temporary table /view 探究_股市动态

temporary table /view 探究

创始人

2025-05-29 08:49:47

0次

explain
select*
from t1union all
select*
from t1

view 每次执行都会有新的值产生

从执行计划上看view 就是用的不同的值参与随机

== Physical Plan ==
Union
:- *(1) Project [random(-3323905141429424159) AS a#44]
: +- *(1) Scan OneRowRelation[]
+- *(2) Project [random(5605563624691597816) AS a#46]
+- *(2) Scan OneRowRelation[]

------------------------------------------------ temporary table

create temporary  table  t1 as (select random() as a
);
-- explain
select*
from t1union all
select*
from t1

查看执行计划拿到的是一个临时的数据, 固定的结果值

== Physical Plan ==
Union
:- Scan hive work_table.spark_temp_application_1677888387085_9802_t1 [a#80], HiveTableRelation [`work_table`.`spark_temp_application_1677888387085_9802_t1`, org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe, Data Cols: [a#80], Partition Cols: []]
+- Scan hive work_table.spark_temp_application_1677888387085_9802_t1 [a#81], HiveTableRelation [`work_table`.`spark_temp_application_1677888387085_9802_t1`, org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe, Data Cols: [a#81], Partition Cols: []]

总结临时表会落表数据, view 重用的是代码段.

词库加载错误:未能找到文件“E:\highferrum_mysql\Configuration\Dict_Stopwords.txt”。

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