Advanced Compression选项是Oracle企业版数据库的一个额外功能,需要额外付费。确保数据库版本符合要求并已购买Advanced Compression选项。 创建表时启用数据压缩。在创建表时,可以通过在CREATE TABLE语句中添加COMPRESSION选项来启用数据压缩。例如: CREATE TABLE my_table ( column1 VARCHAR2(50), column2 NUMBER ) COMPRES...
(1)When you enable table compression by specifying either COMPRESS or COMPRESS BASIC, you enable basic table compression. Oracle Database attempts to compress data during direct-path INSERT operations when it is productive to do so. The original import utility (imp) does not support direct-path ...
This compression method can result in high CPU overhead.Updated rows and rows inserted without using direct-path or array insert are stored in row format instead of column format, and thus have a lower compression level. 使用CREATE table语句的COMPRESS子句指定表压缩。通过在ALTER table语句中使用这些...
1)CREATE TABLE AS SELECT statements 2)Parallel INSERT statements 3)INSERT statements with an APPEND or APPEND_VALUES hint 截止目前,Oracle数据库共有4种表压缩技术: 1)Basic compression 2)OLTP compression 3)Warehouse compression (Hybrid Columnar Compression) 4)Archive compression (Hybrid Columnar Compressi...
SELECT TABLE_NAME, COMPRESSION FROM USER_TABLES; TABLE_NAME COMPRESSION --- --- SALES_HISTORY DISABLED SALES_HISTORY_COMP ENABLED 也可以在表空间级别上定义COMPRESS属性,既可以在生成时利用CREATE TABLESPACE来定义,也可以稍后时间利用ALTER TABLESPACE来定义。与其他存储参数类似,COMPRESS属性也具有一些继承特性...
Create table (no compression) as select; enable compression; move table 为此,我做了另一个测试,创建表,然后一次插入一行,由pl/sql循环提交。在每次测试之后,我们通过查看user_tables获得的结果如下: 我们可以看到的最明显的一点是,对于OLTP压缩pctfree默认值与非压缩表相同都是10(这就解释了为什么在很多情况下...
Table Compression Characteristics 测试: oracle版本11.2.0.4 zx@ORCL>createtablet_basic (id number,name varchar2(10)) compress;Tablecreated. zx@ORCL>createtablet_oltp (id number,name varchar2(10)) compressforoltp;Tablecreated. zx@ORCL>selecttable_name,compression,COMPRESS_FORfromuser_tableswheretable...
create table t1asselect*from all_objects where rownum<=50000;alter table t1 compress basic;alter table t1 move 每一条SQL执行完我都会运行下面的SQL查询数据块的信息: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 select blocks,pct_free,compression,compress_for ...
select table_name, partition_name, compression from user_tab_partitions where table_name=TableName; 1. 表压缩的实现: 压缩表的数据要能够被压缩,必须正确地使用批量装载或插入: SQL 2、执行create table ... as select语句; 3、执行并行插入语句; ...
现在,在 Oracle Database 11g中(但仅限您获得了 Advanced Compression 选件许可的情况下),您可以进行如下操作: create table my_compressed_table ( col1 number(20), col2 varchar2(300), ... ) compress for all operations “compress for all operations”子句在所有 DML 活动(如 INSERT、UPDATE 等)上执...