oracle ASSM和MSSM

一. 官网说明

Logical Storage Structures

http://download.oracle.com/docs/cd/E11882_01/server.112/e16508/logical.htm#CNCPT7668

 

其中有关ASSM 的内容如下：

 

Logical Space Management

Oracle Database must use logical spacemanagement to track and allocate the extents in atablespace. When a database object requires an extent, the databasemust have a method of finding and providing it. Similarly, when anobject no longer requires an extent, the database must have amethod of making the free extent available.

Oracle Database managesspace within a tablespace based on the type that you create. Youcan create either of the following types of tablespaces:

·        Locally managed tablespaces (default)

The database uses bitmaps in the tablespaces themselves tomanage extents. Thus, locally managed tablespaces have a part ofthe tablespace set aside for a bitmap. Within a tablespace, thedatabase can manage segments with automatic segment spacemanagement (ASSM) or manual segment spacemanagement (MSSM).

·        Dictionary-managed tablespaces

The database uses the data dictionary to manage extents (see "Overview of the Data Dictionary").

Figure 12-3 shows the alternatives for logical space managementin a tablespace.

Figure 12-3 Logical SpaceManagement

Descriptionof "Figure 12-3 Logical Space Management"

Locally ManagedTablespaces

A locallymanaged tablespace maintains a bitmap in the data file header totrack free and used space in the data file body. Each bitcorresponds to a group of blocks. When space is allocated or freed,Oracle Database changes the bitmap values to reflect the new statusof the blocks.

The following graphic is a conceptual representation ofbitmap-managed storage. A 1 in the header refers toused space, whereas a 0 refers to free space.

A locally managed tablespace has the following advantages:

·        Avoids using the data dictionary to manage extents

Recursive operations can occur in dictionary-managed tablespacesif consuming or releasing space in an extent results in anotheroperation that consumes or releases space in a data dictionarytable or undo segment.

·        Tracks adjacent free space automatically

In this way, the database eliminates the need to coalesce freeextents.

·        Determines the size of locally managed extents automatically

Alternatively, all extents can have the same size in a locallymanaged tablespace and override object storage options.

Note:

Oracle strongly recommends the use of locally managedtablespaces with Automatic Segment Space Management.

Segment space management is an attributeinherited from the tablespace that contains the segment. Within alocally managed tablespace, the database can manage segmentsautomatically or manually. For example, segments in tablespaceusers can be managed automatically while segments intablespace tools are managed manually.

Automatic Segment Space Management

The ASSM method uses bitmaps to manage space. Bitmaps providethe following advantages:

·        Simplified administration

ASSM avoids the need to manually determine correct settings formany storage parameters. Only one crucial SQL parameter controlsspace allocation: PCTFREE. This parameter specifiesthe percentage of space to be reserved in a block for futureupdates (see "Percentage of Free Space in Data Blocks").

ASSM 管理，只需要一个参数：PCTFREE

·        Increased concurrency

Multiple transactions can search separate lists of free data blocks,thereby reducing contention and waits. For many standard workloads,application performance with ASSM is better than the performance ofa well-tuned application that uses MSSM.

·        Dynamic affinity of space to instances in an Oracle RealApplication Clusters (Oracle RAC) environment

ASSM is more efficient and is the default for permanent, locallymanaged tablespaces.

Note:

This chapter assumes the use of ASSM in all of its discussionsof logical storage space.

 

Manual Segment Space Management

The legacy MSSM method uses a linked list called a freelist to manage free space in the segment. For a databaseobject that has free space, a free list keeps track of blocks underthe high water mark (HWM), which is the dividing line betweensegment space that is used and not yet used. As blocks are used,the database puts blocks on or removes blocks from the free list asneeded.

In addition to PCTFREE, MSSM requires you tocontrol space allocation with SQL parameters such asPCTUSED, FREELISTS, and FREELISTGROUPS. PCTUSED sets the percentage of freespace that must exist in a currently used block for the database toput it on the free list. For example, if you setPCTUSED to 40 in a CREATETABLE statement, then you cannot insert rows into a block inthe segment until less than 40% of the block space is used.

As an illustration, suppose you insert a row into a table. Thedatabase checks a free list of the table for the first availableblock. If the row cannot fit in the block, and if the used space inthe block is greater than or equal to PCTUSED, thenthe database takes the block off the list and searches for anotherblock. If you delete rows from the block, then the database checkswhether used space in the block is now less thanPCTUSED. If so, then the database places the block atthe beginning of the free list.

An object may have multiple free lists. In this way, multiplesessions performing DML on a table can use different lists, whichcan reduce contention. Each database session uses only one freelist for the duration of its session.

As shown in Figure 12-4, you can also create an object with one or morefree list groups, which are collections of freelists. Each group has a master free list thatmanages the individual process free lists in thegroup. Space overhead for free lists, especially for free listgroups, can be significant.

Figure 12-4 Free ListGroups

Descriptionof "Figure 12-4 Free List Groups"

Managing segment space manually can be complex. You must adjustPCTFREE and PCTUSED to reduce rowmigration (see "Chained and Migrated Rows") and avoid wasting space. Forexample, if every used block in a segment is half full, and ifPCTUSED is 40, then the database does not permitinserts into any of these blocks. Because of the difficulty offine-tuning space allocation parameters, Oracle strongly recommendsASSM. In ASSM, PCTFREE determines whether a new rowcan be inserted into a block, but it does not use free lists andignores PCTUSED.

-- ASSM 会忽略PCTUSED 参数

Dictionary-Managed Tablespaces

Adictionary-managed tablespace uses the data dictionary to manageits extents. Oracle Database updates tables in the data dictionarywhenever an extent is allocated or freed for reuse. For example,when a table needs an extent, the database queries the datadictionary tables, and searches for free extents. If the databasefinds space, then it modifies one data dictionary table and insertsa row into another. In this way, the database manages space bymodifying and moving data.

The SQL that the database executes in the background to obtainspace for database objects is recursive SQL.Frequent use of recursive SQL can have a negative impact onperformance because updates to the data dictionary must beserialized. Locally managed tablespaces, which are the default,avoid this performance problem.

 

二.  ASSM 说明

 

           在Orale9i以前，表的剩余空间的管理与分配都是由链接列表freelist来完成的，因为freelist存在串行的问题因此容易引起往往容易引起段头的争用与空间的浪费（其实这一点并不明显），最主要的还是因为需要DBA花费大量的精力去管理这些争用并监控表的空间利用。  

           自动段空间管理（ASSM），它首次出现在Oracle920里。有了ASSM，链接列表freelist被位图所取代，它是一个二进制的数组，能够迅速有效地管理存储扩展和剩余区块（freeblock），因此能够改善分段存储本质，ASSM表空间上创建的段还有另外一个称呼叫Bitmap ManagedSegments（BMB 段）。  

让我们看看位图freelist是如何实现的。从使用区段空间管理自动参数创建tablespace开始：  
create tablespace demo  
datafile '/ora01/oem/demo01.dbf'  
size 5m  
EXTENT MANAGEMENT LOCAL -- Turn onLMT  
SEGMENT SPACE MANAGEMENT AUTO -- Turn onASSM;  

一旦你定义好了tablespace，那么表和索引就能够使用各种方法很容易地被移动到新的tablespace里，带有ASSM的本地管理tablespace会略掉任何为PCTUSED、NEXT和FREELISTS所指定的值。  

           当表格或者索引被分配到这个tablespace以后，用于独立对象的PCTUSED的值会被忽略，而Oracle9i会使用位图数组来自动地管理tablespace里表格和索引的freelist。对于在LMT的tablespace内部创建的表格和索引而言，这个NEXT扩展子句是过时的，因为由本地管理的tablespace会管理它们。但是，INITIAL参数仍然是需要的，因为Oracle不可能提前知道初始表格加载的大小。对于ASSM而言，INITIAL最小的值是三个块。  

           新的管理机制用位图来跟踪或管理每个分配到对象的块，每个块有多少剩余空间根据位图的状态来确定，如>75%,50%-75%,25%-50%和<25%，也就是说位图其实采用了四个状态位来代替以前的pctused，什么时候该利用该数据块则由设定的pctfree来确定。  

           使用ASSM的一个巨大优势是，位图freelist肯定能够减轻缓冲区忙等待（buffer busywait）的负担，这个问题在Oracle9i以前的版本里曾是一个严重的问题 。 

           在没有多个freelist的时候，每个Oracle表格和索引在表格的头部都曾有一个数据块，用来管理对象所使用的剩余区块，并为任何SQL插入声明所创建的新数据行提供数据块。当数据缓冲内的数据块由于被另一个DML事务处理锁定而无法使用的时候，缓冲区忙等待就会发生。当你需要将多个任务插入到同一个表格里的时候，这些任务就被强制等待，而同时Oracle会在同时分派剩余的区块，一次一个。  

           有了ASSM之后，Oracle宣称显著地提高了DML并发操作的性能，因为（同一个）位图的不同部分可以被同时使用，这样就消除了寻找剩余空间的串行化。根据Oracle的测试结果，使用位图freelist会消除所有分段头部（对资源）的争夺，还能获得超快的并发插入操作 

尽管ASSM显示出了令人激动的特性并能够简化OracleDBA的工作，但是Oracle9i的位图分段管理还是有一些局限性的：  
           1.一旦DBA被分配之后，它就无法控制tablespace内部的独立表格和索引的存储行为。  
           2.大型对象不能够使用ASSM，而且必须为包含有LOB数据类型的表格创建分离的tablespace。  
           3.你不能够使用ASSM创建临时的tablespace。这是由排序时临时分段的短暂特性所决定的。  
           4.只有本地管理的tablespace才能够使用位图分段管理。  
           5· 使用超高容量的DML（例如INSERT、UPDATE和DELETE等）的时候可能会出现性能上的问题。

三.相关测试：
  
1、我们先创建一个本地管理的表空间，采用段自动管理方式  

CREATE TABLESPACE demo

DATAFILE 'D:/demo01.dbf'

SIZE 50M

EXTENT MANAGEMENTLOCAL         --一定是本地管理

SEGMENT SPACE MANAGEMENTAUTO;  --ASSM管理的标志
  
2、创建同样一个表  

CREATE TABLE demotab (xNUMBER)

TABLESPACE demo

STORAGE (INITIAL 1000 K);

 

我们指定初试区间大小是1000K
  

SELECT  t.table_name,

        t.initial_extent,

        t.next_extent,

        t.pct_free,

        t.pct_used

 FROM   user_tables t

 WHERE  t.table_name = 'DEMOTAB';

 

TABLE_NAME  INITIAL_EXTENT NEXT_EXTENT  PCT_FREE PCT_USED  
-----------------------  --------------      ---------------    ---------------- -------------------  
DEMOTAB         1024000                        10   
可以看到，NEXT_EXTENT与PCT_USED都为空。  
  
3、执行该过程，检查表的初始状态  
exec show_space('demotab','auto','T','Y'); --show_space() 代码见附件
Total Blocks............................128

Total Bytes.............................1048576

Unused Blocks...........................125

Unused Bytes............................1024000

Last Used Ext FileId....................7

Last Used Ext BlockId...................9

Last Used Block.........................3

 *************************************************

The segment is analyzed

0% -- 25% free space blocks.............0

0% -- 25% free space bytes..............0

25% -- 50% free space blocks............0

25% -- 50% free space bytes.............0

50% -- 75% free space blocks............0

50% -- 75% free space bytes.............0

75% -- 100% free space blocks...........0

75% -- 100% free space bytes............0

Unused Blocks...........................0

Unused Bytes............................0

Total Blocks............................0

Total bytes.............................0

从这里我们能看到一些该表的特性，其中最引人注意的就是表头了，占用了三个块的大小（128-125）  
           另外一个注意的地方就是该表从第9个块开始，文件头占用了64K的空间等于8个块。  

我们从dba_extent中也能看到这样的信息，是从第9个块开始的。
  

SELECT  t.segment_name, t.extent_id, t.block_id

 FROM   dba_extents t

 WHERE  t.segment_name = 'DEMOTAB';

 

SEGMENT_NAME    EXTENT_ID   BLOCK_ID

---------------           ----------     ----------

DEMOTAB                 0         9

DEMOTAB                 1        17

DEMOTAB                 2        25

DEMOTAB                 3        33

DEMOTAB                 4        41

DEMOTAB                 5        49

DEMOTAB                 6        57

DEMOTAB                 7        65

DEMOTAB                 8        73

DEMOTAB                 9        81

DEMOTAB                10        89

DEMOTAB                11        97

DEMOTAB                12       105

DEMOTAB                13       113

DEMOTAB                14       121

DEMOTAB                15       129

从这里可以看到，第一个区间的开始块是9
  
4、我直接开始分析第9，10，11个块（段头）  

SQL> alter system dump datafile 7 block9;  
System altered  
SQL> alter system dump datafile 7 block10;  
System altered  
SQL> alter system dump datafile 7 block11;  
System altered   
  

进入Udump 查看刚才生成的trace 文件

*** 2009-12-07 19:30:16.406

*** SERVICE NAME:(DBA.ANQINGREN.ORG) 2009-12-0719:30:16.390

*** SESSION ID:(123.758) 2009-12-0719:30:16.390

Start dump data blocks tsn: 8 file#: 7 minblk 9maxblk 9

buffer tsn: 8 rdba: 0x01c00009 (7/9)

scn: 0x0000.001a0da0 seq: 0x01 flg: 0x04 tail:0x0da02001

frmt: 0x02 chkval: 0x44e6 type: 0x20=FIRST LEVELBITMAP BLOCK

Hex dump of block: st=0, typ_found=1

Dump of memory from 0x085C8400 to 0x085CA400

85C8400 0000A220 01C00009 001A0DA004010000  [ ...............]

85C8410 000044E6 00000000 0000000000000000  [.D..............]

85C8420 00000000 00000000 0000000000000000  [................]

       Repeat 1 times

85C8440 00000000 00000000 0000000000000004  [................]

85C8450 FFFFFFFF 0000000D 0000000300000010  [................]

85C8460 00010002 00000000 0000000000000000  [................]

85C8470 00000000 00000003 0000000000000000  [................]

85C8480 00000000 00000000 0000000000000000  [................]

85C8490 01C0000A 00000000 0000000000000003  [................]

85C84A0 00000008 01C0000C 0000000000000000  [................]

85C84B0 00000000 00000000 0000000000000001  [................]

85C84C0 0000D302 00000000 0000000001C00009  [................]

85C84D0 00000008 00000000 01C0001100000008  [................]

85C84E0 00000008 00000000 0000000000000000  [................]

85C84F0 00000000 00000000 0000000000000000  [................]

       Repeat 8 times

85C8580 00000000 00000000 0000000000001011  [................]

85C8590 00000000 00000000 0000000000000000  [................]

       Repeat 485 times

85CA3F0 00000000 00000000 000000000DA02001  [............. ..]

Dump of First Level Bitmap Block

 --------------------------------

   nbits : 4nranges:2        parent dba: 0x01c0000a   poffset:0    

   unformatted:13     total:16       first useful block:3     

   owninginstance : 1

   instanceownership changed at

   Lastsuccessful Search

   FreenessStatus:  nf10     nf20     nf30     nf40     

 

   Extent MapBlock Offset: 4294967295

   First freedatablock :3     

   Bitmap blocklock opcode 0

   Lockerxid:    :  0x0000.000.00000000

   Inc #: 0 Objd:54018

  HWM Flag: HWM Set

     Highwater:: 0x01c0000c  ext#:0     blk#:3     ext size:8    

  #blocks in seg. hdr's freelists:0    

  #blocks below:0    

  mapblk 0x00000000  offset:0    

 --------------------------------------------------------

  DBA Ranges :

 --------------------------------------------------------

  0x01c00009  Length:8     Offset:0     

  0x01c00011  Length:8     Offset:8     

 

  0:Metadata  1:Metadata  2:Metadata   3:unformatted

  4:unformatted  5:unformatted  6:unformatted   7:unformatted

  8:unformatted  9:unformatted  10:unformatted  11:unformatted

  12:unformatted  13:unformatted  14:unformatted  15:unformatted

 --------------------------------------------------------

End dump data blocks tsn: 8 file#: 7 minblk 9maxblk 9

*** 2009-12-07 19:35:44.296

Start dump data blocks tsn: 8 file#: 7 minblk 10maxblk 10

buffer tsn: 8 rdba: 0x01c0000a (7/10)

scn: 0x0000.001a0dc1 seq: 0x01 flg: 0x04 tail:0x0dc12101

frmt: 0x02 chkval: 0x5439 type: 0x21=SECOND LEVELBITMAP BLOCK

Hex dump of block: st=0, typ_found=1

Dump of memory from 0x085C8400 to 0x085CA400

85C8400 0000A221 01C0000A 001A0DC104010000  [!...............]

85C8410 00005439 00000000 0000000000000000  [9T..............]

85C8420 00000000 00000000 0000000000000000  [................]

       Repeat 1 times

85C8440 00000000 00000000 0000000001C0000B  [................]

85C8450 00000008 00000008 0000000000000000  [................]

85C8460 00000000 00000000 0000D30200000001  [................]

85C8470 00000000 01C00009 0001000501C00019  [................]

85C8480 00010005 01C00029 0001000501C00039  [....).......9...]

85C8490 00010005 01C00049 0001000501C00059  [....I.......Y...]

85C84A0 00010005 01C00069 0001000501C00079  [....i.......y...]

85C84B0 00010005 00000000 0000000000000000  [................]

85C84C0 00000000 00000000 0000000000000000  [................]

       Repeat 498 times

85CA3F0 00000000 00000000 000000000DC12101  [.............!..]

Dump of Second Level Bitmap Block

   number:8      nfree:8      ffree:0     pdba:    0x01c0000b

   Inc #: 0 Objd:54018

  opcode:0

 xid:

  L1 Ranges :

 --------------------------------------------------------

  0x01c00009  Free: 5 Inst: 1

  0x01c00019  Free: 5 Inst: 1

  0x01c00029  Free: 5 Inst: 1

  0x01c00039  Free: 5 Inst: 1

  0x01c00049  Free: 5 Inst: 1

  0x01c00059  Free: 5 Inst: 1

  0x01c00069  Free: 5 Inst: 1

  0x01c00079  Free: 5 Inst: 1

 

 --------------------------------------------------------

End dump data blocks tsn: 8 file#: 7 minblk 10maxblk 10

Start dump data blocks tsn: 8 file#: 7 minblk 11maxblk 11

buffer tsn: 8 rdba: 0x01c0000b (7/11)

scn: 0x0000.001a0dc6 seq: 0x01 flg: 0x04 tail:0x0dc62301

frmt: 0x02 chkval: 0x79ad type: 0x23=PAGETABLESEGMENT HEADER

Hex dump of block: st=0, typ_found=1

Dump of memory from 0x085C8400 to 0x085CA400

85C8400 0000A223 01C0000B 001A0DC604010000  [#...............]

85C8410 000079AD 00000000 0000000000000000  [.y..............]

85C8420 00000000 00000010 0000008000000A9C  [................]

85C8430 00000000 00000003 0000000801C0000C  [................]

85C8440 00000000 00000000 0000000000000000  [................]

       Repeat 1 times

85C8460 00000003 00000008 01C0000C00000000  [................]

85C8470 00000000 00000000 0000000001C00009  [................]

85C8480 01C00009 00000000 0000000000000000  [................]

85C8490 00000000 00000000 0000000000000000  [................]

       Repeat 3 times

85C84D0 00000001 00002000 0000000000001434  [..... ......4...]

85C84E0 00000000 01C0000A 0000000101C00079  [............y...]

85C84F0 01C0000A 00000000 0000000000000000  [................]

85C8500 00000000 00000000 0000001000000000  [................]

85C8510 0000D302 10000000 01C0000900000008  [................]

85C8520 01C00011 00000008 01C0001900000008  [................]

85C8530 01C00021 00000008 01C0002900000008  [!.......).......]

85C8540 01C00031 00000008 01C0003900000008  [1.......9.......]

85C8550 01C00041 00000008 01C0004900000008  [A.......I.......]

85C8560 01C00051 00000008 01C0005900000008  [Q.......Y.......]

85C8570 01C00061 00000008 01C0006900000008  [a.......i.......]

85C8580 01C00071 00000008 01C0007900000008  [q.......y.......]

85C8590 01C00081 00000008 0000000000000000  [................]

85C85A0 00000000 00000000 0000000000000000  [................]

       Repeat 144 times

85C8EB0 01C00009 01C0000C 01C0000901C00011  [................]

85C8EC0 01C00019 01C0001A 01C0001901C00021  [............!...]

85C8ED0 01C00029 01C0002A 01C0002901C00031  [)...*...)...1...]

85C8EE0 01C00039 01C0003A 01C0003901C00041  [9...:...9...A...]

85C8EF0 01C00049 01C0004A 01C0004901C00051  [I...J...I...Q...]

85C8F00 01C00059 01C0005A 01C0005901C00061  [Y...Z...Y...a...]

85C8F10 01C00069 01C0006A 01C0006901C00071  [i...j...i...q...]

85C8F20 01C00079 01C0007A 01C0007901C00081  [y...z...y.......]

85C8F30 00000000 00000000 0000000000000000  [................]

       Repeat 144 times

85C9840 00000000 00000000 01C0000A00000000  [................]

85C9850 00000000 00000000 0000000000000000  [................]

       Repeat 185 times

85CA3F0 00000000 00000000 000000000DC62301  [.............#..]

  Extent Control Header

 -----------------------------------------------------------------

  Extent Header:: spare1:0     spare2:0     #extents:16    #blocks: 128  

                 last map  0x00000000  #maps:0     offset: 2716 

     Highwater:: 0x01c0000c  ext#:0     blk#:3     ext size:8    

  #blocks in seg. hdr's freelists:0    

  #blocks below:0    

  mapblk 0x00000000  offset:0    

                  Unlocked

 --------------------------------------------------------

  Low HighWater Mark :

     Highwater::  0x01c0000c  ext#:0     blk#:3     ext size:8    

  #blocks in seg. hdr's freelists:0    

  #blocks below:0    

  mapblk 0x00000000  offset:0    

  Level 1 BMB for High HWM block:0x01c00009

  Level 1 BMB for Low HWM block:0x01c00009

 --------------------------------------------------------

  Segment Type: 1 nl2:1     blksz: 8192   fbsz:0     

  L2 Array startoffset:  0x00001434

  First Level 3BMB:  0x00000000

  L2 Hint forinserts:  0x01c0000a

  Last Level 1BMB:  0x01c00079

  Last Level IIBMB:  0x01c0000a

  Last Level IIIBMB:  0x00000000

    Map Header:: next  0x00000000 #extents: 16   obj#:54018  flag: 0x10000000

  Inc # 0

  Extent Map

 -----------------------------------------------------------------

  0x01c00009  length:8    

  0x01c00011  length:8    

  0x01c00019  length:8    

  0x01c00021  length:8    

  0x01c00029  length:8    

  0x01c00031  length:8    

  0x01c00039  length:8    

  0x01c00041  length:8    

  0x01c00049  length:8    

  0x01c00051  length:8    

  0x01c00059  length:8    

  0x01c00061  length:8    

  0x01c00069  length:8    

  0x01c00071  length:8    

  0x01c00079  length:8    

  0x01c00081  length: 8    

 

  Auxillary Map

 --------------------------------------------------------

   Extent0    :  L1 dba:  0x01c00009 Datadba:  0x01c0000c

   Extent1    :  L1 dba:  0x01c00009 Datadba:  0x01c00011

   Extent2    :  L1 dba:  0x01c00019 Datadba:  0x01c0001a

   Extent3    :  L1 dba:  0x01c00019 Datadba:  0x01c00021

   Extent4    :  L1 dba:  0x01c00029 Datadba:  0x01c0002a

   Extent5    :  L1 dba:  0x01c00029 Datadba:  0x01c00031

   Extent6    :  L1 dba:  0x01c00039 Datadba:  0x01c0003a

   Extent7    :  L1 dba:  0x01c00039 Datadba:  0x01c00041

   Extent8    :  L1 dba:  0x01c00049 Datadba:  0x01c0004a

   Extent9    :  L1 dba:  0x01c00049 Datadba:  0x01c00051

   Extent10   :  L1 dba:  0x01c00059 Datadba:  0x01c0005a

   Extent11   :  L1dba:  0x01c00059 Data dba: 0x01c00061

   Extent12   :  L1 dba:  0x01c00069 Datadba:  0x01c0006a

   Extent13   :  L1 dba:  0x01c00069 Datadba:  0x01c00071

   Extent14   :  L1 dba:  0x01c00079 Datadba:  0x01c0007a

   Extent15   :  L1 dba:  0x01c00079 Datadba:  0x01c00081

 --------------------------------------------------------

 

   Second LevelBitmap block DBAs

  --------------------------------------------------------

   DBA1:   0x01c0000a

 

End dump data blocks tsn: 8 file#: 7 minblk 11maxblk 11

 

 

附件：Show_space（）存储过程代码：

 

CREATE OR REPLACE PROCEDURE show_space (p_segname_1IN varchar2,

                                       p_space IN varchar2 DEFAULT 'MANUAL' ,

                                       p_type_1 IN varchar2 DEFAULT 'TABLE' ,

                                       p_analyzed IN varchar2 DEFAULT 'N' ,

                                       p_owner_1 IN varchar2 DEFAULT USER

)

AS

  p_segname             VARCHAR2 (100);

  p_type                VARCHAR2 (10);

  p_owner               VARCHAR2 (30);

 

  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);         -- rainy changed

  p_owner                  := UPPER (p_owner_1);

  p_type                   :=p_type_1;

 

   IF (p_type_1 ='i' OR p_type_1 = 'I')

  THEN                                                       --rainy changed

     p_type   := 'INDEX';

   END IF;

 

   IF (p_type_1 ='t' OR p_type_1 = 'T')

  THEN                                                       --rainychanged

     p_type   := 'TABLE';

   END IF;

 

   IF (p_type_1 ='c' OR p_type_1 = 'C')

  THEN                                                       --rainy changed

     p_type   := 'CLUSTER';

   END IF;

 

 

  DBMS_SPACE.unused_space (segment_owner=> p_owner,

                           segment_name => p_segname,

                           segment_type => p_type,

                           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' ANDp_space <> 'AUTO')

   THEN

     DBMS_SPACE.free_blocks (segment_owner=> p_owner,

                             segment_name=> p_segname,

                             segment_type => p_type,

                             freelist_group_id => 0,

                             free_blks => l_free_blks

     );

 

     p ('Free Blocks', l_free_blks);

   END IF;

 

   p ('TotalBlocks', l_total_blocks);

   p ('TotalBytes', l_total_bytes);

   p ('UnusedBlocks', l_unused_blocks);

   p ('UnusedBytes', l_unused_bytes);

   p ('Last UsedExt FileId', l_lastusedextfileid);

   p ('Last UsedExt BlockId', l_lastusedextblockid);

   p ('Last UsedBlock', l_last_used_block);

 

 

  

   IF p_analyzed= 'Y'

   THEN

     DBMS_SPACE.space_usage (segment_owner=> p_owner,

                             segment_name => p_segname,

                             segment_type=> p_type,

                             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 ('The segment isanalyzed');

     p ('0% -- 25% free space blocks', l_fs1_blocks);

     p ('0% -- 25% free space bytes', l_fs1_bytes);

     p ('25% -- 50% free space blocks', l_fs2_blocks);

     p ('25% -- 50% free space bytes', l_fs2_bytes);

     p ('50% -- 75% free space blocks', l_fs3_blocks);

     p ('50% -- 75% free space bytes', l_fs3_bytes);

     p ('75% -- 100% free space blocks', l_fs4_blocks);

     p ('75% -- 100% free space bytes', 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;

 

exec show_space('abc','auto','T','Y');