ESQL Add esql hash function

docs/changelog/117989.yaml

@@ -0,0 +1,5 @@
+pr: 117989
+summary: ESQL Add esql hash function
+area: ES|QL
+type: enhancement
+issues: []

docs/reference/esql/functions/string-functions.asciidoc

@@ -13,6 +13,7 @@
 * <<esql-concat>>
 * <<esql-ends_with>>
 * <<esql-from_base64>>
+* <<esql-hash>>
 * <<esql-left>>
 * <<esql-length>>
 * <<esql-locate>>
@@ -37,6 +38,7 @@ include::layout/byte_length.asciidoc[]
 include::layout/concat.asciidoc[]
 include::layout/ends_with.asciidoc[]
 include::layout/from_base64.asciidoc[]
+include::layout/hash.asciidoc[]
 include::layout/left.asciidoc[]
 include::layout/length.asciidoc[]
 include::layout/locate.asciidoc[]

x-pack/plugin/esql/qa/testFixtures/src/main/resources/hash.csv-spec

@@ -0,0 +1,52 @@
+hash
+required_capability: hash_function
+
+FROM sample_data 
+| WHERE message != "Connection error"
+| EVAL md5 = hash("md5", message), sha256 = hash("sha256", message) 
+| KEEP message, md5, sha256;
+ignoreOrder:true
+
+message:keyword       | md5:keyword                      | sha256:keyword
+Connected to 10.1.0.1 | abd7d1ce2bb636842a29246b3512dcae | 6d8372129ad78770f7185554dd39864749a62690216460752d6c075fa38ad85c
+Connected to 10.1.0.2 | 8f8f1cb60832d153f5b9ec6dc828b93f | b0db24720f15857091b3c99f4c4833586d0ea3229911b8777efb8d917cf27e9a
+Connected to 10.1.0.3 | 912b6dc13503165a15de43304bb77c78 | 75b0480188db8acc4d5cc666a51227eb2bc5b989cd8ca912609f33e0846eff57
+Disconnected          | ef70e46fd3bbc21e3e1f0b6815e750c0 | 04dfac3671b494ad53fcd152f7a14511bfb35747278aad8ce254a0d6e4ba4718
+;
+
+
+hashOfConvertedType
+required_capability: hash_function
+
+FROM sample_data 
+| WHERE message != "Connection error"
+| EVAL input = event_duration::STRING, md5 = hash("md5", input), sha256 = hash("sha256", input) 
+| KEEP message, input, md5, sha256;
+ignoreOrder:true
+
+message:keyword       | input:keyword | md5:keyword                      | sha256:keyword
+Connected to 10.1.0.1 | 1756467       | c4fc1c57ee9b1d2b2023b70c8c167b54 | 8376a50a7ba7e6bd1bf9ad0c32d27d2f49fd0fa422573f98f239e21048b078f3
+Connected to 10.1.0.2 | 2764889       | 8e8cf005e11a7b5df1d9478a4715a444 | 1031f2bef8eaecbf47319505422300b27ea1f7c38b6717d41332325062f9a56a
+Connected to 10.1.0.3 | 3450233       | 09f2c64f5a55e9edf8ffbad336b561d8 | f77d7545769c4ecc85092f4f0b7ec8c20f467e4beb15fe67ca29f9aa8e9a6900
+Disconnected          | 1232382       | 6beac1485638d51e13c2c53990a2f611 | 9a03c1274a3ebb6c1cb85d170ce0a6fdb9d2232724e06b9f5e7cb9274af3cad6
+;
+
+
+hashOfNullInput
+required_capability: hash_function
+
+ROW input=null::STRING | EVAL md5 = hash("md5", input), sha256 = hash("sha256", input);
+
+input:keyword | md5:keyword | sha256:keyword
+null          | null        | null
+;
+
+
+hashWithNullAlgorithm
+required_capability: hash_function
+
+ROW input="input" | EVAL hash = hash(null, input);
+
+input:keyword | hash:keyword
+input         | null
+;