refactor: always rewrite first -> first_value/last -> last_value …

…for SQL window functions

ibis/backends/bigquery/compiler.py

@@ -18,8 +18,6 @@
     exclude_unsupported_window_frame_from_ops,
     exclude_unsupported_window_frame_from_rank,
     exclude_unsupported_window_frame_from_row_number,
-    rewrite_first_to_first_value,
-    rewrite_last_to_last_value,
     rewrite_sample_as_filter,
 )
 from ibis.common.temporal import DateUnit, IntervalUnit, TimestampUnit, TimeUnit
@@ -33,8 +31,6 @@ class BigQueryCompiler(SQLGlotCompiler):
     udf_type_mapper = BigQueryUDFType
     rewrites = (
         rewrite_sample_as_filter,
-        rewrite_first_to_first_value,
-        rewrite_last_to_last_value,
         exclude_unsupported_window_frame_from_ops,
         exclude_unsupported_window_frame_from_row_number,
         exclude_unsupported_window_frame_from_rank,

ibis/backends/flink/compiler.py

@@ -15,8 +15,6 @@
     exclude_unsupported_window_frame_from_ops,
     exclude_unsupported_window_frame_from_rank,
     exclude_unsupported_window_frame_from_row_number,
-    rewrite_first_to_first_value,
-    rewrite_last_to_last_value,
     rewrite_sample_as_filter,
 )
 
@@ -30,8 +28,6 @@ class FlinkCompiler(SQLGlotCompiler):
         exclude_unsupported_window_frame_from_row_number,
         exclude_unsupported_window_frame_from_ops,
         exclude_unsupported_window_frame_from_rank,
-        rewrite_first_to_first_value,
-        rewrite_last_to_last_value,
         *SQLGlotCompiler.rewrites,
     )
 

ibis/backends/impala/compiler.py

@@ -12,8 +12,6 @@
 from ibis.backends.sql.dialects import Impala
 from ibis.backends.sql.rewrites import (
     rewrite_empty_order_by_window,
-    rewrite_first_to_first_value,
-    rewrite_last_to_last_value,
     rewrite_sample_as_filter,
 )
 
@@ -25,8 +23,6 @@ class ImpalaCompiler(SQLGlotCompiler):
     type_mapper = ImpalaType
     rewrites = (
         rewrite_sample_as_filter,
-        rewrite_first_to_first_value,
-        rewrite_last_to_last_value,
         rewrite_empty_order_by_window,
         *SQLGlotCompiler.rewrites,
     )

ibis/backends/mssql/compiler.py

@@ -24,8 +24,6 @@
     exclude_unsupported_window_frame_from_row_number,
     p,
     replace,
-    rewrite_first_to_first_value,
-    rewrite_last_to_last_value,
     rewrite_sample_as_filter,
 )
 from ibis.common.deferred import var
@@ -66,8 +64,6 @@ class MSSQLCompiler(SQLGlotCompiler):
     type_mapper = MSSQLType
     rewrites = (
         rewrite_sample_as_filter,
-        rewrite_first_to_first_value,
-        rewrite_last_to_last_value,
         exclude_unsupported_window_frame_from_ops,
         exclude_unsupported_window_frame_from_row_number,
         rewrite_rows_range_order_by_window,

ibis/backends/mysql/compiler.py

@@ -18,8 +18,6 @@
     exclude_unsupported_window_frame_from_rank,
     exclude_unsupported_window_frame_from_row_number,
     rewrite_empty_order_by_window,
-    rewrite_first_to_first_value,
-    rewrite_last_to_last_value,
     rewrite_sample_as_filter,
 )
 from ibis.common.patterns import replace
@@ -53,8 +51,6 @@ class MySQLCompiler(SQLGlotCompiler):
     rewrites = (
         rewrite_limit,
         rewrite_sample_as_filter,
-        rewrite_first_to_first_value,
-        rewrite_last_to_last_value,
         exclude_unsupported_window_frame_from_ops,
         exclude_unsupported_window_frame_from_rank,
         exclude_unsupported_window_frame_from_row_number,

ibis/backends/oracle/compiler.py

@@ -18,8 +18,6 @@
     replace_log2,
     replace_log10,
     rewrite_empty_order_by_window,
-    rewrite_first_to_first_value,
-    rewrite_last_to_last_value,
     rewrite_sample_as_filter,
 )
 
@@ -33,8 +31,6 @@ class OracleCompiler(SQLGlotCompiler):
     rewrites = (
         exclude_unsupported_window_frame_from_row_number,
         exclude_unsupported_window_frame_from_ops,
-        rewrite_first_to_first_value,
-        rewrite_last_to_last_value,
         rewrite_empty_order_by_window,
         rewrite_sample_as_filter,
         replace_log2,

ibis/backends/snowflake/compiler.py

@@ -20,8 +20,6 @@
     replace_log2,
     replace_log10,
     rewrite_empty_order_by_window,
-    rewrite_first_to_first_value,
-    rewrite_last_to_last_value,
 )
 
 
@@ -39,8 +37,6 @@ class SnowflakeCompiler(SQLGlotCompiler):
     rewrites = (
         exclude_unsupported_window_frame_from_row_number,
         exclude_unsupported_window_frame_from_ops,
-        rewrite_first_to_first_value,
-        rewrite_last_to_last_value,
         rewrite_empty_order_by_window,
         replace_log2,
         replace_log10,

ibis/backends/sql/rewrites.py

@@ -122,10 +122,23 @@ def sort_to_select(_, **kwargs):
 
 @replace(p.WindowFunction)
 def window_function_to_window(_, **kwargs):
-    """Convert a WindowFunction node to a Window node."""
+    """Convert a WindowFunction node to a Window node.
+
+    Also rewrites first -> first_value, last -> last_value.
+    """
+    func = _.func
+    if isinstance(func, (ops.First, ops.Last)):
+        if func.where is not None:
+            raise com.UnsupportedOperationError(
+                f"`{type(func).__name__.lower()}` with `where` is unsupported "
+                "in a window function"
+            )
+        cls = FirstValue if isinstance(func, ops.First) else LastValue
+        func = cls(func.arg)
+
     return Window(
         how=_.frame.how,
-        func=_.func,
+        func=func,
         start=_.frame.start,
         end=_.frame.end,
         group_by=_.frame.group_by,
@@ -292,26 +305,6 @@ def rewrite_sample_as_filter(_, **kwargs):
     return ops.Filter(_.parent, (ops.LessEqual(ops.RandomScalar(), _.fraction),))
 
 
-@replace(p.WindowFunction(p.First(x, where=y)))
-def rewrite_first_to_first_value(_, x, y, **kwargs):
-    """Rewrite Ibis's first to first_value when used in a window function."""
-    if y is not None:
-        raise com.UnsupportedOperationError(
-            "`first` with `where` is unsupported in a window function"
-        )
-    return _.copy(func=FirstValue(x))
-
-
-@replace(p.WindowFunction(p.Last(x, where=y)))
-def rewrite_last_to_last_value(_, x, y, **kwargs):
-    """Rewrite Ibis's last to last_value when used in a window function."""
-    if y is not None:
-        raise com.UnsupportedOperationError(
-            "`last` with `where` is unsupported in a window function"
-        )
-    return _.copy(func=LastValue(x))
-
-
 @replace(p.WindowFunction(frame=y @ p.WindowFrame(order_by=())))
 def rewrite_empty_order_by_window(_, y, **kwargs):
     return _.copy(frame=y.copy(order_by=(ops.NULL,)))

ibis/backends/sqlite/compiler.py

@@ -10,11 +10,7 @@
 from ibis.backends.sql.compiler import NULL, SQLGlotCompiler
 from ibis.backends.sql.datatypes import SQLiteType
 from ibis.backends.sql.dialects import SQLite
-from ibis.backends.sql.rewrites import (
-    rewrite_first_to_first_value,
-    rewrite_last_to_last_value,
-    rewrite_sample_as_filter,
-)
+from ibis.backends.sql.rewrites import rewrite_sample_as_filter
 from ibis.common.temporal import DateUnit, IntervalUnit
 
 
@@ -24,12 +20,7 @@ class SQLiteCompiler(SQLGlotCompiler):
 
     dialect = SQLite
     type_mapper = SQLiteType
-    rewrites = (
-        rewrite_sample_as_filter,
-        rewrite_first_to_first_value,
-        rewrite_last_to_last_value,
-        *SQLGlotCompiler.rewrites,
-    )
+    rewrites = (rewrite_sample_as_filter, *SQLGlotCompiler.rewrites)
 
     NAN = NULL
     POS_INF = sge.Literal.number("1e999")

ibis/backends/trino/compiler.py

@@ -19,24 +19,15 @@
 )
 from ibis.backends.sql.datatypes import TrinoType
 from ibis.backends.sql.dialects import Trino
-from ibis.backends.sql.rewrites import (
-    exclude_unsupported_window_frame_from_ops,
-    rewrite_first_to_first_value,
-    rewrite_last_to_last_value,
-)
+from ibis.backends.sql.rewrites import exclude_unsupported_window_frame_from_ops
 
 
 class TrinoCompiler(SQLGlotCompiler):
     __slots__ = ()
 
     dialect = Trino
     type_mapper = TrinoType
-    rewrites = (
-        rewrite_first_to_first_value,
-        rewrite_last_to_last_value,
-        exclude_unsupported_window_frame_from_ops,
-        *SQLGlotCompiler.rewrites,
-    )
+    rewrites = (exclude_unsupported_window_frame_from_ops, *SQLGlotCompiler.rewrites)
     quoted = True
 
     NAN = sg.func("nan")