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https://issues.apache.org/jira/browse/HIVE-16496?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dudu Markovitz updated HIVE-16496:
----------------------------------
Description:
support the following syntax:
{code}
select * exclude (a,b,e) from t
{code}
which for a table t with columns a,b,c,d,e would be equal to:
{code}
select c,d from t
{code}
A common use case would be:
{code}
select t1.* exclude (x), t2.* from t1 join t2 on t1.x=t2.x;
{code}
This supplies a very clean way to select all columns without getting "Ambiguous
column reference" and without the need to specify all the columns of at least
one of the tables.
Currently, without this enhancement, the query would look something like this:
{code}
select a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,y,z,t2.* from t1 join t2
on t1.x=t2.x;
{code}
An extension to this enhancement would be supporting positional column
notation, e.g.:
{code}
select * exclude (${1,2,5}) from t /* exclude columns 1, 2 and 5 */
select * exclude (${1-3}) from t /* exclude columns 1 to 3 */
select * exclude (${1,3-5,7}) from t /* exclude columns 1,3 to 5 and 7 */
select * exclude (-${1,2}) from t /* exclude last 2 columns */
select * exclude (-${1-3,7}) from t /* exclude last 3 columns and the 7th
column from the end */
{code}
A complex example would look like:
{code}
select * exclude (${1-4,5,7},x,y,-${1-3}) from t
{code}
exclude:
- first 4 columns
- 5th and 7th columns
- x and y
- last 3 columns
was:
support the following syntax:
{code}
select * exclude (a,b,e) from t
{code}
which for a table t with columns a,b,c,d,e would be equal to:
{code}
select c,d from t
{code}
A common use case would be:
{code}
select t1.* exclude \(x), t2.* from t1 join t2 on t1.x=t2.x;
{code}
This supplies a very clean way to select all columns without getting "Ambiguous
column reference" and without the need to specify all the columns of at least
one of the tables.
Currently, without this enhancement, the query would look something like this:
{code}
select a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,y,z,t2.* from t1 join t2
on t1.x=t2.x;
{code}
An extension to this enhancement would be supporting positional column
notation, e.g.:
{code}
select * exclude (${1,2,5}) from t /* exclude columns 1, 2 and 5 */
select * exclude (${1-3}) from t /* exclude columns 1 to 3 */
select * exclude (${1,3-5,7}) from t /* exclude columns 1,3 to 5 and 7 */
select * exclude (-${1,2}) from t /* exclude last 2 columns */
select * exclude (-${1-3,7}) from t /* exclude last 3 columns and the 7th
column from the end */
{code}
A complex example would look like:
{code}
select * exclude (${1-4,5,7},x,y,-${1-3}) from t
{code}
exclude:
- first 4 columns
- 5th and 7th columns
- x and y
- last 3 columns
> Enhance asterisk expression (as in "select *") with EXCLUDE clause
> ------------------------------------------------------------------
>
> Key: HIVE-16496
> URL: https://issues.apache.org/jira/browse/HIVE-16496
> Project: Hive
> Issue Type: Wish
> Components: Parser
> Reporter: Dudu Markovitz
>
> support the following syntax:
> {code}
> select * exclude (a,b,e) from t
> {code}
> which for a table t with columns a,b,c,d,e would be equal to:
> {code}
> select c,d from t
> {code}
> A common use case would be:
> {code}
> select t1.* exclude (x), t2.* from t1 join t2 on t1.x=t2.x;
> {code}
> This supplies a very clean way to select all columns without getting
> "Ambiguous column reference" and without the need to specify all the columns
> of at least one of the tables.
>
> Currently, without this enhancement, the query would look something like this:
> {code}
> select a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,y,z,t2.* from t1 join t2
> on t1.x=t2.x;
> {code}
> An extension to this enhancement would be supporting positional column
> notation, e.g.:
> {code}
> select * exclude (${1,2,5}) from t /* exclude columns 1, 2 and 5 */
> select * exclude (${1-3}) from t /* exclude columns 1 to 3 */
> select * exclude (${1,3-5,7}) from t /* exclude columns 1,3 to 5 and 7 */
> select * exclude (-${1,2}) from t /* exclude last 2 columns */
> select * exclude (-${1-3,7}) from t /* exclude last 3 columns and the 7th
> column from the end */
> {code}
> A complex example would look like:
> {code}
> select * exclude (${1-4,5,7},x,y,-${1-3}) from t
> {code}
> exclude:
> - first 4 columns
> - 5th and 7th columns
> - x and y
> - last 3 columns
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