本问是对于Oracle 12C中的In-Memory Column Store一个整体的汇总,具体细节知识在以后章节中展开 IM可以针对如下级别进行操作 Column Table Materialized view Tablespace Partition 可以指定In-Memory操作语句 CREATE TABLE ALTER TABLE CREATE TABLESPACE A
本问是对于Oracle 12C中的In-Memory Column Store一个整体的汇总,具体细节知识在以后章节中展开
IM可以针对如下级别进行操作
Column
Table
Materialized view
Tablespace
Partition
可以指定In-Memory操作语句
CREATE TABLE
ALTER TABLE
CREATE TABLESPACE
ALTER TABLESPACE
CREATE MATERIALIZED VIEW
ALTER MATERIALIZED VIEW
压缩级别
优先级
对象级别操作IM
CREATE TABLE t_xifenfei ( id NUMBER(5) PRIMARY KEY, test_col VARCHAR2(15)) INMEMORY; ALTER TABLE t_xifenfei INMEMORY; ALTER TABLE t_xifenfei INMEMORY MEMCOMPRESS FOR CAPACITY LOW; ALTER TABLE t_xifenfei INMEMORY PRIORITY HIGH; ALTER TABLE t_xifenfei INMEMORY MEMCOMPRESS FOR CAPACITY HIGH PRIORITY LOW; ALTER TABLE t_xifenfei INMEMORY MEMCOMPRESS FOR QUERY ( product_id, product_name, category_id, supplier_id, min_price) INMEMORY MEMCOMPRESS FOR CAPACITY HIGH ( product_description, warranty_period, product_status, list_price) NO INMEMORY ( weight_class, catalog_url); ALTER TABLE t_xifenfei NO INMEMORY;
补充说明:列级别设置的优先级无效,优先级是表(物化视图)或者分区表级别
表空间级别操作IM
CREATE TABLESPACE xifenfie_im DATAFILE '/u02/xifenfei.dbf' SIZE 40M ONLINE DEFAULT INMEMORY; ALTER TABLESPACE xifenfie_im DEFAULT INMEMORY MEMCOMPRESS FOR CAPACITY HIGH PRIORITY LOW;
物化视图级别
CREATE MATERIALIZED VIEW oe.prod_info_mv INMEMORY AS SELECT * FROM t_xifenfei; ALTER MATERIALIZED VIEW oe.prod_info_mv INMEMORY PRIORITY HIGH;
适合使用IN-Memory操作
A query that scans a large number of rows and applies filters that use operators such as the following: =, , and IN
A query that selects a small number of columns from a table or materialized view with a large number of columns,
such as a query that selects five columns from a table with 100 columns
A query that joins a small table to a large table
A query that aggregates data
不适合使用IN-Memory操作
Queries with complex predicates
Queries that select a large number of columns
Queries that return a large number of rows
Queries with multiple large table joins
IM控制参数
INMEMORY_SIZE 指定IM分配内存大小,默认值为0,如果启动该值最小为100M;如果在CDB环境中使用,CDB级别设置为整个库级别限制,PDB默认继承CDB设置,但是在实际使用中PDB中总数不能超过CDB限制
INMEMORY_FORCE 指定是否允许数据库中对象使用IM,默认是DEFAULT,即可以实现在对象级别定义INMEMORY or NO INMEMORY,如果设置为OFF 即表示表或者物化视图无法使用IM
INMEMORY_CLAUSE_DEFAULT 默认为空,和NO INMEMORY意义相同,表示创建新对象默认不启用IM,如果配置为INMEMORY,表示新创建对象默认启用IM
INMEMORY_QUERY 默认为TRUE,表示查询是否使用IM特性,设置为FALSE表示查询不使用IM特性
INMEMORY_MAX_POPULATE_SERVERS 默认和系统core一致,用途是把你的表中数据写入到IM中
INMEMORY_TRICKLE_REPOPULATE_SERVERS_PERCENT 控制IM中对象数据的重新载入的进程数,该值为INMEMORY_MAX_POPULATE_SERVERS参数的百分比
OPTIMIZER_INMEMORY_AWARE 该参数是控制优化器成本计算时是否考虑IM,默认为TRUE
impdp 操作IM
TRANSFORM=INMEMORY:y 继承IM导出对象属性
TRANSFORM=INMEMORY:n 不继承IM导出对象属性
TRANSFORM=INMEMORY_CLAUSE:string 修改IM导出对象关于IM的属性
参考文档:https://docs.oracle.com/database/121/ADMIN/memory.htm#ADMIN14257
- ORACLE 12C In-Memory组件初试
- 对于IN Memory Option 部分细节测试—主要当inmemory_size不足之时
- 如何估算表In-Memory需要内存大小
- ORACLE 12C In-Memory功能性能测试
- 物化视图on prebuilt table
- ORACLE 12C Invisible Columns and Column Ordering
- oracle物化视图
- 利用物化视图刷数据
原文地址:In-Memory整体汇总, 感谢原作者分享。

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