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" ...
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_...
这个操作在间隔分区上执行会命中BUG:20598042,ALTER TABLE DROP COLUMN … CHECKPOINT on an INTERVAL PARTITIONED table fails with ORA-600 [17016] 执行结果是: drop column checkpoint操作会报ORA-600[17016]错误; 插入和查询操作,在drop过程以及drop报错之后,均抛出ORA-12986异常; 在打补丁修复bug之前,这个表将...
经过进一步研究发现数据块等待的对象是 I_WRI$_OPTSTAT_H_OBJ#_ICOL#_ST,会话正在更新AWR报告相关视图的索引信息,所以比较慢。 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 t...
ALTERTABLEtable_nameDROP( column_name_1, column_name_2 );Code language:SQL (Structured Query Language)(sql) Oracle DROP COLUMN clause example The following statement removes theemailandphonecolumns from thesupplierstable: In this tutorial, you have learned how to use the Oracle drop column statem...
www.ibm.com|基于103个网页 2. 删除字段 起来/禁止使用,其主要目的是在业务高峰期直接删除字段(DROP COLUMN)的操作可能有风险,先暂时通过 SET UNUSED … www.net527.cn|基于38个网页 3. 删除表中的列 SQL语法与范例详解词典... ... add column 向表中添加新列 4drop column删除表中的列5 modify column...
I have a really big table (4 billion records). I want to drop one column but its taking hours and still running. Any advice/tip on how to drop the column faster? The column has only NULL values. Sorry, you can't reply to this topic. It has been closed. ...
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 ...
ORA-12988: cannot drop column from table owned by SYS 在Oracle中,sys用户下面的表中的列是不可用drop的,如果drop会报错: SQL> desc test Name Null? Type --- --- ID NOTNULL NUMBER(38) NAME VARCHAR2(20) NAME1 CLOB SQL> show user USER is "SYS" SQL> alter table...
mysql> alter table t1 add column c3 char(10), ALGORITHM=INSTANT; Query OK, 0 rows affected (0.01 sec) Records: 0 Duplicates: 0 Warnings: 0 Although, we had few limitations in this early implementation. With ALGORITHM=INSTANT, new column can be added only as the last column of table. ...