87409c42bc
### What changes were proposed in this pull request? Fix typo and highlight that `ADD PARTITIONS` is the default. ### Why are the changes needed? Fix a typo which can mislead users. ### Does this PR introduce _any_ user-facing change? No ### How was this patch tested? n/a Closes #31633 from MaxGekk/repair-table-drop-partitions-followup. Lead-authored-by: Wenchen Fan <cloud0fan@gmail.com> Co-authored-by: Max Gekk <max.gekk@gmail.com> Signed-off-by: HyukjinKwon <gurwls223@apache.org>
79 lines
3 KiB
Markdown
79 lines
3 KiB
Markdown
---
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layout: global
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title: REPAIR TABLE
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displayTitle: REPAIR TABLE
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license: |
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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---
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### Description
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`MSCK REPAIR TABLE` recovers all the partitions in the directory of a table and updates the Hive metastore. When creating a table using `PARTITIONED BY` clause, partitions are generated and registered in the Hive metastore. However, if the partitioned table is created from existing data, partitions are not registered automatically in the Hive metastore. User needs to run `MSCK REPAIR TABLE` to register the partitions. `MSCK REPAIR TABLE` on a non-existent table or a table without partitions throws an exception. Another way to recover partitions is to use `ALTER TABLE RECOVER PARTITIONS`.
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If the table is cached, the command clears cached data of the table and all its dependents that refer to it. The cache will be lazily filled when the next time the table or the dependents are accessed.
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### Syntax
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```sql
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MSCK REPAIR TABLE table_identifier [{ADD|DROP|SYNC} PARTITIONS]
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```
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### Parameters
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* **table_identifier**
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Specifies the name of the table to be repaired. The table name may be optionally qualified with a database name.
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**Syntax:** `[ database_name. ] table_name`
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* **`{ADD|DROP|SYNC} PARTITIONS`**
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Specifies how to recover partitions. If not specified, **ADD** is the default.
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* **ADD**, the command adds new partitions to the session catalog for all sub-folder in the base table folder that don't belong to any table partitions.
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* **DROP**, the command drops all partitions from the session catalog that have non-existing locations in the file system.
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* **SYNC** is the combination of **DROP** and **ADD**.
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### Examples
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```sql
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-- create a partitioned table from existing data /tmp/namesAndAges.parquet
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CREATE TABLE t1 (name STRING, age INT) USING parquet PARTITIONED BY (age)
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LOCATION "/tmp/namesAndAges.parquet";
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-- SELECT * FROM t1 does not return results
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SELECT * FROM t1;
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-- run MSCK REPAIR TABLE to recovers all the partitions
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MSCK REPAIR TABLE t1;
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-- SELECT * FROM t1 returns results
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SELECT * FROM t1;
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+-------+---+
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| name|age|
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+-------+---+
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|Michael| 20|
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+-------+---+
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| Justin| 19|
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+-------+---+
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| Andy| 30|
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+-------+---+
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```
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### Related Statements
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* [ALTER TABLE](sql-ref-syntax-ddl-alter-table.html)
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