

As part of your request, you can supply parameters in your request's body that specify index settings, mappings, and [aliases]({{site.url}}{{site.baseurl}}/opensearch/index-alias/) for your newly created index. The following sections provide more information about index settings and mappings.


### Index settings

Index settings are separated into two varieties: static index settings and dynamic index settings. Static index settings are settings that you specify at index creation and can't change later. You can change dynamic settings at any time, including at index creation.

#### Static index settings

Setting | Description
:--- | :---
index.number_of_shards | The number of primary shards in the index. Default is 1.
index.number_of_routing_shards | The number of routing shards used to split an index.
index.shard.check_on_startup | Whether the index's shards should be checked for corruption. Available options are `false` (do not check for corruption), `checksum` (check for physical corruption), and `true` (check for both physical and logical corruption). Default is `false`.
index.codec | The compression type to use to compress stored data. Available values are `best_compression` and `default`.
index.routing_partition_size | The number of shards a custom routing value can go to. Routing helps an imbalanced cluster by relocating values to a subset of shards rather than just a single shard. To enable, set this value to greater than 1 but less than `index.number_of_shards`. Default is 1.
index.soft_deletes_enabled | Whether to retain a history of operations performed on the index.
index.soft_deletes.retention_lease.period | The maximum amount of time to retain a shard's history of operations. Default is `12h`.
index.load_fixed_bitset_filters_eagerly | Indicates whether cached filters should be pre-loaded for nested queries. Available options are `true` and `false`. Default is `true`.
index.hidden | Whether the index should be hidden. Hidden indices are not returned as part of queries that have wildcards. Available options are `true` and `false`. Default is `false`.

#### Dynamic index Settings

Setting | Description
:--- | :---
index.number_of_replicas | The number of replica shards each primary shard should have. For example, if you have 4 primary shards and set `index.number_of_replicas` to 3, the index has 12 replica shards. Default is 1.
index.auto_expand_replicas | Automatically expands the number of replicas based on the amount of data nodes in the cluster. Specify a lower bound and upper limit (for example, 0-9), or `all` for the upper limit. For example, if you have 5 data nodes and set `index.auto_expand_replicas` to 0-3, then the cluster does not autoamtically add another replica shard. However, if you set this value to `0-all` and add 2 more nodes for a total of 7, the cluster will expand to now have 6 replica shards. Default is disabled.
index.search.idle.after | Amount of time a shard should wait for a search or get request until it goes idle. Default is `30s`.
index.refresh_interval | How often the index should refresh, which publishes its most recent changes and makes them available for searching. Can be set to `-1` to disable refreshing. Default is `1s`.
index.max_result_window | The maximum value of `from` + `size` for searches to the index. `from` is the starting index to search from, and `size` is the amount of results to return. Default: 10000.
index.max_inner_result_window | The maximum value of `from` + `size` for inner hits definitions and top hits aggregations to the index. `from` is the starting index to search from, and `size` is the amount of top hits to return. Default is 100.
index.max_rescore_window | The maximum value of `window_size` for rescore requests to the index. Rescore requests reorder the index's documents and return a new score, which can be more precise. Default is the same as index.max_inner_result_window or 10000 by default.
index.max_docvalue_fields_search | Maximum amount of `docvalue_fields` allowed in a query. Default is 100.
index.max_script_fields | Maximum amount of `script_fields` allowed in a query. Default is 32.
index.max_ngram_diff | Maximum allowed difference between `min_gram` and `max_gram` values for `NGramTokenizer` and `NGramTokenFilter`. Default is 1.
index.max_shingle_diff | Maximum allowed difference between `max_shingle_size` and `min_shingle_size` for the `shingle` token filter. Default is 3.
index.max_refresh_listeners | Maximum amount of refresh listeners available on the index's shards.
index.analyze.max_token_count | Maximum amount of tokens that can return from the `_analyze` API operation. Default is 10000.
index.highlight.max_analyzed_offset | The maximum amount of characters that will be analyzed in a highlight request. Default is 1000000.
index.max_terms_count | The maximum amount of terms that can be used in a terms query. Default is 65536.
index.max_regex_length | The maximum character length of regex that can be in a regexp query. Default is 1000.
index.query.default_field | A field or list of fields that OpenSearch uses in queries in case a field isn't specified in the parameters.
index.routing.allocation.enable | Specifies options for the index's shard allocation. Available options are `all` (allow shard allocation for all shards), `primaries` (allow shard allocation only for primary shards), `new_primaries` (allow shard allocaiton only for new primary shards), and `none` (do not allow shard allocation). Default is `all`.
index.routing.rebalance.enable | Enables shard rebalancing for the index. Available options are `all` (allow shard rebalancing for all shards), `primaries`, (allow shard rebalancing only for primary shards), `replicas` (allow shard rebalancing only for replicas), and `none` (do not allow shard rebalancing). Default is `all`.
index.gc_deletes | Amount of time to retain a deleted document's version number. Default is `60s`.
index.default_pipeline | The default ingest node pipeline for the index. If the default pipeline is set and the pipeline does not exist, then index requests fail. The pipeline name `_none` specifies that the index does not have an ingest pipeline.
index.final_pipeline | The final ingest node pipeline for the index. If the final pipeline is set and the pipeline does not exist, then index requests fail. The pipeline name `_none` specifies that the index does not have an ingest pipeline.

### Mappings

Mappings define how a documents and its fields are stored and indexed. If you're just starting to build out your cluster and data, you may not know exactly how your data should be stored. In those cases, you can use dynamic mappings, which tell OpenSearch to dynamically add data and their fields. However, if you know exactly what types your data fall under and want to enforce that standard, then you can use explicit mappings.

For example, if you want to indicate that `year` should be of type `text` instead of an `integer`, and `age` should be an `integer`, you can do so with explicit mappings. Using dynamic mapping, OpenSearch might interpret both `year` and `age` as integers.

#### Dynamic mapping types

Type | Description
:--- | :---
null | A `null` field can't be indexed or searched. When a field is set to null, OpenSearch behaves as if that field has no values.
boolean | OpenSearch accepts `true` and `false` as boolean values. An empty string is equal to `false.`
float | A single-precision 32-bit floating point number.
double | A double-precision 64-bit floating point number.
integer | A signed 32-bit number.
object | Objects are standard JSON objects, which can have fields and mappings of their own. For example, a `movies` object can have additional properties such as `title`, `year`, and `director`.
array | Arrays in OpenSearch can only store values of one type, such as an array of just integers or strings. Empty arrays are treated as though they are fields with no values.
text | A string sequence of characters that represent full-text values.
keyword | A string sequence of structured characters, such as an email or ZIP code.
date detection string | Enabled by default, if new string fields match a date's format, then the string is processed as a `date` field. For example, `date: "2012/03/11"` is processed as a date.
numeric detection string | If disabled, OpenSearch may automatically process numeric values as strings when they should be processed as numbers. When enabled, OpenSearch can process strings into `long`, `integer`, `short`, `byte`, `double`, `float`, `half_float`, `scaled_float`, `unsigned_long`. Default is disabled.

#### Explicit mapping

If you know exactly what your data's typings need to be, you can specify them in your request body when creating your index.

```json
{
  "mappings": {
    "properties": {
      "year":    { "type" : "text" },
      "age":     { "type" : "integer" },
      "director":{ "type" : "text" }
    }
  }
}
```

## Response
```json
{
    "acknowledged": true,
    "shards_acknowledged": true,
    "index": "sample-index1"
}
```