From 6a93e487c6e08de2180b76e6a68b07cf8b1db20e Mon Sep 17 00:00:00 2001
From: Dmitriy <sevirov@yandex-team.ru>
Date: Mon, 21 Dec 2020 22:30:37 +0300
Subject: [PATCH] Document the countMatches function.
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Задокументировал функцию countMatches.
---
 .../functions/string-search-functions.md      | 57 +++++++++++++++++--
 1 file changed, 53 insertions(+), 4 deletions(-)

diff --git a/docs/en/sql-reference/functions/string-search-functions.md b/docs/en/sql-reference/functions/string-search-functions.md
index 3cde7dd71d4..957866faea3 100644
--- a/docs/en/sql-reference/functions/string-search-functions.md
+++ b/docs/en/sql-reference/functions/string-search-functions.md
@@ -400,7 +400,8 @@ Result:
 └──────────────────────────────────────────────────────────────────────────────────────────┘
 ```
 
-**See also**
+**See Also**
+
 -   [extractAllGroupsVertical](#extractallgroups-vertical)
 
 ## extractAllGroupsVertical {#extractallgroups-vertical}
@@ -440,7 +441,8 @@ Result:
 └────────────────────────────────────────────────────────────────────────────────────────┘
 ```
 
-**See also**
+**See Also**
+
 -   [extractAllGroupsHorizontal](#extractallgroups-horizontal)
 
 ## like(haystack, pattern), haystack LIKE pattern operator {#function-like}
@@ -590,8 +592,55 @@ Result:
 └───────────────────────────────┘
 ```
 
-[Original article](https://clickhouse.tech/docs/en/query_language/functions/string_search_functions/) <!--hide-->
-
 ## countMatches(haystack, pattern) {#countmatcheshaystack-pattern}
 
 Returns the number of regular expression matches for a `pattern` in a `haystack`.
+
+**Syntax**
+
+``` sql
+countMatches(haystack, pattern)
+```
+
+**Parameters**
+
+-   `haystack` — The string to search in. [String](../../sql-reference/syntax.md#syntax-string-literal).
+-   `pattern` — The regular expression with [re2 syntax](https://github.com/google/re2/wiki/Syntax). [String](../../sql-reference/data-types/string.md).
+
+**Returned value**
+
+-   The number of matches.
+
+Type: [UInt64](../../sql-reference/data-types/int-uint.md).
+
+**Examples**
+
+Query:
+
+``` sql
+SELECT countMatches('foobar.com', 'o')
+```
+
+Result:
+
+``` text
+┌─countMatches('foobar.com', 'o')─┐
+│                               3 │
+└─────────────────────────────────┘
+```
+
+Query:
+
+``` sql
+SELECT countMatches('aaaa', 'aa')
+```
+
+Result:
+
+``` text
+┌─countMatches('aaaa', 'aa')─┐
+│                             2 │
+└───────────────────────────────┘
+```
+
+[Original article](https://clickhouse.tech/docs/en/query_language/functions/string_search_functions/) <!--hide-->