fix(snowflake): use convert_timezone for timezone conversion instea…

…d of invalid postgres `AT TIME ZONE` syntax

ibis/backends/snowflake/registry.py

@@ -14,6 +14,8 @@
 from ibis.backends.base.sql.alchemy.registry import (
     fixed_arity,
     geospatial_functions,
+    get_col,
+    get_sqla_table,
     reduction,
     unary,
 )
@@ -66,6 +68,26 @@ def _literal(t, op):
     return _postgres_literal(t, op)
 
 
+def _table_column(t, op):
+    ctx = t.context
+    table = op.table
+
+    sa_table = get_sqla_table(ctx, table)
+    out_expr = get_col(sa_table, op)
+
+    if (dtype := op.output_dtype).is_timestamp() and (
+        timezone := dtype.timezone
+    ) is not None:
+        out_expr = sa.func.convert_timezone(timezone, out_expr).label(op.name)
+
+    # If the column does not originate from the table set in the current SELECT
+    # context, we should format as a subquery
+    if t.permit_subquery and ctx.is_foreign_expr(table):
+        return sa.select(out_expr)
+
+    return out_expr
+
+
 def _string_find(t, op):
     args = [t.translate(op.substr), t.translate(op.arg)]
     if (start := op.start) is not None:
@@ -407,6 +429,7 @@ def _regex_extract(t, op):
         ops.Hash: unary(sa.func.hash),
         ops.ApproxMedian: reduction(lambda x: sa.func.approx_percentile(x, 0.5)),
         ops.Median: reduction(sa.func.median),
+        ops.TableColumn: _table_column,
     }
 )
 

ibis/backends/snowflake/tests/test_client.py

@@ -74,3 +74,13 @@ def test_repeated_memtable_registration(simple_con, mocker):
 
     # assert that we called _register_in_memory_table exactly n times
     assert spy.call_count == n
+
+
+def test_timestamp_tz_column(simple_con):
+    t = simple_con.create_table(
+        ibis.util.gen_name("snowflake_timestamp_tz_column"),
+        schema=ibis.schema({"ts": "string"}),
+        temp=True,
+    ).mutate(ts=lambda t: t.ts.to_timestamp("YYYY-MM-DD HH24-MI-SS"))
+    expr = t.ts
+    assert expr.execute().empty