l******r
发帖数: 99 | 1 I have a table A, which has 50 millions records.
In this table A, I have two columns id and date.
if I run the following query:
select date, sum(id) from A group by date
it will take 10 minutes to finish.
what can I do to improve the performance?
there are 3 bitmap indexes for this table A.
index 1 is on column id.
index 2 is on column date.
index 3 is on column id and column date.
Please help. Thanks. | B*****g
发帖数: 34098 | 2 1. please post execution plan
2. will data in this table be updated?
3. what datatype is for column "date"
【在 l******r 的大作中提到】
: I have a table A, which has 50 millions records.
: In this table A, I have two columns id and date.
: if I run the following query:
: select date, sum(id) from A group by date
: it will take 10 minutes to finish.
: what can I do to improve the performance?
: there are 3 bitmap indexes for this table A.
: index 1 is on column id.
: index 2 is on column date.
: index 3 is on column id and column date.
| l******r
发帖数: 99 | 3
I am using Oracle SQL Developer, here is the execution plan:
the same query like above,
operation object_name options cost
select statement 162443
hash group by 162443
table access tableA full 160439
Yes, by a hourly SQL loading process.
DATETIME
【在 B*****g 的大作中提到】
: 1. please post execution plan
: 2. will data in this table be updated?
: 3. what datatype is for column "date"
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