數(shù)據(jù)被刪除之后，索引只是加了一個(gè)標(biāo)記，并沒有真正的刪除，這樣可以查看碎片率。
drop table test purge;
create table test as select * from dba_objects;insert into test select * from test;insert into test select * from test;commit;create index ind_t_object_id on test(object_id);analyze index ind_t_object_id validate structure;select s.height, round((del_lf_rows_len / lf_rows_len) * 100, 2) || '%' frag_ratio, s.pct_used from index_stats s where s.name = 'IND_T_OBJECT_ID'; HEIGHT FRAG_RATIO PCT_USED---------- ------------- ---------- 3 0% 90 delete from test where object_type in('SYNONYM','java CLASS');commit;analyze index ind_t_object_id validate structure;select s.height, round((del_lf_rows_len / lf_rows_len) * 100, 2) || '%' frag_ratio, s.pct_used from index_stats s where s.name = 'IND_T_OBJECT_ID'; HEIGHT FRAG_RATIO PCT_USED---------- ------------- ---------- 3 70.23% 90 delete from test where object_type in('VIEW','INDEX','TABLE','TYPE');commit;analyze index ind_t_object_id validate structure;select s.height, round((del_lf_rows_len / lf_rows_len) * 100, 2) || '%' frag_ratio, s.pct_used from index_stats s where s.name = 'IND_T_OBJECT_ID'; HEIGHT FRAG_RATIO PCT_USED---------- --------------- ---------- 3 89.53% 84新聞熱點(diǎn)
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