67 lines
2.5 KiB
Markdown
67 lines
2.5 KiB
Markdown
---
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{
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"title": "DELETE",
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"language": "zh-CN"
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}
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---
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<!--
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Licensed to the Apache Software Foundation (ASF) under one
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or more contributor license agreements. See the NOTICE file
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distributed with this work for additional information
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regarding copyright ownership. The ASF licenses this file
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to you under the Apache License, Version 2.0 (the
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"License"); you may not use this file except in compliance
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with 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,
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software distributed under the License is distributed on an
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"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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KIND, either express or implied. See the License for the
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specific language governing permissions and limitations
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under the License.
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-->
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# DELETE
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## description
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该语句用于按条件删除指定 table（base index） partition 中的数据。
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该操作会同时删除和此 base index 相关的 rollup index 的数据。
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语法：
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DELETE FROM table_name [PARTITION partition_name | PARTITIONS (p1, p2)]
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WHERE
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column_name1 op { value | value_list } [ AND column_name2 op { value | value_list } ...];
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说明：
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1) op 的可选类型包括：=, >, <, >=, <=, !=, in, not in
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2) 只能指定 key 列上的条件。
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2) 当选定的 key 列不存在于某个 rollup 中时，无法进行 delete。
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3) 条件之间只能是“与”的关系。
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若希望达成“或”的关系，需要将条件分写在两个 DELETE 语句中。
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4) 如果为分区表，可以指定分区，如不指定，且会话变量 delete_without_partition 为 true，则会应用到所有分区。如果是单分区表，可以不指定。
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注意：
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该语句可能会降低执行后一段时间内的查询效率。
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影响程度取决于语句中指定的删除条件的数量。
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指定的条件越多，影响越大。
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## example
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1. 删除 my_table partition p1 中 k1 列值为 3 的数据行
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DELETE FROM my_table PARTITION p1
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WHERE k1 = 3;
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2. 删除 my_table partition p1 中 k1 列值大于等于 3 且 k2 列值为 "abc" 的数据行
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DELETE FROM my_table PARTITION p1
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WHERE k1 >= 3 AND k2 = "abc";
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3. 删除 my_table partition p1, p2 中 k1 列值大于等于 3 且 k2 列值为 "abc" 的数据行
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DELETE FROM my_table PARTITIONS (p1, p2)
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WHERE k1 >= 3 AND k2 = "abc";
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## keyword
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DELETE
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