andygrove commented on code in PR #6992:
URL: https://github.com/apache/datafusion-comet/pull/6992#discussion_r4289076432
##########
spark/src/main/scala/org/apache/comet/serde/maps.scala:
##########
@@ -132,6 +132,28 @@ object CometMapExtract extends
CometExpressionSerde[GetMapValue] {
}
}
+/**
+ * Shared gate for the native map builders, `map_from_arrays` and
`map_from_entries`, which tell
+ * keys apart by their bits. Spark's `ArrayBasedMapBuilder` finds a duplicate
`FLOAT` or `DOUBLE`
+ * key in a `HashMap` of boxed values, where every NaN is one key, and a
duplicate struct or array
+ * key in a `TreeMap` in Spark's SQL ordering, where `-0.0` equals `0.0` too.
From Spark 4.0 it
+ * also normalizes a `FLOAT` or `DOUBLE` key before the lookup, unless
+ * `spark.sql.legacy.disableMapKeyNormalization` is set, so the two zeros are
one key and
+ * `map_from_entries` stores `0.0`. A key type that holds a float at any depth
is therefore
+ * `Incompatible` on every version.
+ */
+private object MapBuilderKeySupport {
+ val floatingPointReason: String =
+ "Spark finds duplicate map keys that hold a `FLOAT` or `DOUBLE` by value,
so NaNs with " +
+ "different bits are one key, and so are `-0.0` and `0.0` inside a struct
or array key. " +
+ "From Spark 4.0, a `-0.0` key is also normalized to `0.0`, unless " +
+ "`spark.sql.legacy.disableMapKeyNormalization` is set. Comet's native
map construction " +
+ "compares the keys' bits
([#6549](https://github.com/apache/datafusion-comet/issues/6549))."
Review Comment:
Changed the PR description to `Part of #6549`, so the issue stays open until
#6682 lands. The reason string keeps its link to #6549, which is still the
right place for the open difference.
##########
spark/src/main/scala/org/apache/comet/serde/maps.scala:
##########
@@ -132,6 +132,28 @@ object CometMapExtract extends
CometExpressionSerde[GetMapValue] {
}
}
+/**
+ * Shared gate for the native map builders, `map_from_arrays` and
`map_from_entries`, which tell
+ * keys apart by their bits. Spark's `ArrayBasedMapBuilder` finds a duplicate
`FLOAT` or `DOUBLE`
+ * key in a `HashMap` of boxed values, where every NaN is one key, and a
duplicate struct or array
+ * key in a `TreeMap` in Spark's SQL ordering, where `-0.0` equals `0.0` too.
From Spark 4.0 it
+ * also normalizes a `FLOAT` or `DOUBLE` key before the lookup, unless
+ * `spark.sql.legacy.disableMapKeyNormalization` is set, so the two zeros are
one key and
+ * `map_from_entries` stores `0.0`. A key type that holds a float at any depth
is therefore
+ * `Incompatible` on every version.
+ */
+private object MapBuilderKeySupport {
+ val floatingPointReason: String =
+ "Spark finds duplicate map keys that hold a `FLOAT` or `DOUBLE` by value,
so NaNs with " +
+ "different bits are one key, and so are `-0.0` and `0.0` inside a struct
or array key. " +
+ "From Spark 4.0, a `-0.0` key is also normalized to `0.0`, unless " +
+ "`spark.sql.legacy.disableMapKeyNormalization` is set. Comet's native
map construction " +
+ "compares the keys' bits
([#6549](https://github.com/apache/datafusion-comet/issues/6549))."
+
+ def hasFloatingPointKey(dataType: MapType): Boolean =
Review Comment:
Corrected in ee66473fd. The `MapKeySupport` reason and scaladoc no longer
say the builder normalizes keys. They now say the lookup uses Spark's SQL
ordering, where `-0.0` equals `0.0` and all NaNs are equal, on every version,
and point at `MapBuilderKeySupport` for how the builder differs by version. I
kept the two objects separate rather than folding them, because one gates
lookups and the other gates construction. The builder explanation now lives
only in `MapBuilderKeySupport.floatingPointReason`. Three fixtures and
`CometMapExpressionSuite` matched the old reason text, so I updated those.
##########
spark/src/main/scala/org/apache/comet/serde/maps.scala:
##########
@@ -132,6 +132,28 @@ object CometMapExtract extends
CometExpressionSerde[GetMapValue] {
}
}
+/**
Review Comment:
The scaladoc on `MapBuilderKeySupport` now says only why the gate lives
there and points at `floatingPointReason`. The "Map construction" section in
`floating-point.md` is down to the user-facing result, with a link to the
expression compatibility guide for the reason. The audit entries and the
contributor guide rule still describe the builder behavior, since those are the
places a reader looks for the audit trail, so they will need updating when
#6682 lifts the gate.
##########
spark/src/test/resources/sql-tests/expressions/map/map_builders_float_keys.sql:
##########
@@ -0,0 +1,94 @@
+-- Licensed to the Apache Software Foundation (ASF) under one
+-- or more contributor license agreements. See the NOTICE file
+-- distributed with this work for additional information
+-- regarding copyright ownership. The ASF licenses this file
+-- to you under the Apache License, Version 2.0 (the
+-- "License"); you may not use this file except in compliance
+-- with the License. You may obtain a copy of the License at
+--
+-- http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing,
+-- software distributed under the License is distributed on an
+-- "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+-- KIND, either express or implied. See the License for the
+-- specific language governing permissions and limitations
+-- under the License.
+
+-- Map keys that hold a FLOAT or DOUBLE (#6549). Spark finds a duplicate
top-level key in a HashMap
Review Comment:
Renamed in ee66473fd to `map_builders_float_key_gate.sql`,
`map_builders_float_key_gate_legacy.sql` and
`map_builders_float_key_gate_spark_4_0.sql`, so none of the names match the
files in #6682. When #6682 lifts the gate these three should be deleted or
folded into its fixtures, since they assert dispatch and the other PR asserts
native behavior.
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