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_...
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。 altertablet_test_coldropcolumn vard; 1. 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 altertablet_test_colset...
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 ...
alter table tbl_rt_request_event drop column message_clr; The table has 13.4 million rows. The column getting dropped is CLOB and is only 0.125MB in size. The drop column is generating lot of archives and not completing. v$session_longops shows this statement is expected to run 11+ hours....
Oracle SET UNUSED COLUMN example Let’screate a tablenamedsuppliersfor the demonstration: CREATETABLEsuppliers ( supplier_idNUMBERGENERATEDBYDEFAULTASIDENTITY, contact_nameVARCHAR2(255)NOTNULL, company_nameVARCHAR2(255), phoneVARCHAR2(100)NOTNULL, emailVARCHAR2(255)NOTNULL, faxVARCHAR2(100)NOTNULL,...
In other words, the time taken to ADD/DROP new/old column(s) to/from a table with 1 row would be the same as time taken to ADD/DROP new/old column(s) to/from a table having 100M rows. Syntax ALTER TABLE ADD COLUMN <column_name> <column_type> [DEFAULT default_value] [FIRST...
2、Oracle bug,可能性很低 Bug 6781367 - ALTER TABLE ADD COLUMN or mass UPDATE can be slow in ASSM (文档 ID 6781367.8) 解决方案: 清理那个表和索引,收集统计信息 analyze table SYS.WRI$_OPTSTAT_HISTGRM_HISTORY compute statistics ; alter index "sys"."I_WRI$_OPTSTAT_H_OBJ#_ICOL#_ST" rebuild...
Syntax ALTER TABLE ADD COLUMN <column_name> <column_type> [DEFAULTdefault_value] [FIRST]/[AFTERcolumn_name], ALGORITHM=INSTANT; ALTER TABLE DROP COLUMN <column_name>, ALGORITHM=INSTANT; NOTE : ALGORITHM=INSTANT is optional here as, by default, all ADD/DROP columns are done with ALGORITHM...
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...
If no default value for the corresponding column has been specified, then Oracle inserts null.Note: Parallel direct-path INSERT supports only the subquery syntax of the INSERT statement, not the values_clause. Please refer to Oracle9i Database Concepts for information on serial and parallel ...