Github user lw-lin commented on a diff in the pull request:
https://github.com/apache/spark/pull/14116#discussion_r70218352
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/systemcatalog/InformationSchema.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.execution.systemcatalog
+
+import java.sql.{Date, Timestamp}
+
+import scala.collection.mutable.ArrayBuffer
+
+import org.apache.commons.lang3.StringUtils
+
+import org.apache.spark.rdd.RDD
+import org.apache.spark.sql._
+import org.apache.spark.sql.catalyst.dsl.plans._
+import org.apache.spark.sql.catalyst.expressions.Alias
+import org.apache.spark.sql.catalyst.plans.logical.Project
+import org.apache.spark.sql.execution.datasources._
+import org.apache.spark.sql.sources._
+import org.apache.spark.sql.types._
+
+/**
+ * INFORMATION_SCHEMA is a database consisting views which provide
information about all of the
+ * tables, views, columns in a database.
+ */
+object InformationSchema {
+ val INFORMATION_SCHEMA = "information_schema"
+ /**
+ * Register INFORMATION_SCHEMA database.
+ */
+ def registerInformationSchema(sparkSession: SparkSession): Unit = {
+ sparkSession.sql(s"CREATE DATABASE IF NOT EXISTS $INFORMATION_SCHEMA")
+ registerView(sparkSession, new DatabasesRelationProvider,
Seq("schemata", "databases"))
+ registerView(sparkSession, new TablesRelationProvider, Seq("tables"))
+ registerView(sparkSession, new ViewsRelationProvider, Seq("views"))
+ registerView(sparkSession, new ColumnsRelationProvider, Seq("columns"))
+ registerView(sparkSession, new SessionVariablesRelationProvider,
Seq("session_variables"))
+ }
+
+ /**
+ * Register a INFORMATION_SCHEMA relation provider as a temporary view
of Spark Catalog.
+ */
+ private def registerView(
+ sparkSession: SparkSession,
+ relationProvider: SchemaRelationProvider,
+ names: Seq[String]) {
+ val plan =
+
LogicalRelation(relationProvider.createRelation(sparkSession.sqlContext, null,
null)).analyze
+ val projectList = plan.output.zip(plan.schema).map {
+ case (attr, col) => Alias(attr, col.name)()
+ }
+ sparkSession.sessionState.executePlan(Project(projectList, plan))
+ for (name <- names) {
+ // TODO(dongjoon): This is a hack to give a database concept for
Spark temporary views.
+ // We should generalize this later.
+
sparkSession.sessionState.catalog.createTempView(s"$INFORMATION_SCHEMA.$name",
+ plan, overrideIfExists = true)
+ }
+ }
+
+ /**
+ * Compile filter array into single string condition.
+ */
+ private[systemcatalog] def getConditionExpressionString(filters:
Array[Filter]): String = {
+ val str = filters.flatMap(InformationSchema.compileFilter).map(p =>
s"($p)").mkString(" AND ")
+ if (str.length == 0) "TRUE" else str
+ }
+
+ /**
+ * Convert filter into string expression.
+ */
+ private[systemcatalog] def compileFilter(f: Filter): Option[String] = {
--- End diff --
Oh I see. Then if we won't dedup this for now, let's leave some comments
saying if we should change some piece of code please don't forget to change the
other? What do you think?
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For additional commands, e-mail: reviews-h...@spark.apache.org
