[英]Oracle to_date() difference in plan and time execution
我有兩個查詢
select *
from T
where DATE_OF between to_date ('01.02.2012 00:00:00', 'DD.MM.YYYY hh24:mi:ss')
and to_date ('01.02.2012 23:59:59','DD.MM.YYYY hh24:mi:ss')
解釋計划
SELECT STATEMENT ALL_ROWSCost: 146,313 Bytes: 55,799,142 Cardinality: 150,402
2 MAT_VIEW ACCESS BY INDEX ROWID MAT_VIEW T Cost: 146,313 Bytes: 55,799,142 Cardinality: 150,402
1 INDEX RANGE SCAN INDEX IND$T_05 Cost: 464 Cardinality: 150,402
第二查詢
select *
from T
where DATE_OF >= to_date('201202','yyyyMM')
and DATE_OF < to_date('201203','yyyyMM')
解釋計划
SELECT STATEMENT ALL_ROWSCost: 4,242,836 Bytes: 1,618,120,952 Cardinality: 4,361,512
2 MAT_VIEW ACCESS BY INDEX ROWID MAT_VIEW T Cost: 4,242,836 Bytes: 1,618,120,952 Cardinality: 4,361,512
1 INDEX RANGE SCAN INDEX IND$T_05 Cost: 13,368 Cardinality: 4,361,512
索引ddl
CREATE INDEX IND$T_05 ON T(DATE_OF, TP)
DATE_OF是日期類型的列。 MVIEW未分區。
為什么查詢成本有如此大的差異?
這是因為第一個查詢掃描一天( 1 Feb 2012
),第二個查詢掃描一個月( Feb 2012
)。
您想要一天還是一個月?
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