Github user cloud-fan commented on a diff in the pull request: https://github.com/apache/spark/pull/15996#discussion_r92598769 --- Diff: sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala --- @@ -363,48 +365,125 @@ final class DataFrameWriter[T] private[sql](ds: Dataset[T]) { throw new AnalysisException("Cannot create hive serde table with saveAsTable API") } - val tableExists = df.sparkSession.sessionState.catalog.tableExists(tableIdent) - - (tableExists, mode) match { - case (true, SaveMode.Ignore) => - // Do nothing - - case (true, SaveMode.ErrorIfExists) => - throw new AnalysisException(s"Table $tableIdent already exists.") - - case _ => - val existingTable = if (tableExists) { - Some(df.sparkSession.sessionState.catalog.getTableMetadata(tableIdent)) - } else { - None - } - val storage = if (tableExists) { - existingTable.get.storage - } else { - DataSource.buildStorageFormatFromOptions(extraOptions.toMap) - } - val tableType = if (tableExists) { - existingTable.get.tableType - } else if (storage.locationUri.isDefined) { - CatalogTableType.EXTERNAL - } else { - CatalogTableType.MANAGED + val catalog = df.sparkSession.sessionState.catalog + val db = tableIdent.database.getOrElse(catalog.getCurrentDatabase) + val tableIdentWithDB = tableIdent.copy(database = Some(db)) + val tableName = tableIdent.unquotedString + + catalog.getTableMetadataOption(tableIdent) match { + // If the table already exists... + case Some(tableMeta) => + mode match { + case SaveMode.Ignore => // Do nothing + + case SaveMode.ErrorIfExists => + throw new AnalysisException(s"Table $tableName already exists. You can set SaveMode " + + "to SaveMode.Append to insert data into the table or set SaveMode to " + + "SaveMode.Overwrite to overwrite the existing data.") + + case SaveMode.Append => + // Check if the specified data source match the data source of the existing table. + val specifiedProvider = DataSource.lookupDataSource(source) + // TODO: Check that options from the resolved relation match the relation that we are + // inserting into (i.e. using the same compression). + + // Pass a table identifier with database part, so that `lookupRelation` won't get temp + // views unexpectedly. + EliminateSubqueryAliases(catalog.lookupRelation(tableIdentWithDB)) match { + case l @ LogicalRelation(_: InsertableRelation | _: HadoopFsRelation, _, _) => + // check if the file formats match + l.relation match { + case r: HadoopFsRelation if r.fileFormat.getClass != specifiedProvider => + throw new AnalysisException( + s"The file format of the existing table $tableName is " + + s"`${r.fileFormat.getClass.getName}`. It doesn't match the specified " + + s"format `$source`") + case _ => + } + case s: SimpleCatalogRelation if DDLUtils.isDatasourceTable(s.metadata) => // OK. + case c: CatalogRelation if c.catalogTable.provider == Some(DDLUtils.HIVE_PROVIDER) => + throw new AnalysisException(s"Saving data in the Hive serde table $tableName " + + s"is not supported yet. Please use the insertInto() API as an alternative.") + case o => + throw new AnalysisException(s"Saving data in ${o.toString} is not supported.") + } + + val existingSchema = tableMeta.schema + if (df.logicalPlan.schema.size != existingSchema.size) { + throw new AnalysisException( + s"The column number of the existing table $tableName" + + s"(${existingSchema.catalogString}) doesn't match the data schema" + + s"(${df.logicalPlan.schema.catalogString})") + } + + if (partitioningColumns.isDefined) { + logWarning("append to an existing table, the specified partition columns " + + s"[${partitioningColumns.get.mkString(", ")}] will be ignored.") + } + + val specifiedBucketSpec = getBucketSpec + if (specifiedBucketSpec.isDefined) { + logWarning("append to an existing table, the specified bucketing " + + s"(${specifiedBucketSpec.get}) will be ignored.") + } + + // Because we are inserting into an existing table, we should respect the existing + // schema and adjust columns order of the given dataframe according to it. + val adjustedColumns = existingSchema.map(f => Column(df.resolve(f.name))) + df.select(adjustedColumns: _*).write.insertInto(tableIdentWithDB) + + case SaveMode.Overwrite => + EliminateSubqueryAliases(catalog.lookupRelation(tableIdentWithDB)) match { + // Only do the check if the table is a data source table + // (the relation is a BaseRelation). + case LogicalRelation(dest: BaseRelation, _, _) => + // Get all input data source relations of the query. + val srcRelations = df.logicalPlan.collect { + case LogicalRelation(src: BaseRelation, _, _) => src + } + if (srcRelations.contains(dest)) { + throw new AnalysisException( + s"Cannot overwrite table $tableName that is also being read from") + } + case _ => // OK + } + + // Drop the existing table and create it again. + catalog.dropTable(tableIdentWithDB, ignoreIfNotExists = true, purge = false) + createTable(tableIdentWithDB) + + // Refresh the cache of the table in the catalog. + catalog.refreshTable(tableIdentWithDB) } - val tableDesc = CatalogTable( - identifier = tableIdent, - tableType = tableType, - storage = storage, - schema = new StructType, - provider = Some(source), - partitionColumnNames = partitioningColumns.getOrElse(Nil), - bucketSpec = getBucketSpec - ) - df.sparkSession.sessionState.executePlan( - CreateTable(tableDesc, mode, Some(df.logicalPlan))).toRdd + // If the table doesn't exist... + case None => createTable(tableIdentWithDB) } } + private def createTable(tableIdent: TableIdentifier): Unit = { + val storage = DataSource.buildStorageFormatFromOptions(extraOptions.toMap) + val tableType = if (storage.locationUri.isDefined) { --- End diff -- I reverted https://github.com/apache/spark/pull/15983 here because it's not needed anymore after this refactor.
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