oracle 表空间管理再续

   今天是2013-12-17，继续学习。

知识点一：在昨天dump块 的时候经常看到dba：0x22222222222这样的16进制数值。那么怎么转换呢？

oracle 提供了一个软件包dbms_utility,其中包含两个过程data_block_address_file和data_block_address_block;

可以创建一个函数，进而通过这个函数进行转换。

eg：

SQL> create or replace function fno(p_dba in varchar2)
  2  return varchar2
  3  as
  4  l_str varchar2(255) default null;
  5  begin
  6  l_str:='datafile# is  '||dbms_utility.data_block_address_file(to_number(ltrim(p_dba,'0x'),'xxxxxxxxx'))||chr('10')||'datablock# is  '||dbms_utility.data_block_address_block(to_number(ltrim(p_dba,'0x'),'xxxxxxxxx'));
  7  return l_str;
  8  end;
  9  /

Function created.

SQL> select fno('0x00c0000b') from dual;

FNO('0X00C0000B')
--------------------------------------------------------------------------------
datafile# is  3
datablock# is  11

知识点二：

如何降低高水位？（对全表扫描存在性能关系）

1、truncate exp、imp 终端业务
2、rename insert  不适合dml语句频繁操作
3、dbms_redefinition 存在中间表
4、shrink redo过多 维持索引
5、move 索引重建
分区表 可以考虑因素

知识点三：

如何分析segment块的使用：

1、通过rowid xxxxxx-xxx-xxxxxx获的对象使用的block

select count(distinct(substr(rowid,1,15))) blocks from table_name;

2、通过脚本查看数据块的使用情况：

CREATE OR REPLACE PROCEDURE show_space (   p_segname_1     IN VARCHAR2,   p_type_1        IN VARCHAR2 DEFAULT 'TABLE',p_space         IN VARCHAR2 DEFAULT'MANUAL',   p_analyzed      IN VARCHAR2 DEFAULT 'N',p_partition_1   IN VARCHAR2 DEFAULT NULL,   p_owner_1       IN VARCHAR2 DEFAULT USER)   AUTHID CURRENT_USERAS   p_segname              VARCHAR2 (100);   p_type                 VARCHAR2 (30);   p_owner                VARCHAR2 (30);   p_partition            VARCHAR2 (50);    l_unformatted_blocks   NUMBER;   l_unformatted_bytes    NUMBER;   l_fs1_blocks           NUMBER;   l_fs1_bytes            NUMBER;   l_fs2_blocks           NUMBER;   l_fs2_bytes            NUMBER;   l_fs3_blocks           NUMBER;   l_fs3_bytes            NUMBER;   l_fs4_blocks           NUMBER;   l_fs4_bytes            NUMBER;   l_full_blocks          NUMBER;   l_full_bytes           NUMBER;    l_free_blks            NUMBER;   l_total_blocks         NUMBER;   l_total_bytes          NUMBER;   l_unused_blocks        NUMBER;   l_unused_bytes         NUMBER;   l_LastUsedExtFileId    NUMBER;   l_LastUsedExtBlockId   NUMBER;   l_LAST_USED_BLOCK      NUMBER;    PROCEDURE p (p_label IN VARCHAR2,p_num IN NUMBER)   IS   BEGIN      DBMS_OUTPUT.put_line (RPAD(p_label, 40, '.') || p_num);   END;BEGIN   p_segname := UPPER (p_segname_1);   p_owner := UPPER (p_owner_1);   p_type := p_type_1;   p_partition := UPPER(p_partition_1);    IF (p_type_1 = 'i' OR p_type_1 ='I')   THEN      p_type := 'INDEX';   END IF;    IF (p_type_1 = 't' OR p_type_1 ='T')   THEN      p_type := 'TABLE';   END IF;    IF (p_type_1 = 'tp' OR p_type_1 ='TP')   THEN      p_type := 'TABLE PARTITION';   END IF;    IF (p_type_1 = 'ip' OR p_type_1 = 'IP')   THEN      p_type := 'INDEX PARTITION';   END IF;    IF (p_type_1 = 'c' OR p_type_1 ='C')   THEN      p_type := 'CLUSTER';   END IF;    DBMS_SPACE.UNUSED_SPACE (      segment_owner               => p_owner,      segment_name                => p_segname,      segment_type                => p_type,      partition_name              => p_partition,      total_blocks                => l_total_blocks,      total_bytes                 => l_total_bytes,      unused_blocks               => l_unused_blocks,      unused_bytes                => l_unused_bytes,      LAST_USED_EXTENT_FILE_ID    => l_LastUsedExtFileId,      LAST_USED_EXTENT_BLOCK_ID   => l_LastUsedExtBlockId,      LAST_USED_BLOCK             => l_LAST_USED_BLOCK);    IF p_space = 'MANUAL' OR (p_space<> 'auto' AND p_space <> 'AUTO')   THEN      DBMS_SPACE.FREE_BLOCKS (segment_owner       => p_owner,                             segment_name        =>p_segname,                              segment_type        => p_type,                             partition_name      =>p_partition,                             freelist_group_id   => 0,                             free_blks           =>l_free_blks);       p ('Free Blocks', l_free_blks);   END IF;    p ('Total Blocks',l_total_blocks);   p ('Total Bytes', l_total_bytes);   p ('Unused Blocks',l_unused_blocks);   p ('Unused Bytes',l_unused_bytes);   p ('Last Used Ext FileId',l_LastUsedExtFileId);   p ('Last Used Ext BlockId', l_LastUsedExtBlockId);   p ('Last Used Block',l_LAST_USED_BLOCK);    /*IF the segment is analyzed */   IF p_analyzed = 'Y'   THEN      DBMS_SPACE.SPACE_USAGE(segment_owner        => p_owner,                             segment_name         => p_segname,                             segment_type         => p_type,                             partition_name       =>p_partition,                              unformatted_blocks   => l_unformatted_blocks,                             unformatted_bytes    =>l_unformatted_bytes,                             fs1_blocks           =>l_fs1_blocks,                             fs1_bytes            =>l_fs1_bytes,                             fs2_blocks           =>l_fs2_blocks,                              fs2_bytes            => l_fs2_bytes,                             fs3_blocks           =>l_fs3_blocks,                             fs3_bytes            =>l_fs3_bytes,                             fs4_blocks           =>l_fs4_blocks,                              fs4_bytes            => l_fs4_bytes,                             full_blocks          =>l_full_blocks,                             full_bytes           =>l_full_bytes);      DBMS_OUTPUT.put_line (RPAD ('', 50, '*'));      DBMS_OUTPUT.put_line ('Thesegment is analyzed');      p ('0% -- 25% free spaceblocks', l_fs1_blocks);      p ('0% -- 25% free spacebytes', l_fs1_bytes);      p ('25% -- 50% free spaceblocks', l_fs2_blocks);      p ('25% -- 50% free spacebytes', l_fs2_bytes);      p ('50% -- 75% free spaceblocks', l_fs3_blocks);      p ('50% -- 75% free spacebytes', l_fs3_bytes);      p ('75% -- 100% free spaceblocks', l_fs4_blocks);      p ('75% -- 100% free spacebytes', l_fs4_bytes);      p ('Unused Blocks', l_unformatted_blocks);      p ('Unused Bytes',l_unformatted_bytes);      p ('Total Blocks',l_full_blocks);      p ('Total bytes',l_full_bytes);   END IF;END;

知识点四：

四个函数：

substr,

ltrim,截取指定的字符串，

ceil,取靠近该值的最大值

round，四舍五入

eg：

SQL> select ltrim('xxxhellooracle','xxx') ltr from dual;

LTR
-----------
hellooracle

SQL> select ceil(123.3) from dual;

CEIL(123.3)
-----------
        124

SQL> select ceil(123.5) from dual;

CEIL(123.5)
-----------
        124

SQL> select ceil(123.6) from dual;

CEIL(123.6)
-----------
        124

SQL> select round(123.123,2) from dual;

ROUND(123.123,2)
----------------
          123.12

SQL> select round(-123.123,2) from dual;

ROUND(-123.123,2)
-----------------
          -123.12

SQL> select round(123.123,-1) from dual;

ROUND(123.123,-1)
-----------------
              120

SQL>

 知识点5：

以点及面视图：

truncate table xxxx drop all storage；

dbms_space_admin.materialize_deferred_segments
dbms_space_admin.drop_empty_segments;

空间查询rowid，函数查看。
dba_tablespace
dba_data_files
dba_segments

v$segment_statistics
v$segstat_name,v$segstat,v$segment_statistics
dba_thresholds
dba_outstanding_alerts
dba_alert_history
v$alert_types;