fix(impala): remove broken alias elision

ibis/backends/base/sql/alchemy/registry.py

@@ -81,24 +81,27 @@ def get_sqla_table(ctx, table):
     return sa_table
 
 
-def get_col(sa_table, op: ops.TableColumn):
-    """Get a `Column`."""
+def get_col(sa_table, op: ops.TableColumn) -> sa.sql.ColumnClause:
+    """Extract a column from a table."""
     cols = sa_table.exported_columns
     colname = op.name
 
-    try:
-        return cols[colname]
-    except KeyError:
-        # cols is a sqlalchemy column collection which contains column
-        # names that are secretly prefixed by their containing table
-        #
-        # sqlalchemy doesn't let you select by the *un*prefixed column name
-        # despite the uniqueness of `colname`
-        #
-        # however, in ibis we have already deduplicated column names so we can
-        # refer to the name by position
-        colindex = op.table.schema._name_locs[colname]
-        return cols[colindex]
+    if (col := cols.get(colname)) is not None:
+        return col
+
+    # `cols` is a SQLAlchemy column collection that contains columns
+    # with names that are secretly prefixed by table that contains them
+    #
+    # for example, in `t0.join(t1).select(t0.a, t1.b)` t0.a will be named `t0_a`
+    # and t1.b will be named `t1_b`
+    #
+    # unfortunately SQLAlchemy doesn't let you select by the *un*prefixed
+    # column name despite the uniqueness of `colname`
+    #
+    # however, in ibis we have already deduplicated column names so we can
+    # refer to the name by position
+    colindex = op.table.schema._name_locs[colname]
+    return cols[colindex]
 
 
 def _table_column(t, op):

ibis/backends/base/sql/compiler/query_builder.py

@@ -93,7 +93,6 @@ def _format_table(self, op):
 
         if isinstance(ref_op, ops.InMemoryTable):
             result = self._format_in_memory_table(ref_op)
-            is_subquery = True
         elif isinstance(ref_op, ops.PhysicalTable):
             name = ref_op.name
             # TODO(kszucs): add a mandatory `name` field to the base
@@ -102,7 +101,6 @@ def _format_table(self, op):
             if name is None:
                 raise com.RelationError(f'Table did not have a name: {op!r}')
             result = self._quote_identifier(name)
-            is_subquery = False
         else:
             # A subquery
             if ctx.is_extracted(ref_op):
@@ -118,10 +116,8 @@ def _format_table(self, op):
 
             subquery = ctx.get_compiled_expr(op)
             result = f'(\n{util.indent(subquery, self.indent)}\n)'
-            is_subquery = True
 
-        if is_subquery or ctx.need_aliases(op):
-            result += f' {ctx.get_ref(op)}'
+        result += f' {ctx.get_ref(op)}'
 
         return result
 
@@ -302,12 +298,8 @@ def format_select_set(self):
             if isinstance(node, ops.Value):
                 expr_str = self._translate(node, named=True)
             elif isinstance(node, ops.TableNode):
-                # A * selection, possibly prefixed
-                if context.need_aliases(node):
-                    alias = context.get_ref(node)
-                    expr_str = f'{alias}.*' if alias else '*'
-                else:
-                    expr_str = '*'
+                alias = context.get_ref(node)
+                expr_str = f'{alias}.*' if alias else '*'
             else:
                 raise TypeError(node)
             formatted.append(expr_str)

ibis/backends/base/sql/compiler/select_builder.py

@@ -215,22 +215,6 @@ def _populate_context(self):
         if self.table_set is not None:
             self._make_table_aliases(self.table_set)
 
-        # XXX: This is a temporary solution to the table-aliasing / correlated
-        # subquery problem. Will need to revisit and come up with a cleaner
-        # design (also as one way to avoid pathological naming conflicts; for
-        # example, we could define a table alias before we know that it
-        # conflicts with the name of a table used in a subquery, join, or
-        # another part of the query structure)
-
-        # There may be correlated subqueries inside the filters, requiring that
-        # we use an explicit alias when outputting as SQL. For now, we're just
-        # going to see if any table nodes appearing in the where stack have
-        # been marked previously by the above code.
-        for expr in self.filters:
-            needs_alias = self._foreign_ref_check(self, expr)
-            if needs_alias:
-                self.context.set_always_alias()
-
     # TODO(kszucs): should be rewritten using lin.traverse()
     def _make_table_aliases(self, node):
         ctx = self.context

ibis/backends/base/sql/compiler/translator.py

@@ -24,7 +24,7 @@ def __init__(self, compiler, indent=2, parent=None, params=None):
         self.subquery_memo = {}
         self.indent = indent
         self.parent = parent
-        self.always_alias = False
+        self.always_alias = True
         self.query = None
         self.params = params if params is not None else {}
 
@@ -92,9 +92,6 @@ def make_alias(self, node):
         alias = f't{i:d}'
         self.set_ref(node, alias)
 
-    def need_aliases(self, expr=None):
-        return self.always_alias or len(self.table_refs) > 1
-
     def _contexts(
         self,
         *,
@@ -114,14 +111,20 @@ def has_ref(self, node, parent_contexts=False):
     def set_ref(self, node, alias):
         self.table_refs[node] = alias
 
-    def get_ref(self, node):
+    def get_ref(self, node, search_parents=False):
         """Return the alias used to refer to an expression."""
-        assert isinstance(node, ops.Node)
+        assert isinstance(node, ops.Node), type(node)
 
         if self.is_extracted(node):
             return self.top_context.table_refs.get(node)
 
-        return self.table_refs.get(node)
+        if (ref := self.table_refs.get(node)) is not None:
+            return ref
+
+        if search_parents and (parent := self.parent) is not None:
+            return parent.get_ref(node, search_parents=search_parents)
+
+        return None
 
     def is_extracted(self, node):
         return node in self.top_context.extracted_subexprs

ibis/backends/base/sql/registry/main.py

@@ -155,10 +155,9 @@ def table_column(translator, op):
         proj_expr = op.table.to_expr().projection([op.name]).to_array().op()
         return table_array_view(translator, proj_expr)
 
-    if ctx.need_aliases():
-        alias = ctx.get_ref(op.table)
-        if alias is not None:
-            quoted_name = f'{alias}.{quoted_name}'
+    alias = ctx.get_ref(op.table, search_parents=True)
+    if alias is not None:
+        quoted_name = f"{alias}.{quoted_name}"
 
     return quoted_name
 
@@ -175,14 +174,8 @@ def exists_subquery(translator, op):
 
     subquery = ctx.get_compiled_expr(node)
 
-    if isinstance(op, ops.ExistsSubquery):
-        key = 'EXISTS'
-    elif isinstance(op, ops.NotExistsSubquery):
-        key = 'NOT EXISTS'
-    else:
-        raise NotImplementedError
-
-    return f'{key} (\n{util.indent(subquery, ctx.indent)}\n)'
+    prefix = "NOT " * isinstance(op, ops.NotExistsSubquery)
+    return f'{prefix}EXISTS (\n{util.indent(subquery, ctx.indent)}\n)'
 
 
 # XXX this is not added to operation_registry, but looks like impala is

ibis/backends/bigquery/tests/system/test_client.py

@@ -114,13 +114,13 @@ def test_different_partition_col_name(monkeypatch, client):
 
 def test_subquery_scalar_params(alltypes, project_id, dataset_id):
     expected = f"""\
-SELECT count\\(`foo`\\) AS `count`
+SELECT count\\(t0\\.`foo`\\) AS `count`
 FROM \\(
-  SELECT `string_col`, sum\\(`float_col`\\) AS `foo`
+  SELECT t1\\.`string_col`, sum\\(t1\\.`float_col`\\) AS `foo`
   FROM \\(
-    SELECT `float_col`, `timestamp_col`, `int_col`, `string_col`
-    FROM `{project_id}\\.{dataset_id}\\.functional_alltypes`
-    WHERE `timestamp_col` < @param_\\d+
+    SELECT t2\\.`float_col`, t2\\.`timestamp_col`, t2\\.`int_col`, t2\\.`string_col`
+    FROM `{project_id}\\.{dataset_id}\\.functional_alltypes` t2
+    WHERE t2\\.`timestamp_col` < @param_\\d+
   \\) t1
   GROUP BY 1
 \\) t0"""
@@ -225,11 +225,11 @@ def test_cross_project_query(public):
     expr = table[table.tags.contains("ibis")][["title", "tags"]]
     result = expr.compile()
     expected = """\
-SELECT `title`, `tags`
+SELECT t0.`title`, t0.`tags`
 FROM (
-  SELECT *
-  FROM `bigquery-public-data.stackoverflow.posts_questions`
-  WHERE STRPOS(`tags`, 'ibis') - 1 >= 0
+  SELECT t1.*
+  FROM `bigquery-public-data.stackoverflow.posts_questions` t1
+  WHERE STRPOS(t1.`tags`, 'ibis') - 1 >= 0
 ) t0"""
     assert result == expected
     n = 5

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_approx/filter-approx_median/out.sql

@@ -1,2 +1,2 @@
-SELECT APPROX_QUANTILES(if(`month` > 0, `double_col`, NULL), 2)[OFFSET(1)] AS `tmp`
-FROM functional_alltypes
+SELECT APPROX_QUANTILES(if(t0.`month` > 0, t0.`double_col`, NULL), 2)[OFFSET(1)] AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_approx/filter-approx_nunique/out.sql

@@ -1,2 +1,2 @@
-SELECT APPROX_COUNT_DISTINCT(if(`month` > 0, `double_col`, NULL)) AS `tmp`
-FROM functional_alltypes
+SELECT APPROX_COUNT_DISTINCT(if(t0.`month` > 0, t0.`double_col`, NULL)) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_approx/no_filter-approx_median/out.sql

@@ -1,2 +1,2 @@
-SELECT APPROX_QUANTILES(`double_col`, 2)[OFFSET(1)] AS `tmp`
-FROM functional_alltypes
+SELECT APPROX_QUANTILES(t0.`double_col`, 2)[OFFSET(1)] AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_approx/no_filter-approx_nunique/out.sql

@@ -1,2 +1,2 @@
-SELECT APPROX_COUNT_DISTINCT(`double_col`) AS `tmp`
-FROM functional_alltypes
+SELECT APPROX_COUNT_DISTINCT(t0.`double_col`) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_binary/out.sql

@@ -1,2 +1,2 @@
-SELECT CAST(`value` AS BYTES) AS `tmp`
-FROM t
+SELECT CAST(t0.`value` AS BYTES) AS `tmp`
+FROM t t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_bit/filter-bit_and/out.sql

@@ -1,2 +1,2 @@
-SELECT BIT_AND(if(`bigint_col` > 0, `int_col`, NULL)) AS `tmp`
-FROM functional_alltypes
+SELECT BIT_AND(if(t0.`bigint_col` > 0, t0.`int_col`, NULL)) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_bit/filter-bit_or/out.sql

@@ -1,2 +1,2 @@
-SELECT BIT_OR(if(`bigint_col` > 0, `int_col`, NULL)) AS `tmp`
-FROM functional_alltypes
+SELECT BIT_OR(if(t0.`bigint_col` > 0, t0.`int_col`, NULL)) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_bit/filter-bit_xor/out.sql

@@ -1,2 +1,2 @@
-SELECT BIT_XOR(if(`bigint_col` > 0, `int_col`, NULL)) AS `tmp`
-FROM functional_alltypes
+SELECT BIT_XOR(if(t0.`bigint_col` > 0, t0.`int_col`, NULL)) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_bit/no_filter-bit_and/out.sql

@@ -1,2 +1,2 @@
-SELECT BIT_AND(`int_col`) AS `tmp`
-FROM functional_alltypes
+SELECT BIT_AND(t0.`int_col`) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_bit/no_filter-bit_or/out.sql

@@ -1,2 +1,2 @@
-SELECT BIT_OR(`int_col`) AS `tmp`
-FROM functional_alltypes
+SELECT BIT_OR(t0.`int_col`) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_bit/no_filter-bit_xor/out.sql

@@ -1,2 +1,2 @@
-SELECT BIT_XOR(`int_col`) AS `tmp`
-FROM functional_alltypes
+SELECT BIT_XOR(t0.`int_col`) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_bool_reducers/mean/out.sql

@@ -1,2 +1,2 @@
-SELECT avg(CAST(`bool_col` AS INT64)) AS `tmp`
-FROM functional_alltypes
+SELECT avg(CAST(t0.`bool_col` AS INT64)) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_bool_reducers/sum/out.sql

@@ -1,2 +1,2 @@
-SELECT sum(CAST(`bool_col` AS INT64)) AS `tmp`
-FROM functional_alltypes
+SELECT sum(CAST(t0.`bool_col` AS INT64)) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_bool_reducers_where_conj/out.sql

@@ -1,2 +1,2 @@
-SELECT sum(if((`month` > 6) AND (`month` < 10), CAST(`bool_col` AS INT64), NULL)) AS `tmp`
-FROM functional_alltypes
+SELECT sum(if((t0.`month` > 6) AND (t0.`month` < 10), CAST(t0.`bool_col` AS INT64), NULL)) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_bool_reducers_where_simple/out.sql

@@ -1,2 +1,2 @@
-SELECT avg(if(`month` > 6, CAST(`bool_col` AS INT64), NULL)) AS `tmp`
-FROM functional_alltypes
+SELECT avg(if(t0.`month` > 6, CAST(t0.`bool_col` AS INT64), NULL)) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_bucket/out.sql

@@ -1,7 +1,7 @@
 SELECT
   CASE
-    WHEN (0 <= `value`) AND (`value` < 1) THEN 0
-    WHEN (1 <= `value`) AND (`value` <= 3) THEN 1
+    WHEN (0 <= t0.`value`) AND (t0.`value` < 1) THEN 0
+    WHEN (1 <= t0.`value`) AND (t0.`value` <= 3) THEN 1
     ELSE CAST(NULL AS INT64)
   END AS `tmp`
-FROM t
+FROM t t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_compile_toplevel/out.sql

@@ -1,2 +1,2 @@
-SELECT sum(`foo`) AS `tmp`
-FROM t0
+SELECT sum(t0.`foo`) AS `tmp`
+FROM t0 t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_cov/pop/out.sql

@@ -1,2 +1,2 @@
-SELECT COVAR_POP(`double_col`, `double_col`) AS `tmp`
-FROM functional_alltypes
+SELECT COVAR_POP(t0.`double_col`, t0.`double_col`) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_cov/sample/out.sql

@@ -1,2 +1,2 @@
-SELECT COVAR_SAMP(`double_col`, `double_col`) AS `tmp`
-FROM functional_alltypes
+SELECT COVAR_SAMP(t0.`double_col`, t0.`double_col`) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_divide_by_zero/floordiv/out.sql

@@ -1,2 +1,2 @@
-SELECT CAST(FLOOR(IEEE_DIVIDE(`double_col`, 0)) AS INT64) AS `tmp`
-FROM functional_alltypes
+SELECT CAST(FLOOR(IEEE_DIVIDE(t0.`double_col`, 0)) AS INT64) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_divide_by_zero/truediv/out.sql

@@ -1,2 +1,2 @@
-SELECT IEEE_DIVIDE(`double_col`, 0) AS `tmp`
-FROM functional_alltypes
+SELECT IEEE_DIVIDE(t0.`double_col`, 0) AS `tmp`
+FROM functional_alltypes t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_extract_temporal_from_timestamp/date/out.sql

@@ -1,2 +1,2 @@
-SELECT DATE(`ts`) AS `tmp`
-FROM t
+SELECT DATE(t0.`ts`) AS `tmp`
+FROM t t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_extract_temporal_from_timestamp/time/out.sql

@@ -1,2 +1,2 @@
-SELECT TIME(`ts`) AS `tmp`
-FROM t
+SELECT TIME(t0.`ts`) AS `tmp`
+FROM t t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_geospatial_azimuth/out.sql

@@ -1,2 +1,2 @@
-SELECT ST_AZIMUTH(`p0`, `p1`) AS `tmp`
-FROM t
+SELECT ST_AZIMUTH(t0.`p0`, t0.`p1`) AS `tmp`
+FROM t t0

ibis/backends/bigquery/tests/unit/snapshots/test_compiler/test_geospatial_binary/contains/out.sql

@@ -1,2 +1,2 @@
-SELECT ST_CONTAINS(`geog0`, `geog1`) AS `tmp`
-FROM t
+SELECT ST_CONTAINS(t0.`geog0`, t0.`geog1`) AS `tmp`
+FROM t t0