Unquoted column names fold to lower case

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Unquoted column names fold to lower case

Dev Kumkar
Hello,

All unquoted identifiers are assumed by PostgreSQL to be lower case by default. This means
- SELECT MY_COLUMN FROM my_table
- SELECT my_column FROM my_table
- SELECT my_column as MY_COLUMN FROM my_table
All refer to my_column and has column name in lowercase as my_column.

If the aliases are in upper case and quoted then those are returned in upper case.
- SELECT my_column as "MY_COLUMN" FROM my_table

Is there any workaround to set the alias columns to be returned as upper case with adding quotes. Is there any connection level parameter to flip this behavior?

Thanks in advance!

Regards...
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Re: Unquoted column names fold to lower case

Dev Kumkar
Resending

On Wed, Jul 3, 2013 at 2:42 PM, Dev Kumkar <[hidden email]> wrote:
Hello,

All unquoted identifiers are assumed by PostgreSQL to be lower case by default. This means
- SELECT MY_COLUMN FROM my_table
- SELECT my_column FROM my_table
- SELECT my_column as MY_COLUMN FROM my_table
All refer to my_column and has column name in lowercase as my_column.

If the aliases are in upper case and quoted then those are returned in upper case.
- SELECT my_column as "MY_COLUMN" FROM my_table

Is there any workaround to set the alias columns to be returned as upper case without adding quotes. Is there any connection level parameter to flip this behavior?

Thanks in advance!

Regards...
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Re: Unquoted column names fold to lower case

Vik Fearing
In reply to this post by Dev Kumkar
On 07/03/2013 11:12 AM, Dev Kumkar wrote:

> All unquoted identifiers are assumed by PostgreSQL to be lower case by
> default. This means
> - SELECT MY_COLUMN FROM my_table
> - SELECT my_column FROM my_table
> - SELECT my_column as MY_COLUMN FROM my_table
> All refer to my_column and has column name in lowercase as my_column.
>
> If the aliases are in upper case and quoted then those are returned in
> upper case.
> - SELECT my_column as "MY_COLUMN" FROM my_table
>
> Is there any workaround to set the alias columns to be returned as
> upper case with adding quotes.

There is no workaround because there is no bug.

> Is there any connection level parameter to flip this behavior?

No.


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Re: Unquoted column names fold to lower case

Dev Kumkar
Thanks!

Sure this is not a bug. Just want to know if there is any possible way to achieve this.
Reason being - need to change all the data layer of project where the column mapping has been done with Upper Case.


Regards...
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Re: Unquoted column names fold to lower case

Theodore Petrosky
In reply to this post by Dev Kumkar
sorry, but you misunderstand. this is the correct behavior of SQL.

It is part of the specification to do this.

--- On Wed, 7/3/13, Dev Kumkar <[hidden email]> wrote:

> From: Dev Kumkar <[hidden email]>
> Subject: [SQL] Unquoted column names fold to lower case
> To: [hidden email]
> Date: Wednesday, July 3, 2013, 5:12 AM
> Hello,
>
> All unquoted identifiers are assumed by PostgreSQL to be
> lower case by default. This means
> - SELECT MY_COLUMN FROM my_table
> - SELECT my_column FROM my_table
> - SELECT my_column as MY_COLUMN FROM my_table
>
> All refer to my_column and has column name in lowercase as
> my_column.
>
> If the aliases are in upper case and quoted then
> those are returned in upper case.
> - SELECT my_column as "MY_COLUMN" FROM
> my_table
>
>
> Is there any workaround to set the alias columns
> to be returned as upper case with adding quotes. Is there
> any connection level parameter to flip this behavior?
>
> Thanks in advance!
>
>
> Regards...
>
>


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Re: Unquoted column names fold to lower case

Thomas Kellerer
Theodore Petrosky, 03.07.2013 15:41:
> sorry, but you misunderstand. this is the correct behavior of SQL.
>
> It is part of the specification to do this.
>

Not quite. The SQL standard requires folding to uppercase.






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Re: Unquoted column names fold to lower case

Bruce Momjian
On Wed, Jul  3, 2013 at 04:16:41PM +0200, Thomas Kellerer wrote:
> Theodore Petrosky, 03.07.2013 15:41:
> > sorry, but you misunderstand. this is the correct behavior of SQL.
> >
> > It is part of the specification to do this.
> >
>
> Not quite. The SQL standard requires folding to uppercase.

Agreed.  The original poster specifically wanted "MYTABLE" and mytable
to be the same, not "mytable" and mytable.  Postgres is certainly
non-standard in this area.  I think the ability visiually distinguish
lower-case letters better than upper-case letters has led to our
behavior.

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Re: Unquoted column names fold to lower case

Dev Kumkar
On Wed, Jul 3, 2013 at 8:54 PM, Bruce Momjian <[hidden email]> wrote:
Agreed.  The original poster specifically wanted "MYTABLE" and mytable
to be the same, not "mytable" and mytable.  Postgres is certainly
non-standard in this area.  I think the ability visiually distinguish
lower-case letters better than upper-case letters has led to our
behavior.

Not really, actually am looking for column aliases here and not the table. Here is the example again when the aliases are unquoted:
- SELECT my_column as MY_COLUMN FROM my_table

The above SELECT will fold the alias name as my_column and not MY_COLUMN.

Regards...
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Re: Unquoted column names fold to lower case

Bruce Momjian
On Wed, Jul  3, 2013 at 09:02:20PM +0530, Dev Kumkar wrote:

> On Wed, Jul 3, 2013 at 8:54 PM, Bruce Momjian <[hidden email]> wrote:
>
>     Agreed.  The original poster specifically wanted "MYTABLE" and mytable
>     to be the same, not "mytable" and mytable.  Postgres is certainly
>     non-standard in this area.  I think the ability visiually distinguish
>     lower-case letters better than upper-case letters has led to our
>     behavior.
>
>
> Not really, actually am looking for column aliases here and not the table. Here
> is the example again when the aliases are unquoted:
> - SELECT my_column as MY_COLUMN FROM my_table
>
> The above SELECT will fold the alias name as my_column and not MY_COLUMN.

Yes, both the identifier names and alias names are folded to lower case.
I never thought of them as different, but you are right, they are, and
we are non-standard in both areas.  Sorry.

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Re: Unquoted column names fold to lower case

Dev Kumkar
On Wed, Jul 3, 2013 at 9:05 PM, Bruce Momjian <[hidden email]> wrote:
Yes, both the identifier names and alias names are folded to lower case.
I never thought of them as different, but you are right, they are, and
we are non-standard in both areas.  Sorry.

Any plans to fix this in next release or having a patch to fix this?
The default PostgreSQL behavior is folding column names to lower case but when an alias is used it should fold as per alias name.

Note that adding quotes for aliases will be blessed by PostgreSQL and then those will be folded to upper case BUT this adds up to lot of changes in the SQL layer.

Regards...
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Re: Unquoted column names fold to lower case

Thomas Kellerer
Dev Kumkar wrote on 03.07.2013 17:50:
> Note that adding quotes for aliases will be blessed by PostgreSQL and
> then those will be folded to upper case BUT this adds up to lot of
> changes in the SQL layer.

I wonder why you need that. I never had the requirement for that.

Which driver/interface do you use that requires an alias to be all uppercase?





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Re: Unquoted column names fold to lower case

Tom Lane-2
In reply to this post by Dev Kumkar
Dev Kumkar <[hidden email]> writes:
> Any plans to fix this in next release or having a patch to fix this?

No.

This has been discussed (many times) before.  There isn't any feasible
way to change this behavior without breaking an incredible amount of
code, much of which isn't even under our control.  The marginal increase
in standards compliance is not worth the pain --- especially when the
aspect of the standard in question isn't even one that most of us like.
(All-upper-case is hard to read.)

If this is a deal-breaker for you, then I'm sorry, but you need to find
another database.  Postgres settled on this behavior fifteen years ago,
and we're not changing it now.

                        regards, tom lane


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Re: Unquoted column names fold to lower case

Bruce Momjian
On Wed, Jul  3, 2013 at 12:20:06PM -0400, Tom Lane wrote:

> Dev Kumkar <[hidden email]> writes:
> > Any plans to fix this in next release or having a patch to fix this?
>
> No.
>
> This has been discussed (many times) before.  There isn't any feasible
> way to change this behavior without breaking an incredible amount of
> code, much of which isn't even under our control.  The marginal increase
> in standards compliance is not worth the pain --- especially when the
> aspect of the standard in question isn't even one that most of us like.
> (All-upper-case is hard to read.)
>
> If this is a deal-breaker for you, then I'm sorry, but you need to find
> another database.  Postgres settled on this behavior fifteen years ago,
> and we're not changing it now.

Agreed.  I guess we could add it to the "Features We Do Not Want"
section of the TODO list, but it rarely comes up.

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Re: Unquoted column names fold to lower case

Dev Kumkar
In reply to this post by Thomas Kellerer
On Wed, Jul 3, 2013 at 9:35 PM, Thomas Kellerer <[hidden email]> wrote:
I wonder why you need that. I never had the requirement for that.

Which driver/interface do you use that requires an alias to be all uppercase?

Looks like you didn't get me, am not saying aliases to be all upper case by default (BTW upper case behavior is seen in Oracle by default which is exactly reverse of postgres).

But what I am asking here is if an alias name is provided be it upper case, lower case, or a mix then shouldn't it be preserved as as it is given. All this talk is when alias names are unquoted, when quoted then its standard behavior as seen in other databases.

Regards...
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Re: Unquoted column names fold to lower case

Dev Kumkar
In reply to this post by Tom Lane-2
On Wed, Jul 3, 2013 at 9:50 PM, Tom Lane <[hidden email]> wrote:
> Any plans to fix this in next release or having a patch to fix this?

No.

This has been discussed (many times) before.  There isn't any feasible
way to change this behavior without breaking an incredible amount of
code, much of which isn't even under our control.  The marginal increase
in standards compliance is not worth the pain --- especially when the
aspect of the standard in question isn't even one that most of us like.
(All-upper-case is hard to read.)

If this is a deal-breaker for you, then I'm sorry, but you need to find
another database.  Postgres settled on this behavior fifteen years ago,
and we're not changing it now.

Again my question was not to change the default behavior and make then All-upper-case as there is no need to change it.

Rather it was for alias names and if those are with upper case or mix case then wouldn't it will be good to preserve same. For me these changes to have aliases quoted are manageable and I was just checking for any thoughts here.

Regards...
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Re: Unquoted column names fold to lower case

Alvaro Herrera-9
In reply to this post by Dev Kumkar
Dev Kumkar escribió:

> But what I am asking here is if an alias name is provided be it upper case,
> lower case, or a mix then shouldn't it be preserved as as it is given. All
> this talk is when alias names are unquoted, when quoted then its standard
> behavior as seen in other databases.

Aliases are treated just like any other identifier.  The downcasing
happens in the lexer (src/backend/parser/scan.l), which is totally
unaware of the context in which this is happening; so there's no way to
tweak the downcasing behavior for only aliases and not other
identifiers.

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PostgreSQL Development, 24x7 Support, Training & Services


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Re: Unquoted column names fold to lower case

Dev Kumkar
On Thu, Jul 4, 2013 at 12:38 AM, Alvaro Herrera <[hidden email]> wrote:
Aliases are treated just like any other identifier.  The downcasing
happens in the lexer (src/backend/parser/scan.l), which is totally
unaware of the context in which this is happening; so there's no way to
tweak the downcasing behavior for only aliases and not other
identifiers.

Oh OK, that makes sense and yes can see through complexity.
So I believe when aliases are quoted then the scan process might be different and hence quotes aliases TEXT CASE gets preserved.

Regards...
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Re: Unquoted column names fold to lower case

Tom Lane-2
In reply to this post by Alvaro Herrera-9
Alvaro Herrera <[hidden email]> writes:
> Dev Kumkar escribió:
>> But what I am asking here is if an alias name is provided be it upper case,
>> lower case, or a mix then shouldn't it be preserved as as it is given. All
>> this talk is when alias names are unquoted, when quoted then its standard
>> behavior as seen in other databases.

> Aliases are treated just like any other identifier.  The downcasing
> happens in the lexer (src/backend/parser/scan.l), which is totally
> unaware of the context in which this is happening; so there's no way to
> tweak the downcasing behavior for only aliases and not other
> identifiers.

Quite aside from implementation difficulty, restricting the change to
just column aliases doesn't make it more palatable.  You'd entirely lose
the argument that the change increases spec compliance, because the spec
is perfectly clear that a column alias is an identifier just like any
other.  And you'd still be paying a large part of the application
breakage costs, because the identifiers coming back in query descriptors
are one of the main ways applications would notice such a change.

                        regards, tom lane


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Re: Unquoted column names fold to lower case

Bruce Momjian
On Wed, Jul  3, 2013 at 03:47:37PM -0400, Tom Lane wrote:

> Alvaro Herrera <[hidden email]> writes:
> > Dev Kumkar escribi�:
> >> But what I am asking here is if an alias name is provided be it upper case,
> >> lower case, or a mix then shouldn't it be preserved as as it is given. All
> >> this talk is when alias names are unquoted, when quoted then its standard
> >> behavior as seen in other databases.
>
> > Aliases are treated just like any other identifier.  The downcasing
> > happens in the lexer (src/backend/parser/scan.l), which is totally
> > unaware of the context in which this is happening; so there's no way to
> > tweak the downcasing behavior for only aliases and not other
> > identifiers.
>
> Quite aside from implementation difficulty, restricting the change to
> just column aliases doesn't make it more palatable.  You'd entirely lose
> the argument that the change increases spec compliance, because the spec
> is perfectly clear that a column alias is an identifier just like any
> other.  And you'd still be paying a large part of the application
> breakage costs, because the identifiers coming back in query descriptors
> are one of the main ways applications would notice such a change.

And let's not forget that column aliases can be used as indentifiers in
queries:

        test=> SELECT 1 AS x
        test-> ORDER BY x;
         x
        ---
         1
        (1 row)

        test=> SELECT 1 AS "X"
        ORDER BY x;
        ERROR:  column "x" does not exist
        LINE 2: ORDER BY x;

Changing this would mean that the same identifier would have different
case-folding rules depending on where it appeared in the query.

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Re: Unquoted column names fold to lower case

Dev Kumkar
On Thu, Jul 4, 2013 at 1:36 AM, Bruce Momjian <[hidden email]> wrote:
And let's not forget that column aliases can be used as indentifiers in
queries:

        test=> SELECT 1 AS x
        test-> ORDER BY x;
         x
        ---
         1
        (1 row)

        test=> SELECT 1 AS "X"
        ORDER BY x;
        ERROR:  column "x" does not exist
        LINE 2: ORDER BY x;

Changing this would mean that the same identifier would have different
case-folding rules depending on where it appeared in the query.
 
Sorry but I am not sure about your point here. Currently if the alias is quoted then same needs to be used in queries as identifies:
SELECT 1 AS "X"
        ORDER BY "X";

Regards...
12