dtenedor commented on a change in pull request #35982:
URL: https://github.com/apache/spark/pull/35982#discussion_r836702379
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/ResolveDefaultColumns.scala
##########
@@ -18,14 +18,227 @@
package org.apache.spark.sql.catalyst.util
import org.apache.spark.sql.AnalysisException
-import org.apache.spark.sql.catalyst.analysis.Analyzer
+import org.apache.spark.sql.catalyst.TableIdentifier
+import org.apache.spark.sql.catalyst.analysis.{Analyzer, NoSuchTableException,
UnresolvedAttribute, UnresolvedInlineTable, UnresolvedRelation}
+import org.apache.spark.sql.catalyst.catalog.{SessionCatalog,
UnresolvedCatalogRelation}
import org.apache.spark.sql.catalyst.expressions._
import org.apache.spark.sql.catalyst.optimizer.ConstantFolding
import org.apache.spark.sql.catalyst.parser.{CatalystSqlParser, ParseException}
import org.apache.spark.sql.catalyst.plans.logical._
+import org.apache.spark.sql.catalyst.rules.Rule
+import org.apache.spark.sql.catalyst.util.ResolveDefaultColumns._
import org.apache.spark.sql.internal.SQLConf
import org.apache.spark.sql.types._
+/**
+ * This is a rule to process DEFAULT columns in statements such as
CREATE/REPLACE TABLE.
+ *
+ * Background: CREATE TABLE and ALTER TABLE invocations support setting column
default values for
+ * later operations. Following INSERT, and INSERT MERGE commands may then
reference the value
+ * using the DEFAULT keyword as needed.
+ *
+ * Example:
+ * CREATE TABLE T(a INT DEFAULT 4, b INT NOT NULL DEFAULT 5);
+ * INSERT INTO T VALUES (1, 2);
+ * INSERT INTO T VALUES (1, DEFAULT);
+ * INSERT INTO T VALUES (DEFAULT, 6);
+ * SELECT * FROM T;
+ * (1, 2)
+ * (1, 5)
+ * (4, 6)
+ *
+ * @param analyzer analyzer to use for processing DEFAULT values stored as
text.
+ * @param catalog the catalog to use for looking up the schema of INSERT INTO
table objects.
+ * @param insert the enclosing INSERT statement for which this rule is
processing the query, if any.
+ */
+case class ResolveDefaultColumns(
+ analyzer: Analyzer,
+ catalog: SessionCatalog,
+ insert: Option[InsertIntoStatement] = None) extends Rule[LogicalPlan] {
+ override def apply(plan: LogicalPlan): LogicalPlan =
plan.resolveOperatorsWithPruning(
+ (_ => SQLConf.get.enableDefaultColumns), ruleId) {
+ case i@InsertIntoStatement(_, _, _, _, _, _)
+ if i.query.collectFirst { case u: UnresolvedInlineTable => u }.isDefined
=>
+ // Create a helper instance of this same rule with the `insert` argument
populated as `i`.
+ // Then recursively apply it on the `query` of `i` to transform the
result. This recursive
+ // application lets the below case matching against
`UnresolvedInlineTable` to trigger
+ // anywhere that operator may appear in the descendants of `i.query`.
+ val helper = ResolveDefaultColumns(analyzer, catalog, Some(i))
+ val newQuery = helper.apply(i.query)
+ i.copy(query = newQuery)
+
+ case table: UnresolvedInlineTable
+ if insert.isDefined &&
+ table.rows.nonEmpty && table.rows.forall(_.size == table.rows(0).size)
=>
+ val expanded: UnresolvedInlineTable =
addMissingDefaultColumnValues(table).getOrElse(table)
+ replaceExplicitDefaultColumnValues(analyzer, expanded).getOrElse(table)
+
+ case i@InsertIntoStatement(_, _, _, project: Project, _, _)
+ if !project.resolved =>
+ val helper = ResolveDefaultColumns(analyzer, catalog, Some(i))
+ val replaced: Option[Project] =
helper.replaceExplicitDefaultColumnValues(analyzer, project)
+ if (replaced.isDefined) i.copy(query = replaced.get) else i
+
+ case i@InsertIntoStatement(_, _, _, project: Project, _, _)
+ if project.resolved =>
+ val helper = ResolveDefaultColumns(analyzer, catalog, Some(i))
+ val expanded: Project =
helper.addMissingDefaultColumnValues(project).getOrElse(project)
+ val replaced: Option[Project] =
helper.replaceExplicitDefaultColumnValues(analyzer, expanded)
+ if (replaced.isDefined) i.copy(query = replaced.get) else i
+ }
+
+ // Helper method to check if an expression is an explicit DEFAULT column
reference.
+ private def isExplicitDefaultColumn(expr: Expression): Boolean = expr match {
+ case u: UnresolvedAttribute if
u.name.equalsIgnoreCase(CURRENT_DEFAULT_COLUMN_NAME) => true
+ case _ => false
+ }
+
+ // Each of the following methods adds a projection over the input plan to
generate missing default
+ // column values.
+ private def addMissingDefaultColumnValues(
+ table: UnresolvedInlineTable): Option[UnresolvedInlineTable] = {
+ assert(insert.isDefined)
+ val numQueryOutputs: Int = table.rows(0).size
+ val schema: StructType = getInsertTableSchema.getOrElse(return None)
+ val schemaWithoutPartitionCols =
+ StructType(schema.fields.dropRight(insert.get.partitionSpec.size))
+ val newDefaultExprs: Seq[Expression] =
+ getDefaultExprs(numQueryOutputs, schemaWithoutPartitionCols)
+ val newNames: Seq[String] =
+ schemaWithoutPartitionCols.fields.drop(numQueryOutputs).map { _.name }
+ if (newDefaultExprs.isEmpty) return None
+ Some(table.copy(names = table.names ++ newNames,
+ rows = table.rows.map { row => row ++ newDefaultExprs }))
+ }
+
+ private def addMissingDefaultColumnValues(project: Project): Option[Project]
= {
+ val numQueryOutputs: Int = project.projectList.size
+ val schema: StructType = getInsertTableSchema.getOrElse(return None)
+ val schemaWithoutPartitionCols =
+ StructType(schema.fields.dropRight(insert.get.partitionSpec.size))
+ val newDefaultExprs: Seq[Expression] =
+ getDefaultExprs(numQueryOutputs, schemaWithoutPartitionCols)
+ val newAliases: Seq[NamedExpression] =
+ newDefaultExprs.zip(schemaWithoutPartitionCols.fields).map {
+ case (expr, field) => Alias(expr, field.name)()
+ }
+ if (newDefaultExprs.isEmpty) return None
+ Some(project.copy(projectList = project.projectList ++ newAliases))
+ }
+
+ // This is a helper for the addMissingDefaultColumnValues methods above.
+ private def getDefaultExprs(
+ numQueryOutputs: Int, schemaWithoutPartitionCols: StructType):
Seq[Expression] = {
+ val remainingFields: Seq[StructField] =
schemaWithoutPartitionCols.fields.drop(numQueryOutputs)
+ val numDefaultExprsToAdd: Int = {
+ if (SQLConf.get.useNullsForMissingDefaultColumnValues) {
+ remainingFields.size
+ } else {
+
remainingFields.takeWhile(_.metadata.contains(CURRENT_DEFAULT_COLUMN_METADATA_KEY)).size
+ }
+ }
+
Seq.fill(numDefaultExprsToAdd)(UnresolvedAttribute(CURRENT_DEFAULT_COLUMN_NAME))
+ }
+
+ // Each of the following methods replaces unresolved "DEFAULT" column
references with matching
+ // default column values.
+ private def replaceExplicitDefaultColumnValues(
+ analyzer: Analyzer,
+ table: UnresolvedInlineTable): Option[UnresolvedInlineTable] = {
+ assert(insert.isDefined)
+ val schema: StructType = getInsertTableSchema.getOrElse(return None)
+ val schemaWithoutPartitionCols =
+ StructType(schema.fields.dropRight(insert.get.partitionSpec.size))
+ val defaultExprs: Seq[Expression] = schemaWithoutPartitionCols.fields.map {
+ case f if f.metadata.contains(CURRENT_DEFAULT_COLUMN_METADATA_KEY) =>
+ analyze(analyzer, f, "INSERT")
+ case _ => Literal(null)
+ }
+ var replaced = false
+ val newRows: Seq[Seq[Expression]] = {
+ table.rows.map { row: Seq[Expression] =>
+ for {
+ i <- 0 until row.size
+ expr = row(i)
+ defaultExpr = if (i < defaultExprs.size) defaultExprs(i) else
Literal(null)
+ } yield expr match {
+ case u: UnresolvedAttribute if isExplicitDefaultColumn(u) =>
+ replaced = true
+ defaultExpr
+ case expr@_ if expr.find{isExplicitDefaultColumn}.isDefined =>
+ // Return a more descriptive error message if the user tries to
nest the DEFAULT column
+ // reference inside some other expression, such as DEFAULT + 1
(this is not allowed).
+ throw new AnalysisException(DEFAULTS_IN_EXPRESSIONS_ERROR)
+ case _ => expr
+ }
+ }
+ }
+ if (!replaced) return None
+ Some(table.copy(rows = newRows))
Review comment:
Good idea, done.
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