From 0f4366743b04aa2d29986dbdfb85914841abf61b Mon Sep 17 00:00:00 2001
From: Phillip Cloud <417981+cpcloud@users.noreply.github.com>
Date: Sat, 27 Jan 2024 06:03:58 -0500
Subject: [PATCH] fix(polars): avoid using unnecessary subquery for schema
 inference

---
 ibis/backends/polars/__init__.py    |  4 +---
 ibis/backends/tests/test_client.py  |  2 +-
 ibis/backends/tests/test_dot_sql.py | 19 ++-----------------
 3 files changed, 4 insertions(+), 21 deletions(-)

diff --git a/ibis/backends/polars/__init__.py b/ibis/backends/polars/__init__.py
index 15b2fcca6120..1619ac927371 100644
--- a/ibis/backends/polars/__init__.py
+++ b/ibis/backends/polars/__init__.py
@@ -395,9 +395,7 @@ def compile(
         return translate(node, ctx=ctx)
 
     def _get_schema_using_query(self, query: str) -> sch.Schema:
-        return schema_from_polars(
-            self._context.execute(f"SELECT * FROM ({query}) LIMIT 0").schema
-        )
+        return schema_from_polars(self._context.execute(query).schema)
 
     def execute(
         self,
diff --git a/ibis/backends/tests/test_client.py b/ibis/backends/tests/test_client.py
index 4e96eb509088..ac0c8dfa4e51 100644
--- a/ibis/backends/tests/test_client.py
+++ b/ibis/backends/tests/test_client.py
@@ -189,7 +189,7 @@ def test_query_schema(ddl_backend, expr_fn, expected):
 }
 
 
-@pytest.mark.notimpl(["datafusion", "polars", "mssql"])
+@pytest.mark.notimpl(["datafusion", "mssql"])
 @pytest.mark.never(["dask", "pandas"], reason="dask and pandas do not support SQL")
 @pytest.mark.notimpl(
     ["flink"], raises=AttributeError, reason="'Backend' object has no attribute 'sql'"
diff --git a/ibis/backends/tests/test_dot_sql.py b/ibis/backends/tests/test_dot_sql.py
index df23895034ae..b5aec3ebcc95 100644
--- a/ibis/backends/tests/test_dot_sql.py
+++ b/ibis/backends/tests/test_dot_sql.py
@@ -33,14 +33,7 @@
 @pytest.mark.parametrize(
     "schema",
     [
-        param(
-            None,
-            id="implicit_schema",
-            marks=[
-                pytest.mark.notimpl(["druid"]),
-                pytest.mark.notyet(["polars"], raises=PolarsComputeError),
-            ],
-        ),
+        param(None, id="implicit_schema", marks=[pytest.mark.notimpl(["druid"])]),
         param({"s": "string", "new_col": "double"}, id="explicit_schema"),
     ],
 )
@@ -82,7 +75,6 @@ def test_con_dot_sql(backend, con, schema):
 @dot_sql_notimpl
 @dot_sql_notyet
 @dot_sql_never
-@pytest.mark.notyet(["polars"], raises=PolarsComputeError)
 def test_table_dot_sql(backend, con):
     alltypes = con.table("functional_alltypes")
     t = (
@@ -120,7 +112,6 @@ def test_table_dot_sql(backend, con):
 @dot_sql_notimpl
 @dot_sql_notyet
 @dot_sql_never
-@pytest.mark.notyet(["polars"], raises=PolarsComputeError)
 def test_table_dot_sql_with_join(backend, con):
     alltypes = con.table("functional_alltypes")
     t = (
@@ -168,7 +159,6 @@ def test_table_dot_sql_with_join(backend, con):
 @dot_sql_notimpl
 @dot_sql_notyet
 @dot_sql_never
-@pytest.mark.notyet(["polars"], raises=PolarsComputeError)
 def test_table_dot_sql_repr(con):
     alltypes = con.table("functional_alltypes")
     t = (
@@ -235,12 +225,8 @@ def test_dot_sql_reuse_alias_with_different_types(backend, alltypes, df):
 
 @pytest.mark.parametrize(
     "dialect",
-    [
-        *sorted(_get_backend_names() - _NO_SQLGLOT_DIALECT),
-        *no_sqlglot_dialect,
-    ],
+    [*sorted(_get_backend_names() - _NO_SQLGLOT_DIALECT), *no_sqlglot_dialect],
 )
-@pytest.mark.notyet(["polars"], raises=PolarsComputeError)
 @table_dot_sql_notimpl
 @dot_sql_notimpl
 @dot_sql_notyet
@@ -264,7 +250,6 @@ def test_table_dot_sql_transpile(backend, alltypes, dialect, df):
         *no_sqlglot_dialect,
     ],
 )
-@pytest.mark.notyet(["polars"], raises=PolarsComputeError)
 @pytest.mark.notyet(["druid"], raises=ValueError)
 @pytest.mark.notyet(["snowflake", "bigquery"])
 @pytest.mark.notyet(