From 93d28ef5c9c0d425c74c674db485597c418cbdb0 Mon Sep 17 00:00:00 2001
From: hexiaoting <hewenting_ict@163.com>
Date: Tue, 22 Dec 2020 21:48:40 +0800
Subject: [PATCH] Implement untuple field access (#18309)

---
 src/Interpreters/TreeRewriter.cpp                     | 11 +++++++++++
 .../0_stateless/01616_untuple_access_field.reference  |  1 +
 .../0_stateless/01616_untuple_access_field.sql        |  1 +
 3 files changed, 13 insertions(+)
 create mode 100644 tests/queries/0_stateless/01616_untuple_access_field.reference
 create mode 100644 tests/queries/0_stateless/01616_untuple_access_field.sql

diff --git a/src/Interpreters/TreeRewriter.cpp b/src/Interpreters/TreeRewriter.cpp
index 1ad22efc3fc..92ff4e69817 100644
--- a/src/Interpreters/TreeRewriter.cpp
+++ b/src/Interpreters/TreeRewriter.cpp
@@ -286,6 +286,17 @@ void removeUnneededColumnsFromSelectClause(const ASTSelectQuery * select_query,
         {
             new_elements.push_back(elem);
         }
+        else
+        {
+            ASTFunction * func = elem->as<ASTFunction>();
+            if (func && func->name == "untuple")
+                for (const auto & col : required_result_columns)
+                    if (col.rfind("_ut_", 0) == 0)
+                    {
+                        new_elements.push_back(elem);
+                        break;
+                    }
+        }
     }
 
     elements = std::move(new_elements);
diff --git a/tests/queries/0_stateless/01616_untuple_access_field.reference b/tests/queries/0_stateless/01616_untuple_access_field.reference
new file mode 100644
index 00000000000..d00491fd7e5
--- /dev/null
+++ b/tests/queries/0_stateless/01616_untuple_access_field.reference
@@ -0,0 +1 @@
+1
diff --git a/tests/queries/0_stateless/01616_untuple_access_field.sql b/tests/queries/0_stateless/01616_untuple_access_field.sql
new file mode 100644
index 00000000000..569efca5349
--- /dev/null
+++ b/tests/queries/0_stateless/01616_untuple_access_field.sql
@@ -0,0 +1 @@
+select _ut_1 from (select untuple((1,2)));