mirror of https://github.com/postgres/postgres
Update TODO list.
This commit is contained in:
Bruce Momjian
parent
f66393514f
commit
ebd2391546
3
doc/TODO
3
doc/TODO
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@ -49,6 +49,9 @@ PARSER
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* -select * from pg_class where oid in (0,-1)
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* have INTERSECT/EXCEPT prevent duplicates unless ALL is specified
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* prevent primary key of nine columns(see TODO.detail/primary)
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* SELECT COUNT('asdf') FROM pg_class WHERE oid=12 crashes
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* SELECT DISTINCT ON col1 col1 col2 FROM tab1 is broken
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(see TODO.detail/distinct)
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VIEWS
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@ -0,0 +1,483 @@
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From owner-pgsql-sql@hub.org Sat Jul 10 16:31:14 1999
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Date: Sun, 11 Jul 1999 00:16:39 +0400 (MSD)
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From: Oleg Bartunov <oleg@sai.msu.su>
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X-Sender: megera@ra
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Reply-To: Oleg Bartunov <oleg@sai.msu.su>
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To: hackers@postgreSQL.org
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cc: pgsql-sql@postgreSQL.org
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||||
Subject: [SQL] SELECT DISTINCT question
|
||||
Message-ID: <Pine.GSO.3.96.SK.990711000908.2043R-100000@ra>
|
||||
Organization: Sternberg Astronomical Institute (Moscow University)
|
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MIME-Version: 1.0
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Content-Type: TEXT/PLAIN; charset=US-ASCII
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Sender: owner-pgsql-sql@postgreSQL.org
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Precedence: bulk
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Status: RO
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I got a problem with query:
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select distinct (date), bytes from access_log;
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which works but not as I expect. I thought this query will select
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all rows with distinct values of 'date' column, but it get
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distinct pairs 'date, bytes' . From documnetation I see
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"DISTINCT will eliminate all duplicate rows from the selection.
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DISTINCT ON column will eliminate all duplicates in the specified column;
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this is equivalent to using GROUP BY column.
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ALL will return all candidate rows, including duplicates."
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discovery=> select distinct on date,bytes from access_log;
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ERROR: parser: parse error at or near ","
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||||
|
||||
Regards,
|
||||
|
||||
Oleg
|
||||
_____________________________________________________________
|
||||
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
|
||||
Sternberg Astronomical Institute, Moscow University (Russia)
|
||||
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
|
||||
phone: +007(095)939-16-83, +007(095)939-23-83
|
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From owner-pgsql-sql@hub.org Sat Jul 10 18:01:17 1999
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To: Oleg Bartunov <oleg@sai.msu.su>
|
||||
cc: hackers@postgreSQL.org, pgsql-sql@postgreSQL.org
|
||||
Subject: [SQL] Re: [HACKERS] SELECT DISTINCT question
|
||||
In-reply-to: Your message of Sun, 11 Jul 1999 00:16:39 +0400 (MSD)
|
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<Pine.GSO.3.96.SK.990711000908.2043R-100000@ra>
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Date: Sat, 10 Jul 1999 17:18:28 -0400
|
||||
Message-ID: <5707.931641508@sss.pgh.pa.us>
|
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From: Tom Lane <tgl@sss.pgh.pa.us>
|
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Sender: owner-pgsql-sql@postgreSQL.org
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Precedence: bulk
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Status: RO
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Oleg Bartunov <oleg@sai.msu.su> writes:
|
||||
> discovery=> select distinct on date,bytes from access_log;
|
||||
> ERROR: parser: parse error at or near ","
|
||||
|
||||
The syntax for SELECT DISTINCT ON is just as brain-damaged as the
|
||||
functionality itself: there's no comma after the column name.
|
||||
You want
|
||||
|
||||
select distinct on date date,bytes from access_log;
|
||||
|
||||
The reason the functionality is brain-damaged is that there's no way to
|
||||
know which tuple out of the set of tuples with a given "date" value will
|
||||
be the one returned.
|
||||
|
||||
SELECT DISTINCT ON is not in SQL92, and I think it shouldn't be in
|
||||
Postgres either...
|
||||
|
||||
regards, tom lane
|
||||
|
||||
|
||||
From owner-pgsql-sql@hub.org Sun Jul 11 12:01:23 1999
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Received: from renoir.op.net (root@renoir.op.net [209.152.193.4])
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Date: Sun, 11 Jul 1999 10:09:24 +0400 (MSD)
|
||||
From: Oleg Bartunov <oleg@sai.msu.su>
|
||||
X-Sender: megera@ra
|
||||
To: Tom Lane <tgl@sss.pgh.pa.us>
|
||||
cc: hackers@postgreSQL.org, pgsql-sql@postgreSQL.org
|
||||
Subject: Re: [SQL] Re: [HACKERS] SELECT DISTINCT question
|
||||
In-Reply-To: <5707.931641508@sss.pgh.pa.us>
|
||||
Message-ID: <Pine.GSO.3.96.SK.990711100405.2043V-100000@ra>
|
||||
Organization: Sternberg Astronomical Institute (Moscow University)
|
||||
MIME-Version: 1.0
|
||||
Content-Type: TEXT/PLAIN; charset=US-ASCII
|
||||
Sender: owner-pgsql-sql@postgreSQL.org
|
||||
Precedence: bulk
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Status: RO
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||||
|
||||
On Sat, 10 Jul 1999, Tom Lane wrote:
|
||||
|
||||
> Date: Sat, 10 Jul 1999 17:18:28 -0400
|
||||
> From: Tom Lane <tgl@sss.pgh.pa.us>
|
||||
> To: Oleg Bartunov <oleg@sai.msu.su>
|
||||
> Cc: hackers@postgreSQL.org, pgsql-sql@postgreSQL.org
|
||||
> Subject: [SQL] Re: [HACKERS] SELECT DISTINCT question
|
||||
>
|
||||
> Oleg Bartunov <oleg@sai.msu.su> writes:
|
||||
> > discovery=> select distinct on date,bytes from access_log;
|
||||
> > ERROR: parser: parse error at or near ","
|
||||
>
|
||||
> The syntax for SELECT DISTINCT ON is just as brain-damaged as the
|
||||
> functionality itself: there's no comma after the column name.
|
||||
> You want
|
||||
>
|
||||
> select distinct on date date,bytes from access_log;
|
||||
>
|
||||
|
||||
thanks, this works. But why parser complains about such query:
|
||||
|
||||
discovery=> select distinct on a.date a.date, a.bytes from access_log a;
|
||||
ERROR: parser: parse error at or near "."
|
||||
|
||||
In this query I could just omit '.', but in more complex query
|
||||
I probably could need one.
|
||||
|
||||
> The reason the functionality is brain-damaged is that there's no way to
|
||||
> know which tuple out of the set of tuples with a given "date" value will
|
||||
> be the one returned.
|
||||
>
|
||||
> SELECT DISTINCT ON is not in SQL92, and I think it shouldn't be in
|
||||
> Postgres either...
|
||||
|
||||
|
||||
I'm not an SQL expert, but if it works and this feature is in standard
|
||||
but only syntax is diffrent, why just not to use standard
|
||||
|
||||
select distinct(date), bytes from access_log;
|
||||
|
||||
Or I'm missing here ?
|
||||
|
||||
|
||||
Regards,
|
||||
Oleg
|
||||
>
|
||||
> regards, tom lane
|
||||
>
|
||||
|
||||
_____________________________________________________________
|
||||
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
|
||||
Sternberg Astronomical Institute, Moscow University (Russia)
|
||||
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
|
||||
phone: +007(095)939-16-83, +007(095)939-23-83
|
||||
|
||||
|
||||
|
||||
From owner-pgsql-hackers@hub.org Sun Jul 11 12:01:26 1999
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Received: from renoir.op.net (root@renoir.op.net [209.152.193.4])
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Sun, 11 Jul 1999 10:09:24 +0400 (MSD)
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Date: Sun, 11 Jul 1999 10:09:24 +0400 (MSD)
|
||||
From: Oleg Bartunov <oleg@sai.msu.su>
|
||||
X-Sender: megera@ra
|
||||
To: Tom Lane <tgl@sss.pgh.pa.us>
|
||||
cc: hackers@postgreSQL.org, pgsql-sql@postgreSQL.org
|
||||
Subject: Re: [SQL] Re: [HACKERS] SELECT DISTINCT question
|
||||
In-Reply-To: <5707.931641508@sss.pgh.pa.us>
|
||||
Message-ID: <Pine.GSO.3.96.SK.990711100405.2043V-100000@ra>
|
||||
Organization: Sternberg Astronomical Institute (Moscow University)
|
||||
MIME-Version: 1.0
|
||||
Content-Type: TEXT/PLAIN; charset=US-ASCII
|
||||
Sender: owner-pgsql-hackers@postgreSQL.org
|
||||
Precedence: bulk
|
||||
Status: RO
|
||||
|
||||
On Sat, 10 Jul 1999, Tom Lane wrote:
|
||||
|
||||
> Date: Sat, 10 Jul 1999 17:18:28 -0400
|
||||
> From: Tom Lane <tgl@sss.pgh.pa.us>
|
||||
> To: Oleg Bartunov <oleg@sai.msu.su>
|
||||
> Cc: hackers@postgreSQL.org, pgsql-sql@postgreSQL.org
|
||||
> Subject: [SQL] Re: [HACKERS] SELECT DISTINCT question
|
||||
>
|
||||
> Oleg Bartunov <oleg@sai.msu.su> writes:
|
||||
> > discovery=> select distinct on date,bytes from access_log;
|
||||
> > ERROR: parser: parse error at or near ","
|
||||
>
|
||||
> The syntax for SELECT DISTINCT ON is just as brain-damaged as the
|
||||
> functionality itself: there's no comma after the column name.
|
||||
> You want
|
||||
>
|
||||
> select distinct on date date,bytes from access_log;
|
||||
>
|
||||
|
||||
thanks, this works. But why parser complains about such query:
|
||||
|
||||
discovery=> select distinct on a.date a.date, a.bytes from access_log a;
|
||||
ERROR: parser: parse error at or near "."
|
||||
|
||||
In this query I could just omit '.', but in more complex query
|
||||
I probably could need one.
|
||||
|
||||
> The reason the functionality is brain-damaged is that there's no way to
|
||||
> know which tuple out of the set of tuples with a given "date" value will
|
||||
> be the one returned.
|
||||
>
|
||||
> SELECT DISTINCT ON is not in SQL92, and I think it shouldn't be in
|
||||
> Postgres either...
|
||||
|
||||
|
||||
I'm not an SQL expert, but if it works and this feature is in standard
|
||||
but only syntax is diffrent, why just not to use standard
|
||||
|
||||
select distinct(date), bytes from access_log;
|
||||
|
||||
Or I'm missing here ?
|
||||
|
||||
|
||||
Regards,
|
||||
Oleg
|
||||
>
|
||||
> regards, tom lane
|
||||
>
|
||||
|
||||
_____________________________________________________________
|
||||
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
|
||||
Sternberg Astronomical Institute, Moscow University (Russia)
|
||||
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
|
||||
phone: +007(095)939-16-83, +007(095)939-23-83
|
||||
|
||||
|
||||
|
||||
From owner-pgsql-sql@hub.org Sun Jul 11 12:01:16 1999
|
||||
Received: from renoir.op.net (root@renoir.op.net [209.152.193.4])
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Sun, 11 Jul 1999 11:38:44 -0400 (EDT)
|
||||
To: Oleg Bartunov <oleg@sai.msu.su>
|
||||
cc: hackers@postgreSQL.org, pgsql-sql@postgreSQL.org
|
||||
Subject: Re: [SQL] Re: [HACKERS] SELECT DISTINCT question
|
||||
In-reply-to: Your message of Sun, 11 Jul 1999 10:09:24 +0400 (MSD)
|
||||
<Pine.GSO.3.96.SK.990711100405.2043V-100000@ra>
|
||||
Date: Sun, 11 Jul 1999 11:38:43 -0400
|
||||
Message-ID: <15129.931707523@sss.pgh.pa.us>
|
||||
From: Tom Lane <tgl@sss.pgh.pa.us>
|
||||
Sender: owner-pgsql-sql@postgreSQL.org
|
||||
Precedence: bulk
|
||||
Status: RO
|
||||
|
||||
Oleg Bartunov <oleg@sai.msu.su> writes:
|
||||
> thanks, this works. But why parser complains about such query:
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||||
|
||||
> discovery=> select distinct on a.date a.date, a.bytes from access_log a;
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> ERROR: parser: parse error at or near "."
|
||||
|
||||
Probably the grammar specifies just <column name> and not anything
|
||||
more complex after DISTINCT ON. It'd be risky to try to accept a
|
||||
general expression after ON, due to the silly decision to leave out
|
||||
any terminating punctuation.
|
||||
|
||||
>> SELECT DISTINCT ON is not in SQL92, and I think it shouldn't be in
|
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>> Postgres either...
|
||||
|
||||
> I'm not an SQL expert, but if it works and this feature is in standard
|
||||
> but only syntax is diffrent,
|
||||
|
||||
No, there is no feature in SQL that allows DISTINCT on a subset of
|
||||
columns, period. This is not merely a matter of syntax, it's a
|
||||
fundamental semantic issue.
|
||||
|
||||
> why just not to use standard
|
||||
>
|
||||
> select distinct(date), bytes from access_log;
|
||||
>
|
||||
> Or I'm missing here ?
|
||||
|
||||
I don't think that does what you expect it to (hint: the
|
||||
parentheses are redundant).
|
||||
|
||||
regards, tom lane
|
||||
|
||||
|
||||
From owner-pgsql-sql@hub.org Tue Jul 13 18:02:01 1999
|
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||||
Tue, 13 Jul 1999 17:31:49 -0400 (EDT)
|
||||
To: Hannu Krosing <hannu@trust.ee>
|
||||
cc: hackers@postgreSQL.org, pgsql-sql@postgreSQL.org
|
||||
Subject: [SQL] Re: [HACKERS] SELECT DISTINCT question
|
||||
In-reply-to: Your message of Tue, 13 Jul 1999 23:50:57 +0300
|
||||
<378BA6B1.2B226DDB@trust.ee>
|
||||
Date: Tue, 13 Jul 1999 17:31:48 -0400
|
||||
Message-ID: <24413.931901508@sss.pgh.pa.us>
|
||||
From: Tom Lane <tgl@sss.pgh.pa.us>
|
||||
Sender: owner-pgsql-sql@postgreSQL.org
|
||||
Precedence: bulk
|
||||
Status: ROr
|
||||
|
||||
Hannu Krosing <hannu@trust.ee> writes:
|
||||
>> "DISTINCT will eliminate all duplicate rows from the selection.
|
||||
>> DISTINCT ON column will eliminate all duplicates in the specified column;
|
||||
>> this is equivalent to using GROUP BY column."
|
||||
|
||||
> If it is equivalent to GROUP BY then it should allow only aggregates
|
||||
> in non-distinct columns, like:
|
||||
> select distinct on date date, sum(bytes) from access_log;
|
||||
> If it does not, then it should be files as a bug imho.
|
||||
|
||||
It does not. Whether that is a bug is hard to say, since there is no
|
||||
standard I know of that says what it *is* supposed to do.
|
||||
|
||||
If you look at the select_distinct_on regress test outputs, I bet you
|
||||
will be even less happy:
|
||||
|
||||
QUERY: SELECT DISTINCT ON string4 two, string4, ten
|
||||
FROM tmp
|
||||
ORDER BY two using <, string4 using <, ten using <;
|
||||
two|string4|ten
|
||||
---+-------+---
|
||||
0|AAAAxx | 0
|
||||
0|HHHHxx | 0
|
||||
0|OOOOxx | 0
|
||||
0|VVVVxx | 0
|
||||
1|AAAAxx | 1
|
||||
1|HHHHxx | 1
|
||||
1|OOOOxx | 1
|
||||
1|VVVVxx | 1
|
||||
(8 rows)
|
||||
|
||||
That's not exactly my idea of "distinct" values of string4 ---
|
||||
but apparently whoever made up the regress test thought it was OK!
|
||||
|
||||
Can anyone defend this feature or provide a coherent definition
|
||||
of what it's supposed to be doing? My urge to rip it out is
|
||||
growing stronger and stronger...
|
||||
|
||||
regards, tom lane
|
||||
|
||||
|
||||
From tgl@sss.pgh.pa.us Thu Sep 23 17:27:49 1999
|
||||
Received: from sss.sss.pgh.pa.us (sss.pgh.pa.us [209.114.166.2])
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|
||||
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|
||||
Thu, 23 Sep 1999 17:27:38 -0400 (EDT)
|
||||
To: Bruce Momjian <maillist@candle.pha.pa.us>
|
||||
cc: Hannu Krosing <hannu@trust.ee>, hackers@postgreSQL.org,
|
||||
pgsql-sql@postgreSQL.org
|
||||
Subject: Re: [SQL] Re: [HACKERS] SELECT DISTINCT question
|
||||
In-reply-to: Your message of Thu, 23 Sep 1999 13:18:18 -0400 (EDT)
|
||||
<199909231718.NAA19629@candle.pha.pa.us>
|
||||
Date: Thu, 23 Sep 1999 17:27:37 -0400
|
||||
Message-ID: <15767.938122057@sss.pgh.pa.us>
|
||||
From: Tom Lane <tgl@sss.pgh.pa.us>
|
||||
Status: ROr
|
||||
|
||||
Bruce Momjian <maillist@candle.pha.pa.us> writes:
|
||||
> Tom, any status on this DISTINCT ON ripout?
|
||||
|
||||
I haven't done anything about it, if that's what you mean.
|
||||
|
||||
I didn't get any indication of whether anyone else agreed with me
|
||||
(maybe the lack of loud complaints should be taken as consent?)
|
||||
|
||||
regards, tom lane
|
||||
|
||||
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Reference in New Issue