add truncate token filter docs #8450 (#8462)

* add truncate token filter docs #8450 Signed-off-by: Anton Rubin <[email protected]> * updating parameter table Signed-off-by: Anton Rubin <[email protected]> * Doc review Signed-off-by: Fanit Kolchina <[email protected]> * Apply suggestions from code review Co-authored-by: Nathan Bower <[email protected]> Signed-off-by: kolchfa-aws <[email protected]> --------- Signed-off-by: Anton Rubin <[email protected]> Signed-off-by: Fanit Kolchina <[email protected]> Signed-off-by: kolchfa-aws <[email protected]> Co-authored-by: Fanit Kolchina <[email protected]> Co-authored-by: kolchfa-aws <[email protected]> Co-authored-by: Nathan Bower <[email protected]> (cherry picked from commit 0ab0751) Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
opensearch-project · Dec 3, 2024 · ef1e564 · ef1e564
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diff --git a/_analyzers/token-filters/index.md b/_analyzers/token-filters/index.md
@@ -60,7 +60,7 @@ Token filter | Underlying Lucene token filter|  Description
 [`synonym`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/synonym/) | N/A | Supplies a synonym list for the analysis process. The synonym list is provided using a configuration file.
 [`synonym_graph`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/synonym-graph/) | N/A | Supplies a synonym list, including multiword synonyms, for the analysis process.
 [`trim`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/trim/) | [TrimFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/TrimFilter.html) | Trims leading and trailing white space characters from each token in a stream. 
-`truncate` | [TruncateTokenFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/TruncateTokenFilter.html) | Truncates tokens whose length exceeds the specified character limit. 
+[`truncate`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/truncate/) | [TruncateTokenFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/TruncateTokenFilter.html) | Truncates tokens with lengths exceeding the specified character limit. 
 `unique` | N/A | Ensures each token is unique by removing duplicate tokens from a stream. 
 [`uppercase`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/uppercase/) | [UpperCaseFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/core/LowerCaseFilter.html) | Converts tokens to uppercase. 
 `word_delimiter` | [WordDelimiterFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/WordDelimiterFilter.html) | Splits tokens at non-alphanumeric characters and performs normalization based on the specified rules. 

diff --git a/_analyzers/token-filters/truncate.md b/_analyzers/token-filters/truncate.md
@@ -0,0 +1,107 @@
+---
+layout: default
+title: Truncate
+parent: Token filters
+nav_order: 440
+---
+
+# Truncate token filter
+
+The `truncate` token filter is used to shorten tokens exceeding a specified length. It trims tokens to a maximum number of characters, ensuring that tokens exceeding this limit are truncated. 
+
+## Parameters
+
+The `truncate` token filter can be configured with the following parameter.
+
+Parameter | Required/Optional | Data type | Description
+:--- | :--- | :--- | :--- 
+`length` | Optional | Integer | Specifies the maximum length of the generated token. Default is `10`.
+
+## Example
+
+The following example request creates a new index named `truncate_example` and configures an analyzer with a `truncate` filter:
+
+```json
+PUT /truncate_example
+{
+  "settings": {
+    "analysis": {
+      "filter": {
+        "truncate_filter": {
+          "type": "truncate",
+          "length": 5
+        }
+      },
+      "analyzer": {
+        "truncate_analyzer": {
+          "type": "custom",
+          "tokenizer": "standard",
+          "filter": [
+            "lowercase",
+            "truncate_filter"
+          ]
+        }
+      }
+    }
+  }
+}
+```
+{% include copy-curl.html %}
+
+## Generated tokens
+
+Use the following request to examine the tokens generated using the analyzer:
+
+```json
+GET /truncate_example/_analyze
+{
+  "analyzer": "truncate_analyzer",
+  "text": "OpenSearch is powerful and scalable"
+}
+
+```
+{% include copy-curl.html %}
+
+The response contains the generated tokens:
+
+```json
+{
+  "tokens": [
+    {
+      "token": "opens",
+      "start_offset": 0,
+      "end_offset": 10,
+      "type": "<ALPHANUM>",
+      "position": 0
+    },
+    {
+      "token": "is",
+      "start_offset": 11,
+      "end_offset": 13,
+      "type": "<ALPHANUM>",
+      "position": 1
+    },
+    {
+      "token": "power",
+      "start_offset": 14,
+      "end_offset": 22,
+      "type": "<ALPHANUM>",
+      "position": 2
+    },
+    {
+      "token": "and",
+      "start_offset": 23,
+      "end_offset": 26,
+      "type": "<ALPHANUM>",
+      "position": 3
+    },
+    {
+      "token": "scala",
+      "start_offset": 27,
+      "end_offset": 35,
+      "type": "<ALPHANUM>",
+      "position": 4
+    }
+  ]
+}
+```