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fix(clickhouse): correctly transpile arrayMap and arrayFilter higher-order functions [CLAUDE] #7794

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fix(clickhouse): correctly transpile arrayMap and arrayFilter higher-order functions [CLAUDE] #7794

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fix(clickhouse): correctly transpile arrayMap and arrayFilter higher-…
gaoflow Jun 24, 2026
e7e9362
style: collapse ARRAYMAP lambda to single line [CLAUDE]
gaoflow Jun 25, 2026
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1 change: 1 addition & 0 deletions sqlglot/generators/clickhouse.py
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Original file line number Diff line number Diff line change
Expand Up @@ -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"),
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6 changes: 6 additions & 0 deletions sqlglot/parsers/clickhouse.py
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Expand Up @@ -262,6 +262,12 @@ 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.
Comment on lines +265 to +266

@geooo109 geooo109 Jun 25, 2026

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Let's remove the comments here, to simplify the code.

"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,
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22 changes: 22 additions & 0 deletions tests/dialects/test_clickhouse.py
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Expand Up @@ -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",
},
)
Comment on lines +1772 to +1782

@geooo109 geooo109 Jun 25, 2026 •
edited
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There are cases that the transpilation results into different semantics.

clickhouse (input):
SELECT arrayMap(NULL, [1, 2]) AS res

Query id: 0db4a81e-03b1-4253-8593-6a73112a447f

   ┌─res──┐
1. │ ᴺᵁᴸᴸ │
   └──────┘

1 row in set. Elapsed: 0.002 sec. 

transpiled duckdb (output):
memory D SELECT LIST_TRANSFORM([1,2], NULL) AS res;
Binder Error:
Invalid lambda expression!

transpiled spark 4 (output):
spark-sql (default)> SELECT TRANSFORM(array(1,2), NULL);
[null,null]
Time taken: 0.051 seconds, Fetched 1 row(s)

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",
},
)
Comment on lines +1783 to +1792

@geooo109 geooo109 Jun 25, 2026

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Same as https://github.com/tobymao/sqlglot/pull/7794/changes#r3473795554 :

clickhouse (input):
SELECT arrayFilter(NULL, [1, 2, 3])

Query id: 2b70a67e-8db5-47e5-b60a-02551e878843

   ┌─arrayFilter(NULL, [1, 2, 3])─┐
1. │ ᴺᵁᴸᴸ                         │
   └──────────────────────────────┘

1 row in set. Elapsed: 0.002 sec. 

transpiled duckdb(output): 
memory D SELECT LIST_FILTER([1, 2, 3], NULL);
Binder Error:
Invalid lambda expression!


def test_array_offset(self):
with self.assertLogs(helper_logger) as cm:
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