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Remove unused TODO.detail files.

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This commit is contained in:
Bruce Momjian 2000-07-04 05:17:03 +00:00
parent c229f7d2ab
commit e799f19f0c
10 changed files with 0 additions and 8582 deletions
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317
doc/TODO.detail/alpha
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@ -1,317 +0,0 @@
From owner-pgsql-hackers@hub.org Fri May 14 16:00:46 1999
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Date: Fri, 14 May 1999 16:49:44 -0300 (ADT)
From: The Hermit Hacker <scrappy@hub.org>
To: pgsql-hackers@postgreSQL.org
cc: Jack Howarth <howarth@nitro.med.uc.edu>
Subject: [HACKERS] postgresql bug report (fwd)
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Marc G. Fournier ICQ#7615664 IRC Nick: Scrappy
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---------- Forwarded message ----------
Date: Fri, 14 May 1999 14:50:58 -0400
From: Jack Howarth <howarth@nitro.med.uc.edu>
To: scrappy@hub.org
Subject: postgresql bug report
Marc,
In porting the RedHat 6.0 srpm set for a linuxppc release we
believe a bug has been identified in
the postgresql source for 6.5-0.beta1. Our development tools are as
follows...
glibc 2.1.1 pre 2
linux 2.2.6
egcs 1.1.2
the latest binutils snapshot
The bug that we see is that when egcs compiles postgresql at -O1 or
higher (-O0 is fine),
postgresql creates incorrectly formed databases such that when the user
does a destroydb
the database can not be destroyed. Franz Sirl has identified the problem
as follows...
it seems that this problem is a type casting/promotion bug in the
source. The
routine _bt_checkkeys() in backend/access/nbtree/nbtutils.c calls
int2eq() in
backend/utils/adt/int.c via a function pointer
*fmgr_faddr(&key[0].sk_func). As
the type information for int2eq is lost via the function pointer,
the compiler
passes 2 ints, but int2eq expects 2 (preformatted in a 32bit reg)
int16's.
This particular bug goes away, if I for example change int2eq to:
bool
int2eq(int32 arg1, int32 arg2)
{
return (int16)arg1 == (int16)arg2;
}
This moves away the type casting/promotion "work" from caller to the
callee and
is probably the right thing to do for functions used via function
pointers.
...because of the large number of changes required to do this, Franz
thought we should
pass this on to the postgresql maintainers for correction. Please feel
free to contact
Franz Sirl (Franz.Sirl-kernel@lauterbach.com) if you have any questions
on this bug
report.
--
------------------------------------------------------------------------------
Jack W. Howarth, Ph.D. 231 Bethesda Avenue
NMR Facility Director Cincinnati, Ohio 45267-0524
Dept. of Molecular Genetics phone: (513) 558-4420
Univ. of Cincinnati College of Medicine fax: (513) 558-8474
From gatgul@voicenet.com Thu Jul 22 21:58:42 1999
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Date: Thu, 22 Jul 1999 21:54:56 -0400
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To: Bruce Momjian <maillist@candle.pha.pa.us>
Subject: Re: [PORTS] RedHat6.0 & Alpha
References: <199907221830.OAA06403@candle.pha.pa.us>
Content-Type: multipart/mixed; boundary="------------8DF2D5BA86BB12328C66DD16"
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--------------8DF2D5BA86BB12328C66DD16
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Bruce Momjian wrote:
>
> Can I now put back optimization to -O2 on alpha? Please send me your
> other diffs.
>
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--------------8DF2D5BA86BB12328C66DD16--

59
doc/TODO.detail/default
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@ -1,59 +0,0 @@
From tgl@sss.pgh.pa.us Sun May 23 18:59:22 1999
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To: Bruce Momjian <maillist@candle.pha.pa.us>
cc: PostgreSQL-development <pgsql-hackers@postgreSQL.org>
Subject: Re: [HACKERS] DEFAULT fixed
In-reply-to: Your message of Sat, 22 May 1999 21:12:19 -0400 (EDT)
<199905230112.VAA13489@candle.pha.pa.us>
Date: Sun, 23 May 1999 18:58:52 -0400
Message-ID: <27950.927500332@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
Status: ROr
Actually, it's not as fixed as all that...
create table foo1 (a char(5) default '', b int4);
insert into foo1 (b) values (334);
select * from foo1;
a | b
-----+---
|334
(1 row)
Good, the basic case is fixed, but:
create table foo2 (a char(5) default text '', b int4);
insert into foo2 (b) values (334);
select * from foo2;
a| b
-+--
|16
(1 row)
Ooops.
What you seem to have done is twiddle the handling of DEFAULT clauses
so that the value stored for the default expression is pre-coerced to the
column type. That's good as far as it goes, but it fails in cases where
the stored value has to be of a different type.
My guess is that what *really* ought to happen here is that
transformInsertStmt should check the type of the value it's gotten from
the default clause and apply coerce_type if necessary.
Unless someone can come up with a less artificial example than the one
above, I'm inclined to leave it alone for 6.5. This is the same code
area that will have to be redone to fix the INSERT ... SELECT problem
I was chasing earlier today: coercion of the values produced by SELECT
will have to wait until the tail end of transformInsertStmt, and we
might as well make wrong-type default constants get fixed in the same
place. So I'm not eager to write some throwaway code to patch a problem
that no one is likely to see in practice. What's your feeling about it?
regards, tom lane

483
doc/TODO.detail/distinct
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@ -1,483 +0,0 @@
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)
From: Oleg Bartunov <oleg@sai.msu.su>
X-Sender: megera@ra
Reply-To: Oleg Bartunov <oleg@sai.msu.su>
To: hackers@postgreSQL.org
cc: pgsql-sql@postgreSQL.org
Subject: [SQL] SELECT DISTINCT question
Message-ID: <Pine.GSO.3.96.SK.990711000908.2043R-100000@ra>
Organization: Sternberg Astronomical Institute (Moscow University)
MIME-Version: 1.0
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Sender: owner-pgsql-sql@postgreSQL.org
Precedence: bulk
Status: RO
I got a problem with query:
select distinct (date), bytes from access_log;
which works but not as I expect. I thought this query will select
all rows with distinct values of 'date' column, but it get
distinct pairs 'date, bytes' . From documnetation I see
"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.
ALL will return all candidate rows, including duplicates."
discovery=> select distinct on date,bytes from access_log;
ERROR: parser: parse error at or near ","
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
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)
<Pine.GSO.3.96.SK.990711000908.2043R-100000@ra>
Date: Sat, 10 Jul 1999 17:18:28 -0400
Message-ID: <5707.931641508@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:
> 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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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)
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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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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)
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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-sql@hub.org Sun Jul 11 12:01:16 1999
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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>
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Oleg Bartunov <oleg@sai.msu.su> writes:
> 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 "."
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
>> 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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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>
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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
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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

351
doc/TODO.detail/flock
View File

@ -1,351 +0,0 @@
From tgl@sss.pgh.pa.us Sun Aug 30 11:25:23 1998
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To: Bruce Momjian <maillist@candle.pha.pa.us>
cc: dz@cs.unitn.it (Massimo Dal Zotto), hackers@postgreSQL.org
Subject: Re: [HACKERS] flock patch breaks things here
In-reply-to: Your message of Sun, 30 Aug 1998 08:19:52 -0400 (EDT)
<199808301219.IAA08821@candle.pha.pa.us>
Date: Sun, 30 Aug 1998 11:23:38 -0400
Message-ID: <15786.904490618@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
Status: RO
Bruce Momjian <maillist@candle.pha.pa.us> writes:
> Can't we just have configure check for flock(). Another idea is to
> create a 'pid' file in the pgsql/data/base directory, and do a kill -0
> to see if it is stil running before removing the lock.
The latter approach is what I was going to suggest. Writing a pid file
would be a fine idea anyway --- for one thing, it makes it a lot easier
to write a "kill the postmaster" script. Given that the postmaster
should write a pid file, a new postmaster should look for an existing
pid file, and try to do a kill(pid, 0) on the number contained therein.
If this doesn't return an error, then you figure there is already a
postmaster running, complain, and exit. Otherwise you figure you is it,
(re)write the pid file and away you go. Then pqcomm.c can just
unconditionally delete any old file that's in the way of making the
pipe.
The pidfile checking and creation probably ought to go in postmaster.c,
not down inside pqcomm.c. I never liked the fact that a critical
interlock function was being done by a low-level library that one might
not even want to invoke (if all your clients are using TCP, opening up
the Unix-domain socket is a waste of time, no?).
BTW, there is another problem with relying on flock on the socket file
for this purpose: it opens up a hole for a denial-of-service attack.
Anyone who can write the file can flock it. (We already had a problem
with DOS via creating a dummy file at /tmp/.s.PGSQL.5432, but it would
be harder to spot the culprit with an flock-based interference.)
regards, tom lane
From owner-pgsql-hackers@hub.org Sun Aug 30 12:27:41 1998
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From: Massimo Dal Zotto <dz@cs.unitn.it>
Message-Id: <199808301621.SAA05993@boogie.cs.unitn.it>
Subject: Re: [HACKERS] flock patch breaks things here
To: hackers@postgreSQL.org (PostgreSQL Hackers)
Date: Sun, 30 Aug 1998 18:21:41 +0200 (MET DST)
Cc: tgl@sss.pgh.pa.us (Tom Lane)
In-Reply-To: <15786.904490618@sss.pgh.pa.us> from "Tom Lane" at Aug 30, 98 11:23:38 am
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>
> Bruce Momjian <maillist@candle.pha.pa.us> writes:
> > Can't we just have configure check for flock(). Another idea is to
> > create a 'pid' file in the pgsql/data/base directory, and do a kill -0
> > to see if it is stil running before removing the lock.
>
> The latter approach is what I was going to suggest. Writing a pid file
> would be a fine idea anyway --- for one thing, it makes it a lot easier
> to write a "kill the postmaster" script. Given that the postmaster
> should write a pid file, a new postmaster should look for an existing
> pid file, and try to do a kill(pid, 0) on the number contained therein.
> If this doesn't return an error, then you figure there is already a
> postmaster running, complain, and exit. Otherwise you figure you is it,
> (re)write the pid file and away you go. Then pqcomm.c can just
> unconditionally delete any old file that's in the way of making the
> pipe.
>
> The pidfile checking and creation probably ought to go in postmaster.c,
> not down inside pqcomm.c. I never liked the fact that a critical
> interlock function was being done by a low-level library that one might
> not even want to invoke (if all your clients are using TCP, opening up
> the Unix-domain socket is a waste of time, no?).
>
> BTW, there is another problem with relying on flock on the socket file
> for this purpose: it opens up a hole for a denial-of-service attack.
> Anyone who can write the file can flock it. (We already had a problem
> with DOS via creating a dummy file at /tmp/.s.PGSQL.5432, but it would
> be harder to spot the culprit with an flock-based interference.)
This came to my mind, but I didn't think this would have happened so
quickly. In my opinion the socket and the pidfile should be created in a
directory owned by postgres, for example /tmp/.Pgsql-unix, like does X.
--
Massimo Dal Zotto
+----------------------------------------------------------------------+
| Massimo Dal Zotto email: dz@cs.unitn.it |
| Via Marconi, 141 phone: ++39-461-534251 |
| 38057 Pergine Valsugana (TN) www: http://www.cs.unitn.it/~dz/ |
| Italy pgp: finger dz@tango.cs.unitn.it |
+----------------------------------------------------------------------+
From owner-pgsql-hackers@hub.org Sun Aug 30 13:01:10 1998
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To: Massimo Dal Zotto <dz@cs.unitn.it>
cc: hackers@postgreSQL.org (PostgreSQL Hackers)
Subject: Re: [HACKERS] flock patch breaks things here
In-reply-to: Your message of Sun, 30 Aug 1998 18:21:41 +0200 (MET DST)
<199808301621.SAA05993@boogie.cs.unitn.it>
Date: Sun, 30 Aug 1998 12:50:55 -0400
Message-ID: <16092.904495855@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
Sender: owner-pgsql-hackers@hub.org
Precedence: bulk
Status: RO
Massimo Dal Zotto <dz@cs.unitn.it> writes:
> In my opinion the socket and the pidfile should be created in a
> directory owned by postgres, for example /tmp/.Pgsql-unix, like does X.
The pidfile belongs at the top level of the database directory (eg,
/usr/local/pgsql/data/postmaster.pid), because what it actually
represents is that there is a postmaster running *for that database
group*.
If you want to support multiple database sets on one machine (which I
do), then the interlock has to be per database directory. Putting the
pidfile into a common directory would mean we'd have to invent some
kind of pidfile naming convention to keep multiple postmasters from
tromping on each other. This is unnecessarily complex.
I agree with you that putting the socket file into a less easily munged
directory than /tmp would be a good idea for security. But that's a
separate issue. On machines that understand stickybits for directories,
the security hole is not really very big.
At this point, the fact that /tmp/.s.PGSQL.port# is the socket path is
effectively a version-independent aspect of the FE/BE protocol, and so
we can't change it without breaking old applications. I'm not sure that
that's worth the security improvement.
What I'd like to see someday is a postmaster command line switch to tell
it to use *only* TCP connections and not create a Unix socket at all.
That hasn't been possible so far, because we were relying on the socket
file to provide a safety interlock against starting multiple
postmasters. But an interlock using a pidfile would be much better.
(Look around; *every* other Unix daemon I know of that wants to ensure
that there's only one of it uses a pidfile interlock. Not file locking.
There's a reason why that's the well-trodden path.)
regards, tom lane
From owner-pgsql-hackers@hub.org Sun Aug 30 15:31:13 1998
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Date: Sun, 30 Aug 1998 16:21:28 -0300 (ADT)
From: The Hermit Hacker <scrappy@hub.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
cc: Massimo Dal Zotto <dz@cs.unitn.it>,
PostgreSQL Hackers <hackers@postgreSQL.org>
Subject: Re: [HACKERS] flock patch breaks things here
In-Reply-To: <16092.904495855@sss.pgh.pa.us>
Message-ID: <Pine.BSF.4.02.9808301618350.343-100000@thelab.hub.org>
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On Sun, 30 Aug 1998, Tom Lane wrote:
> Massimo Dal Zotto <dz@cs.unitn.it> writes:
> > In my opinion the socket and the pidfile should be created in a
> > directory owned by postgres, for example /tmp/.Pgsql-unix, like does X.
>
> The pidfile belongs at the top level of the database directory (eg,
> /usr/local/pgsql/data/postmaster.pid), because what it actually
> represents is that there is a postmaster running *for that database
> group*.
I have to agree with this one...but then it also negates the
argument about the flock() DoS...*grin*
BTW...I like the kill(pid,0) solution myself, primarily because it
is, i think, the most portable solution.
I would not consider a patch to remove the flock() solution and
replace it with the kill(pid,0) solution a new feature, just an
improvement of an existing one...either way, moving the pid file (or
socket, for that matter) from /tmp should be listed as a security related
requirement for v6.4 :)
Marc G. Fournier
Systems Administrator @ hub.org
primary: scrappy@hub.org secondary: scrappy@{freebsd|postgresql}.org
From owner-pgsql-hackers@hub.org Sun Aug 30 22:41:10 1998
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To: The Hermit Hacker <scrappy@hub.org>
cc: PostgreSQL Hackers <hackers@postgreSQL.org>
Subject: Re: [HACKERS] flock patch breaks things here
In-reply-to: Your message of Sun, 30 Aug 1998 16:21:28 -0300 (ADT)
<Pine.BSF.4.02.9808301618350.343-100000@thelab.hub.org>
Date: Sun, 30 Aug 1998 22:34:40 -0400
Message-ID: <20073.904530880@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
Sender: owner-pgsql-hackers@hub.org
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The Hermit Hacker <scrappy@hub.org> writes:
> either way, moving the pid file (or
> socket, for that matter) from /tmp should be listed as a security related
> requirement for v6.4 :)
Huh? There is no pid file being generated in /tmp (or anywhere else)
at the moment. If we do add one, it should not go into /tmp for the
reasons I gave before.
Where the Unix-domain socket file lives is an entirely separate issue.
If we move the socket out of /tmp then we have just kicked away all the
work we did to preserve backwards compatibility of the FE/BE protocol
with existing clients. Being able to talk to a 1.0 client isn't much
good if you aren't listening where he's going to try to contact you.
So I think I have to vote in favor of leaving the socket where it is.
regards, tom lane
From owner-pgsql-hackers@hub.org Mon Aug 31 11:31:19 1998
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Date: Mon, 31 Aug 1998 09:09:01 -0600 (MDT)
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From: Brook Milligan <brook@trillium.NMSU.Edu>
To: tgl@sss.pgh.pa.us
CC: dg@informix.com, hackers@postgreSQL.org
In-reply-to: <23042.904573041@sss.pgh.pa.us> (message from Tom Lane on Mon, 31
Aug 1998 10:17:21 -0400)
Subject: Re: [HACKERS] flock patch breaks things here
References: <23042.904573041@sss.pgh.pa.us>
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I just came up with an idea that might help alleviate the /tmp security
exposure without creating a backwards-compatibility problem. It works
like this:
1. During installation, create a subdirectory of /tmp to hold Postgres'
socket files and associated pid lockfiles. This subdirectory should be
owned by the Postgres superuser and have permissions 755
(world-readable, writable only by Postgres superuser). Maybe call it
/tmp/.pgsql --- the name should start with a dot to keep it out of the
way. (Bruce points out that some systems clear /tmp during reboot, so
it might be that a postmaster will have to be prepared to recreate this
directory at startup --- anyone know if subdirectories of /tmp are
zapped too? My system doesn't do that...)
...
I notice that on my system, the X11 socket files in /tmp/.X11-unix are
actually symlinks to socket files in /usr/spool/sockets/X11. I dunno if
it's worth our trouble to get into putting our sockets under /usr/spool
or /var/spool or whatever --- seems like another configuration choice to
mess up. It'd be nice if the socket directory lived somewhere where the
parent dirs weren't world-writable, but this would mean one more thing
that you have to have root permissions for in order to install pgsql.
It seems like we need a directory for locks (= pid files) and one for
sockets (perhaps the same one). I strongly suggest that the location
for these be configurable. By default, it might make sense to put
them in ~pgsql/locks and ~pgsql/sockets. It is easy (i.e., I'll be
glad to do it) to modify configure.in to take options like
--lock-dir=/var/spool/lock
--socket-dir=/var/spool/sockets
that set cc defines and have the code respond accordingly. This way,
those who don't care (or don't have root access) can use the defaults,
whereas those with root access who like to keep locks and sockets in a
common place can do so easily. Either way, multiple postmasters (all
compiled with the same options of course) can check the appropriate
locks in the well-known places. Finally, drop the link into /tmp for
the old socket and document that it will be disappearing at some
point, and all is fine.
If someone wants to give me some guidance on what preprocessor
variables should be set in response to the above options (or something
like them), I'll do the configure stuff.
Cheers,
Brook

69
doc/TODO.detail/fsync
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@ -1,69 +0,0 @@
From owner-pgsql-general@hub.org Fri Dec 18 06:31:23 1998
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Date: Fri, 18 Dec 1998 16:41:40 +0700
From: Vadim Mikheev <vadim@krs.ru>
Organization: OJSC Rostelecom (Krasnoyarsk)
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To: Anton de Wet <adw@obsidian.co.za>
CC: pgsql-general@postgreSQL.org
Subject: Re: [GENERAL] Why PostgreSQL is better than other commerial softwares?
References: <Pine.LNX.4.04.9812181046030.9458-100000@ra.obsidian.co.za>
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Anton de Wet wrote:
>
> >
> > Often quick mailing list support?
>
> :-)
>
> While on the subject I finally found the solution to a problem I (and one
> or two other people) posted about without answer. (So sometimes it's slow
> mailing list support).
>
> In importing about 5 million records (which I copy in blocks of 10000) the
> copy became linearly slower. After a friend RTFM and refered me, I used
> the -F switch (passed by the postmaster to the backend processes) and the
> time became linear and a LOT shorter. Import time for the 5000000 records
> now the same (or maybe even slightly faster, I didn't accurately time
> them) as importing the data into oracle on the same machine.
"While on the subject..." -:)
This is the problem of buffer manager, known for very long time:
when copy eats all buffers, manager begins write/fsync each
durty buffer to free buffer for new data. All updated relations
should be fsynced _once_ @ transaction commit. You would get
the same results without -F...
I still have no time to implement this -:(
Vadim

616
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@ -1,616 +0,0 @@
From tgl@sss.pgh.pa.us Mon Jun 14 20:50:41 1999
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Mon, 14 Jun 1999 20:51:07 -0400 (EDT)
To: Bruce Momjian <maillist@candle.pha.pa.us>
cc: Roman.Hodek@informatik.uni-erlangen.de, olly@lfix.co.uk,
PostgreSQL-development <pgsql-hackers@postgreSQL.org>
Subject: Cleaning up function interface (was Re: Patch for m68k architecture)
In-reply-to: Your message of Mon, 14 Jun 1999 17:53:25 -0400 (EDT)
<199906142153.RAA16276@candle.pha.pa.us>
Date: Mon, 14 Jun 1999 20:51:06 -0400
Message-ID: <21504.929407866@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
Status: RO
Bruce Momjian <maillist@candle.pha.pa.us> writes:
>> ANSI C says results are undefined if you call a function via pointer
>> and the pointer is declared to return another type than the function
>> actually returns. So m68k compilers conform to the standard here.
> Yes, we admit that we break the standard with fmgr_ptr, because we
> return a variety of values depending on what function they call. It
> appears the egcs optimization on the powerpc or alpha cause a problem
> when optimization is -O2, but not -O. We may see more platforms with
> problems as optimizers get smarter.
Seeing as how we also know that the function-call interface ought to be
redesigned to handle NULLs better, maybe we should just bite the bullet
and fix all of these problems at once by adopting a new standard
interface for everything that can be called via fmgr. It'd uglify the
code, no doubt, but I think we are starting to see an accumulation of
problems that justify doing something.
Here is a straw-man proposal:
Datum function (bool *resultnull,
Datum *args,
bool *argnull,
int nargs)
args[i] is the i'th parameter, or undefined (perhaps always 0?)
when argnull[i] is true. The function is responsible for setting
*resultnull, and returns a Datum value if *resultnull is false.
Most standard functions could ignore nargs since they'd know what it
should be, but we ought to pass it for flexibility.
A useful addition to this scheme would be for fmgr to preset *resultnull
to the OR of the input argnull[] array just before calling the function.
In the typical case where the function is "strict" (ie, result is NULL
if any input is NULL), this would save the function from having to look
at argnull[] at all; it'd just check *resultnull and immediately return
if true.
As an example, int4 addition goes from
int32
int4pl(int32 arg1, int32 arg2)
{
return arg1 + arg2;
}
to
Datum
int4pl (bool *resultnull, Datum *args, bool *argnull, int nargs)
{
if (*resultnull)
return (Datum) 0; /* value doesn't really matter ... */
/* we can ignore argnull and nargs */
return Int32GetDatum(DatumGetInt32(args[0]) + DatumGetInt32(args[1]));
}
This is, of course, much uglier than the existing code, but we might be
able to improve matters with some well-chosen macros for the boilerplate
parts. What we actually end up writing might look something like
Datum
int4pl (PG_FUNCTION_ARGS)
{
PG_STRICT_FUNCTION( /* encapsulates null check */
PG_ARG0_INT32;
PG_ARG1_INT32;
PG_RESULT_INT32( arg0 + arg1 );
);
}
where the macros expand to things like "int32 arg0 = DatumGetInt32(args[0])"
and "return Int32GetDatum( x )". It'd be worth a little thought to
try to set up a group of macros like that, I think.
regards, tom lane
From owner-pgsql-hackers@hub.org Wed Sep 22 20:31:02 1999
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To: pgsql-hackers@postgreSQL.org
Subject: [HACKERS] Progress report: buffer refcount bugs and SQL functions
Date: Wed, 22 Sep 1999 20:05:39 -0400
Message-ID: <6408.938045139@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
Sender: owner-pgsql-hackers@postgreSQL.org
Precedence: bulk
Status: RO
I have been finding a lot of interesting stuff while looking into
the buffer reference count/leakage issue.
It turns out that there were two specific things that were camouflaging
the existence of bugs in this area:
1. The BufferLeakCheck routine that's run at transaction commit was
only looking for nonzero PrivateRefCount to indicate a missing unpin.
It failed to notice nonzero LastRefCount --- which meant that an
error in refcount save/restore usage could leave a buffer pinned,
and BufferLeakCheck wouldn't notice.
2. The BufferIsValid macro, which you'd think just checks whether
it's handed a valid buffer identifier or not, actually did more:
it only returned true if the buffer ID was valid *and* the buffer
had positive PrivateRefCount. That meant that the common pattern
if (BufferIsValid(buf))
ReleaseBuffer(buf);
wouldn't complain if it were handed a valid but already unpinned buffer.
And that behavior masks bugs that result in buffers being unpinned too
early. For example, consider a sequence like
1. LockBuffer (buffer now has refcount 1). Store reference to
a tuple on that buffer page in a tuple table slot.
2. Copy buffer reference to a second tuple-table slot, but forget to
increment buffer's refcount.
3. Release second tuple table slot. Buffer refcount drops to 0,
so it's unpinned.
4. Release original tuple slot. Because of BufferIsValid behavior,
no assert happens here; in fact nothing at all happens.
This is, of course, buggy code: during the interval from 3 to 4 you
still have an apparently valid tuple reference in the original slot,
which someone might try to use; but the buffer it points to is unpinned
and could be replaced at any time by another backend.
In short, we had errors that would mask both missing-pin bugs and
missing-unpin bugs. And naturally there were a few such bugs lurking
behind them...
3. The buffer refcount save/restore stuff, which I had suspected
was useless, is not only useless but also buggy. The reason it's
buggy is that it only works if used in a nested fashion. You could
save state A, pin some buffers, save state B, pin some more
buffers, restore state B (thereby unpinning what you pinned since
the save), and finally restore state A (unpinning the earlier stuff).
What you could not do is save state A, pin, save B, pin more, then
restore state A --- that might unpin some of A's buffers, or some
of B's buffers, or some unforeseen combination thereof. If you
restore A and then restore B, you do not necessarily return to a zero-
pins state, either. And it turns out the actual usage pattern was a
nearly random sequence of saves and restores, compounded by a failure to
do all of the restores reliably (which was masked by the oversight in
BufferLeakCheck).
What I have done so far is to rip out the buffer refcount save/restore
support (including LastRefCount), change BufferIsValid to a simple
validity check (so that you get an assert if you unpin something that
was pinned), change ExecStoreTuple so that it increments the refcount
when it is handed a buffer reference (for symmetry with ExecClearTuple's
decrement of the refcount), and fix about a dozen bugs exposed by these
changes.
I am still getting Buffer Leak notices in the "misc" regression test,
specifically in the queries that invoke more than one SQL function.
What I find there is that SQL functions are not always run to
completion. Apparently, when a function can return multiple tuples,
it won't necessarily be asked to produce them all. And when it isn't,
postquel_end() isn't invoked for the function's current query, so its
tuple table isn't cleared, so we have dangling refcounts if any of the
tuples involved are in disk buffers.
It may be that the save/restore code was a misguided attempt to fix
this problem. I can't tell. But I think what we really need to do is
find some way of ensuring that Postquel function execution contexts
always get shut down by the end of the query, so that they don't leak
resources.
I suppose a straightforward approach would be to keep a list of open
function contexts somewhere (attached to the outer execution context,
perhaps), and clean them up at outer-plan shutdown.
What I am wondering, though, is whether this addition is actually
necessary, or is it a bug that the functions aren't run to completion
in the first place? I don't really understand the semantics of this
"nested dot notation". I suppose it is a Berkeleyism; I can't find
anything about it in the SQL92 document. The test cases shown in the
misc regress test seem peculiar, not to say wrong. For example:
regression=> SELECT p.hobbies.equipment.name, p.hobbies.name, p.name FROM person p;
name |name |name
-------------+-----------+-----
advil |posthacking|mike
peet's coffee|basketball |joe
hightops |basketball |sally
(3 rows)
which doesn't appear to agree with the contents of the underlying
relations:
regression=> SELECT * FROM hobbies_r;
name |person
-----------+------
posthacking|mike
posthacking|jeff
basketball |joe
basketball |sally
skywalking |
(5 rows)
regression=> SELECT * FROM equipment_r;
name |hobby
-------------+-----------
advil |posthacking
peet's coffee|posthacking
hightops |basketball
guts |skywalking
(4 rows)
I'd have expected an output along the lines of
advil |posthacking|mike
peet's coffee|posthacking|mike
hightops |basketball |joe
hightops |basketball |sally
Is the regression test's expected output wrong, or am I misunderstanding
what this query is supposed to do? Is there any documentation anywhere
about how SQL functions returning multiple tuples are supposed to
behave?
regards, tom lane
************
From owner-pgsql-hackers@hub.org Thu Sep 23 11:03:19 1999
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To: Andreas Zeugswetter <andreas.zeugswetter@telecom.at>
cc: hackers@postgreSQL.org
Subject: Re: [HACKERS] Progress report: buffer refcount bugs and SQL functions
In-reply-to: Your message of Thu, 23 Sep 1999 10:07:24 +0200
<37E9DFBC.5C0978F@telecom.at>
Date: Thu, 23 Sep 1999 10:51:10 -0400
Message-ID: <14209.938098270@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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Andreas Zeugswetter <andreas.zeugswetter@telecom.at> writes:
> That is what I use it for. I have never used it with a
> returns setof function, but reading the comments in the regression test,
> -- mike needs advil and peet's coffee,
> -- joe and sally need hightops, and
> -- everyone else is fine.
> it looks like the results you expected are correct, and currently the
> wrong result is given.
Yes, I have concluded the same (and partially fixed it, per my previous
message).
> Those that don't have a hobbie should return name|NULL|NULL. A hobbie
> that does'nt need equipment name|hobbie|NULL.
That's a good point. Currently (both with and without my uncommitted
fix) you get *no* rows out from ExecTargetList if there are any Iters
that return empty result sets. It might be more reasonable to treat an
empty result set as if it were NULL, which would give the behavior you
suggest.
This would be an easy change to my current patch, and I'm prepared to
make it before committing what I have, if people agree that that's a
more reasonable definition. Comments?
regards, tom lane
************
From owner-pgsql-hackers@hub.org Thu Sep 23 04:31:15 1999
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From: Andreas Zeugswetter <andreas.zeugswetter@telecom.at>
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To: hackers@postgreSQL.org
Subject: Re: [HACKERS] Progress report: buffer refcount bugs and SQL functions
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> Is the regression test's expected output wrong, or am I
> misunderstanding
> what this query is supposed to do? Is there any
> documentation anywhere
> about how SQL functions returning multiple tuples are supposed to
> behave?
They are supposed to behave somewhat like a view.
Not all rows are necessarily fetched.
If used in a context that needs a single row answer,
and the answer has multiple rows it is supposed to
runtime elog. Like in:
select * from tbl where col=funcreturningmultipleresults();
-- this must elog
while this is ok:
select * from tbl where col in (select funcreturningmultipleresults());
But the caller could only fetch the first row if he wanted.
The nested notation is supposed to call the function passing it the tuple
as the first argument. This is what can be used to "fake" a column
onto a table (computed column).
That is what I use it for. I have never used it with a
returns setof function, but reading the comments in the regression test,
-- mike needs advil and peet's coffee,
-- joe and sally need hightops, and
-- everyone else is fine.
it looks like the results you expected are correct, and currently the
wrong result is given.
But I think this query could also elog whithout removing substantial
functionality.
SELECT p.name, p.hobbies.name, p.hobbies.equipment.name FROM person p;
Actually for me it would be intuitive, that this query return one row per
person, but elog on those that have more than one hobbie or a hobbie that
needs more than one equipment. Those that don't have a hobbie should
return name|NULL|NULL. A hobbie that does'nt need equipment name|hobbie|NULL.
Andreas
************
From owner-pgsql-hackers@hub.org Wed Sep 22 22:01:07 1999
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From: wieck@debis.com (Jan Wieck)
Subject: Re: [HACKERS] Progress report: buffer refcount bugs and SQL functions
To: tgl@sss.pgh.pa.us (Tom Lane)
Date: Thu, 23 Sep 1999 03:19:39 +0200 (MET DST)
Cc: pgsql-hackers@postgreSQL.org
Reply-To: wieck@debis.com (Jan Wieck)
In-Reply-To: <6408.938045139@sss.pgh.pa.us> from "Tom Lane" at Sep 22, 99 08:05:39 pm
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Tom Lane wrote:
> [...]
>
> What I am wondering, though, is whether this addition is actually
> necessary, or is it a bug that the functions aren't run to completion
> in the first place? I don't really understand the semantics of this
> "nested dot notation". I suppose it is a Berkeleyism; I can't find
> anything about it in the SQL92 document. The test cases shown in the
> misc regress test seem peculiar, not to say wrong. For example:
>
> [...]
>
> Is the regression test's expected output wrong, or am I misunderstanding
> what this query is supposed to do? Is there any documentation anywhere
> about how SQL functions returning multiple tuples are supposed to
> behave?
I've said some time (maybe too long) ago, that SQL functions
returning tuple sets are broken in general. This nested dot
notation (which I think is an artefact from the postquel
querylanguage) is implemented via set functions.
Set functions have total different semantics from all other
functions. First they don't really return a tuple set as
someone might think - all that screwed up code instead
simulates that they return something you could consider a
scan of the last SQL statement in the function. Then, on
each subsequent call inside of the same command, they return
a "tupletable slot" containing the next found tuple (that's
why their Func node is mangled up after the first call).
Second they have a targetlist what I think was originally
intended to extract attributes out of the tuples returned
when the above scan is asked to get the next tuple. But as I
read the code it invokes the function again and this might
cause the resource leakage you see.
Third, all this seems to never have been implemented
(thought?) to the end. A targetlist doesn't make sense at
this place because it could at max contain a single attribute
- so a single attno would have the same power. And if set
functions could appear in the rangetable (FROM clause), than
they would be treated as that and regular Var nodes in the
query would do it.
I think you shouldn't really care for that regression test
and maybe we should disable set functions until we really
implement stored procedures returning sets in the rangetable.
Set functions where planned by Stonebraker's team as
something that today is called stored procedures. But AFAIK
they never reached the useful state because even in Postgres
4.2 you haven't been able to get more than one attribute out
of a set function. It was a feature of the postquel
querylanguage that you could get one attribute from a set
function via
RETRIEVE (attributename(setfuncname()))
While working on the constraint triggers I've came across
another regression test (triggers :-) that's errorneous too.
The funny_dup17 trigger proc executes an INSERT into the same
relation where it get fired for by a previous INSERT. And it
stops this recursion only if it reaches a nesting level of
17, which could only occur if it is fired DURING the
execution of it's own SPI_exec(). After Vadim quouted some
SQL92 definitions about when constraint checks and triggers
are to be executed, I decided to fire regular triggers at the
end of a query too. Thus, there is absolutely no nesting
possible for AFTER triggers resulting in an endless loop.
Jan
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#========================================= wieck@debis.com (Jan Wieck) #
************
From owner-pgsql-hackers@hub.org Thu Sep 23 11:01:06 1999
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To: wieck@debis.com (Jan Wieck)
cc: pgsql-hackers@postgreSQL.org
Subject: Re: [HACKERS] Progress report: buffer refcount bugs and SQL functions
In-reply-to: Your message of Thu, 23 Sep 1999 03:19:39 +0200 (MET DST)
<m11TxXw-0003kLC@orion.SAPserv.Hamburg.dsh.de>
Date: Thu, 23 Sep 1999 10:18:01 -0400
Message-ID: <13251.938096281@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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wieck@debis.com (Jan Wieck) writes:
> Tom Lane wrote:
>> What I am wondering, though, is whether this addition is actually
>> necessary, or is it a bug that the functions aren't run to completion
>> in the first place?
> I've said some time (maybe too long) ago, that SQL functions
> returning tuple sets are broken in general.
Indeed they are. Try this on for size (using the regression database):
SELECT p.name, p.hobbies.equipment.name FROM person p;
SELECT p.hobbies.equipment.name, p.name FROM person p;
You get different result sets!?
The problem in this example is that ExecTargetList returns the isDone
flag from the last targetlist entry, regardless of whether there are
incomplete iterations in previous entries. More generally, the buffer
leak problem that I started with only occurs if some Iter nodes are not
run to completion --- but execQual.c has no mechanism to make sure that
they have all reached completion simultaneously.
What we really need to make functions-returning-sets work properly is
an implementation somewhat like aggregate functions. We need to make
a list of all the Iter nodes present in a targetlist and cycle through
the values returned by each in a methodical fashion (run the rightmost
through its full cycle, then advance the next-to-rightmost one value,
run the rightmost through its cycle again, etc etc). Also there needs
to be an understanding of the hierarchy when an Iter appears in the
arguments of another Iter's function. (You cycle the upper one for
*each* set of arguments created by cycling its sub-Iters.)
I am not particularly interested in working on this feature right now,
since AFAIK it's a Berkeleyism not found in SQL92. What I've done
is to hack ExecTargetList so that it behaves semi-sanely when there's
more than one Iter at the top level of the target list --- it still
doesn't really give the right answer, but at least it will keep
generating tuples until all the Iters are done at the same time.
It happens that that's enough to give correct answers for the examples
shown in the misc regress test. Even when it fails to generate all
the possible combinations, there will be no buffer leaks.
So, I'm going to declare victory and go home ;-). We ought to add a
TODO item along the lines of
* Functions returning sets don't really work right
in hopes that someone will feel like tackling this someday.
regards, tom lane
************

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From owner-pgsql-general@hub.org Fri Oct 9 18:22:09 1998
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Date: Fri, 9 Oct 1998 18:18:00 -0400 (EDT)
From: Steve Doliov <statsol@statsol.com>
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To: pgsql-general@postgreSQL.org
Subject: Re: [GENERAL] Making NULLs visible.
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On Fri, 9 Oct 1998, Bruce Momjian wrote:
> [Charset iso-8859-1 unsupported, filtering to ASCII...]
> > > Yes, \ always outputs as \\, excepts someone changed it last week, and I
> > > am requesting a reversal. Do you like the \N if it is unique?
> >
> > Well, it's certainly clear, but could be confused with \n (newline). Can we
> > have \0 instead?
>
> Yes, but it is uppercase. \0 looks like an octal number to me, and I
> think we even output octals sometimes, don't we?
>
my first suggestion may have been hare-brained, but why not just make the
specifics of the output user-configurable. So if the user chooses \0, so
be it, if the user chooses \N so be it, if the user likes NULL so be it.
but the option would only have one value per database at any given point
in time. so database x could use \N on tuesday and NULL on wednesday, but
database x could never have two references to the characters(s) used to
represent a null value.
steve
From owner-pgsql-general@hub.org Sun Oct 11 17:31:08 1998
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Date: Sun, 11 Oct 1998 16:28:41 -0400 (EDT)
From: Thomas Good <tomg@admin.nrnet.org>
To: pgsql-general@postgreSQL.org
Subject: Re: [GENERAL] Making NULLs visible.
In-Reply-To: <Pine.GSO.3.96.981009181716.545B-100000@gecko>
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Watching all this go by...as a guy who has to move alot of data
from legacy dbs to postgres, I've gotten used to \N being a null.
My vote, if I were allowed to cast one, would be to have one null
and that would be the COPY command null. I have no difficulty
distinguishing a null from a newline...
At the pgsql command prompt I would find seeing \N rather reassuring.
I've seen alot of these little guys.
---------- Sisters of Charity Medical Center ----------
Department of Psychiatry
----
Thomas Good <tomg@q8.nrnet.org>
Coordinator, North Richmond C.M.H.C. Information Systems
75 Vanderbilt Ave, Quarters 8 Phone: 718-354-5528
Staten Island, NY 10304 Fax: 718-354-5056

55
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Subject: [HACKERS] TODO item: make pg_shadow updates more robust
Date: Sun, 02 Aug 1998 19:28:13 -0400
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From: Tom Lane <tgl@sss.pgh.pa.us>
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I learned the hard way last night that the postmaster's password
authentication routines don't look at the pg_shadow table. They
look at a separate file named pg_pwd, which certain backend operations
will update from pg_shadow. (This is not documented in any user
documentation that I could find; I had to burrow into
src/backend/commands/user.c to discover it.)
Unfortunately, if a clueless dbadmin (like me ;-)) tries to update
password data with the obvious thing,
update pg_shadow set passwd = 'xxxxx' where usename = 'yyyy';
pg_pwd doesn't get fixed.
A more drastic problem is that pg_dump believes it can save and
restore pg_shadow data using "copy". Following an initdb and restore
from a pg_dump -z script, pg_shadow will look just fine, but only
the database admin will be listed in pg_pwd. This is likely to provoke
some confusion, IMHO.
As a short-term thing, the fact that you *must* set passwords with
ALTER USER ought to be documented, preferably someplace where a
dbadmin who's never heard of ALTER USER is likely to find it.
As a longer-term thing, I think it would be far better if ordinary
SQL operations on pg_shadow just did the right thing. Wouldn't it
be possible to implement copying to pg_pwd by means of a trigger on
pg_shadow updates, or something like that?
(I'm afraid that pg_dump -z is pretty well broken for operations on
a password-protected database, btw. Has anyone used it successfully
in that situation?)
regards, tom lane

805
doc/TODO.detail/primary
View File

@ -1,805 +0,0 @@
From owner-pgsql-hackers@hub.org Fri Sep 4 00:47:06 1998
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Date: Fri, 04 Sep 1998 11:03:00 +0800
From: Vadim Mikheev <vadim@krs.ru>
Organization: OJSC Rostelecom (Krasnoyarsk)
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To: "D'Arcy J.M. Cain" <darcy@druid.net>
CC: "Thomas G. Lockhart" <lockhart@alumni.caltech.edu>, hackers@postgreSQL.org
Subject: Re: [HACKERS] Adding PRIMARY KEY info
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D'Arcy J.M. Cain wrote:
>
> Thus spake Vadim Mikheev
> > Imho, indices should be used/created for FOREIGN keys and so pg_index
> > is good place for both PRIMARY and FOREIGN keys infos.
>
> Are you sure? I don't know about implementing it but it seems more
> like an attribute thing rather than an index thing. Certainly from a
> database design viewpoint you want to refer to the fields, not the
> index on them. If you put it into the index then you have to do
> an extra join to get the information.
>
> Perhaps you have to do the extra join anyway for other purposes so it
> may not matter. All I want is to be able to be able to extract the
> field that the designer specified as the key. As long as I can design
> a select statement that gives me that I don't much care how it is
> implemented. I'll cache the information anyway so it won't have a
> huge impact on my programs.
First, let me note that you have to add int28 field to pg_class,
not just oid field, to know what attributeS are in primary key
(we support multi-attribute primary keys).
This could be done...
But what about foreign and unique (!) keys ?
There may be _many_ foreign/unique keys defined for one table!
And so foreign/unique keys info have to be stored somewhere else,
not in pg_class.
pg_index is good place for all _3_ key types because of:
1. index should be created for each foreign key -
just for performance.
2. pg_index already has int28 field for key attributes.
3. pg_index already has indisunique (note that foreign keys
may reference unique keys, not just primary ones).
- so we have just add two fields to pg_index:
bool indisprimary;
oid indreferenced;
^^^^^^^^^^^^^^^^^^
this is for foreign keys: oid of referenced relation'
primary/unique key index.
I agreed that indices are just implementation...
If you don't like to store key infos in pg_index then
new pg_key relation have to be added...
Comments ?
Vadim
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Date: Sat, 05 Sep 1998 13:40:43 +0800
From: Vadim Mikheev <vadim@krs.ru>
Organization: OJSC Rostelecom (Krasnoyarsk)
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To: "D'Arcy J.M. Cain" <darcy@druid.net>
CC: hackers@postgreSQL.org, pgsql-core@postgreSQL.org
Subject: Re: [HACKERS] Adding PRIMARY KEY info
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D'Arcy J.M. Cain wrote:
>
> >
> > pg_index is good place for all _3_ key types because of:
> >
> > 1. index should be created for each foreign key -
> > just for performance.
> > 2. pg_index already has int28 field for key attributes.
> > 3. pg_index already has indisunique (note that foreign keys
> > may reference unique keys, not just primary ones).
> >
> > - so we have just add two fields to pg_index:
> >
> > bool indisprimary;
> > oid indreferenced;
> > ^^^^^^^^^^^^^^^^^^
> > this is for foreign keys: oid of referenced relation'
> > primary/unique key index.
>
> Sounds fine to me. Any chance of seeing this in 6.4?
I could add this (and FOREIGN key implementation) before
11-13 Sep... But not the ALTER TABLE ADD/DROP CONSTRAINT
stuff (ok for Entry SQL).
But we are in beta...
Comments?
> Nope, pg_index is fine by me. Now, once we have this, how do we find
> the index for a particular attribute? I can't seem to figure out the
> relationship between pg_attribute and pg_index. The chart in the docs
> suggests that indkey is the relation but I can't see any useful info
> there for joining the tables.
pg_index:
indrelid - oid of indexed relation
indkey - up to the 8 attnums
pg_attribute:
attrelid - oid of relation
attnum - ...
Without outer join you have to query pg_attribute for each
valid attnum from pg_index->indkey -:(
Vadim
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From: wieck@debis.com (Jan Wieck)
Subject: [HACKERS] Re: Referential Integrity In PostgreSQL
To: pgsql-hackers@postgreSQL.org (PostgreSQL HACKERS)
Date: Tue, 21 Sep 1999 10:37:21 +0200 (MET DST)
Reply-To: wieck@debis.com (Jan Wieck)
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>
> Hi , Jan
>
> my name is Max .
Hi Max,
>
> I have contributed to SPI interface ,
> that with external Trigger try to make
> a referential integrity.
>
> If I can Help , in something ,
> I'm here .
>
You're welcome.
I've CC'd the hackers list because we might get some ideas
from there too (and to surface once in a while - Bruce
already missed me).
Currently I'm very busy for serious work so I don't find
enough spare time to start on such a big change to
PostgreSQL. But I'd like to give you an overview of what I
have in mind so far so you can decide if you're able to help.
Referential integrity (RI) is based on constraints defined in
the schema of a database. There are some different types of
constraints:
1. Uniqueness constraints.
2. Foreign key constraints that ensure that a key value used
in an attribute exists in another relation. One
constraint must ensure you're unable to INSERT/UPDATE to
a value that doesn't exist, another one must prevent
DELETE on a referenced key item or that it is changed
during UPDATE.
3. Cascading deletes that let rows referring to a key follow
on DELETE silently.
Even if not defined in the standard (AFAIK) there could be
others like letting references automatically follow on UPDATE
to a key value.
All constraints can be enabled and/or default to be deferred.
That means, that the RI checks aren't performed when they are
triggerd. Instead, they're checked at transaction end or if
explicitly invoked by some special statement. This is really
important because someone must be able to setup cyclic RI
checks that could never be satisfied if the checks would be
performed immediately. The major problem on this is the
amount of data affected until the checks must be performed.
The number of statements executed, that trigger such deferred
constraints, shouldn't be limited. And one single
INSERT/UPDATE/DELETE could affect thousands of rows.
Due to these problems I thought, it might not be such a good
idea to remember CTID's or the like to get back OLD/NEW rows
at the time the constraints are checked. Instead I planned to
misuse the rule system for it. Unfortunately, the rule system
has damned tricky problems itself when it comes to having-,
distinct and other clauses and extremely on aggregates and
subselects. These problems would have to get fixed first. So
it's a solution that cannot be implemented right now.
Fallback to CTID remembering though. There are problems too
:-(. Let's enhance the trigger mechanism with a deferred
feature. First this requires two additional bool attributes
in the pg_trigger relation that tell if this trigger is
deferrable and if it is deferred by default. While at it we
should add another bool that tells if the trigger is enabled
(ALTER TRIGGER {ENABLE|DISABLE} trigger).
Second we need an internal list of triggers, that are
currently DEFINED AS DEFERRED. Either because they default to
it, or the user explicitly asked to deferr it.
Third we need an internal list of triggers that must be
invoked later because at the time an event occured where they
should have been triggered, they appeared in the other list
and their execution is delayed until transaction end or
explicit execution. This list must remember the OID of the
trigger to invoke (to identify the procedure and the
arguments), the relation that caused the trigger and the
CTID's of the OLD and NEW row.
That last list could grow extremely! Think of a trigger
that's executing commands over SPI which in turn activate
deferred triggers. Since the order of trigger execution is
very important for RI, I can't see any chance to
simplify/condense this information. Thus it is 16 bytes at
least per deferred trigger call (2 OID's plus 2 CTID's). I
think one or more temp files would fit best for this.
A last tricky point is if one of a bunch of deferred triggers
is explicitly called for execution. At this time, the entries
for it in the temp file(s) must get processed and marked
executed (maybe by overwriting the triggers OID with the
invalid OID) while other trigger events still have to get
recorded.
Needless to say that reading thousands of those entries just
to find a few isn't good on performance. But better have this
special case slow that dealing with hundreds of temp files or
other overhead slowing down the usual case where ALL deferred
triggers get called at transaction end.
Trigger invocation is simple now - fetch the OLD and NEW rows
by CTID and execute the trigger as done by the trigger
manager. Oh - well - vacuum shouldn't touch relations where
deferred triggers are outstanding. Might require some
special lock entry - Vadim?
Did I miss something?
Jan
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#========================================= wieck@debis.com (Jan Wieck) #
************
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From: wieck@debis.com (Jan Wieck)
Subject: Re: [HACKERS] Re: Referential Integrity In PostgreSQL
To: andreas.zeugswetter@telecom.at (Andreas Zeugswetter)
Date: Tue, 21 Sep 1999 13:39:27 +0200 (MET DST)
Cc: hackers@postgresql.org
Reply-To: wieck@debis.com (Jan Wieck)
In-Reply-To: <37E74EB9.44F9766E@telecom.at> from "Andreas Zeugswetter" at Sep 21, 99 11:24:09 am
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>
> > Oh - well - vacuum shouldn't touch relations where
> > deferred triggers are outstanding. Might require some
> > special lock entry - Vadim?
>
> All modified data will be in this same still open transaction.
> Therefore no relevant data can be removed by vacuum anyway.
I expect this, but I really need to be sure that not even the
location of the tuple in the heap will change. I need to find
the tuples at the time the deferred triggers must be executed
via heap_fetch() by their CTID!
>
> It is my understanding, that the RI check is performed on the newest
> available (committed) data (+ modified data from my own tx).
> E.g. a primary key that has been removed by another transaction after
> my begin work will lead to an RI violation if referenced as foreign key.
Absolutely right. The function that will fire the deferred
triggers must switch to READ COMMITTED isolevel while doing
so.
What I'm not sure about is which snapshot to use to get the
OLD tuples (outdated in this transaction by a previous
command). Vadim?
Jan
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#========================================= wieck@debis.com (Jan Wieck) #
************
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Date: Tue, 21 Sep 1999 22:33:20 +0800
From: Vadim Mikheev <vadim@krs.ru>
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To: Jan Wieck <wieck@debis.com>
CC: Andreas Zeugswetter <andreas.zeugswetter@telecom.at>,
hackers@postgreSQL.org
Subject: Re: [HACKERS] Re: Referential Integrity In PostgreSQL
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Jan Wieck wrote:
>
> > It is my understanding, that the RI check is performed on the newest
> > available (committed) data (+ modified data from my own tx).
> > E.g. a primary key that has been removed by another transaction after
> > my begin work will lead to an RI violation if referenced as foreign key.
>
> Absolutely right. The function that will fire the deferred
> triggers must switch to READ COMMITTED isolevel while doing
^^^^^^^^^^^^^^
> so.
NO!
What if one transaction deleted PK, another one inserted FK
and now both performe RI check? Both transactions _must_
use DIRTY READs to notice that RI violated by another
in-progress transaction and wait for concurrent transaction...
BTW, using triggers to check _each_ modified tuple
(i.e. run Executor for each modified tuple) is bad for
performance. We could implement direct support for
standard RI constraints.
Using rules (statement level triggers) for INSERT...SELECT,
UPDATE and DELETE queries would be nice! Actually, RI constraint
checks need in very simple queries (i.e. without distinct etc)
and the only we would have to do is
> What I'm not sure about is which snapshot to use to get the
> OLD tuples (outdated in this transaction by a previous
> command). Vadim?
1. Add CommandId to Snapshot.
2. Use Snapshot->CommandId instead of global CurrentScanCommandId.
3. Use Snapshots with different CommandId-s to get OLD/NEW
versions.
But I agreed that the size of parsetrees may be big and for
COPY...FROM/INSERTs we should remember IDs of modified
tuples. Well. Please remember that I implement WAL right
now, already have 1000 lines of code and hope to run first
tests after writing additional ~200 lines -:)
We could read modified tuple IDs from WAL...
Vadim
************
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From: wieck@debis.com (Jan Wieck)
Subject: Re: [HACKERS] Re: Referential Integrity In PostgreSQL
To: vadim@krs.ru (Vadim Mikheev)
Date: Tue, 21 Sep 1999 16:55:33 +0200 (MET DST)
Cc: wieck@debis.com, andreas.zeugswetter@telecom.at, hackers@postgreSQL.org
Reply-To: wieck@debis.com (Jan Wieck)
In-Reply-To: <37E79730.CC415030@krs.ru> from "Vadim Mikheev" at Sep 21, 99 10:33:20 pm
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>
> Jan Wieck wrote:
> >
> > > It is my understanding, that the RI check is performed on the newest
> > > available (committed) data (+ modified data from my own tx).
> > > E.g. a primary key that has been removed by another transaction after
> > > my begin work will lead to an RI violation if referenced as foreign key.
> >
> > Absolutely right. The function that will fire the deferred
> > triggers must switch to READ COMMITTED isolevel while doing
> ^^^^^^^^^^^^^^
> > so.
>
> NO!
> What if one transaction deleted PK, another one inserted FK
> and now both performe RI check? Both transactions _must_
> use DIRTY READs to notice that RI violated by another
> in-progress transaction and wait for concurrent transaction...
Oh - I see - yes.
>
> BTW, using triggers to check _each_ modified tuple
> (i.e. run Executor for each modified tuple) is bad for
> performance. We could implement direct support for
> standard RI constraints.
As I want to implement it, there would be not much difference
between a regular trigger invocation and a deferred one. If
that causes a performance problem, I think we should speed up
the trigger call mechanism in general instead of not using
triggers.
>
> Using rules (statement level triggers) for INSERT...SELECT,
> UPDATE and DELETE queries would be nice! Actually, RI constraint
> checks need in very simple queries (i.e. without distinct etc)
> and the only we would have to do is
>
> > What I'm not sure about is which snapshot to use to get the
> > OLD tuples (outdated in this transaction by a previous
> > command). Vadim?
>
> 1. Add CommandId to Snapshot.
> 2. Use Snapshot->CommandId instead of global CurrentScanCommandId.
> 3. Use Snapshots with different CommandId-s to get OLD/NEW
> versions.
>
> But I agreed that the size of parsetrees may be big and for
> COPY...FROM/INSERTs we should remember IDs of modified
> tuples. Well. Please remember that I implement WAL right
> now, already have 1000 lines of code and hope to run first
> tests after writing additional ~200 lines -:)
> We could read modified tuple IDs from WAL...
Not only on COPY. One regular INSERT/UPDATE/DELETE statement
can actually fire thousands of trigger calls right now. These
triggers normally use SPI to execute their own queries. If
such a trigger now uses a query that in turn causes a
deferred constraint, we might have to save thousands of
deferred querytrees - impossible mission.
That's IMHO a clear drawback against using rules for
deferrable RI.
What I'm currently doing is clearly encapsulated in some
functions in commands/trigger.c (except for some additional
attributes in pg_trigger). If it later turns out that we can
combine the information required into WAL, I think we have
time enough to do so and shouldn't really care if v6.6
doesn't have it already combined.
Jan
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
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#========================================= wieck@debis.com (Jan Wieck) #
************
From owner-pgsql-hackers@hub.org Tue Sep 21 15:30:29 1999
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From: wieck@debis.com (Jan Wieck)
Subject: [HACKERS] RI question
To: pgsql-hackers@postgreSQL.org (PostgreSQL HACKERS)
Date: Tue, 21 Sep 1999 20:46:06 +0200 (MET DST)
Reply-To: wieck@debis.com (Jan Wieck)
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Uh oh,
I think deferred RI constraints must only fire the actions
that remain after all commands during the entire transaction
are condensed to the total minimum required to get that
state, because deferred RI must only check what VISIBLY
happened during the transaction.
Thinking on the tuple level, a sequence of
INSERT,UPDATE,UPDATE must fire only one INSERT trigger, but
with the values of the last UPDATE. An UPDATE,DELETE sequence
is in fact a DELETE of the original tuple and an
INSERT,UPDATE,DELETE sequence is nothing.
That means that the recording mechnism of the trigger events
must be very smart on UPDATE and DELETE events, looking at
the x_min of the old tuple if that resulted from the current
transaction. If so, follow the events backward, disable
previous ones and change the new event into what it really
has to be.
But some problems remain unsolvable by this:
- PK has an ON DELETE CASCADE for FK
- BEGIN
- DELETE PK
- INSERT same PK
- COMMIT.
This really shouldn't invoke the cascading delete, because at
COMMIT the PK still is there. Same for a constraint that
forbids deletion of a PK while referenced by FK. Therefore
the deferred event recorder must check on INSERT any previous
DELETES for the same relation if the key does match and drop
both deferred triggers if so. Therefore it needs to know
which attributes build the PK of that relation
(<relname>_pkey guaranteed?).
Well, I think that's finally the death of RI over rules. The
code managing those rules during CREATE/ALTER TABLE would
become totally unmaintainable. And (sorry Vadim) it's the
death of SLT for this too because this event tracking must be
done on the tuple level.
It complicated the trigger approach too, but IMHO not too
bad. Anyway, some co-developer(s) doing the parser- and
utility-statement stuff (SET CONSTRAINTS ... etc.) would be
great.
Volunteers?
Jan
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#========================================= wieck@debis.com (Jan Wieck) #
************
From owner-pgsql-hackers@hub.org Tue Jul 13 22:30:50 1999
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From: "Hiroshi Inoue" <Inoue@tpf.co.jp>
To: "pgsql-hackers" <pgsql-hackers@postgreSQL.org>
Subject: [HACKERS] 9-key index ?
Date: Wed, 14 Jul 1999 11:25:09 +0900
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Hi all,
I could create a 9-key index.
create table ix9 (
i1 int4,
i2 int4,
i3 int4,
i4 int4,
i5 int4,
i6 int4,
i7 int4,
i8 int4,
i9 int4,
primary key (i1,i2,i3,i4,i5,i6,i7,i8,i9)
);
NOTICE: CREATE TABLE/PRIMARY KEY will create implicit index 'ix9_pkey'
for table 'ix9'
CREATE
\d ix9_pkey
Table = ix9_pkey
+----------------------------------+----------------------------------+-----
--+
| Field | Type |
Length|
+----------------------------------+----------------------------------+-----
--+
| i1 | int4 |
4 |
| i2 | int4 |
4 |
| i3 | int4 |
4 |
| i4 | int4 |
4 |
| i5 | int4 |
4 |
| i6 | int4 |
4 |
| i7 | int4 |
4 |
| i8 | int4 |
4 |
| i9 | int4 |
4 |
+----------------------------------+----------------------------------+-----
--+
Is it right ?
Regards.
Hiroshi Inoue
Inoue@tpf.co.jp