Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/15263#discussion_r80844741
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JdbcRelationProvider.scala
---
@@ -50,67 +51,48 @@ class JdbcRelationProvider extends
CreatableRelationProvider
JDBCRelation(jdbcOptions.url, jdbcOptions.table, parts,
properties)(sqlContext.sparkSession)
}
- /*
- * The following structure applies to this code:
- * | tableExists | !tableExists
-
*------------------------------------------------------------------------------------
- * Ignore | BaseRelation | CreateTable, saveTable,
BaseRelation
- * ErrorIfExists | ERROR | CreateTable, saveTable,
BaseRelation
- * Overwrite* | (DropTable, CreateTable,) | CreateTable, saveTable,
BaseRelation
- * | saveTable, BaseRelation |
- * Append | saveTable, BaseRelation | CreateTable, saveTable,
BaseRelation
- *
- * *Overwrite & tableExists with truncate, will not drop & create, but
instead truncate
- */
override def createRelation(
sqlContext: SQLContext,
mode: SaveMode,
parameters: Map[String, String],
- data: DataFrame): BaseRelation = {
- val jdbcOptions = new JDBCOptions(parameters)
- val url = jdbcOptions.url
- val table = jdbcOptions.table
-
+ df: DataFrame): BaseRelation = {
+ val options = new JDBCOptions(parameters)
+ val url = options.url
+ val table = options.table
+ val createTableOptions = options.createTableOptions
+ val isTruncate = options.isTruncate
val props = new Properties()
props.putAll(parameters.asJava)
- val conn = JdbcUtils.createConnectionFactory(url, props)()
+ val conn = JdbcUtils.createConnectionFactory(url, props)()
try {
val tableExists = JdbcUtils.tableExists(conn, url, table)
+ if (tableExists) {
+ mode match {
+ case SaveMode.Overwrite =>
+ if (isTruncate &&
isCascadingTruncateTable(url).contains(false)) {
+ // In this case, we should truncate table and then load.
+ truncateTable(conn, table)
+ saveTable(df, url, table, props)
+ } else {
+ // Otherwise, do not truncate but just drop.
+ dropTable(conn, table)
+ createTable(df, url, table, createTableOptions, conn)
+ saveTable(df, url, table, props)
+ }
+ case SaveMode.Append =>
+ saveTable(df, url, table, props)
- val (doCreate, doSave) = (mode, tableExists) match {
- case (SaveMode.Ignore, true) => (false, false)
- case (SaveMode.ErrorIfExists, true) => throw new AnalysisException(
- s"Table or view '$table' already exists, and SaveMode is set to
ErrorIfExists.")
- case (SaveMode.Overwrite, true) =>
- if (jdbcOptions.isTruncate &&
JdbcUtils.isCascadingTruncateTable(url) == Some(false)) {
- JdbcUtils.truncateTable(conn, table)
- (false, true)
- } else {
- JdbcUtils.dropTable(conn, table)
- (true, true)
- }
- case (SaveMode.Append, true) => (false, true)
- case (_, true) => throw new IllegalArgumentException(s"Unexpected
SaveMode, '$mode'," +
- " for handling existing tables.")
- case (_, false) => (true, true)
- }
+ case SaveMode.ErrorIfExists =>
+ throw new AnalysisException(
+ s"Table or view '$table' already exists, and SaveMode is set
to ErrorIfExists.")
- if (doCreate) {
- val schema = JdbcUtils.schemaString(data, url)
- // To allow certain options to append when create a new table,
which can be
- // table_options or partition_options.
- // E.g., "CREATE TABLE t (name string) ENGINE=InnoDB DEFAULT
CHARSET=utf8"
- val createtblOptions = jdbcOptions.createTableOptions
- val sql = s"CREATE TABLE $table ($schema) $createtblOptions"
- val statement = conn.createStatement
- try {
- statement.executeUpdate(sql)
- } finally {
- statement.close()
+ case SaveMode.Ignore => // Just ignore this case.
--- End diff --
Please explicitly explain the behavior. `// Just ignore this case` is
almost useless.
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