[ES\QL] Add a section for vector functions in the doc. (#136077)

Author: afoucret

docs/reference/query-languages/esql/_snippets/functions/layout/knn.md

@@ -0,0 +1,8 @@
+* {applies_to}`stack: preview 9.2` {applies_to}`serverless: preview` [`KNN`](../../functions-operators/dense-vector-functions.md#esql-knn)
+
+% * {applies_to}`stack: preview 9.3` {applies_to}`serverless: preview` [`V_COSINE`](../../functions-operators/dense-vector-functions.md#esql-v_cosine)
+% * {applies_to}`stack: preview 9.3` {applies_to}`serverless: preview` [`V_DOT_PRODUCT`](../../functions-operators/dense-vector-functions.md#esql-v_dot_product)
+% * {applies_to}`stack: preview 9.3` {applies_to}`serverless: preview`[`V_HAMMING`](../../functions-operators/dense-vector-functions.md#esql-v_hamming)
+% * {applies_to}`stack: preview 9.3` {applies_to}`serverless: preview` [`V_L1_NORM`](../../functions-operators/dense-vector-functions.md#esql-v_l1_norm)
+% * {applies_to}`stack: preview 9.3` {applies_to}`serverless: preview` [`V_L2_NORM`](../../functions-operators/dense-vector-functions.md#esql-v_l2_norm)
+% * {applies_to}`stack: preview 9.3` {applies_to}`serverless: preview` [`V_MAGNITUDE`](../../functions-operators/dense-vector-functions.md#esql-v_magnitude)

docs/reference/query-languages/esql/_snippets/functions/parameters/knn.md

@@ -80,6 +80,12 @@ mapped_pages:
 :::
 ::::
 
+::::{dropdown} Dense vector functions
+:open:
+:::{include} _snippets/lists/dense-vector-functions.md
+:::
+::::
+
 ::::{dropdown} Multi value functions
 :open:
 :::{include} _snippets/lists/mv-functions.md

docs/reference/query-languages/esql/_snippets/lists/dense-vector-functions.md

@@ -0,0 +1,60 @@
+---
+applies_to:
+  stack: preview
+  serverless: preview
+navigation_title: "Dense vector functions"
+mapped_pages:
+  - https://www.elastic.co/guide/en/elasticsearch/reference/current/esql-functions-operators.html#esql-dense-vector-functions
+---
+
+# {{esql}} dense vector functions [esql-dense-vector-functions]
+
+{{esql}} supports dense vector functions for vector similarity calculations and
+k-nearest neighbor search.
+Dsense vector functions work with [
+`dense_vector` fields](/reference/elasticsearch/mapping-reference/dense-vector.md)
+and require appropriate field mappings.
+
+{{esql}} supports these vector functions:
+
+:::{include} ../_snippets/lists/dense-vector-functions.md
+:::
+
+:::{include} ../_snippets/functions/layout/knn.md
+:::
+
+% V_COSINE is currently a hidden feature
+% To make it visible again, uncomment this and the line in
+% lists/dense-vector-functions.md
+% :::{include} ../_snippets/functions/layout/v_cosine.md
+% :::
+
+% V_DOT_PRODUCT is currently a hidden feature
+% To make it visible again, uncomment this and the line in
+% lists/dense-vector-functions.md
+% :::{include} ../_snippets/functions/layout/v_dot_product.md
+% :::
+
+% V_HAMMING is currently a hidden feature
+% To make it visible again, uncomment this and the line in
+% lists/dense-vector-functions.md
+% :::{include} ../_snippets/functions/layout/v_hamming.md
+% :::
+
+% V_L1_NORM is currently a hidden feature
+% To make it visible again, uncomment this and the line in
+% lists/dense-vector-functions.md
+% :::{include} ../_snippets/functions/layout/v_l1_norm.md
+% :::
+
+% V_L2_NORM is currently a hidden feature
+% To make it visible again, uncomment this and the line in
+% lists/dense-vector-functions.md
+% :::{include} ../_snippets/functions/layout/v_l2_norm.md
+% :::
+
+% V_MAGNITUDE is currently a hidden feature
+% To make it visible again, uncomment this and the line in
+% lists/dense-vector-functions.md
+% :::{include} ../_snippets/functions/layout/v_magnitude.md
+% :::

docs/reference/query-languages/esql/esql-functions-operators.md

@@ -14,12 +14,12 @@ Get started with {{esql}} for search use cases with
 our [hands-on tutorial](/reference/query-languages/esql/esql-search-tutorial.md).
 
 For a high-level overview of search functionalities in {{esql}}, and to learn about relevance scoring, refer to [{{esql}} for search](docs-content://solutions/search/esql-for-search.md#esql-for-search-scoring).
-:::
 
-{{esql}} provides a set of functions for performing searching on text fields.
+For information regarding dense vector search functions,
+including [KNN](dense-vector-functions.md#esql-knn), please refer to
+the [Dense vector functions](dense-vector-functions.md) documentation.
+:::
 
-Use these functions
-for [full-text search](docs-content://solutions/search/full-text.md)
 and [semantic search](docs-content://solutions/search/semantic-search/semantic-search-semantic-text.md).
 
 Full text functions can be used to

docs/reference/query-languages/esql/functions-operators/dense-vector-functions.md

@@ -133,6 +133,7 @@ toc:
               - file: esql/functions-operators/search-functions.md
               - file: esql/functions-operators/spatial-functions.md
               - file: esql/functions-operators/string-functions.md
+              - file: esql/functions-operators/dense-vector-functions.md
               - file: esql/functions-operators/type-conversion-functions.md
               - file: esql/functions-operators/mv-functions.md
               - file: esql/functions-operators/operators.md

docs/reference/query-languages/esql/functions-operators/search-functions.md

@@ -103,7 +103,7 @@ public class Knn extends FullTextFunction
         description = "Finds the k nearest vectors to a query vector, as measured by a similarity metric. "
             + "knn function finds nearest vectors through approximate search on indexed dense_vectors or semantic_text fields.",
         examples = { @Example(file = "knn-function", tag = "knn-function") },
-        appliesTo = { @FunctionAppliesTo(lifeCycle = FunctionAppliesToLifecycle.PREVIEW) }
+        appliesTo = { @FunctionAppliesTo(lifeCycle = FunctionAppliesToLifecycle.PREVIEW, version = "9.2.0") }
     )
     public Knn(
         Source source,
@@ -153,7 +153,7 @@ public Knn(
                         + "(docs-content://solutions/search/vector/knn.md#dense-vector-knn-search-rescoring) for details."
                 ), },
             description = "(Optional) kNN additional options as <<esql-function-named-params,function named parameters>>."
-                + " See <<query-dsl-knn-query,knn query>> for more information.",
+                + " See [knn query](/reference/query-languages/query-dsl/query-dsl-knn-query.md) for more information.",
             optional = true
         ) Expression options
     ) {