统计信息的备份

一般重新收集table 或index 都会有风险，需要把之前的统计信息备份下，万一收集后performance 没有之前好，已经将备份的统计信息导入快速恢复。

创建统计信息备份表

begin

dbms_stats.create_stat_table(ownname => 'SYSTEM',stattab => 'STAT_BK');

end;

/

 

生成表统计信息导出备份脚本

select 'begin dbms_stats.export_table_stats(ownname => ' || chr(39) ||

       b.owner || chr(39) || ',tabname =>' || chr(39) || b.table_name ||

      chr(39) || ',stattab =>' || chr(39) || 'STAT_BK' || chr(39) ||

       ',statown =>' || chr(39) || 'SYSTEM' || chr(39) ||

       ',cascade => true); end; /'
 from dba_segments a, dba_tables b
 where a.tablespace_name IN ('DW_100M_DT')
   and a.segment_type = 'TABLE'
   and a.owner = b.owner
   and a.segment_name = b.table_name;

 

begin

SYS.dbms_stats.export_table_stats(ownname => 'MESTST',tabname =>'ACTIONMAP',stattab =>'STAT_BK',cascade => true,statown=>'SYSTEM');

end;

/

 

生成索引统计信息导出备份脚本

select 'begin dbms_stats.export_index_stats(ownname => ' || chr(39) ||

       b.owner || chr(39) || ',indname =>' || chr(39) || b.index_name ||

       chr(39) || ',stattab =>' || chr(39) || 'STAT_BK' || chr(39) ||

       ',statown =>' || chr(39) || 'SYSTEM' || chr(39) || '); end; / '
 from dba_segments a, dba_indexes b
 where a.tablespace_name IN ('GW_100M_DATN', 'GW_100M_IDXN')
   and a.segment_type = 'INDEX'
   and a.owner = b.owner
   and a.segment_name = b.index_name

union

select 'begin dbms_stats.export_index_stats(ownname => ' || chr(39) ||

       b.owner || chr(39) || ',indname =>' || chr(39) || b.index_name ||

       chr(39) || ',stattab =>' || chr(39) || 'STAT_BK' || chr(39) ||

       ',statown =>' || chr(39) || 'SYSTEM' || chr(39) || '); end; / '
 from dba_segments a, dba_indexes b
 where a.tablespace_name IN ('GW_100M_DATN', 'GW_100M_IDXN')

  and a.segment_type = 'TABLE'
   and a.owner = b.table_owner
   and a.segment_name = b.table_name;

 

IMPORT 表的统计信息

begin

SYS.dbms_stats.IMPORT_TABLE_STATS(ownname => 'MESTST',tabname =>'ACTIONMAP',stattab =>'STAT_BK',cascade => true,statown=>'SYSTEM');

end;

/