一般重新收集table 或index 都會有風險，需要把之前的統計信息備份下，萬一收集后performance 沒有之前好，已經將備份的統計信息導入快速恢復。

創建統計信息備份表

begin

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

end;

/

?

生成表統計信息導出備份腳本

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;

/

?

生成索引統計信息導出備份腳本

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 表的統計信息

begin

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

end;

/

轉載于:https://www.cnblogs.com/yifan268/archive/2011/01/27/1946353.html

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