一个SQL如何选择多个分区? [英] How does one do a SQL select over multiple partitions?

问题描述

有没有比以下更有效的方法?

Is there a more efficient way than:

select * from transactions partition( partition1 ) 
union all 
select * from transactions partition( partition2 ) 
union all 
select * from transactions partition( partition3 ); 

推荐答案

在查询中使用PARTITION(partitionN)语法应该很少见.

It should be exceptionally rare that you use the PARTITION( partitionN ) syntax in a query.

您通常只想为分区键指定值，并允许Oracle执行分区消除.例如，如果您的表是根据TRANSACTION_DATE每天进行分区的，则为

You would normally just want to specify values for the partition key and allow Oracle to perform partition elimination. If your table is partitioned daily based on TRANSACTION_DATE, for example

SELECT *
  FROM transactions
 WHERE transaction_date IN (date '2010-11-22', 
                            date '2010-11-23', 
                            date '2010-11-24')

将从今天的分区，昨天的分区和前一天的分区中选择所有数据.

would select all the data from today's partition, yesterday's partition, and the day before's partition.

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