Since I'm about to have to edit pg_proc.h to add a namespace column,
I thought this would be a good time to revise the current proiscachable
column into the three-way cachability distinction we've discussed
before.  But I need some names for the values, and I'm not satisfied
with the ideas I've had so far.

To refresh people's memory: what we want is to be able to distinguish
between functions that are:

1. Strictly cachable (a/k/a constant-foldable): given fixed input
values, the same result value will always be produced, for ever and
ever, amen.  Examples: addition operator, sin(x).  Given a call
of such a function with all-constant input values, the system is
entitled to fold the function call to a constant on sight.

2. Cachable within a single command: given fixed input values, the
result will not change if the function were to be repeatedly evaluated
within a single SQL command; but the result could change over time.
Examples: now(); datetime-related operations that depend on the current
timezone (or other SET-able variables); any function that looks in
database tables to determine its result.

3. Totally non-cachable: result may change from one call to the next,
even within a single SQL command.  Examples: nextval(), random(),
timeofday().  (Yes, timeofday() and now() are in different categories.
See http://www.ca.postgresql.org/users-lounge/docs/7.2/postgres/functions-datetime.html#FUNCTIONS-DATETIME-CURRENT)

Currently the system can only distinguish cases 1 and 3, so functions
that are really case 2 have to be labeled as case 3; this prevents a lot
of useful optimizations.  In particular, it is safe to use expressions
involving only case-1 and case-2 functions as indexscan conditions,
whereas case-3 functions cannot be optimized into an indexscan.  So this
is an important fix to make.

BTW, because of MVCC semantics, case 2 covers more ground than you might
think.  We are interested in functions whose values cannot change during
a single "scan", ie, while the intra-transaction command counter does
not increment.  So functions that do SELECTs are actually guaranteed to
be case 2, even if stuff outside the function is changing the table
being looked at.

My problem is picking names for the three categories of functions.
Currently we use "with (isCachable)" to identify category 1, but it
seems like this name might actually be more sensible for category 2.
I'm having a hard time picking simple names that convey these meanings
accurately, or even with a reasonable amount of suggestiveness.

Comments, ideas?

			regards, tom lane

Tue, 02 Apr 2002 16:40:57 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Suggestions please: names for function cachability attributes
Tom Lane wrote:
> BTW, because of MVCC semantics, case 2 covers more ground than you might
> think.  We are interested in functions whose values cannot change during
> a single "scan", ie, while the intra-transaction command counter does
> not increment.  So functions that do SELECTs are actually guaranteed to
> be case 2, even if stuff outside the function is changing the table
> being looked at.
> 
> My problem is picking names for the three categories of functions.
> Currently we use "with (isCachable)" to identify category 1, but it
> seems like this name might actually be more sensible for category 2.
> I'm having a hard time picking simple names that convey these meanings
> accurately, or even with a reasonable amount of suggestiveness.
> 
> Comments, ideas?
> 


How about:

case 1: Cachable
case 2: ScanCachable or Optimizable
case 3: NonCachable

Joe




Tue, 02 Apr 2002 13:57:04 -0800
Joe Conway <mail@joeconway.com>
Re: Suggestions please: names for function cachability
My 2 cents.

Level 1. with (isCachableStatic)
Level 2. with (isCachableDynamic)
Level 3. default

In my mind (isCachable) sounds like level 1

On Tuesday 02 April 2002 03:40 pm, Tom Lane wrote:
> Since I'm about to have to edit pg_proc.h to add a namespace column,
> I thought this would be a good time to revise the current proiscachable
> column into the three-way cachability distinction we've discussed
> before.  But I need some names for the values, and I'm not satisfied
> with the ideas I've had so far.
>
> To refresh people's memory: what we want is to be able to distinguish
> between functions that are:
>
> 1. Strictly cachable (a/k/a constant-foldable): given fixed input
> values, the same result value will always be produced, for ever and
> ever, amen.  Examples: addition operator, sin(x).  Given a call
> of such a function with all-constant input values, the system is
> entitled to fold the function call to a constant on sight.
>
> 2. Cachable within a single command: given fixed input values, the
> result will not change if the function were to be repeatedly evaluated
> within a single SQL command; but the result could change over time.
> Examples: now(); datetime-related operations that depend on the current
> timezone (or other SET-able variables); any function that looks in
> database tables to determine its result.
>
> 3. Totally non-cachable: result may change from one call to the next,
> even within a single SQL command.  Examples: nextval(), random(),
> timeofday().  (Yes, timeofday() and now() are in different categories.
> See
> http://www.ca.postgresql.org/users-lounge/docs/7.2/postgres/functions-datet
>ime.html#FUNCTIONS-DATETIME-CURRENT)
>
> Currently the system can only distinguish cases 1 and 3, so functions
> that are really case 2 have to be labeled as case 3; this prevents a lot
> of useful optimizations.  In particular, it is safe to use expressions
> involving only case-1 and case-2 functions as indexscan conditions,
> whereas case-3 functions cannot be optimized into an indexscan.  So this
> is an important fix to make.
>
> BTW, because of MVCC semantics, case 2 covers more ground than you might
> think.  We are interested in functions whose values cannot change during
> a single "scan", ie, while the intra-transaction command counter does
> not increment.  So functions that do SELECTs are actually guaranteed to
> be case 2, even if stuff outside the function is changing the table
> being looked at.
>
> My problem is picking names for the three categories of functions.
> Currently we use "with (isCachable)" to identify category 1, but it
> seems like this name might actually be more sensible for category 2.
> I'm having a hard time picking simple names that convey these meanings
> accurately, or even with a reasonable amount of suggestiveness.
>
> Comments, ideas?
>
> 			regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 5: Have you checked our extensive FAQ?
>
> http://www.postgresql.org/users-lounge/docs/faq.html

Tue, 2 Apr 2002 16:09:14 -0600
David Walker <pgsql@grax.com>
Re: Suggestions please: names for function cachability attributes
* Tom Lane (tgl@sss.pgh.pa.us) [020402 16:42]:
> Since I'm about to have to edit pg_proc.h to add a namespace column,
> I thought this would be a good time to revise the current proiscachable
> column into the three-way cachability distinction we've discussed
> before.  But I need some names for the values, and I'm not satisfied
> with the ideas I've had so far.

Invariant
Cachable
Noncachable


Tue, 2 Apr 2002 17:46:15 -0500
Bradley McLean <brad@bradm.net>
Re: Suggestions please: names for function cachability attributes
I am full agreement with proposal. I love it!!

(1) const or constant
(2) cacheable
(3) volatile

P.S.
Tom: My mail doesn't reach you. As an AT&T user, you block my machine's IP
address with the anti-spam blocking. :-(

Tom Lane wrote:
> 
> Since I'm about to have to edit pg_proc.h to add a namespace column,
> I thought this would be a good time to revise the current proiscachable
> column into the three-way cachability distinction we've discussed
> before.  But I need some names for the values, and I'm not satisfied
> with the ideas I've had so far.
> 
> To refresh people's memory: what we want is to be able to distinguish
> between functions that are:
> 
> 1. Strictly cachable (a/k/a constant-foldable): given fixed input
> values, the same result value will always be produced, for ever and
> ever, amen.  Examples: addition operator, sin(x).  Given a call
> of such a function with all-constant input values, the system is
> entitled to fold the function call to a constant on sight.
> 
> 2. Cachable within a single command: given fixed input values, the
> result will not change if the function were to be repeatedly evaluated
> within a single SQL command; but the result could change over time.
> Examples: now(); datetime-related operations that depend on the current
> timezone (or other SET-able variables); any function that looks in
> database tables to determine its result.
> 
> 3. Totally non-cachable: result may change from one call to the next,
> even within a single SQL command.  Examples: nextval(), random(),
> timeofday().  (Yes, timeofday() and now() are in different categories.
> See http://www.ca.postgresql.org/users-lounge/docs/7.2/postgres/functions-datetime.html#FUNCTIONS-DATETIME-CURRENT)
> 
> Currently the system can only distinguish cases 1 and 3, so functions
> that are really case 2 have to be labeled as case 3; this prevents a lot
> of useful optimizations.  In particular, it is safe to use expressions
> involving only case-1 and case-2 functions as indexscan conditions,
> whereas case-3 functions cannot be optimized into an indexscan.  So this
> is an important fix to make.
> 
> BTW, because of MVCC semantics, case 2 covers more ground than you might
> think.  We are interested in functions whose values cannot change during
> a single "scan", ie, while the intra-transaction command counter does
> not increment.  So functions that do SELECTs are actually guaranteed to
> be case 2, even if stuff outside the function is changing the table
> being looked at.
> 
> My problem is picking names for the three categories of functions.
> Currently we use "with (isCachable)" to identify category 1, but it
> seems like this name might actually be more sensible for category 2.
> I'm having a hard time picking simple names that convey these meanings
> accurately, or even with a reasonable amount of suggestiveness.
> 
> Comments, ideas?
> 
>                         regards, tom lane
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 5: Have you checked our extensive FAQ?
> 
> http://www.postgresql.org/users-lounge/docs/faq.html

Tue, 02 Apr 2002 19:51:47 -0500
mlw <markw@nospam.not>
Re: Suggestions please: names for function cachability attributes
Tom Lane writes:

> Since I'm about to have to edit pg_proc.h to add a namespace column,
> I thought this would be a good time to revise the current proiscachable
> column into the three-way cachability distinction we've discussed
> before.  But I need some names for the values, and I'm not satisfied
> with the ideas I've had so far.

Well, for one thing, we might want to change the name to the correct
spelling "cacheable".

> 1. Strictly cachable (a/k/a constant-foldable): given fixed input
> values, the same result value will always be produced, for ever and
> ever, amen.  Examples: addition operator, sin(x).  Given a call
> of such a function with all-constant input values, the system is
> entitled to fold the function call to a constant on sight.

deterministic

(That's how SQL99 calls it.)

> 2. Cachable within a single command: given fixed input values, the
> result will not change if the function were to be repeatedly evaluated
> within a single SQL command; but the result could change over time.
> Examples: now(); datetime-related operations that depend on the current
> timezone (or other SET-able variables); any function that looks in
> database tables to determine its result.

"cacheable" seems OK for this.

> 3. Totally non-cachable: result may change from one call to the next,
> even within a single SQL command.  Examples: nextval(), random(),
> timeofday().  (Yes, timeofday() and now() are in different categories.
> See http://www.ca.postgresql.org/users-lounge/docs/7.2/postgres/functions-datetime.html#FUNCTIONS-DATETIME-CURRENT)

not deterministic, not cacheable

-- 
Peter Eisentraut   peter_e@gmx.net


Tue, 2 Apr 2002 19:59:35 -0500 (EST)
Peter Eisentraut <peter_e@gmx.net>
Re: Suggestions please: names for function cachability
On Tue, 2 Apr 2002, Peter Eisentraut wrote:

> Tom Lane writes:
> 
> > Since I'm about to have to edit pg_proc.h to add a namespace column,
> > I thought this would be a good time to revise the current proiscachable
> > column into the three-way cachability distinction we've discussed
> > before.  But I need some names for the values, and I'm not satisfied
> > with the ideas I've had so far.
> 
> Well, for one thing, we might want to change the name to the correct
> spelling "cacheable".
> 
> > 1. Strictly cachable (a/k/a constant-foldable): given fixed input
> > values, the same result value will always be produced, for ever and
> > ever, amen.  Examples: addition operator, sin(x).  Given a call
> > of such a function with all-constant input values, the system is
> > entitled to fold the function call to a constant on sight.
> 
> deterministic
> 
> (That's how SQL99 calls it.)
> 
> > 2. Cachable within a single command: given fixed input values, the
> > result will not change if the function were to be repeatedly evaluated
> > within a single SQL command; but the result could change over time.
> > Examples: now(); datetime-related operations that depend on the current
> > timezone (or other SET-able variables); any function that looks in
> > database tables to determine its result.
> 
> "cacheable" seems OK for this.

SQL99 suggests that there are only two types of user defined
routines: deterministic and 'possibly non-deterministic'. However, in
section 11.49 it defines 

<deterministic characteristic> ::= DETERMINISTIC | NOT DETERMINISTIC

So the real problem is how to qualify this.

TRANSACTIONAL DETERMINISTIC

or

NOT DETERMINISTIC CACHEABLE

are the only ways that come to mind. I'll admit that I don't like either.

> 
> > 3. Totally non-cachable: result may change from one call to the next,
> > even within a single SQL command.  Examples: nextval(), random(),
> > timeofday().  (Yes, timeofday() and now() are in different categories.
> > See http://www.ca.postgresql.org/users-lounge/docs/7.2/postgres/functions-datetime.html#FUNCTIONS-DATETIME-CURRENT)
> 
> not deterministic, not cacheable
> 
> 

Gavin


Wed, 3 Apr 2002 11:47:29 +1000 (EST)
Gavin Sherry <swm@linuxworld.com.au>
Re: Suggestions please: names for function cachability
Peter Eisentraut <peter_e@gmx.net> writes:
> Well, for one thing, we might want to change the name to the correct
> spelling "cacheable".

Is that correct?

I looked in the Oxford English Dictionary, the Random House Dictionary,
and a couple other dictionaries of less substantial heft, and could not
find anything authoritative at all.  RH gives the derived forms "cached"
and "caching"; OED offers nothing.  I'd be interested to see an
authoritative reference for the spelling of the adjective form.

Possibly we should avoid the issue by using another word ;-)

			regards, tom lane

Tue, 02 Apr 2002 23:39:35 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: Suggestions please: names for function cachability 
On Tue, 02 Apr 2002 23:39:35 -0500
"Tom Lane" <tgl@sss.pgh.pa.us> wrote:
> Peter Eisentraut <peter_e@gmx.net> writes:
> > Well, for one thing, we might want to change the name to the correct
> > spelling "cacheable".
> 
> Is that correct?

Apparently, other people are confused as well:

	http://www.xent.com/FoRK-archive/august97/0431.html

FWIW, google has ~30,000 results for -eable, and ~8,000 results for
-able. A couple other software projects (notably Apache Jakarta)
use -eable.

My preference would be for -eable, but that's just on the basis of
"it looks right", which is hardly authoritative.

Cheers,

Neil

-- 
Neil Conway <neilconway@rogers.com>
PGP Key ID: DB3C29FC

Tue, 2 Apr 2002 23:54:35 -0500
Neil Conway <nconway@klamath.dyndns.org>
Re: Suggestions please: names for function cachability

I am full agreement with proposal. I love it!!

(1) const or constant
(2) cacheable
(3) volatile

P.S.
Tom: My mail doesn't reach you. As an AT&T user, you block my machine's IP
address with the anti-spam blocking. :-(

Wed, 03 Apr 2002 10:02:15 -0500
mlw <markw@mohawksoft.com>
Re: Suggestions please: names for function cachability attributes
Tom Lane wrote:
> 
> mlw <markw@mohawksoft.com> writes:
> > Tom: My mail doesn't reach you. As an AT&T user, you block my machine's IP
> > address with the anti-spam blocking. :-(
> 
> Sorry about that.  I like 510sg's dnsbl list precisely because it's
> aggressive, but sometimes it's too aggressive.  I can whitelist you
> if you have a stable IP address ... is 24.147.138.78 a permanently
> assigned address, or not?

Alas we have the irony of me trying to respond to you via email, to give you
information on how to unblock me so I can respond via email. I am laughing.

I wish I could say I have a fixed IP, but I do not. It is a DHCP assigned AT&T
cable modem. Sorry.

I'm not sure I'm the only one, am I?

Wed, 03 Apr 2002 11:11:28 -0500
mlw <markw@mohawksoft.com>
Re: Suggestions please: names for function cachability 
mlw <markw@mohawksoft.com> writes:
> (1) const or constant
> (2) cacheable
> (3) volatile

I was wondering about "const" for case 1, also.  I think there is some
precedent for using "const" with this meaning in other programming
languages.  "volatile" for case 3 seems reasonable.

> Tom: My mail doesn't reach you. As an AT&T user, you block my machine's IP
> address with the anti-spam blocking. :-(

Sorry about that.  I like 510sg's dnsbl list precisely because it's
aggressive, but sometimes it's too aggressive.  I can whitelist you
if you have a stable IP address ... is 24.147.138.78 a permanently
assigned address, or not?

			regards, tom lane

Wed, 03 Apr 2002 11:12:09 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: Suggestions please: names for function cachability attributes 
...
> I'm not sure I'm the only one, am I?

No, I was also blocked from Tom's mail a while ago. I have a static IP,
but my ISP's entire block of addresses made it on to the spam list Tom
uses, and the strategy of the list maintainers seems to be to maximize
the collateral damage to force me to somehow force my ISP to change
their policies, whatever those are. If I researched it enough, I might
be able to find out what my ISP does or does not do, and what I'm
supposed to do or not do. What a pain...

Not sure if my status has changed. I'll bet not, since the anti-spam
folks have high enough standards that someone like me can't make the
grade. I suppose they don't rely on PostgreSQL for their database... ;)

That said, I'd like to block some spam myself. I'd rather find a spam
list which doesn't already have me disallowed however...

                     - Thomas

Wed, 03 Apr 2002 08:45:03 -0800
Thomas Lockhart <thomas@fourpalms.org>
Re: Suggestions please: names for function cachability
Peter Eisentraut wrote:
> 
> Tom Lane writes:
> 
> > mlw <markw@mohawksoft.com> writes:
> > > (1) const or constant
> > > (2) cacheable
> > > (3) volatile
> >
> > I was wondering about "const" for case 1, also.  I think there is some
> > precedent for using "const" with this meaning in other programming
> > languages.
> 
> I think the meaning of "const" tends to be "cannot change the result" --
> which may actually make sense in SQL in a future life if you can pass
> around table descriptors or cursor references.

A function, such as sin(x) could be considered constant for the result based on
value 'x'

Wed, 03 Apr 2002 11:46:37 -0500
mlw <markw@mohawksoft.com>
Re: Suggestions please: names for function 
Tom Lane writes:

> mlw <markw@mohawksoft.com> writes:
> > (1) const or constant
> > (2) cacheable
> > (3) volatile
>
> I was wondering about "const" for case 1, also.  I think there is some
> precedent for using "const" with this meaning in other programming
> languages.

I think the meaning of "const" tends to be "cannot change the result" --
which may actually make sense in SQL in a future life if you can pass
around table descriptors or cursor references.

-- 
Peter Eisentraut   peter_e@gmx.net


Wed, 3 Apr 2002 11:54:20 -0500 (EST)
Peter Eisentraut <peter_e@gmx.net>
Re: Suggestions please: names for function cachability
Thomas Lockhart <thomas@fourpalms.org> writes:
> That said, I'd like to block some spam myself. I'd rather find a spam
> list which doesn't already have me disallowed however...

In case it makes you feel better: my *own* address was on the 510sg list
for awhile last month.  But I still use the list ;-).  Nothing to stop
you from using some less-aggressive list though; see
http://relays.osirusoft.com/ for links to a dozen or more possibilities.

In practice, any DNSBL list can cause denial-of-service problems.
(The original and still most conservatively run one, MAPS RBL, had a
memorable episode where someone put 127.0.0.1 into the blacklist for
a few hours...)  I deal with this by installing local whitelist
exceptions for people I talk to regularly.  Otherwise, there's always
the mailing lists.

			regards, tom lane

Wed, 03 Apr 2002 11:57:26 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: Suggestions please: names for function cachability 
On Wed, Apr 03, 2002 at 11:11:28AM -0500, mlw wrote:
> 
> I'm not sure I'm the only one, am I?

Nope, we're on AT&T lines, too.

A

-- 
----
Andrew Sullivan                               87 Mowat Avenue 
Liberty RMS                           Toronto, Ontario Canada
<andrew@libertyrms.info>                              M6K 3E3
                                         +1 416 646 3304 x110


Wed, 3 Apr 2002 12:00:35 -0500
Andrew Sullivan <andrew@libertyrms.info>
Re: [HACKERS] Suggestions please: names for function cachability
mlw <markw@mohawksoft.com> writes:
> Tom Lane wrote:
>> Sorry about that.  I like 510sg's dnsbl list precisely because it's
>> aggressive, but sometimes it's too aggressive.  I can whitelist you
>> if you have a stable IP address ... is 24.147.138.78 a permanently
>> assigned address, or not?

> I wish I could say I have a fixed IP, but I do not. It is a DHCP assigned AT&T
> cable modem. Sorry.

Cable modem IPs are more stable than you might think --- a quick look in
the list archives shows you've had this one since early January.  In
practice you'll keep the same IP as long as you don't lose connectivity.

I'll whitelist 24.147.138.* and hope for the best...

			regards, tom lane

Wed, 03 Apr 2002 12:10:42 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: Suggestions please: names for function cachability 
Peter Eisentraut wrote:
> 
> Tom Lane writes:
> 
> > mlw <markw@mohawksoft.com> writes:
> > > (1) const or constant
> > > (2) cacheable
> > > (3) volatile
> >
> > I was wondering about "const" for case 1, also.  I think there is some
> > precedent for using "const" with this meaning in other programming
> > languages.
> 
> I think the meaning of "const" tends to be "cannot change the result" --
> which may actually make sense in SQL in a future life if you can pass
> around table descriptors or cursor references.

I can buy that. Ok, const isn't a good name.

How about 'immutable' ?

Wed, 03 Apr 2002 12:10:45 -0500
mlw <markw@mohawksoft.com>
Re: Suggestions please: names for function cachability
On Wed, Apr 03, 2002 at 08:45:03AM -0800, Thomas Lockhart wrote:
> ...
> > I'm not sure I'm the only one, am I?
> 
> No, I was also blocked from Tom's mail a while ago. I have a static IP,
> but my ISP's entire block of addresses made it on to the spam list Tom
> uses, and the strategy of the list maintainers seems to be to maximize
> the collateral damage to force me to somehow force my ISP to change
> their policies, whatever those are. If I researched it enough, I might
> be able to find out what my ISP does or does not do, and what I'm
> supposed to do or not do. What a pain...

We had the same problem here.  I spoke to the 5-10 list provider and
got our ISP delisted since they seem to have kicked the 3 or so spammers
off their network.  It seems a little unreasonable to blacklist an entire
large ISP's netblock just because they have a very small number of spam
sites.  It is also pretty unreasonable to think that any company is
going to switch providers because of one blacklist or somehow complain
to their ISP about the spammers the ISP is hosting without any more
detail than:

	"Blacklist X says you provide spam support and/or have too many
	 spammers on your network.  Please remove them so I can send
	 my email."


Martin

Wed, 3 Apr 2002 12:16:21 -0500
Martin Renters <martin@datafax.com>
Re: Suggestions please: names for function cachability
mlw writes:

> A function, such as sin(x) could be considered constant for the result based on
> value 'x'

It could also be considered deterministic, strict, cacheable,
mathematically sensible, real, pleasant, or good. ;-)

Out of those, I believe "const" is the worst term, because saying "sin(x)
is a constant function" sounds pretty wrong.

-- 
Peter Eisentraut   peter_e@gmx.net


Wed, 3 Apr 2002 12:16:41 -0500 (EST)
Peter Eisentraut <peter_e@gmx.net>
Re: Suggestions please: names for function  cachabilityattributes
Martin Renters <martin@datafax.com> writes:
> It is also pretty unreasonable to think that any company is
> going to switch providers because of one blacklist or somehow complain
> to their ISP about the spammers the ISP is hosting without any more
> detail than:

> 	"Blacklist X says you provide spam support and/or have too many
> 	 spammers on your network.  Please remove them so I can send
> 	 my email."

FWIW, all the blacklists I use (and 510sg is only the first line of
defense ;-)) have documentation available about the reasons for listing
IP blocks.  F'r instance, looking up Thomas' IP I get:

  xo.com.spam-support.blackholes.five-ten-sg.com.  23h32m50s IN TXT  "added 2002-01-05; spam support - dns server at 64.1.121.57 supporting http://www.poxteam2001.com"
  xo.com.spam-support.blackholes.five-ten-sg.com.  23h32m50s IN TXT  "added 2002-01-07; spam support - dns server at 64.1.121.57 supporting http://compower.numberop.com"
  xo.com.spam-support.blackholes.five-ten-sg.com.  23h32m50s IN TXT  "added 2002-03-07; spam support - hosting http://207.88.179.193 - terminated"
  xo.com.spam-support.blackholes.five-ten-sg.com.  23h32m50s IN TXT  "added 2002-03-10; spam support - hosting http://thecottagemonitor.com"
  xo.com.spam-support.blackholes.five-ten-sg.com.  23h32m50s IN TXT  "added 2002-03-13; spam support - hosting http://shortcuts2learning.com"
  xo.com.spam-support.blackholes.five-ten-sg.com.  23h32m50s IN TXT  "added 2002-03-24; spam support - hosting http://209.164.32.75/consumer_first_funding"

But this is getting pretty far off-topic for the PG lists.

			regards, tom lane

Wed, 03 Apr 2002 12:24:37 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: Suggestions please: names for function cachability 
Peter Eisentraut <peter_e@gmx.net> writes:
> It could also be considered deterministic, strict, cacheable,
> mathematically sensible, real, pleasant, or good. ;-)

> Out of those, I believe "const" is the worst term, because saying "sin(x)
> is a constant function" sounds pretty wrong.

Yeah, that was my problem with "const" too.  But "deterministic" has the
same problem --- in the ordinary meaning of the term, a function doesn't
become nondeterministic just because it depends on SET TIMEZONE as well
as its explicit parameters.  It's also too long and too hard to spell
correctly ;-).

"cacheable" (whatever spelling; I suppose we should consider accepting
both, cf analyze/analyse) is a fine term except that it isn't quite clear
whether to use it for case 1 or case 2, which means that people won't be
able to remember which case it applies to ... unless we come up with
some really memorable choice for the other case.

So far the only suggestion I've seen that really makes me happy is
"volatile" for case 3.  Brad's idea of "invariant" for case 1 isn't
too bad, but as a partner for "cacheable" it seems a bit weak;
if you haven't looked at the manual lately, will you remember which
is which?

			regards, tom lane

Wed, 03 Apr 2002 12:38:06 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: Suggestions please: names for function cachabilityattributes 
It occurs to me that we also need a better term for the overall concept.
"cacheability" has misled at least two people (that I can recall) into
thinking that we maintain some kind of function result cache --- which
is not true, and if it were true we'd need the term "cacheable" for
control parameters for the cache, which this categorization is not.

I am thinking that "mutability" might be a good starting point instead
of "cacheability".  This leads immediately to what seems like a fairly
reasonable set of names:

pg_proc column: promutable or proismutable

case 1: "immutable"
case 2: "mutable", or perhaps "stable"
case 3: "volatile"

Thoughts?

			regards, tom lane

Wed, 03 Apr 2002 13:29:40 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: Suggestions please: names for function cachabilityattributes 
Tom Lane wrote:
> 
> It occurs to me that we also need a better term for the overall concept.
> "cacheability" has misled at least two people (that I can recall) into
> thinking that we maintain some kind of function result cache --- which
> is not true, and if it were true we'd need the term "cacheable" for
> control parameters for the cache, which this categorization is not.
> 
> I am thinking that "mutability" might be a good starting point instead
> of "cacheability".  This leads immediately to what seems like a fairly
> reasonable set of names:
> 
> pg_proc column: promutable or proismutable
> 
> case 1: "immutable"
> case 2: "mutable", or perhaps "stable"
> case 3: "volatile"

I like 1 and 3 :-) 

I think 2 should be something like "stable." Mutable and volitile have very
similar meanings.

I'm not sure, the word stable is right, though. Cacheable has the best meaning,
but implies something that isn't. How about "persistent" or "fixed?"

Wed, 03 Apr 2002 13:43:21 -0500
mlw <markw@mohawksoft.com>
Re: Suggestions please: names for function 
> FWIW, all the blacklists I use (and 510sg is only the first line of
> defense ;-)) have documentation available about the reasons for listing
> IP blocks.  F'r instance, looking up Thomas' IP I get:
...
> But this is getting pretty far off-topic for the PG lists.

I'll guess that the list of reasons for the blacklisting I find today is
different than the list I found a few months ago when this first came
up. What is relevant to me is that I absolutely cannot get my machine
removed from this blacklist, no matter what I do to secure that machine.
And that, istm, reduces the relevance of that particular blacklisting
strategy.

I was just using this as an example (I happen to send mail directly to
you so have run across it in this context).

I'm interested because spam has affected me in other contexts too, and
every time it takes time away from PostgreSQL.

We could sent up Yet Another List, say pgsql-spam-whiners, and I could
be a charter member, and maybe y'all would suggest I should also be on
pgsql-clueless-spam-whiners. But maybe it is better to have an
occasional discussion on topics that people find affecting their use of
the mailing list(s) ;)

I have to say that spam is bumming me out more now than it ever has in
the past. So let's hope that the blacklists *do* help somehow!

                    - Thomas

Wed, 03 Apr 2002 14:26:44 -0800
Thomas Lockhart <thomas@fourpalms.org>
Re: Suggestions please: names for function cachability
Tom Lane writes:

> Peter Eisentraut <peter_e@gmx.net> writes:
> > It could also be considered deterministic, strict, cacheable,
> > mathematically sensible, real, pleasant, or good. ;-)
>
> > Out of those, I believe "const" is the worst term, because saying "sin(x)
> > is a constant function" sounds pretty wrong.
>
> Yeah, that was my problem with "const" too.  But "deterministic" has the
> same problem --- in the ordinary meaning of the term, a function doesn't
> become nondeterministic just because it depends on SET TIMEZONE as well
> as its explicit parameters.  It's also too long and too hard to spell
> correctly ;-).

As it turns out, Oracle, IBM, and Microsoft use it for exactly the same
purpose, and it is standard ...

If you're not happy with labelling case 2 nondeterministic, add an
additional clause, like USES EXTERNAL STATE.  We could dig through all the
adjectives in the world, but I don't think any will catch the situation
quite like saying what's actually going on.

> So far the only suggestion I've seen that really makes me happy is
> "volatile" for case 3.

Volatile means "subject to rapid or unexpected change", which is not
really what case 3 is.

> Brad's idea of "invariant" for case 1 isn't too bad, but as a partner
> for "cacheable" it seems a bit weak; if you haven't looked at the
> manual lately, will you remember which is which?

Actually, IBM has VARIANT as an alias for NOT DETERMINISTIC (and NOT
VARIANT for DETERMINISTIC).

-- 
Peter Eisentraut   peter_e@gmx.net


Wed, 3 Apr 2002 18:19:31 -0500 (EST)
Peter Eisentraut <peter_e@gmx.net>
Re: Suggestions please: names for function cachabilityattributes
Peter Eisentraut <peter_e@gmx.net> writes:
> Tom Lane writes:
>> case 1: "immutable"
>> case 2: "mutable", or perhaps "stable"
>> case 3: "volatile"

> Since they've changed anyway, how about dropping the silly "is" in front
> of the names?

"volatile" would conflict with a C keyword.  Possibly we could get away
with this at the SQL level, but I was worried...

			regards, tom lane

Sat, 13 Apr 2002 02:05:54 -0400
Tom Lane <tgl@sss.pgh.pa.us>
Re: Suggestions please: names for function cachabilityattributes 
Tom Lane writes:

> case 1: "immutable"
> case 2: "mutable", or perhaps "stable"
> case 3: "volatile"

Since they've changed anyway, how about dropping the silly "is" in front
of the names?

-- 
Peter Eisentraut   peter_e@gmx.net


Sat, 13 Apr 2002 02:08:08 -0400 (EDT)
Peter Eisentraut <peter_e@gmx.net>
Re: Suggestions please: names for function cachabilityattributes
Tom Lane writes:

> Peter Eisentraut <peter_e@gmx.net> writes:
> > Tom Lane writes:
> >> case 1: "immutable"
> >> case 2: "mutable", or perhaps "stable"
> >> case 3: "volatile"
>
> > Since they've changed anyway, how about dropping the silly "is" in front
> > of the names?
>
> "volatile" would conflict with a C keyword.  Possibly we could get away
> with this at the SQL level, but I was worried...

In general, I was thinking about migrating the CREATE FUNCTION syntax more
into consistency with other commmands and with the SQL standard.
Basically I'd like to write

    CREATE FUNCTION name (args, ...) RETURNS type
      AS '...'
      LANGUAGE foo
      STATIC
      IMPLICIT CAST

(where everything after RETURNS can be in random order).

OK, so the key words are not the same as SQL, but it looks a lot
friendlier this way.  We're already migrating CREATE DATABASE, I think,
and the names of the options have changed, too, so this might be a good
time.

-- 
Peter Eisentraut   peter_e@gmx.net


Sat, 13 Apr 2002 02:33:51 -0400 (EDT)
Peter Eisentraut <peter_e@gmx.net>
Re: Suggestions please: names for function cachabilityattributes
Peter Eisentraut <peter_e@gmx.net> writes:
> Basically I'd like to write

>     CREATE FUNCTION name (args, ...) RETURNS type
>       AS '...'
>       LANGUAGE foo
>       STATIC
>       IMPLICIT CAST

> (where everything after RETURNS can be in random order).

No strong objection here; but you'll still have to accept the old syntax
for backwards compatibility with existing dump scripts.  I also worry
that this will end up forcing us to reserve a lot more keywords.  Not so
much for CREATE FUNCTION, but in CREATE OPERATOR, CREATE DOMAIN and
friends I do not think you'll be able to do this without making the
keywords reserved (else how do you tell 'em from parts of typenames
and expressions?).

Given that it's not gonna be SQL-spec anyway, I'm not entirely sure
I see the point of changing.

			regards, tom lane

Sat, 13 Apr 2002 11:34:34 -0400
Tom Lane <tgl@sss.pgh.pa.us>
Re: Suggestions please: names for function cachabilityattributes 