kevinyu98 commented on a change in pull request #25549: [SPARK-28828][DOC] Document REFRESH TABLE command URL: https://github.com/apache/spark/pull/25549#discussion_r323885689
########## File path: docs/sql-ref-syntax-aux-refresh-table.md ########## @@ -0,0 +1,47 @@ +--- +layout: global +title: REFRESH TABLE +displayTitle: REFRESH TABLE +license: | + 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. +--- + +### Description +`REFRESH TABLE` statement first invalidates all the cached entries, which includes data and metadata of the given table +or view, then cache lazily when the table is scanned next time. +For Hive metastore table, the metadata is refreshed. For data source tables, the schema will not be inferred and +refreshed. + +### Syntax +{% highlight sql %} +REFRESH TABLE tableIdentifier + +tableIdentifier:= [db.][table_name] +{% endhighlight %} +**Note**<br> +* table_name is either a qualified or unqualified name that designates a table/view. If no database identifier is +provided, it refers to a temporary view or a table/view in the current database. + +### Examples +{% highlight sql %} +-- The cached entries of the table will be refreshed +-- The table is resolved from the current database as the table name is unqualified. +REFRESH TABLE tbl1 +-- The cached entries of the view will be refreshed or invalidated +-- The view is resolved from tempDB database, as the view name is qualified. +REFRESH TABLE tempDB.view1 Review comment: ok ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
