[DOC] Add split processor documentation

_ingest-pipelines/processors/split.md

@@ -0,0 +1,181 @@
+---
+layout: default
+title: Split
+parent: Ingest processors
+nav_order: 270
+---
+
+# Split processor
+
+The `split` processor is used to split a string field into an array of substrings based on a specified delimiter.
+
+The following is the syntax for the `split` processor:
+
+```json
+{
+  "split": {
+    "field": "field_to_split",
+    "separator": "<delimiter>",
+    "target_field": "split_field"
+  }
+}
+```
+{% include copy-curl.html %}
+
+## Configuration parameters
+
+The following table lists the required and optional parameters for the `split` processor.
+
+Parameter | Required/Optional | Description |
+|-----------|-----------|-----------|
+`field` | Required | The field containing the string to be split.
+`separator` | Required | The delimiter used to split the string. This can be a regular expression pattern.
+`preserve_field` | Optional | If set to `true`, preserves empty trailing fields (for example, `''`) in the resulting array. If set to `false`, empty trailing fields are removed from the resulting array. Default is `false`.
+`target_field` | Optional | The field where the array of substrings is stored. If not specified, then the field is updated in-place.
+`ignore_missing` | Optional	| Specifies whether the processor should ignore documents that do not contain the specified 
+field. If set to `true`, the processor ignores missing values in the field and leaves the `target_field` unchanged. Default is `false`. 
+`description` | Optional | A brief description of the processor.
+`if` | Optional | A condition for running the processor.
+`ignore_failure` | Optional | Specifies whether the processor continues execution even if it encounters an error. If set to 
+`true`, failures are ignored. Default is `false`.
+`on_failure` | Optional | A list of processors to run if the processor fails.
+`tag` | Optional | An identifier tag for the processor. Useful for debugging in order to distinguish between processors of the same type.
+
+## Using the processor
+
+Follow these steps to use the processor in a pipeline.
+
+### Step 1: Create a pipeline
+
+The following query creates a pipeline named `split_pipeline` that uses the `split` processor to split the `log_message` field on the comma character and store the resulting array in the `log_parts` field: 
+
+```json
+PUT _ingest/pipeline/split_pipeline
+{
+  "description": "Split log messages by comma",
+  "processors": [
+    {
+      "split": {
+        "field": "log_message",
+        "separator": ",",
+        "target_field": "log_parts"
+      }
+    }
+  ]
+}
+```
+{% include copy-curl.html %}
+
+### Step 2 (Optional): Test the pipeline
+
+It is recommended that you test your pipeline before you ingest documents.
+{: .tip}
+
+To test the pipeline, run the following query:
+
+```json
+POST _ingest/pipeline/split_pipeline/_simulate
+{
+  "docs": [
+    {
+      "_source": {
+        "log_message": "error,warning,info"
+      }
+    }
+  ]
+}
+```
+{% include copy-curl.html %}
+
+#### Response
+
+The following example response confirms that the pipeline is working as expected:
+
+```json
+{
+  "docs": [
+    {
+      "doc": {
+        "_index": "_index",
+        "_id": "_id",
+        "_source": {
+          "log_message": "error,warning,info",
+          "log_parts": [
+            "error",
+            "warning",
+            "info"
+          ]
+        },
+        "_ingest": {
+          "timestamp": "2024-04-26T22:29:23.207849376Z"
+        }
+      }
+    }
+  ]
+}
+```
+{% include copy-curl.html %}
+
+### Step 3: Ingest a document 
+
+The following query ingests a document into an index named `testindex1`:
+
+```json
+PUT testindex1/_doc/1?pipeline=split_pipeline
+{
+  "log_message": "error,warning,info"
+}
+```
+{% include copy-curl.html %}
+
+#### Response
+
+The request indexes the document into the index `testindex1` and splits the `log_message` field on the comma delimiter before indexing.
+
+```json
+{
+  "_index": "testindex1",
+  "_id": "1",
+  "_version": 70,
+  "result": "updated",
+  "_shards": {
+    "total": 2,
+    "successful": 1,
+    "failed": 0
+  },
+  "_seq_no": 72,
+  "_primary_term": 47
+}
+```
+
+### Step 4 (Optional): Retrieve the document
+
+To retrieve the document, run the following query:
+
+```json
+GET testindex1/_doc/1
+```
+{% include copy-curl.html %}
+
+#### Response 
+
+The response shows the `log_message` field as an array of values split on the comma delimiter:
+
+```json
+{
+  "_index": "testindex1",
+  "_id": "1",
+  "_version": 70,
+  "_seq_no": 72,
+  "_primary_term": 47,
+  "found": true,
+  "_source": {
+    "log_message": "error,warning,info",
+    "log_parts": [
+      "error",
+      "warning",
+      "info"
+    ]
+  }
+}
+```