From eb02c0a92611a00381d7286d4ffd9baa3b49fcb6 Mon Sep 17 00:00:00 2001
From: Vincent Gao <gaobing1230@gmail.com>
Date: Thu, 25 Jun 2026 00:49:32 +0200
Subject: [PATCH 1/2] fix(clickhouse): correctly transpile arrayMap and
 arrayFilter higher-order functions [CLAUDE]

ClickHouse's higher-order array functions arrayMap(lambda, arr) and
arrayFilter(lambda, arr) were being parsed as Anonymous expressions because
the ClickHouse parser lacked entries for their uppercased forms (ARRAYMAP,
ARRAYFILTER). As a result, transpiling to DuckDB produced invalid ARRAYMAP()
and ARRAYFILTER() calls instead of LIST_TRANSFORM() and LIST_FILTER().

Additionally, the ClickHouse generator had no Transform entry, so DuckDB's
LIST_TRANSFORM and Spark's TRANSFORM arrived in ClickHouse as the wrong name.

Note: argument order in ClickHouse is reversed relative to the canonical
exp.Transform/exp.ArrayFilter convention (lambda first, array second).
---
 sqlglot/generators/clickhouse.py  |  1 +
 sqlglot/parsers/clickhouse.py     |  8 ++++++++
 tests/dialects/test_clickhouse.py | 22 ++++++++++++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/sqlglot/generators/clickhouse.py b/sqlglot/generators/clickhouse.py
index d2b5381486..e95b375522 100644
--- a/sqlglot/generators/clickhouse.py
+++ b/sqlglot/generators/clickhouse.py
@@ -280,6 +280,7 @@ class ClickHouseGenerator(generator.Generator):
         exp.ArrayConcat: rename_func("arrayConcat"),
         exp.ArrayContains: rename_func("has"),
         exp.ArrayFilter: lambda self, e: self.func("arrayFilter", e.expression, e.this),
+        exp.Transform: lambda self, e: self.func("arrayMap", e.expression, e.this),
         exp.ArrayRemove: remove_from_array_using_filter,
         exp.ArrayReverse: rename_func("arrayReverse"),
         exp.ArraySlice: rename_func("arraySlice"),
diff --git a/sqlglot/parsers/clickhouse.py b/sqlglot/parsers/clickhouse.py
index 45bdf03af4..eb793e8e53 100644
--- a/sqlglot/parsers/clickhouse.py
+++ b/sqlglot/parsers/clickhouse.py
@@ -262,6 +262,14 @@ class ClickHouseParser(parser.Parser):
         "ARRAYMIN": exp.ArrayMin.from_arg_list,
         "ARRAYREVERSE": exp.ArrayReverse.from_arg_list,
         "ARRAYSLICE": exp.ArraySlice.from_arg_list,
+        # ClickHouse higher-order array functions: the lambda comes first, the array second.
+        # This is the opposite of exp.ArrayFilter(this=array, expression=lambda) convention.
+        "ARRAYFILTER": lambda args: exp.ArrayFilter(
+            this=seq_get(args, 1), expression=seq_get(args, 0)
+        ),
+        "ARRAYMAP": lambda args: exp.Transform(
+            this=seq_get(args, 1), expression=seq_get(args, 0)
+        ),
         "CURRENTDATABASE": exp.CurrentDatabase.from_arg_list,
         "CURRENTSCHEMAS": exp.CurrentSchemas.from_arg_list,
         "COUNTIF": _build_count_if,
diff --git a/tests/dialects/test_clickhouse.py b/tests/dialects/test_clickhouse.py
index f81ff63904..d05738dac7 100644
--- a/tests/dialects/test_clickhouse.py
+++ b/tests/dialects/test_clickhouse.py
@@ -1768,6 +1768,28 @@ def test_functions(self):
         self.validate_identity(
             "SELECT TRANSFORM(foo, [1, 2], ['first', 'second'], 'default') FROM table"
         )
+        self.validate_all(
+            "SELECT arrayMap(x -> x + 1, arr) FROM t",
+            read={
+                "duckdb": "SELECT LIST_TRANSFORM(arr, x -> x + 1) FROM t",
+                "spark": "SELECT TRANSFORM(arr, x -> x + 1) FROM t",
+            },
+            write={
+                "clickhouse": "SELECT arrayMap(x -> x + 1, arr) FROM t",
+                "duckdb": "SELECT LIST_TRANSFORM(arr, x -> x + 1) FROM t",
+                "spark": "SELECT TRANSFORM(arr, x -> x + 1) FROM t",
+            },
+        )
+        self.validate_all(
+            "SELECT arrayFilter(x -> x > 0, arr) FROM t",
+            read={
+                "duckdb": "SELECT LIST_FILTER(arr, x -> x > 0) FROM t",
+            },
+            write={
+                "clickhouse": "SELECT arrayFilter(x -> x > 0, arr) FROM t",
+                "duckdb": "SELECT LIST_FILTER(arr, x -> x > 0) FROM t",
+            },
+        )
 
     def test_array_offset(self):
         with self.assertLogs(helper_logger) as cm:

From e7e93628abcd8f8fb16f5ea4b603fbfa5d29fcdf Mon Sep 17 00:00:00 2001
From: Vincent Gao <gaobing1230@gmail.com>
Date: Thu, 25 Jun 2026 13:47:40 +0200
Subject: [PATCH 2/2] style: collapse ARRAYMAP lambda to single line [CLAUDE]

ruff-format requires the multi-arg lambda to fit on one line.
---
 sqlglot/parsers/clickhouse.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/sqlglot/parsers/clickhouse.py b/sqlglot/parsers/clickhouse.py
index eb793e8e53..4e86252571 100644
--- a/sqlglot/parsers/clickhouse.py
+++ b/sqlglot/parsers/clickhouse.py
@@ -267,9 +267,7 @@ class ClickHouseParser(parser.Parser):
         "ARRAYFILTER": lambda args: exp.ArrayFilter(
             this=seq_get(args, 1), expression=seq_get(args, 0)
         ),
-        "ARRAYMAP": lambda args: exp.Transform(
-            this=seq_get(args, 1), expression=seq_get(args, 0)
-        ),
+        "ARRAYMAP": lambda args: exp.Transform(this=seq_get(args, 1), expression=seq_get(args, 0)),
         "CURRENTDATABASE": exp.CurrentDatabase.from_arg_list,
         "CURRENTSCHEMAS": exp.CurrentSchemas.from_arg_list,
         "COUNTIF": _build_count_if,