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  • 表数据压缩

    Oracle提供了一下几种类型的表压缩方法:
    1、Basic Compression:压缩等级High,CPU开销较小
    2、OLTP Compression:压缩等级High,CPU开销较小
    3、Warehouse Compression:压缩等级Higher,CPU开销较大(取决于压缩参数是Low还是High)
    4、Archive Compression:压缩等级Highest,CPU开销很大(取决于压缩参数是Low还是High)
     
    ALTERTABLE …COMPRESS FOR OLTP
     
     
    #1 将表转换为basic压缩表
    alter table emp move compress basic;
     
    #2 将表转换为OLTP压缩表
    alter table emp move compress for oltp;
     
    #3 将一个分区转换为basic压缩表
    alter table table_name move partitoin partition_name compress basic;
     
    #4 将一个分区转换为oltp压缩表
    alter table table_name move partitoin partition_name compress for oltp;
     
    #5 修改一个分区的现有压缩算法,修改之后只对新记录有效
    alter table table_name modify partition,partiton_name compress for oltp;
     
    #查看记录是压缩记录
    select decode(
        DBMS_COMPRESSION.GET_COMPRESSION_TYPE(
            OWNNAME => 'SCOTT',
            TABNAME => 'EMP',
            ROW_ID => 'AAAVVhAAEAAAACzAAC'),
        1,'No Compression',
        2,'Basic or OLTP Compression for Query High',
        3,'Hybrid Columnar Compression for Query Low',
        4,'Hybrid Columnar Compression for Archive High',
        5,'Hybrid Columnar Compression for Archive Low',
        'Unknown Compression Type') compression_type
    from dual;
    SQL> desc dbms_compression
    PROCEDURE GET_COMPRESSION_RATIO
    Argument Name                  Type                    In/Out Default?
    ------------------------------ ----------------------- ------ --------
    SCRATCHTBSNAME                 VARCHAR2                IN
    OWNNAME                        VARCHAR2                IN
    TABNAME                        VARCHAR2                IN
    PARTNAME                       VARCHAR2                IN
    COMPTYPE                       NUMBER                  IN
    BLKCNT_CMP                     BINARY_INTEGER          OUT
    BLKCNT_UNCMP                   BINARY_INTEGER          OUT
    ROW_CMP                        BINARY_INTEGER          OUT
    ROW_UNCMP                      BINARY_INTEGER          OUT
    CMP_RATIO                      NUMBER                  OUT
    COMPTYPE_STR                   VARCHAR2                OUT
    SUBSET_NUMROWS                 NUMBER                  IN     DEFAULT
    FUNCTION GET_COMPRESSION_TYPE RETURNS NUMBER
    Argument Name                  Type                    In/Out Default?
    ------------------------------ ----------------------- ------ --------
    OWNNAME                        VARCHAR2                IN
    TABNAME                        VARCHAR2                IN
    ROW_ID                         ROWID                   IN
    PROCEDURE INCREMENTAL_COMPRESS
    Argument Name                  Type                    In/Out Default?
    ------------------------------ ----------------------- ------ --------
    OWNNAME                        VARCHAR2(30)            IN
    TABNAME                        VARCHAR2(128)           IN
    PARTNAME                       VARCHAR2(30)            IN
    COLNAME                        VARCHAR2                IN
    DUMP_ON                        NUMBER                  IN     DEFAULT
    AUTOCOMPRESS_ON                NUMBER                  IN     DEFAULT
    WHERE_CLAUSE                   VARCHAR2                IN     DEFAULT
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  • 原文地址:https://www.cnblogs.com/kawashibara/p/9438112.html
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