RyanBerti commented on code in PR #40615: URL: https://github.com/apache/spark/pull/40615#discussion_r1172907828
########## sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/datasketchesAggregates.scala: ########## @@ -0,0 +1,336 @@ +/* + * 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. + */ + +package org.apache.spark.sql.catalyst.expressions.aggregate + + +import java.util.Locale + +import org.apache.datasketches.SketchesArgumentException +import org.apache.datasketches.hll.{HllSketch, TgtHllType, Union} +import org.apache.datasketches.memory.Memory + +import org.apache.spark.sql.catalyst.InternalRow +import org.apache.spark.sql.catalyst.expressions.{ExpectsInputTypes, Expression, ExpressionDescription, Literal} +import org.apache.spark.sql.catalyst.trees.{BinaryLike, TernaryLike} +import org.apache.spark.sql.types.{AbstractDataType, AnyDataType, BinaryType, DataType, IntegerType, LongType, StringType} +import org.apache.spark.unsafe.types.UTF8String + + +/** + * The HllSketchAgg function utilizes a Datasketches HllSketch instance to + * probabilistically count the number of unique values in a given column, and + * outputs the binary representation of the HllSketch. + * + * See [[https://datasketches.apache.org/docs/HLL/HLL.html]] for more information + * + * @param child child expression against which unique counting will occur + * @param lgConfigK the log-base-2 of K, where K is the number of buckets or slots for the sketch + * @param tgtHllType the target type of the HllSketch to be used (HLL_4, HLL_6, HLL_8) + */ +@ExpressionDescription( + usage = """ + _FUNC_(expr, lgConfigK, tgtHllType) - Returns the HllSketch's compact binary representation. + `lgConfigK` (optional) the log-base-2 of K, with K = the number of buckets for the HllSketch. + `tgtHllType` (optional) the target type of the HllSketch (HLL_4, HLL_6, HLL_8). """, + examples = """ + Examples: + > SELECT hll_sketch_estimate(_FUNC_(col1, 12, 'HLL_4')) + FROM VALUES (1), (1), (2), (2), (3) tab(col1); + 3 + """, + group = "agg_funcs", + since = "3.5.0") +case class HllSketchAgg( + child: Expression, + lgConfigKExpression: Expression, + tgtHllTypeExpression: Expression, + mutableAggBufferOffset: Int = 0, + inputAggBufferOffset: Int = 0) + extends TypedImperativeAggregate[HllSketch] with TernaryLike[Expression] with ExpectsInputTypes { + + // Hllsketch config - mark as lazy so that they're not evaluated during tree transformation. + + lazy val lgConfigK: Int = second.eval().asInstanceOf[Int] + lazy val tgtHllType: TgtHllType = try { + TgtHllType.valueOf(third.eval().asInstanceOf[UTF8String].toString.toUpperCase(Locale.ROOT)) + } catch { + case _: IllegalArgumentException => + throw new SketchesArgumentException("Invalid tgtHllType value") + } + + // Constructors + + def this(child: Expression) = { + this(child, Literal(HllSketch.DEFAULT_LG_K), Literal(HllSketch.DEFAULT_HLL_TYPE.toString), 0, 0) + } + + def this(child: Expression, lgConfigK: Expression) = { + this(child, lgConfigK, Literal(HllSketch.DEFAULT_HLL_TYPE.toString), 0, 0) + } + + def this(child: Expression, lgConfigK: Int) = { + this(child, Literal(lgConfigK), Literal(HllSketch.DEFAULT_HLL_TYPE.toString), 0, 0) + } + + def this(child: Expression, lgConfigK: Expression, tgtHllType: Expression) = { + this(child, lgConfigK, tgtHllType, 0, 0) + } + + def this(child: Expression, lgConfigK: Int, tgtHllType: String) = { + this(child, Literal(lgConfigK), Literal(tgtHllType), 0, 0) + } + + // Copy constructors required by ImperativeAggregate + + override def withNewMutableAggBufferOffset(newMutableAggBufferOffset: Int): HllSketchAgg = + copy(mutableAggBufferOffset = newMutableAggBufferOffset) + + override def withNewInputAggBufferOffset(newInputAggBufferOffset: Int): HllSketchAgg = + copy(inputAggBufferOffset = newInputAggBufferOffset) + + override protected def withNewChildrenInternal(newFirst: Expression, + newSecond: Expression, + newThird: Expression): HllSketchAgg = + copy(child = newFirst, lgConfigKExpression = newSecond, tgtHllTypeExpression = newThird) + + // Overrides for TernaryLike + + override def first: Expression = child + + override def second: Expression = lgConfigKExpression + + override def third: Expression = tgtHllTypeExpression + + // Overrides for TypedImperativeAggregate + + override def prettyName: String = "hll_sketch_agg" + + override def inputTypes: Seq[AbstractDataType] = Seq(AnyDataType, IntegerType, StringType) Review Comment: Just found an example of using TypeCollection to define the full set of types supported by the function's first arg; will update the implementation to use that object. -- This is an automated message from the Apache Git Service. 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