mccheah commented on a change in pull request #25040: [SPARK-28238][SQL] Implement DESCRIBE TABLE for Data Source V2 Tables. URL: https://github.com/apache/spark/pull/25040#discussion_r306581768
########## File path: sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/DescribeTableExec.scala ########## @@ -0,0 +1,96 @@ +/* + * 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.execution.datasources.v2 + +import scala.collection.JavaConverters._ +import scala.collection.mutable.ArrayBuffer + +import org.apache.spark.rdd.RDD +import org.apache.spark.sql.catalog.v2.{Identifier, TableCatalog} +import org.apache.spark.sql.catalyst.InternalRow +import org.apache.spark.sql.catalyst.encoders.RowEncoder +import org.apache.spark.sql.catalyst.expressions.{AttributeReference, GenericRowWithSchema} +import org.apache.spark.sql.catalyst.plans.DescribeTableSchemas +import org.apache.spark.sql.execution.LeafExecNode +import org.apache.spark.sql.sources.v2.Table + +case class DescribeTableExec( + catalog: TableCatalog, + ident: Identifier, + isExtended: Boolean) extends LeafExecNode { + + import DescribeTableExec._ + + override def output: Seq[AttributeReference] = DescribeTableSchemas.DESCRIBE_TABLE_ATTRIBUTES + + override protected def doExecute(): RDD[InternalRow] = { + val rows = new ArrayBuffer[InternalRow]() + if (catalog.tableExists(ident)) { + val table = catalog.loadTable(ident) + addSchema(rows, table) + + if (isExtended) { + addPartitioning(rows, table) + addProperties(rows, table) + } + + } else { + rows += toCatalystRow(s"Table $ident does not exist.", "", "") + } + sparkContext.parallelize(rows) + } + + private def addSchema(rows: ArrayBuffer[InternalRow], table: Table): Unit = { + rows ++= table.schema.map{ column => + toCatalystRow( + column.name, column.dataType.simpleString, column.getComment().getOrElse("")) + } + } + + private def addPartitioning(rows: ArrayBuffer[InternalRow], table: Table): Unit = { + rows += EMPTY_ROW + rows += toCatalystRow(" Partitioning", "", "") + rows += toCatalystRow("--------------", "", "") + if (table.partitioning.isEmpty) { + rows += toCatalystRow("Not partitioned", "", "") + } else { + rows ++= table.partitioning.zipWithIndex.map { + case (transform, index) => toCatalystRow(s"Part $index", transform.describe(), "") + } + } + } + + private def addProperties(rows: ArrayBuffer[InternalRow], table: Table): Unit = { + rows += EMPTY_ROW + rows += toCatalystRow(" Table Property", " Value", "") + rows += toCatalystRow("----------------", "-------", "") + rows ++= table.properties.asScala.toList.sortBy(_._1).map { + case (key, value) => toCatalystRow(key, value, "") + } + } +} + +private object DescribeTableExec { + private val ENCODER = RowEncoder(DescribeTableSchemas.DESCRIBE_TABLE_SCHEMA) + private val EMPTY_ROW = toCatalystRow("", "", "") + + private def toCatalystRow(strs: String*): InternalRow = { + ENCODER.resolveAndBind().toRow( Review comment: Fixed it - we have to copy the rows generated by the encoder since the encoder re-uses the same memory space. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
