[jira] [Commented] (SPARK-29900) make relation lookup behavior consistent within Spark SQL

["Lauri Koobas (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-29900?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17196812#comment-17196812 ] 

Lauri Koobas commented on SPARK-29900:
--------------------------------------

Bringing up a related point - `show tables in <database>` always shows also temporary views. Same with `sqlContext.tableNames("database")`. This seems counter-intuitive.

There should be an additional flag to either include or exclude temporary views from that list.

> make relation lookup behavior consistent within Spark SQL
> ---------------------------------------------------------
>
>                 Key: SPARK-29900
>                 URL: https://issues.apache.org/jira/browse/SPARK-29900
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 3.1.0
>            Reporter: Wenchen Fan
>            Priority: Major
>
> Currently, Spark has 2 different relation resolution behaviors:
> 1. try to look up temp view first, then try table/persistent view.
> 2. try to look up table/persistent view.
> The first behavior is used in SELECT, INSERT and a few commands that support views, like DESC TABLE.
> The second behavior is used in most commands.
> It's confusing to have inconsistent relation resolution behaviors, and the benefit is super small. It's only useful when there are temp view and table with the same name, but users can easily use qualified table name to disambiguate.
> In postgres, the relation resolution behavior is consistent
> {code}
> cloud0fan=# create schema s1;
> CREATE SCHEMA
> cloud0fan=# SET search_path TO s1;
> SET
> cloud0fan=# create table s1.t (i int);
> CREATE TABLE
> cloud0fan=# insert into s1.t values (1);
> INSERT 0 1
> # access table with qualified name
> cloud0fan=# select * from s1.t;
>  i 
> ---
>  1
> (1 row)
> # access table with single name
> cloud0fan=# select * from t;
>  i 
> ---
>  1
> (1 rows)
> # create a temp view with conflicting name
> cloud0fan=# create temp view t as select 2 as i;
> CREATE VIEW
> # same as spark, temp view has higher proirity during resolution
> cloud0fan=# select * from t;
>  i 
> ---
>  2
> (1 row)
> # DROP TABLE also resolves temp view first
> cloud0fan=# drop table t;
> ERROR:  "t" is not a table
> # DELETE also resolves temp view first
> cloud0fan=# delete from t where i = 0;
> ERROR:  cannot delete from view "t"
> {code}



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