由于 PostgreSQL 不允许在 DELETE 语句中直接使用 WITH 子句的结果,我们需要使用一个临时表或者 CTE(公用表表达式)的嵌套来实现。 sql WITH duplicate_rows AS ( SELECT id -- 假设 id 是主键或唯一标识符 FROM ( SELECT *, ROW_NUMBER() OVER (PARTITION BY email ORDER BY id) AS row_num FROM users ...
Deleting duplicate rows from a table is a little bit tricky. Finding and deleting duplicate rows is pretty easy if the table has a limited number of records. However, if the table has enormous data, then finding and deleting the duplicates can be challenging. PostgreSQL provides multiple ways ...
createtemporarytablemytmp(idintprimarykey, note text)oncommitdeleterows; 使用\dt命令查看表会发现,临时表会被存放在一个pg_temp开头的Schema下。 临时表后的on commit关键字有三种行为: on commit preserve rows:和默认不带on commit一样,表和数据会存在于整个会话的生命周期; on commit delete rows:表示在事...
Delete on testtab04 (cost=0.00..22.30 rows=1230 width=6) -> Seq Scan on testtab04 (cost=0.00..22.30 rows=1230 width=6) (2 rows) 更新语句的执行计划如下: osdba=# explain update testtab04 set note='bbbbbbbbbbbbbbbb'; QUERY PLAN --- Update on testtab04 (cost=0.00..22.30 rows=1230...
delete from [表名] 1. or TRUNCATE TABLE [表名] 1. 区别:Truncate table 表名 (注:不带where语句) 速度快,而且效率高。 因为DELETE 语句每次删除一行,并在事务日志中为所删除的每行记录一项。TRUNCATE TABLE 通过释放存储表数据所用的数据页来删除数据,并且只在事务日志中记录页的释放 ...
How to delete duplicate rows in PostgreSQL –show you various ways to delete duplicate rows from a table. How to generate a random number in a range –illustrate how to generate a random number in a specific range. EXPLAIN statement–guide you on how to use the EXPLAIN statement to return...
SELECT DISTINCT –Eliminate duplicate rows from a result set by values of one or more columns. SELECT DISTINCT ON –Learn how to group rows into distinct groups and select the first row in each group. Section 12. Database Views # In this section, you’ll learn how to use database views...
ERROR: 21000: ON CONFLICT DO UPDATE command cannot affect row a second time HINT: Ensure that no rows proposed for insertion within the same command have duplicate constrained values. LOCATION: ExecOnConflictUpdate, nodeModifyTable.c:1133
在逻辑复制过程中,如果在复制过程中出现任何冲突,如主键冲突,逻辑复制都会停止。这时候需要我们手动去解决。修复冲入的方法共有两种:在订阅端手动找到冲突的数据并删除,然后重新让订阅继续。在订阅端调用 pg_replication_origin_advance 函数,跳过有冲突的事务。
Duplicate 3.1 Aggregate 模型 我们以实际的例子来说明什么是聚合模型,以及如何正确的使用聚合模型。 示例1:导入数据聚合 假设业务有如下数据表模式: 如果转换成建表语句则如下(省略建表语句中的 Partition 和 Distribution 信息) CREATE TABLE IF NOT EXISTS example_db.expamle_tbl ...