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https://issues.apache.org/jira/browse/HIVE-24664?focusedWorklogId=538440&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-538440
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ASF GitHub Bot logged work on HIVE-24664:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 20/Jan/21 13:36
Start Date: 20/Jan/21 13:36
Worklog Time Spent: 10m
Work Description: kasakrisz opened a new pull request #1892:
URL: https://github.com/apache/hive/pull/1892
### What changes were proposed in this pull request?
1. Declare a list in `IdentifiersParser` for storing aliases specified after
expressions in the values clause first row. If no alias is specified generate
one implicitly.
2. Add methods to manipulate and query the list.
3. Create a new `firstValueRowConstructor` from parser rule
`valueRowConstructor` to parse the first and rest of the rows in a different
way. Inline the brackets to these new rules like in `expressionsInParenthesis`
4. Create `firstExpressionsWithAlias` and `moreExpressionsWithAlias` rules
and call them from `firstValueRowConstructor`/`valueRowConstructor` rules based
on the merge of existing rules: `expressionsNotInParenthesis` and
`expressionPart`: since `isStruct` and `forceStruct` is always true when
calling from `valueRowConstructor` keep only the branch which is used when
these two parameters are true in the new rules.
5. Create parser rule `expressionWithAlias`. This rule handles expressions
with and without alias and it stores the parsed/generated alias in a list
mentioned in 1.
6. Create parser rule `expressionWithStoredAlias` to parse a single
expression without an alias explicitly specified but assign one from the stored
ones.
7. Rename the first parameter of parser rule `expressionPart`.
### Why are the changes needed?
Support column aliases in Values clause. See jira or `values_alias.q` for
example.
### Does this PR introduce _any_ user-facing change?
Yes, but existing queries are not affected. With this patch users can define
column aliases in the first row of Values clause. This type of alias definition
is not supported in `INSERT INTO <table>[<column alias list>] VALUES([actual
values])` statements.
### How was this patch tested?
```
mvn test -Dtest=TestValuesClause -pl parser
mvn test -Dtest.output.overwrite -DskipSparkTests
-Dtest=TestMiniLlapLocalCliDriver -Dqfile=values.q,values_alias.q -pl
itests/qtest -Pitests
```
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Issue Time Tracking
-------------------
Worklog Id: (was: 538440)
Remaining Estimate: 0h
Time Spent: 10m
> Support column aliases in Values clause
> ---------------------------------------
>
> Key: HIVE-24664
> URL: https://issues.apache.org/jira/browse/HIVE-24664
> Project: Hive
> Issue Type: Improvement
> Reporter: Krisztian Kasa
> Assignee: Krisztian Kasa
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Enable explicitly specify column aliases in the first row of Values clause.
> If not all the columns has alias specified generate one.
> {code:java}
> values(1, 2 b, 3 c),(4, 5, 6);
> {code}
> {code:java}
> _col1 b c
> 1 2 3
> 4 5 6
> {code}
> This is not an standard SQL feature but some database engines like Impala
> supports it.
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