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ShowCreateTableCommand Logical Command

ShowCreateTableCommand is a logical command that <> a SHOW CREATE TABLE SQL statement (with a data source / non-Hive or a Hive table).

ShowCreateTableCommand is <> when SparkSqlAstBuilder is requested to parse <> SQL statement.

[[output]] ShowCreateTableCommand uses a single createtab_stmt column (of type StringType) for the output schema.

import org.apache.spark.sql.SaveMode
spark.range(10e4.toLong)
  .write
  .bucketBy(4, "id")
  .sortBy("id")
  .mode(SaveMode.Overwrite)
  .saveAsTable("bucketed_4_10e4")
scala> sql("SHOW CREATE TABLE bucketed_4_10e4").show(truncate = false)
+----------------------------------------------------------------------------------------------------------------------------------------------------+
|createtab_stmt                                                                                                                                      |
+----------------------------------------------------------------------------------------------------------------------------------------------------+
|CREATE TABLE `bucketed_4_10e4` (`id` BIGINT)
USING parquet
OPTIONS (
  `serialization.format` '1'
)
CLUSTERED BY (id)
SORTED BY (id)
INTO 4 BUCKETS
|
+----------------------------------------------------------------------------------------------------------------------------------------------------+

scala> sql("SHOW CREATE TABLE bucketed_4_10e4").as[String].collect.foreach(println)
CREATE TABLE `bucketed_4_10e4` (`id` BIGINT)
USING parquet
OPTIONS (
  `serialization.format` '1'
)
CLUSTERED BY (id)
SORTED BY (id)
INTO 4 BUCKETS

[[table]] [[creating-instance]] ShowCreateTableCommand takes a single TableIdentifier when created.

=== [[run]] Executing Logical Command -- run Method

[source, scala]

run(sparkSession: SparkSession): Seq[Row]

NOTE: run is part of <> to execute (run) a logical command.

run requests the SparkSession for the <> that is used to access the <>.

run then requests the SessionCatalog to retrieve the table metadata from the external catalog (metastore).

run then <> for a data source / non-Hive table or <> for a Hive table (per the table metadata).

In the end, run returns the CREATE TABLE statement in a single Row.

=== [[showHiveTableNonDataColumns]] showHiveTableNonDataColumns Internal Method

[source, scala]

showHiveTableNonDataColumns(metadata: CatalogTable, builder: StringBuilder): Unit

showHiveTableNonDataColumns...FIXME

NOTE: showHiveTableNonDataColumns is used exclusively when ShowCreateTableCommand logical command is requested to <>.

=== [[showCreateHiveTable]] showCreateHiveTable Internal Method

[source, scala]

showCreateHiveTable(metadata: CatalogTable): String

showCreateHiveTable...FIXME

NOTE: showCreateHiveTable is used exclusively when ShowCreateTableCommand logical command is executed (with a Hive <>).

=== [[showHiveTableHeader]] showHiveTableHeader Internal Method

[source, scala]

showHiveTableHeader(metadata: CatalogTable, builder: StringBuilder): Unit

showHiveTableHeader...FIXME

NOTE: showHiveTableHeader is used exclusively when ShowCreateTableCommand logical command is requested to <>.


Last update: 2020-11-07