Oracle 中的高水位（High Water Mark）指的是表或段中曾经使用过的最高数据块位置。哪怕后来数据被删除了，Oracle 仍然认为这些块“已被使用”，不会自动回收，导致：
1、表空间看起来很大（占了磁盘）；
2、实际数据却不多；
3、新数据插入时，可能会跳过这些空闲但“不可用”的块。
表空间高水位收缩通常是因操作系统磁盘空间压力所引发，主要是被了腾空间。出于对生产环境稳定性的考量，我们一般仅在迫不得已的情况下才实施此类高风险调整。
本文档是针对某个特定用户表空间收缩的文档，实际操作要结合生产库具体情况。主要包括以下几个流程：
收集当前数据库相关信息
降低数据库表高水位线
Resize 收缩数据文件
1、查看表空间使用情况
SQL> SELECT total.tablespace_name,
Round(total.MB, 2) AS Total_MB,
Round(total.MB - free.MB, 2) AS Used_MB,
Round(( 1 - free.MB / total.MB ) * 100, 2)
|| '%' AS Used_Pct
FROM (SELECT tablespace_name,
Sum(bytes) / 1024 / 1024 AS MB
FROM dba_free_space
GROUP BY tablespace_name) free,
(SELECT tablespace_name,
Sum(bytes) / 1024 / 1024 AS MB
FROM dba_data_files
GROUP BY tablespace_name) total
WHERE free.tablespace_name = total.tablespace_name;
TABLESPACE_NAME TOTAL_MB USED_MB USED_PCT
------------------------------ ---------- ---------- -----------------------------------------
SYSAUX 5000 1359.19 27.18%
SYSTEM 1024 625.13 61.05%
TS_AUD 4000 1483.19 37.08%
TS_BJCA 512 118.63 23.17%
TS_BT 512 .06 .01%
TS_CHDD 2000 864.06 43.2%
TS_DATA 2167482 496135.81 22.89%
TS_FCCH 512 1.94 .38%
TS_FDC 50000 36266.88 72.53%
TS_INDEX 390000 294789.81 75.59%
TS_LOG 30000 23551.81 78.51%
TS_RMAN 512 266.06 51.97%
TS_SB 6000 4594 76.57%
TS_SCJY 10000 5618.5 56.19%
TS_WHMS 512 310.38 60.62%
TS_ZLPT 2048 484.06 23.64%
UNDOTBS1 60000 59999.63 100%
USERS 5000 1060.06 21.2%
# 与客户描述的一致，TS_DATA表空间量大，但实际使用量小。
2、查看表空间上的用户
SQL> select owner,tablespace_name ,sum(bytes)/1024/1024/1024 G from dba_segments where tablespace_name = 'TS_DATA' group by owner,tablespace_name;
OWNER TABLESPACE_NAME G
------------------------------ ------------------------------ ----------
TMC TS_DATA 454.085266
IBMS_SEC TS_DATA .005004883
PLATFORM TS_DATA .290893555
SZFDC TS_DATA .661071777
GTB_APP TS_DATA .20111084
FDC_ZJJYJZX TS_DATA 7.76208496
SZFDCOA TS_DATA 1.01373291
BWPLATFORM TS_DATA 16.6900024
SZFDC_CA TS_DATA 2.73272705
FDC_YJZX TS_DATA 1.35357666
FLOOR TS_DATA 108.474243
SHENBAO TS_DATA .002502441
IBMS TS_DATA 1.8303833
FCCH TS_DATA .26361084
PUCHA TS_DATA .19140625
FDCYS TS_DATA 7.56640625
RIS_ACCESS TS_DATA 1.08044434
17 rows selected.
3、查看表空间TOP 10大表
SQL> select * from (
2 select owner, segment_name, segment_type, tablespace_name, bytes/1024/1024/1024 "G"
3 from dba_segments where segment_type = 'TABLE' and tablespace_name = 'TS_DATA' order by bytes desc)
4 where rownum <= 10;
OWNER SEGMENT_NAME SEGMENT_TYPE TABLESPACE_NAME G
------------------- ------------------------------------ ------------------ ------------------- ----------
TMC FDC_INFO_QRY_LOG_2020 TABLE TS_DATA 144.490234
TMC TMC_LOG TABLE TS_DATA 86.6728516
TMC BIN$tvmjhUBAC37gVAALXeBfRg==$0 TABLE TS_DATA 50.9677734
TMC BIN$tvSoznk+ICjgVAALXeBfRg==$0 TABLE TS_DATA 30.59375
TMC REMC_WS_LOG_REQUEST TABLE TS_DATA 9.87109375
FDCYS SYS_20191171126389483_TEMP TABLE TS_DATA 3.4375
BWPLATFORM SOA_SYSTEM_LOG TABLE TS_DATA 3.125
FDCYS TRADE_RECORD TABLE TS_DATA 2.90625
TMC JG_TBL_FDC_EST_REGISTE TABLE TS_DATA 2.87890625
TMC MLOG$_FDC_TMC_CONTRACT TABLE TS_DATA 1.44433594
4、查看表空间TOP 10大索引
SQL> select * from (
2 select owner, segment_name, segment_type, tablespace_name, bytes/1024/1024/1024 "G"
3 from dba_segments where segment_type = 'INDEX' and tablespace_name = 'TS_DATA' order by bytes desc)
4 where rownum <= 10;
OWNER SEGMENT_NAME SEGMENT_TYPE TABLESPACE_NAME G
----------------- ---------------------------- ------------------ ------------------ ----------
TMC TMC_LOG_PK INDEX TS_DATA 13.03125
BWPLATFORM SOA_SYSTEM_LOG INDEX TS_DATA .433837891
TMC INDEX_USER INDEX TS_DATA .419921875
TMC INDEX_ORGAN INDEX TS_DATA .390625
BWPLATFORM PK_PLAT_USER_LOGIN_LOG INDEX TS_DATA .267150879
TMC SEI_IX_NAME INDEX TS_DATA .216796875
TMC FTVC_IX_EXPIRE_DATE INDEX TS_DATA .1953125
FDCYS I_TR_YWBJSJ INDEX TS_DATA .1953125
BWPLATFORM SYS_C0066879 INDEX TS_DATA .1484375
TMC FTVC_UK_CERT_NO_FO_ID INDEX TS_DATA .1328125
10 rows selected.
5、查看表空间管理方式
SQL> select tablespace_name, block_size,contents, extent_management, segment_space_management, allocation_type, segment_space_management from dba_tablespaces where tablespace_name='TS_DATA';
TABLESPACE_NAME BLOCK_SIZE CONTENTS EXTENT_MAN SEGMEN ALLOCATIO SEGMEN
------------------------------ ---------- --------- ---------- ------ --------- ------
TS_DATA 8192 PERMANENT LOCAL AUTO SYSTEM AUTO
6、查看数据文件使用情况
SQL> col file_name for a50
SQL> select file_name, tablespace_name, bytes/1024/1024/1024 "used G", maxbytes/1024/1024/1024 "total G" from dba_data_files where tablespace_name = 'TS_DATA' order by bytes;
FILE_NAME TABLESPACE_NAME used G total G
-------------------------------------------------- ------------------------------ ---------- ----------
/Oradata/2nd_fdc/TS_DATA74.dbf TS_DATA 5 0
/Oradata/2nd_fdc/TS_DATA76.dbf TS_DATA 5 0
/Oradata/2nd_fdc/TS_DATA75.dbf TS_DATA 5 0
...................
/Oradata/2nd_fdc/TS_DATA18.dbf TS_DATA 31.9921875 31.9999847
/Oradata/2nd_fdc/TS_DATA19.dbf TS_DATA 31.9921875 31.9999847
/Oradata/2nd_fdc/TS_DATA11.dbf TS_DATA 31.9921875 31.9999847
/Oradata/2nd_fdc/TS_DATA14.dbf TS_DATA 31.9921875 31.9999847
76 rows selected.
7、查看表空间高水位情况
SQL> select max(block_id)*8/1024/1024 "G size" from dba_extents where tablespace_name='TS_DATA';
G size
----------
31.9920731
降低高水位
1、检查失效索引
（建议处理高水位前和后都要检查。并及时处理失效索引）--检查分区索引（包括分区表的分区本地索引，分区表的分区全局索引），如果存在重建，并修改并行度
select 'alter index '||a.index_owner||'.'||a.index_name||' rebuild partition '||a.partition_name ||' parallel 10;' from
dba_ind_partitions a
where a.status='UNUSABLE';
select 'alter index '||a.index_owner||'.'||a.index_name||' parallel 1;' from
dba_ind_partitions a
where a.status='UNUSABLE’;
--检查普通索引(包括普通表的索引，分区表的普通全局索引)，如果存在重建，并修改并行度
select 'alter index '||a.owner||'.'||a.index_name||' rebuild parallel 10;' from
dba_indexes a
where a.status='UNUSABLE';
select 'alter index '||a.owner||'.'||a.index_name||' parallel 1;' from
dba_indexes a
where a.status='UNUSABLE’;
2、查询指定用户中的高水位
# 比较表的行数和表的大小关系。如果行数为0，而表的当前占用大小减去初始化时的大小（INITIAL_EXTENT）后依然很大，那么说明该表有高水位。=====为了保证结果准确，建议先对表进行统计信息收集。
# 查看TMC用户高水位
SQL> SELECT D.OWNER,
2 ROUND(D.NUM_ROWS / D.BLOCKS, 2),
3 D.NUM_ROWS,
4 D.BLOCKS,
5 D.TABLE_NAME,
6 ROUND((d.BLOCKS*8-D.INITIAL_EXTENT/1024)/1024) t_size
7 FROM DBA_TABLES D
8 WHERE D.BLOCKS > 10
9 AND ROUND(D.NUM_ROWS / D.BLOCKS, 2) < 5
10 AND d.OWNER = 'TMC' ;
OWNER ROUND(D.NUM_ROWS/D.BLOCKS,2) NUM_ROWS BLOCKS TABLE_NAME T_SIZE
-------- ---------------------------- ---------- ---------- ------------------------------ ----------
TMC 2.6 2597 1000 EX_ZQ_MIDDLE_ACCESS 8
TMC 2.31 30 13 EX_ZW_SRV_CONFIG 0
TMC 1.1 66 60 FDC_ROLES_CATALOG -1
TMC .35 21 60 FDC_ORGANTYPE_SUBSYSTEM -1
TMC .1 6 58 FDC_USER_DEV_UPLOAD 0
TMC 3.05 1149260 377166 JG_TBL_FDC_EST_REGISTE 2947
TMC 0 0 1522 JG_TBL_JSYDGH 12
TMC 0 0 2410 JG_TBL_LAND_CONTRACT 19
TMC 4.83 713497 147670 FDC_YS_CONTRACT_APPENDIX 1154
TMC 1.94 3646 1882 SIREA_REPORT_3 15
TMC 2.56 625 244 DZZZ_FDC_YS_PREPROJECT 2
TMC .22 9703 44390 FDC_ORGAN_REPORT_DEV_USER 347
TMC 0 0 13 SYS_20185311110401376_TEMP 0
TMC 1.57 1902326 1210229 REMC_WS_LOG_REQUEST 9455
# 查看表上边的索引
SQL> select index_name, status from dba_indexes where owner = 'TMC' and table_name = 'JG_TBL_FDC_EST_REGISTE';
INDEX_NAME STATUS
------------------------------ --------
EST_REGISTE_PARCEL_NO VALID
EST_REGISTE_PROJ_NO VALID
SQL> select index_name, status from dba_indexes where owner = 'TMC' and table_name = 'FDC_YS_CONTRACT_APPENDIX';
INDEX_NAME STATUS
------------------------------ --------
SYS_IL0000060570C00006$$ VALID
SYS_IL0000060570C00020$$ VALID
FYCA_IX_FYC_ID VALID
FYCA_IX_YS_FYB_ID VALID
SYS_IL0000060570C00026$$ VALID
FYCA_PK VALID
6 rows selected.
SQL> select index_name, status from dba_indexes where owner = 'TMC' and table_name = 'REMC_WS_LOG_REQUEST';
INDEX_NAME STATUS
------------------------------ --------
SYS_IL0000142741C00026$$ VALID
SYS_IL0000142741C00027$$ VALID
SYS_IL0000142741C00028$$ VALID
# 查看FDCYS用户高水位线
SELECT D.OWNER,
ROUND(D.NUM_ROWS / D.BLOCKS, 2),
D.NUM_ROWS,
D.BLOCKS,
D.TABLE_NAME,
ROUND((d.BLOCKS*8-D.INITIAL_EXTENT/1024)/1024) t_size
FROM DBA_TABLES D
WHERE D.BLOCKS > 10
AND ROUND(D.NUM_ROWS / D.BLOCKS, 2) < 5
AND d.OWNER = 'FDCYS' ;
OWNER ROUND(D.NUM_ROWS/D.BLOCKS,2) NUM_ROWS BLOCKS TABLE_NAME T_SIZE
------------------------------ ---------------------------- ---------- ---------- ------------------------------ ----------
FDCYS 0 0 449636 SYS_20191171126389483_TEMP 3513
# 查看表上的索引
SQL> select index_name,status from dba_indexes where owner = 'FDCYS' and table_name = 'SYS_20191171126389483_TEMP';
INDEX_NAME STATUS
------------------------------ --------
SYS_C0060562 VALID
3、收缩指定表的高水位
# TMC用户收缩高水位线
alter table TMC.JG_TBL_FDC_EST_REGISTE enable row movement;
alter table TMC.JG_TBL_FDC_EST_REGISTE shrink space;
alter index TMC.EST_REGISTE_PARCEL_NO rebuild;
alter index TMC.EST_REGISTE_PROJ_NO rebuild;
alter table TMC.JG_TBL_FDC_EST_REGISTE disable row movement;
alter table TMC.FDC_YS_CONTRACT_APPENDIX enable row movement;
alter table TMC.FDC_YS_CONTRACT_APPENDIX shrink space;
alter index TMC.FYCA_IX_FYC_ID rebuild parallel 4 nologging;
alter index TMC.FYCA_IX_YS_FYB_ID rebuild parallel 4 nologging;
alter index TMC.FYCA_PK rebuild parallel 4 nologging;
alter index TMC.FYCA_IX_FYC_ID parallel 1 ;
alter index TMC.FYCA_IX_YS_FYB_ID parallel 1 ;
alter index TMC.FYCA_PK parallel 1 ;
alter index TMC.FDC_YS_CONTRACT_APPENDIX disable row movement;
alter table TMC.REMC_WS_LOG_REQUEST enable row movement;
alter table TMC. REMC_WS_LOG_REQUEST shrink space;
alter table TMC.REMC_WS_LOG_REQUEST disable row movement;
# FDCYS用户收缩高水位线
alter table FDCYS.SYS_20191171126389483_TEMP enable row movement;
alter table FDCYS.SYS_20191171126389483_TEMP shrink space;
alter index SYS_C0060562 rebuild;
alter table FDCYS.SYS_20191171126389483_TEMP disable row movement;
4、重新收集表的统计信息
exec dbms_stats.gather_table_stats('TMC','JG_TBL_FDC_EST_REGISTE',cascade=>true);
exec dbms_stats.gather_table_stats('TMC','FDC_YS_CONTRACT_APPENDIX',cascade=>true);
exec dbms_stats.gather_table_stats('TMC','REMC_WS_LOG_REQUEST',cascade=>true);
exec dbms_stats.gather_table_stats('FDCYS','SYS_20191171126389483_TEMP',cascade=>true);
如果是大表，建议使用如下语句进行统计信息收集
说明：需要替换用户名、表名、及分区名（如果是分区表）
如果要单独分析表的某个分区，将 --granularity和-- partname=>'p200902', 这句注释去掉，并替换分区名
begin
DBMS_STATS.GATHER_TABLE_STATS(ownname=>'NETFORCE',
tabname=>'TBL_PROCESS_DRAFT',
--granularity => 'PARTITION',
--partname=>'POPERATIONPROCESS0102',
estimate_percent=>1,
method_opt=>'FOR ALL COLUMNS SIZE 1',
no_invalidate=>false,
cascade=>true,
degree => 10);
end ;
Resize数据库文件
# 查看最大可resize的数据文件大小
col name for a50
col resizecmd for a90
select a.file#,
a.name,
a.bytes / 1024 / 1024 CurrentMB,
ceil(HWM * a.block_size / 1024 / 1024) Resizeto,
(a.bytes - HWM * a.block_size) / 1024 / 1024 releaseMB,
'alter database datafile ''' || a.name || ''' resize ' ||
ceil(HWM * a.block_size / 1024 / 1024) || 'M;' ResizeCmd
from v$datafile a,
(select file_id, max(block_id + blocks - 1) HWM
from dba_extents
where tablespace_name = 'TS_DATA'
group by file_id) b
where a.file# = b.file_id(+)
and (a.bytes - HWM * a.block_size) > 0
order by 5;
FILE# NAME CURRENTMB RESIZETO RELEASEMB RESIZECMD
----- -------------------------------- ---------- ---------- ---------- -------------------------------------------------------------------------
7 /Oradata/2nd_fdc/TS_DATA02.dbf 30000 30000 .0625 alter database datafile '/Oradata/2nd_fdc/TS_DATA02.dbf' resize 30000M;
9 /Oradata/2nd_fdc/TS_DATA04.dbf 30000 30000 .0625 alter database datafile '/Oradata/2nd_fdc/TS_DATA04.dbf' resize 30000M;
6 /Oradata/2nd_fdc/TS_DATA01.dbf 30000 30000 .0625 alter database datafile '/Oradata/2nd_fdc/TS_DATA01.dbf' resize 30000M;
41 /Oradata/2nd_fdc/TS_DATA29.dbf 30000 30000 .0625 alter database datafile '/Oradata/2nd_fdc/TS_DATA29.dbf' resize 30000M;
12 /Oradata/2nd_fdc/TS_DATA07.dbf 30000 30000 .0625 alter database datafile '/Oradata/2nd_fdc/TS_DATA07.dbf' resize 30000M;
61 /Oradata/2nd_fdc/TS_DATA45.dbf 30000 30000 .0625 alter database datafile '/Oradata/2nd_fdc/TS_DATA45.dbf' resize 30000M;
26 /Oradata/2nd_fdc/TS_DATA17.dbf 30000 30000 .0625 alter database datafile '/Oradata/2nd_fdc/TS_DATA17.dbf' resize 30000M;
31 /Oradata/2nd_fdc/TS_DATA22.dbf 30000 30000 .0625 alter database datafile '/Oradata/2nd_fdc/TS_DATA22.dbf' resize 30000M;
................
88 /Oradata/2nd_fdc/TS_DATA69.dbf 29980 22035 7945.9375 alter database datafile '/Oradata/2nd_fdc/TS_DATA69.dbf' resize 22035M;
86 /Oradata/2nd_fdc/TS_DATA68.dbf 29980 21958 8022.9375 alter database datafile '/Oradata/2nd_fdc/TS_DATA68.dbf' resize 21958M;
92 /Oradata/2nd_fdc/TS_DATA72.dbf 30720 21246 9474.875 alter database datafile '/Oradata/2nd_fdc/TS_DATA72.dbf' resize 21246M;
93 /Oradata/2nd_fdc/TS_DATA73.dbf 30720 20626 10094.875 alter database datafile '/Oradat
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发表于 2025-4-20 17:30:01
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