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Posted to dev@calcite.apache.org by Yanjing Wang <zh...@gmail.com> on 2022/04/12 03:36:04 UTC
[DISCUSS] Should DEFAULT be a keyword
Hi community,
In hive, DEFAULT is a default database, so one can write sql
SELECT * FROM DEFAULT.t
In trino, one can write
SELECT * FROM HIVE.DEFAULT.t
But now Calcite treat DEFAULT as a keyword which will be resolved to
DEFAULT() function.
What should I do to make the parser to support the DEFAULT in the table
identifier?
I tried to add the DEFAULT to non-keywords but it would cause DEFAULT()
function fails.
Now I must tell the user wrap the DEFAULT using quotes like this
SELECT * FROM HIVE."DEFAULT".t
Thanks in advance.
Re: [DISCUSS] Should DEFAULT be a keyword
Posted by Yanjing Wang <zh...@gmail.com>.
Thanks Gavin and Julian, If The DEFAULT can't be removed from core parser,
I think the quote is a must. Sorry, I don't know why the hive
choose DEFAULT as its default current database.
Julian Hyde <jh...@gmail.com> 于2022年4月13日周三 02:45写道：
> On reflection, I still think that DEFAULT should be a reserved keyword.
> But I don’t think that wouldn’t prevent us from supporting it as a prefix
> to a table name in the core parser.
>
> Are the deliberations of Hive or Trino (Presto/PrestoDB) public? I’d like
> to know their rationale.
>
> Julian
>
>
> > On Apr 12, 2022, at 11:40 AM, Julian Hyde <jh...@gmail.com>
> wrote:
> >
> > DEFAULT is from the SQL standard. You can use it when invoking UDFs with
> named parameters, e.g.
> >
> > SELECT myFun(p1 => 1, p2 => DEFAULT, p3 => 3)
> > FROM t
> >
> > and in an INSERT statement:
> >
> > INSERT INTO t (x, y, z) VALUES (1, DEFAULT, 2)
> >
> > as long as parameter p2 and column y have default values.
> >
> > So yes, DEFAULT should be a reserved keyword. And Hive screwed up by not
> reading the standard.
> >
> > If there is a database or schema called DEFAULT then you can quote it,
> e.g.
> >
> > SELECT *
> > FROM “DEFAULT”.t
> >
> > We could consider making DEFAULT non-reserved in the Babel parser.
> >
> > Julian
> >
> >
> >
> >
> >> On Apr 12, 2022, at 9:06 AM, Gavin Ray <ra...@gmail.com> wrote:
> >>
> >> The hacky way would be to add a grammar clause like this I think:
> >>
> >> | "DEFAULT"
> >>
> >> To the "TableRef2" node in the parser grammar:
> >>
> https://github.com/apache/calcite/blob/82dd78a14f6aef2eeec2f9c94978d04b4acc5359/core/src/main/codegen/templates/Parser.jj#L2087-L2276
> >>
> >> Not sure all the implications this would have elsewhere though.
> >>
> >> Also for personal opinion -- the notion of a "DEFAULT" database I'm not
> >> sure is a universal thing.
> >> I've never worked with analytical DB's, only Postgres/MySQL -- and in
> these
> >> DB's the default database is implicit in your queries.
> >>
> >> IE if I connect to a database called "mydb", all queries are
> automatically
> >> prefixed implicitly with "mydb."
> >>
> >> MySQL I don't think has a default database. A brand-new MySQL DB has 0
> >> databases.
> >> There is one called "mysql" but that's a system DB, like "pg_catalog" or
> >> "information_schema".
> >>
> >> Confusingly this is different in Postgres, where the "postgres" DB is
> one
> >> that exists by default
> >> and IS intended to be a user-facing DB.
> >>
> >>
> >> On Mon, Apr 11, 2022 at 11:36 PM Yanjing Wang <
> zhuangzixiaoyou@gmail.com>
> >> wrote:
> >>
> >>> Hi community,
> >>>
> >>> In hive, DEFAULT is a default database, so one can write sql
> >>> SELECT * FROM DEFAULT.t
> >>>
> >>> In trino, one can write
> >>> SELECT * FROM HIVE.DEFAULT.t
> >>>
> >>> But now Calcite treat DEFAULT as a keyword which will be resolved to
> >>> DEFAULT() function.
> >>>
> >>> What should I do to make the parser to support the DEFAULT in the table
> >>> identifier?
> >>>
> >>> I tried to add the DEFAULT to non-keywords but it would cause DEFAULT()
> >>> function fails.
> >>>
> >>> Now I must tell the user wrap the DEFAULT using quotes like this
> >>> SELECT * FROM HIVE."DEFAULT".t
> >>>
> >>> Thanks in advance.
> >>>
> >
>
>
Re: [DISCUSS] Should DEFAULT be a keyword
Posted by Julian Hyde <jh...@gmail.com>.
On reflection, I still think that DEFAULT should be a reserved keyword. But I don’t think that wouldn’t prevent us from supporting it as a prefix to a table name in the core parser.
Are the deliberations of Hive or Trino (Presto/PrestoDB) public? I’d like to know their rationale.
Julian
> On Apr 12, 2022, at 11:40 AM, Julian Hyde <jh...@gmail.com> wrote:
>
> DEFAULT is from the SQL standard. You can use it when invoking UDFs with named parameters, e.g.
>
> SELECT myFun(p1 => 1, p2 => DEFAULT, p3 => 3)
> FROM t
>
> and in an INSERT statement:
>
> INSERT INTO t (x, y, z) VALUES (1, DEFAULT, 2)
>
> as long as parameter p2 and column y have default values.
>
> So yes, DEFAULT should be a reserved keyword. And Hive screwed up by not reading the standard.
>
> If there is a database or schema called DEFAULT then you can quote it, e.g.
>
> SELECT *
> FROM “DEFAULT”.t
>
> We could consider making DEFAULT non-reserved in the Babel parser.
>
> Julian
>
>
>
>
>> On Apr 12, 2022, at 9:06 AM, Gavin Ray <ra...@gmail.com> wrote:
>>
>> The hacky way would be to add a grammar clause like this I think:
>>
>> | "DEFAULT"
>>
>> To the "TableRef2" node in the parser grammar:
>> https://github.com/apache/calcite/blob/82dd78a14f6aef2eeec2f9c94978d04b4acc5359/core/src/main/codegen/templates/Parser.jj#L2087-L2276
>>
>> Not sure all the implications this would have elsewhere though.
>>
>> Also for personal opinion -- the notion of a "DEFAULT" database I'm not
>> sure is a universal thing.
>> I've never worked with analytical DB's, only Postgres/MySQL -- and in these
>> DB's the default database is implicit in your queries.
>>
>> IE if I connect to a database called "mydb", all queries are automatically
>> prefixed implicitly with "mydb."
>>
>> MySQL I don't think has a default database. A brand-new MySQL DB has 0
>> databases.
>> There is one called "mysql" but that's a system DB, like "pg_catalog" or
>> "information_schema".
>>
>> Confusingly this is different in Postgres, where the "postgres" DB is one
>> that exists by default
>> and IS intended to be a user-facing DB.
>>
>>
>> On Mon, Apr 11, 2022 at 11:36 PM Yanjing Wang <zh...@gmail.com>
>> wrote:
>>
>>> Hi community,
>>>
>>> In hive, DEFAULT is a default database, so one can write sql
>>> SELECT * FROM DEFAULT.t
>>>
>>> In trino, one can write
>>> SELECT * FROM HIVE.DEFAULT.t
>>>
>>> But now Calcite treat DEFAULT as a keyword which will be resolved to
>>> DEFAULT() function.
>>>
>>> What should I do to make the parser to support the DEFAULT in the table
>>> identifier?
>>>
>>> I tried to add the DEFAULT to non-keywords but it would cause DEFAULT()
>>> function fails.
>>>
>>> Now I must tell the user wrap the DEFAULT using quotes like this
>>> SELECT * FROM HIVE."DEFAULT".t
>>>
>>> Thanks in advance.
>>>
>
Re: [DISCUSS] Should DEFAULT be a keyword
Posted by Julian Hyde <jh...@gmail.com>.
DEFAULT is from the SQL standard. You can use it when invoking UDFs with named parameters, e.g.
SELECT myFun(p1 => 1, p2 => DEFAULT, p3 => 3)
FROM t
and in an INSERT statement:
INSERT INTO t (x, y, z) VALUES (1, DEFAULT, 2)
as long as parameter p2 and column y have default values.
So yes, DEFAULT should be a reserved keyword. And Hive screwed up by not reading the standard.
If there is a database or schema called DEFAULT then you can quote it, e.g.
SELECT *
FROM “DEFAULT”.t
We could consider making DEFAULT non-reserved in the Babel parser.
Julian
> On Apr 12, 2022, at 9:06 AM, Gavin Ray <ra...@gmail.com> wrote:
>
> The hacky way would be to add a grammar clause like this I think:
>
> | "DEFAULT"
>
> To the "TableRef2" node in the parser grammar:
> https://github.com/apache/calcite/blob/82dd78a14f6aef2eeec2f9c94978d04b4acc5359/core/src/main/codegen/templates/Parser.jj#L2087-L2276
>
> Not sure all the implications this would have elsewhere though.
>
> Also for personal opinion -- the notion of a "DEFAULT" database I'm not
> sure is a universal thing.
> I've never worked with analytical DB's, only Postgres/MySQL -- and in these
> DB's the default database is implicit in your queries.
>
> IE if I connect to a database called "mydb", all queries are automatically
> prefixed implicitly with "mydb."
>
> MySQL I don't think has a default database. A brand-new MySQL DB has 0
> databases.
> There is one called "mysql" but that's a system DB, like "pg_catalog" or
> "information_schema".
>
> Confusingly this is different in Postgres, where the "postgres" DB is one
> that exists by default
> and IS intended to be a user-facing DB.
>
>
> On Mon, Apr 11, 2022 at 11:36 PM Yanjing Wang <zh...@gmail.com>
> wrote:
>
>> Hi community,
>>
>> In hive, DEFAULT is a default database, so one can write sql
>> SELECT * FROM DEFAULT.t
>>
>> In trino, one can write
>> SELECT * FROM HIVE.DEFAULT.t
>>
>> But now Calcite treat DEFAULT as a keyword which will be resolved to
>> DEFAULT() function.
>>
>> What should I do to make the parser to support the DEFAULT in the table
>> identifier?
>>
>> I tried to add the DEFAULT to non-keywords but it would cause DEFAULT()
>> function fails.
>>
>> Now I must tell the user wrap the DEFAULT using quotes like this
>> SELECT * FROM HIVE."DEFAULT".t
>>
>> Thanks in advance.
>>
Re: [DISCUSS] Should DEFAULT be a keyword
Posted by Gavin Ray <ra...@gmail.com>.
The hacky way would be to add a grammar clause like this I think:
| "DEFAULT"
To the "TableRef2" node in the parser grammar:
https://github.com/apache/calcite/blob/82dd78a14f6aef2eeec2f9c94978d04b4acc5359/core/src/main/codegen/templates/Parser.jj#L2087-L2276
Not sure all the implications this would have elsewhere though.
Also for personal opinion -- the notion of a "DEFAULT" database I'm not
sure is a universal thing.
I've never worked with analytical DB's, only Postgres/MySQL -- and in these
DB's the default database is implicit in your queries.
IE if I connect to a database called "mydb", all queries are automatically
prefixed implicitly with "mydb."
MySQL I don't think has a default database. A brand-new MySQL DB has 0
databases.
There is one called "mysql" but that's a system DB, like "pg_catalog" or
"information_schema".
Confusingly this is different in Postgres, where the "postgres" DB is one
that exists by default
and IS intended to be a user-facing DB.
On Mon, Apr 11, 2022 at 11:36 PM Yanjing Wang <zh...@gmail.com>
wrote:
> Hi community,
>
> In hive, DEFAULT is a default database, so one can write sql
> SELECT * FROM DEFAULT.t
>
> In trino, one can write
> SELECT * FROM HIVE.DEFAULT.t
>
> But now Calcite treat DEFAULT as a keyword which will be resolved to
> DEFAULT() function.
>
> What should I do to make the parser to support the DEFAULT in the table
> identifier?
>
> I tried to add the DEFAULT to non-keywords but it would cause DEFAULT()
> function fails.
>
> Now I must tell the user wrap the DEFAULT using quotes like this
> SELECT * FROM HIVE."DEFAULT".t
>
> Thanks in advance.
>