再次查询DBA_UNUSED_COL_TABS视图中的数据,将得到一个空的结果集。 Oracle使用DROP COLUMN子句删除列 要从物理表中删除列,请使用以下语句: ALTER TABLE table_name DROP COLUMN column_name; 要删除多个列,请使用以下语句: ALTER TABLE table_name DROP ( column_name_1, column_name_2 ); Oracle DROP COLUMN...
We often need to drop the column in the table. There are two ways to drop the column in Oracle (a) alter table drop column in oracle (b) alter table set unused column in oracle DROP COLUMN using DROP COLUMN Here in this wedrop the column from table using below command. ALTER TABLE ...
场景一:直接drop column 运行业务模拟程序,开始正常插入日志,然后删除大表的字段。 alter table t_test_col drop column vard; 影响范围: drop column操作耗时30多秒; insert 语句在drop column完成之前无法执行,等待事件为enq:TM-contention; select不受影响。 场景二:先set unused然后再drop alter table t_test_...
Oracle Drop Column Summary: in this tutorial, you will learn how to use the Oracle drop column statements to remove one or more columns from a table. Oracle Drop Column using SET UNUSED COLUMN clause The process of dropping a column from a big table can be time and resource-consuming. ...
In Oracle, the possibility to drop a column/columns in an existing table can be available only after the origin of oracle 8i. The column/columns in a table can be dropped either logically or physically, but most of the time we use the logic delete. And for this the "ALTER TABLE" ...
在OceanBase 数据库 MySQL 模式以及 Oracle 模式中直接删除含主键的列可以通过先删除主键、再删除对应的列的方式,来实现删除主键列的目的。涉及的语句如下。 ALTER TABLE table_a DROP PRIMARY KEY; ALTER TABLE table_a DROP COLUMN ID; OceanBase 数据库 MySQL 模式下删除主键的操作。 创建表。 obclient [mys...
In Oracle, SQL Server, and Google BigQuery, the syntax for ALTER TABLE Drop Column is, ALTER TABLE "table_name" DROP COLUMN "column_name"; Let's look at the example. Assuming our starting point is the Customer table created in the CREATE TABLE section: Table Customer ...
对该对象的模式的 DROPIN 特权 对象的所有者(记录在该对象的目录视图的 OWNER 列中) 对该对象的 CONTROL 特权(仅适用于索引、索引规范、昵称、程序包、表和视图) 用户定义的类型的所有者(记录在 SYSCAT.DATATYPES 目录视图的 OWNER 列中)(仅当删除与用户定义的类型相关联的方法时适用) ...
2、Oracle bug,可能性很低 Bug 6781367 - ALTER TABLE ADD COLUMN or mass UPDATE can be slow in ASSM (文档 ID 6781367.8) 解决方案: 清理那个表和索引,收集统计信息 analyze table SYS.WRI$_OPTSTAT_HISTGRM_HISTORY compute statistics ; alter index "sys"."I_WRI$_OPTSTAT_H_OBJ#_ICOL#_ST" rebuild...
The DBMS_PART.CLEANUP_GIDX procedure will identify and cleanup these global indexes to ensure efficiency in terms of storage and performance. DBMS_PART.CLEANUP_GIDX过程将识别并清除这些全局索引,以确保存储和性能方面的效率。 Partial Global Index Optimization 局部全局索引优化 The column ORPHANED_ENTRIES is...