subject:"\[HACKERS\] Problems with question marks in operators $JDBC, ECPG, ...$"

On Tue, May 19, 2015 at 9:51 PM, Dave Cramer p...@fastcrypt.com wrote:



 Actually the issue is what to do about a number of connectors which use a
 fairly standard '?' as a placeholder.
 Notably absent from the discussion is ODBC upon which JDBC was modelled
 and probably predates any use of ? as an operator


Ah, good point. I must admit I don't normally use ODBC, but I've given it a
try, and it doesn't look good regarding the question mark. Maybe I simply
don't know how it should be escaped, but my attempts (shown below) didn't
work.

This is run using PowerShell. Of all those tests, only the first one works
(it's not using the question mark, just to make sure something worked).
Interestingly, the question mark in the pseudo-column name (Does it
work?) doesn't cause problems. (The errors are slightly different
depending on the attempt.)


Best wishes,

Bruno.


__ Output


*** Test query: SELECT ('{key1:123,key2:Hello}'::jsonb -
?::text)::text AS Does it work?

Does it
work?

-

123




*** Test query: SELECT ('{key1:123,key2:Hello}'::jsonb ?
?::text)::text AS Does it work?
Exception calling Fill with 1 argument(s): ERROR [42601] ERROR: syntax
error at or near $1;
Error while preparing parameters

*** Test query: SELECT ('{key1:123,key2:Hello}'::jsonb \?
?::text)::text AS Does it work?
Exception calling Fill with 1 argument(s): ERROR [42601] ERROR: syntax
error at or near \;
Error while preparing parameters

*** Test query: SELECT ('{key1:123,key2:Hello}'::jsonb ??
?::text)::text AS Does it work?
Exception calling Fill with 1 argument(s): ERROR [42601] ERROR: syntax
error at or near $1;
Error while preparing parameters

*** Test query: SELECT ('{key1:123,key2:Hello}'::jsonb {?}
?::text)::text AS Does it work?
Exception calling Fill with 1 argument(s): ERROR [07002] The # of
binded parameters  the # of parameter markers

*** Test query: SELECT ('{key1:123,key2:Hello}'::jsonb {'?'}
?::text)::text
Exception calling Fill with 1 argument(s): ERROR [HY000] ODBC escape
convert error


__ PowerShell script

function test_query($query) {
$conn = New-Object System.Data.Odbc.OdbcConnection
try {
$conn.ConnectionString = DSN=PostgreSQL35W
$conn.Open()
Write-Output *** Test query: $query;
$cmd = New-Object System.Data.Odbc.OdbcCommand($query, $conn)
$cmd.Parameters.Add(key, key1) | out-null
$ds = New-Object System.Data.DataSet
(New-Object system.Data.odbc.odbcDataAdapter($cmd)).fill($ds) |
out-null
$ds.Tables[0] | Format-Table
} catch {
Write-Output $_.Exception
} finally {
if ($conn.State -eq 'Open' ) {
$conn.Close()
}
}
Write-Output 
}

test_query(@'
SELECT ('{key1:123,key2:Hello}'::jsonb - ?::text)::text AS
Does it work?
'@)

test_query(@'
SELECT ('{key1:123,key2:Hello}'::jsonb ? ?::text)::text AS Does
it work?
'@)

test_query(@'
SELECT ('{key1:123,key2:Hello}'::jsonb \? ?::text)::text AS Does
it work?
'@)

test_query(@'
SELECT ('{key1:123,key2:Hello}'::jsonb ?? ?::text)::text AS Does
it work?
'@)

test_query(@'
SELECT ('{key1:123,key2:Hello}'::jsonb {?} ?::text)::text AS
Does it work?
'@)

test_query(@'
SELECT ('{key1:123,key2:Hello}'::jsonb {'?'} ?::text)::text
'@)

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-20 Thread Andrew Dunstan



On 05/20/2015 03:34 PM, Tom Lane wrote:

Dave Cramer p...@fastcrypt.com writes:

Notably absent from the discussion is ODBC upon which JDBC was modelled and
probably predates any use of ? as an operator

historical-nitpicking

It would be a mistake to imagine that operators containing '?' are some
johnny-come-lately.  The ? operator for tintervals can be traced back
at least to Postgres v4r2 (1994), which is the oldest tarball I have at
hand.  Most of the current list are geometric operators that were added
by Tom Lockhart in 1997.  The only ones that aren't old enough to vote
are the JSONB ones we added last year.

Not that the problem's not real, but these operators predate any attempt
to make Postgres work with ODBC or JDBC or any other connector.  Otherwise
we might've thought better of using '?'.

/historical-nitpicking


Yeah, I knew they were pretty old.

When did the SQL standard add any mention of ?

cheers

andrew


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

Andrew Dunstan and...@dunslane.net writes:
 When did the SQL standard add any mention of ?

It's in SQL92.  I don't have a copy of SQL89, or whatever the previous
spec was, to look at.

(So you could argue that Yu and Chen should've removed ? from the set of
allowed operator characters when they grafted SQL syntax onto Postgres.
But they didn't ...)

regards, tom lane


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-20 Thread Kevin Grittner

Andrew Dunstan and...@dunslane.net wrote:
 On 05/20/2015 03:34 PM, Tom Lane wrote:

 The ? operator for tintervals can be traced back at least to
 Postgres v4r2 (1994), which is the oldest tarball I have at
 hand.  Most of the current list are geometric operators that
 were added by Tom Lockhart in 1997.

 When did the SQL standard add any mention of ?

FWIW, the first public, production release of Java in 1995 used it
for parameters.  ODBC 1.0 was released in 1992.  I would guess that
the question mark for parameters was there from the beginning, but
can't swear to it before 1995.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

Jeff Janes jeff.ja...@gmail.com writes:
 What if something like this was made to work?
  select '{3:5}'::jsonb operator(pg_catalog.?) '3';
 (Where the double quotes around the ? would be tolerated, which they
 currently are not)

 Is there a reason it can't be made to work?

It could be made to work, I'm sure, but I fail to see why any user
would prefer to write that over ?? or \? or {?} or pretty much any
of the other notations that've been suggested.  It's ten times as
many keystrokes ...

regards, tom lane


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On Wed, May 20, 2015 at 7:04 PM, Jeff Janes jeff.ja...@gmail.com wrote:


 What if something like this was made to work?

  select '{3:5}'::jsonb operator(pg_catalog.?) '3';

 (Where the double quotes around the ? would be tolerated, which they
 currently are not)

 Is there a reason it can't be made to work?



I'm not sure whether that could be made to work, but wouldn't that defeat
the point of using operators, i.e. something rather short, as opposed to
functions? (That's also partly one of the arguments against too much
escaping: over-complicating what's intended to be a relatively simple
notation, as the Hibernate example I mentioned earlier showed: SELECT
. \\?\\? .)

Best wishes,

Bruno.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-20 Thread Jeff Janes

On Fri, May 15, 2015 at 1:23 PM, Dave Cramer p...@fastcrypt.com wrote:




 On 15 May 2015 at 16:21, Robert Haas robertmh...@gmail.com wrote:

 On Fri, May 15, 2015 at 4:13 PM, Dave Cramer p...@fastcrypt.com wrote:
  Not sure what the point of this is: as you indicated the ship has
 sailed so
  to speak

 Well, if we were to agree this was a problem, we could introduce new,
 less-problematic operator names and then eventually deprecate the old
 ones.  Personally, it wouldn't take a lot to convince me that if a
 certain set of operator names is problematic for important connectors,
 we should avoid using those and switch to other ones.  I expect others
 on this mailing list to insist that if the connectors don't work,
 that's the connector drivers fault for coding their connectors wrong.
 And maybe that's the right answer, but on the other hand, maybe it's a
 little myopic.  I think the discussion is worth having.


 In that case my vote is new operators. This has been a sore point for the
 JDBC driver



What if something like this was made to work?

 select '{3:5}'::jsonb operator(pg_catalog.?) '3';

(Where the double quotes around the ? would be tolerated, which they
currently are not)

Is there a reason it can't be made to work?

Cheers,

Jeff

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On Wed, May 20, 2015 at 5:46 PM, Robert Haas robertmh...@gmail.com wrote:

 I think we should be more focused on this part of the issue.  It seems
 to me that it's a good idea for connectors to have an escaping
 mechanism.  Pretty much any syntax that supports funny characters that
 do magical things should also have a way to turn the magic off when
 it's not wanted.


I certainly don't disagree it's a good idea for connectors to have an
escaping mechanism, but the problem here is that there's a blurred line
regarding whose magic it is. It would make sense for connectors to allow
for their magic to be escaped, but it turns out that the magic they do is a
very close match to what seems to be in the SQL spec under the Dynamic SQL
section.
It could be argued that ? should be always escaped anyway, even in a direct
SQL query, simply not to make it conflict with Dynamic SQL, but there
doesn't seem to be such a mechanism in the SQL spec as far as I can see
(and always having to escape the end result doesn't really make sense).

More practically, getting connectors to add an escape mechanism can work
for some connectors where the authors are more reactive and where the user
base can also upgrade quickly (e.g. Perl's DBD::Pg), but the hopes of
getting ODBC and JDBC and whatever depends on them to adapt are extremely
low. (I'm also not sure if ECPG is used much compare to libpq, but in
principle, not being able to use these operators there isn't great.)

In contrast, providing a new set of operators (that wouldn't have this
problem) should be doable with a rather smooth transition (since CREATE
OPERATOR can be run on existing installations, if backporting the new
operators is needed). (The existing operators wouldn't have to be removed
in the short term, if ever.)

Best wishes,

Bruno.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-20 Thread Jeff Janes

On Wed, May 20, 2015 at 11:13 AM, Tom Lane t...@sss.pgh.pa.us wrote:

 Jeff Janes jeff.ja...@gmail.com writes:
  What if something like this was made to work?
   select '{3:5}'::jsonb operator(pg_catalog.?) '3';
  (Where the double quotes around the ? would be tolerated, which they
  currently are not)

  Is there a reason it can't be made to work?

 It could be made to work, I'm sure, but I fail to see why any user
 would prefer to write that over ?? or \? or {?} or pretty much any
 of the other notations that've been suggested.  It's ten times as
 many keystrokes ...


Because it is a completely general solution using the existing escaping
infrastructure, on both ends, except for this one small exception.

It is ugly, but so is leaning toothpick syndrome where you have to escape
your escapes from someone else's escapes.

Anyway, I've never looked at code written to use JDBC and thought Boy,
that sure is pretty.

Cheers,

Jeff

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

Dave Cramer p...@fastcrypt.com writes:
 Back to the issue at hand. Does anyone have a recommendation for a
 replacement operator besides ?

The bikeshedding potential here might be the worst part of the whole
thing.  Still, if we can agree on reasonable substitute names, I wouldn't
be against it, even with the huge lead time in mind.

 When I first noticed this one thought was to create duplicate operators
 specifically for the use of the JDBC driver.

 I had dismissed this at the time, now I'm not so sure

If you mean fixing the problem with an extension that adds replacement
operators without any core code changes, I'm afraid probably not.
It would work okay for operators that are not indexable, but not for
those that can be indexed.  (I think only a couple of the existing problem
operators are indexable, but that's enough to make the idea not fly.)

The difficulty with indexable operators is that there is no provision for
multiple operators sharing the same strategy slot in an opclass.  So
the only way to add additional operators to an opclass is to give them
new strategy numbers, which requires teaching the opclass' support
functions to know about those numbers.  This would be just a minor change
(add some case labels) but it *is* a change in the core code.

regards, tom lane


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

Dave Cramer p...@fastcrypt.com writes:
 Notably absent from the discussion is ODBC upon which JDBC was modelled and
 probably predates any use of ? as an operator

historical-nitpicking

It would be a mistake to imagine that operators containing '?' are some
johnny-come-lately.  The ? operator for tintervals can be traced back
at least to Postgres v4r2 (1994), which is the oldest tarball I have at
hand.  Most of the current list are geometric operators that were added
by Tom Lockhart in 1997.  The only ones that aren't old enough to vote
are the JSONB ones we added last year.

Not that the problem's not real, but these operators predate any attempt
to make Postgres work with ODBC or JDBC or any other connector.  Otherwise
we might've thought better of using '?'.

/historical-nitpicking

regards, tom lane


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On Tue, May 19, 2015 at 10:31 PM, Greg Sabino Mullane g...@turnstep.com
wrote:


 If you are running into situations
 where you have question mark operators in your queries, you have already
 lost
 the query abstraction battle. There will be no seamless switching if you
 are using jsonb, hstore, ltree, etc.


Actually, no, you haven't quite lost that battle, or rather, that battle
doesn't even need to take place.

You can still use common tools for operations that are not really
RDMBS-specific AND use PostgreSQL extensions on a case-by-case basis
depending on your application requirements.
Some of these tools already allow you to tweak slightly their capabilities
by implementing dialects, and let you use specific features if required.

I think this is a major advantage of having these extensions in PostgreSQL:
you can have the best of both worlds. It's not so much about being able to
switch to another RDMBS, it's about not having to re-implement the bulk of
the structure when you just want to benefit from a few additional
extensions (for example, mixing the classic RDBMS model with the JSON store
model).

Best wishes,

Bruno.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread Jan de Visser

On May 19, 2015 09:31:32 PM Greg Sabino Mullane wrote:
 Jan de Visser wrote:
  Well, one could argue that it *is* their problem, as they should be using
  the standard Postgres way for placeholders, which is $1, $2, $3...
  
  Shirley you are joking: Many products use JDBC as an abstraction layer
  facilitating (mostly) seamless switching between databases. I know the
  product I worked on did. Are you advocating that every single statement
  should use SELECT * FROM foo WHERE bar = $1 on pg and SELECT * FROM
  foo WHERE bar = ? on every other database?
 
 I'm not joking, and don't call me Shirley. If you are running into
 situations where you have question mark operators in your queries, you have
 already lost the query abstraction battle. There will be no seamless
 switching if you are using jsonb, hstore, ltree, etc. My statement was more
 about pointing out that Postgres already offers a complete placeholder
 system, which drivers are free to implement if they want.

I must have misunderstood you strikeShirley/strike Greg, because to me it 
parsed as if you were suggesting (paraphrasing) ah forget about those pesky 
standardized drivers and their pesky syntax requirements. Just use ours like a 
big boy.

I understand that once you start using '?' as (part of) operator names in your 
queries you're not portable anymore. I just thought that your proposed 
solution was to throw all portability out the window. But I was probably 
(hopefully?) wrong.

jan



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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread Kevin Grittner

David G. Johnston david.g.johns...@gmail.com wrote:
 On Mon, May 18, 2015 at 3:31 PM, Bruno Harbulot 
 br...@distributedmatter.netwrote:

 In the discussion on the OpenJDK JDBC list two years ago
 ( 
 http://mail.openjdk.java.net/pipermail/jdbc-spec-discuss/2013-February/50.html
  ),
 Lance Andersen said There is nothing in the SQL standard that
 would support the use of an '?' as anything but a parameter
 marker..

 CREATE OPERATOR is a PostgreSQL extension. There are no
 provisions for user-defined operators in the SQL standard.

Exactly.  The standard specifies the characters to use for the
predicates that it defines, and provides no mechanism for adding
additional predicates; but who in the world would want to exclude
all extensions to the standard?

 And by extension if indeed the standard does require the use of
 ? for parameters we are in violation there because the backend
 protocol deals with $# placeholders and not ?

We're talking about a different specification that has question
marks as parameter placeholders.  That's in the Java Database
Connector (JDBC) specification.  (It is apparently also specified
in other documents, although I'm not familiar enough with those to
comment.)  Note that it would create all sorts of pain if both the
SQL statements and a connector issuing them used the same
convention for substituting parameters; it is a *good* thing that
plpgsql and SQL function definitions use a different convention
than JDBC!

The JDBC spec provides for escapes using curly braces (including
product-specific escapes); it seems like a big mistake for us to
have chosen a completely different mechanism for escaping the
question mark character in a SQL statement.  Perhaps the least
painful path would be to add support for {?} as the escape for a
question mark, and a connection option to supplement that with
support for the legacy \? escape.  I would bet a lot of money that
even with an if test for that option, the curly brace escape
would be faster than what's there now (when the option was not
set).  Some operators would look a little funny in Java string
literals, but that's not so bad.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On 18 May 2015 at 18:49, David G. Johnston david.g.johns...@gmail.com
wrote:

 On Mon, May 18, 2015 at 3:31 PM, Bruno Harbulot 
 br...@distributedmatter.net wrote:

 On Sun, May 17, 2015 at 5:15 PM, Greg Sabino Mullane g...@turnstep.com
 wrote:



  In that case my vote is new operators. This has been a sore point for
 the
  JDBC driver

 Um, no, new operators is a bad idea. Question marks are used by hstore,
 json, geometry, and who knows what else. I think the onus is solely on
 JDBC to solve this problem. DBD::Pg solved it in 2008 with
 the pg_placeholder_dollaronly solution, and earlier this year by allowing
 backslashes before the question mark (because other parts of the stack
 were
 not able to smoothly implement pg_placeholder_dollaronly.) I recommend
 all drivers implement \? as a semi-standard workaround.

 See also:
 http://blog.endpoint.com/2015/01/dbdpg-escaping-placeholders-with.html


 I'm not sure the onus is solely on JDBC. Using question marks in
 operators clearly has required a number of connectors to implement their
 own workarounds, in different ways. This also seems to affect some
 libraries and frameworks that depend on those connectors (and for which the
 workarounds may even be more convoluted).

 My main point was that this is not specific to JDBC. Considering that
 even PostgreSQL's own ECPG is affected, the issue goes probably deeper than
 it seems. I'm just not convinced that passing the problem onto connectors,
 libraries and ultimately application developers is the right thing to do
 here.

 In the discussion on the OpenJDK JDBC list two years ago (
 http://mail.openjdk.java.net/pipermail/jdbc-spec-discuss/2013-February/50.html
 ), Lance Andersen said There is nothing in the SQL standard that would
 support the use of an '?' as anything but a parameter marker.. It might be
 worth finding out whether this is indeed the case according to the SQL
 specifications (I'm afraid I'm not familiar with these specifications to do
 it myself).


 CREATE OPERATOR is a PostgreSQL extension. There are no provisions for
 user-defined operators in the SQL standard.

 http://www.postgresql.org/docs/9.4/interactive/sql-createoperator.html

 And by extension if indeed the standard does require the use of ? for
 parameters we are in violation there because the backend protocol deals
 with $# placeholders and not ?

 I too do not know enough here.

 Note that it would not be enough to change the existing operators - any
 use of ? would have to be forbidden including those created by users.

 The first step on this path would be for someone to propose a patch adding
 alternative operators for every existing operator that uses ?.  If this
 idea is to move forward at all that patch would have to be accepted.  Such
 a patch is likely to see considerable bike-shedding.  We then at least
 provide an official way to avoid ? operators that shops can make use of
 at their discretion.  Removing the existing operators or forbidding custom
 operators is a separate discussion.

 David J.


It would seem that choosing ? for operators was ill advised; I'm not
convinced that deprecating them is a bad idea. If we start now, in 5 years
they should be all but gone

Agreed a patch would be the first place to start

Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On 19 May 2015 at 10:23, Kevin Grittner kgri...@ymail.com wrote:

 David G. Johnston david.g.johns...@gmail.com wrote:
  On Mon, May 18, 2015 at 3:31 PM, Bruno Harbulot 
 br...@distributedmatter.netwrote:

  In the discussion on the OpenJDK JDBC list two years ago
  (
 http://mail.openjdk.java.net/pipermail/jdbc-spec-discuss/2013-February/50.html
 ),
  Lance Andersen said There is nothing in the SQL standard that
  would support the use of an '?' as anything but a parameter
  marker..

  CREATE OPERATOR is a PostgreSQL extension. There are no
  provisions for user-defined operators in the SQL standard.

 Exactly.  The standard specifies the characters to use for the
 predicates that it defines, and provides no mechanism for adding
 additional predicates; but who in the world would want to exclude
 all extensions to the standard?

  And by extension if indeed the standard does require the use of
  ? for parameters we are in violation there because the backend
  protocol deals with $# placeholders and not ?

 We're talking about a different specification that has question
 marks as parameter placeholders.  That's in the Java Database
 Connector (JDBC) specification.  (It is apparently also specified
 in other documents, although I'm not familiar enough with those to
 comment.)  Note that it would create all sorts of pain if both the
 SQL statements and a connector issuing them used the same
 convention for substituting parameters; it is a *good* thing that
 plpgsql and SQL function definitions use a different convention
 than JDBC!

 The JDBC spec provides for escapes using curly braces (including
 product-specific escapes); it seems like a big mistake for us to
 have chosen a completely different mechanism for escaping the
 question mark character in a SQL statement.  Perhaps the least
 painful path would be to add support for {?} as the escape for a
 question mark, and a connection option to supplement that with
 support for the legacy \? escape.  I would bet a lot of money that
 even with an if test for that option, the curly brace escape
 would be faster than what's there now (when the option was not
 set).  Some operators would look a little funny in Java string
 literals, but that's not so bad.


Perhaps reviewing https://github.com/pgjdbc/pgjdbc/pull/187 might help
understand why we chose ??

Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On Tue, May 19, 2015 at 3:23 PM, Kevin Grittner kgri...@ymail.com wrote:

David G. Johnston david.g.johns...@gmail.com wrote:
On Mon, May 18, 2015 at 3:31 PM, Bruno Harbulot
br...@distributedmatter.netwrote:

In the discussion on the OpenJDK JDBC list two years ago
(
http://mail.openjdk.java.net/pipermail/jdbc-spec-discuss/2013-February/50.html
),
Lance Andersen said There is nothing in the SQL standard that
would support the use of an '?' as anything but a parameter
marker..

CREATE OPERATOR is a PostgreSQL extension. There are no
provisions for user-defined operators in the SQL standard.

Exactly. The standard specifies the characters to use for the
predicates that it defines, and provides no mechanism for adding
additional predicates; but who in the world would want to exclude
all extensions to the standard?

I was certainly not suggesting custom operators should be excluded. I was
suggesting using something that was actually not incompatible with the SQL
standards (and, even with standards aside, the expectations implementors
have regarding the question mark, since it affects other tools too).

And by extension if indeed the standard does require the use of
? for parameters we are in violation there because the backend
protocol deals with $# placeholders and not ?

We're talking about a different specification that has question
marks as parameter placeholders. That's in the Java Database
Connector (JDBC) specification. (It is apparently also specified
in other documents, although I'm not familiar enough with those to
comment.) Note that it would create all sorts of pain if both the
SQL statements and a connector issuing them used the same
convention for substituting parameters; it is a *good* thing that
plpgsql and SQL function definitions use a different convention
than JDBC!

Actually, we were not just talking about JDBC. I don't know the
specifications in details, but the SQL:201x (preliminary) documents linked
from
https://wiki.postgresql.org/wiki/Developer_FAQ#Where_can_I_get_a_copy_of_the_SQL_standards.3F
seem to have some information. The Foundation document (Section 4.25
Dynamic SQL concepts) says that dynamic parameters are represented by a
question mark.

In addition, the BNF grammar available at
http://www.savage.net.au/SQL/sql-2003-2.bnf.html#dynamic%20parameter%20specification
also says:
dynamic parameter specification::= question mark

I'm not familiar enough with these documents to know whether I'm missing
some context, but it would seem that the question mark is a reserved
character, beyond the scope of JDBC (at the very least, it seems
incompatible with Dynamic SQL and its implementation in ECPG).

Best wishes,

Bruno.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread Tom Lane

Mike Blackwell mike.blackw...@rrd.com writes:
 See for example
 http://docs.oracle.com/cd/B19306_01/text.102/b14218/cqoper.htm#i997330,
 Table 3-1, third row, showing the precedence of '?'.  Further down the
 page, under Fuzzy see Backward Compatibility Syntax.

If I'm reading that right, that isn't a SQL-level operator but an operator
in their text search query language, which would only appear in SQL
queries within string literals (compare tsquery's query operators in PG).
So it wouldn't be a hazard for ?-substitution, as long as the substituter
was bright enough to not change string literals.

regards, tom lane


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread Mike Blackwell

A Google search suggests Oracle 9.x supports a unary '?' operator (fuzzy
match), so the use of '?' in an operator name is not without precedent.


__
*Mike Blackwell | Technical Analyst, Distribution Services/Rollout
Management | RR Donnelley*
1750 Wallace Ave | St Charles, IL 60174-3401
Office: 630.313.7818
mike.blackw...@rrd.com
http://www.rrdonnelley.com


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* mike.blackw...@rrd.com*

On Tue, May 19, 2015 at 10:03 AM, Bruno Harbulot 
br...@distributedmatter.net wrote:



 On Tue, May 19, 2015 at 3:23 PM, Kevin Grittner kgri...@ymail.com wrote:

 David G. Johnston david.g.johns...@gmail.com wrote:
  On Mon, May 18, 2015 at 3:31 PM, Bruno Harbulot 
 br...@distributedmatter.netwrote:

  In the discussion on the OpenJDK JDBC list two years ago
  (
 http://mail.openjdk.java.net/pipermail/jdbc-spec-discuss/2013-February/50.html
 ),
  Lance Andersen said There is nothing in the SQL standard that
  would support the use of an '?' as anything but a parameter
  marker..

  CREATE OPERATOR is a PostgreSQL extension. There are no
  provisions for user-defined operators in the SQL standard.

 Exactly.  The standard specifies the characters to use for the
 predicates that it defines, and provides no mechanism for adding
 additional predicates; but who in the world would want to exclude
 all extensions to the standard?


 I was certainly not suggesting custom operators should be excluded. I was
 suggesting using something that was actually not incompatible with the SQL
 standards (and, even with standards aside, the expectations implementors
 have regarding the question mark, since it affects other tools too).



  And by extension if indeed the standard does require the use of
  ? for parameters we are in violation there because the backend
  protocol deals with $# placeholders and not ?

 We're talking about a different specification that has question
 marks as parameter placeholders.  That's in the Java Database
 Connector (JDBC) specification.  (It is apparently also specified
 in other documents, although I'm not familiar enough with those to
 comment.)  Note that it would create all sorts of pain if both the
 SQL statements and a connector issuing them used the same
 convention for substituting parameters; it is a *good* thing that
 plpgsql and SQL function definitions use a different convention
 than JDBC!


 Actually, we were not just talking about JDBC. I don't know the
 specifications in details, but the SQL:201x (preliminary) documents linked
 from
 https://wiki.postgresql.org/wiki/Developer_FAQ#Where_can_I_get_a_copy_of_the_SQL_standards.3F
 seem to have some information. The Foundation document (Section 4.25
 Dynamic SQL concepts) says that dynamic parameters are represented by a
 question mark.

 In addition, the BNF grammar available at
 http://www.savage.net.au/SQL/sql-2003-2.bnf.html#dynamic%20parameter%20specification
 also says:
 dynamic parameter specification::=   question mark

 I'm not familiar enough with these documents to know whether I'm missing
 some context, but it would seem that the question mark is a reserved
 character, beyond the scope of JDBC (at the very least, it seems
 incompatible with Dynamic SQL and its implementation in ECPG).

 Best wishes,

 Bruno.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

On 19 May 2015 at 13:15, Mike Blackwell mike.blackw...@rrd.com wrote:

 A Google search suggests Oracle 9.x supports a unary '?' operator (fuzzy
 match), so the use of '?' in an operator name is not without precedent.


Interesting argument. There is considerable precedent where we take the
position that just because xyz supports it we don't.

Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread David G. Johnston

On Tue, May 19, 2015 at 1:36 PM, Kevin Grittner kgri...@ymail.com wrote:

 Gavin Flower gavinflo...@archidevsys.co.nz wrote:

  I prefer the $1 approach, others can't use that, and there are
  situations where I could not either.
 
  So, how about defaulting to the '?' approach, but have a method
  to explicitly set the mode - to switch to using '$'?

 Are you suggesting that we implement something other than what is
 described in these documents for prepared statement parameters?:

 http://docs.oracle.com/javase/7/docs/api/java/sql/PreparedStatement.html


 http://download.oracle.com/otn-pub/jcp/jdbc-4_1-mrel-spec/jdbc4.1-fr-spec.pdf

 If so, I strongly oppose that.  If we are not going to deprecate
 use of the question mark character for operators, we need some
 nonstandard hack to our JDBC implementation, but an alternative
 syntax for specifying PreparedStatement and CallableStatement
 parameters seems entirely the wrong way to go.


I'll repeat my earlier comment that having a mode that allows for libpq
syntax while still conforming to the JDBC class API would have value for
those users willing to admit their application and code is not portable
(and if they are using these operators it is not) and would rather conform
as closely to native PostgreSQL language mechanics as possible.

That said I would not argue that the current official driver needs to be
so modified.


 The issue here is what to do about the difficulties in using JDBC
 prepared statements in combination with the PostgreSQL extension of
 operator names containing question marks.  Using a double question
 mark is not horrible as a solution.  It may not be what we would
 have arrived at had the discussion taken place on the pgsql-jdbc
 list rather than underneath a github pull request, but we can
 only move forward from where we are.

 Out of curiosity, how long has the ?? solution been implemented in
 a driver jar file available as a public download?


Less than 6 months...discussion started a few months prior to that.


 What are the
 guidelines for what discussion belongs on the pgsql-jdbc list and
 what discussion belongs on github?  Is someone interested in
 participating in the discussions leading to decisions about our
 JDBC connector expected to follow both?


As things stand now - it seems that way.  There are no guidelines that I
can tell but I'd likely consider pgsql-jdbc the equivalent of -general and
GitHub looks like -hackers.  Neither is particularly high volume.

David J.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread David G. Johnston

On Tue, May 19, 2015 at 2:34 PM, Bruno Harbulot br...@distributedmatter.net
 wrote:


 While I can imagine a Java PostgreSQL driver that would use the libpq
 syntax, I can't see it being able to have any useful sort of
 half-compatibility with JDBC, whether it mimics its interfaces or not. I'm
 not sure it would be very useful at all, considering how much the existing
 tooling the the Java world relies on JDBC.


I won't claim to have studied this in great detail but there is a lot more
to the JDBC spec beyond the semantics of PreparedStatement.parse(String).
No need to throw out the baby with the bath water and reinvent ResultSet,
Connection and various other interfaces that are perfectly usable before
and after a suitable query has been fully parsed.

When I say setInteger(1, new Integer(1000)) I don't care whether I had to
write SELECT ? AS int_val OR SELECT $1 AS int_val; though the later has
the nice property of providing corresponding numbers so that I would write
something like SELECT $1 AS int_val, $1 AS int_val_2 and not be forced to
write setInteger(2, new Integer(1000)) to pass in a value to the second -
but identical - parameter.  Maybe it violates the semantics defined by the
API - which I could be making too lightly of - but having the same
mechanics involved to solve the same problem - with only minor semantic
nuances to remember seems within the realm of reasonable.

David J.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread Kevin Grittner

Gavin Flower gavinflo...@archidevsys.co.nz wrote:

 I prefer the $1 approach, others can't use that, and there are
 situations where I could not either.

 So, how about defaulting to the '?' approach, but have a method
 to explicitly set the mode - to switch to using '$'?

Are you suggesting that we implement something other than what is
described in these documents for prepared statement parameters?:

http://docs.oracle.com/javase/7/docs/api/java/sql/PreparedStatement.html

http://download.oracle.com/otn-pub/jcp/jdbc-4_1-mrel-spec/jdbc4.1-fr-spec.pdf

If so, I strongly oppose that.  If we are not going to deprecate
use of the question mark character for operators, we need some
nonstandard hack to our JDBC implementation, but an alternative
syntax for specifying PreparedStatement and CallableStatement
parameters seems entirely the wrong way to go.

The issue here is what to do about the difficulties in using JDBC
prepared statements in combination with the PostgreSQL extension of
operator names containing question marks.  Using a double question
mark is not horrible as a solution.  It may not be what we would
have arrived at had the discussion taken place on the pgsql-jdbc
list rather than underneath a github pull request, but we can
only move forward from where we are.

Out of curiosity, how long has the ?? solution been implemented in
a driver jar file available as a public download?  What are the
guidelines for what discussion belongs on the pgsql-jdbc list and
what discussion belongs on github?  Is someone interested in
participating in the discussions leading to decisions about our
JDBC connector expected to follow both?

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread Greg Sabino Mullane


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Hash: RIPEMD160


Jan de Visser wrote:
 Well, one could argue that it *is* their problem, as they should be using
 the standard Postgres way for placeholders, which is $1, $2, $3...

 Shirley you are joking: Many products use JDBC as an abstraction layer 
 facilitating (mostly) seamless switching between databases. I know the 
 product 
 I worked on did. Are you advocating that every single statement should use 
 SELECT * FROM foo WHERE bar = $1 on pg and SELECT * FROM foo WHERE bar = 
 ? 
 on every other database?

I'm not joking, and don't call me Shirley. If you are running into situations 
where you have question mark operators in your queries, you have already lost 
the query abstraction battle. There will be no seamless switching if you 
are using jsonb, hstore, ltree, etc. My statement was more about pointing out 
that Postgres already offers a complete placeholder system, which drivers 
are free to implement if they want.

 A database is only as valuable as the the part of the outside world it can 
 interact with. Large parts of the data-consuming world are developed in java 
 using JDBC. If your opinion is that JDBC developers should adapt themselves 
 to 
 pg then you instantaneously diminish the value of pg.

Well, they will have to adapt to one way or another: using ?? or \? is doing 
so, and the other solution (Postgres adapting itself to the driver by 
deprecating the ? operator) is not realistically likely to happen.

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End Point Corporation http://www.endpoint.com/
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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread Gavin Flower


On 20/05/15 07:37, Jan de Visser wrote:

On May 19, 2015 07:04:56 PM Greg Sabino Mullane wrote:

Bruno Harbulot asked for a devil's advocate by saying:

My main point was that this is not specific to JDBC. Considering that even
PostgreSQL's own ECPG is affected, the issue goes probably deeper than it
seems. I'm just not convinced that passing the problem onto connectors,
libraries and ultimately application developers is the right thing to do
here.

Well, one could argue that it *is* their problem, as they should be using
the standard Postgres way for placeholders, which is $1, $2, $3...

Shirley you are joking: Many products use JDBC as an abstraction layer
facilitating (mostly) seamless switching between databases. I know the product
I worked on did. Are you advocating that every single statement should use
SELECT * FROM foo WHERE bar = $1 on pg and SELECT * FROM foo WHERE bar = ?
on every other database?

A database is only as valuable as the the part of the outside world it can
interact with. Large parts of the data-consuming world are developed in java
using JDBC. If your opinion is that JDBC developers should adapt themselves to
pg then you instantaneously diminish the value of pg.

jan



I prefer the $1 approach, others can't use that, and there are 
situations where I could not either.


So, how about defaulting to the '?' approach, but have a method to 
explicitly set the mode - to switch to using '$'?




Cheers,
Gavin


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On 19 May 2015 at 16:36, Kevin Grittner kgri...@ymail.com wrote:

 Gavin Flower gavinflo...@archidevsys.co.nz wrote:

  I prefer the $1 approach, others can't use that, and there are
  situations where I could not either.
 
  So, how about defaulting to the '?' approach, but have a method
  to explicitly set the mode - to switch to using '$'?

 Are you suggesting that we implement something other than what is
 described in these documents for prepared statement parameters?:

 http://docs.oracle.com/javase/7/docs/api/java/sql/PreparedStatement.html


 http://download.oracle.com/otn-pub/jcp/jdbc-4_1-mrel-spec/jdbc4.1-fr-spec.pdf

 If so, I strongly oppose that.  If we are not going to deprecate
 use of the question mark character for operators, we need some
 nonstandard hack to our JDBC implementation, but an alternative
 syntax for specifying PreparedStatement and CallableStatement
 parameters seems entirely the wrong way to go.



 The issue here is what to do about the difficulties in using JDBC
 prepared statements in combination with the PostgreSQL extension of
 operator names containing question marks.  Using a double question
 mark is not horrible as a solution.


Actually the issue is what to do about a number of connectors which use a
fairly standard '?' as a placeholder.
Notably absent from the discussion is ODBC upon which JDBC was modelled and
probably predates any use of ? as an operator

It may not be what we would
 have arrived at had the discussion taken place on the pgsql-jdbc
 list rather than underneath a github pull request, but we can
 only move forward from where we are.

 possibly, however all of the current JDBC maintainers opined and reached
an agreement on this.


 Out of curiosity, how long has the ?? solution been implemented in
 a driver jar file available as a public download?


 At least since February of this year

What are the
 guidelines for what discussion belongs on the pgsql-jdbc list and
 what discussion belongs on github?  Is someone interested in
 participating in the discussions leading to decisions about our
 JDBC connector expected to follow both?

 Currently pull requests are the easiest to deal with so most discussion is
on github.

I guess updating the JDBC web page would be in order.



Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On Tue, May 19, 2015 at 9:50 PM, David G. Johnston 
david.g.johns...@gmail.com wrote:

 On Tue, May 19, 2015 at 1:36 PM, Kevin Grittner kgri...@ymail.com wrote:

 Gavin Flower gavinflo...@archidevsys.co.nz wrote:

  I prefer the $1 approach, others can't use that, and there are
  situations where I could not either.
 
  So, how about defaulting to the '?' approach, but have a method
  to explicitly set the mode - to switch to using '$'?

 Are you suggesting that we implement something other than what is
 described in these documents for prepared statement parameters?:

 http://docs.oracle.com/javase/7/docs/api/java/sql/PreparedStatement.html


 http://download.oracle.com/otn-pub/jcp/jdbc-4_1-mrel-spec/jdbc4.1-fr-spec.pdf

 If so, I strongly oppose that.  If we are not going to deprecate
 use of the question mark character for operators, we need some
 nonstandard hack to our JDBC implementation, but an alternative
 syntax for specifying PreparedStatement and CallableStatement
 parameters seems entirely the wrong way to go.


 I'll repeat my earlier comment that having a mode that allows for libpq
 syntax while still conforming to the JDBC class API would have value for
 those users willing to admit their application and code is not portable
 (and if they are using these operators it is not) and would rather conform
 as closely to native PostgreSQL language mechanics as possible.


I don't think that approach is workable at all. JDBC isn't limited to a
number of classes and their methods, the documentation that surrounds it
obviously has an impact on how it was implemented internally and what users
should and shouldn't be allowed to expect when using these classes. While
there are tools that convert various parameter styles to ? (e.g. Groovy SQL
or Hibernate's named parameter) and a layer of conversion from $1 to ?
could exist, the bottleneck here will still be the JDBC layer itself, since
it's what sends the query to the database.

Users of question mark operators are already admitting their application
and code isn't portable (since they are specific to PostgreSQL and its
extensions). The problem has more to do with how the other tools around
handle these customisations. For example, it can be useful to have a model
based on Hibernate in Java and be able to use ? operators for specific
features. (Other tools like SQLAlchemy in Python also allow you to have
customisations specific to the RDMBS platform, while being able to use the
core features in a more platform-neutral way.)

It turns out that you can indeed use ? in JSONB with a custom Hibernate
query, you just need to double-escape it as follows: ? becomes ?? and has
to be escaped as \?\?, but \ has to be escaped itself...

SQLQuery query = session
.createSQLQuery(SELECT
CAST((CAST('{\key1\:123,\key2\:\Hello\}' AS jsonb) \\?\\? CAST(? AS
text)) AS BOOLEAN));
query.setString(0, key1);

Again, this may have to do with the fact that these tools may have a
legitimate expectation that ? should be reserved for parameters, partly
because it seems to be very common in practice, but more importantly if the
SQL specification itself says it's what ? is for.

While I can imagine a Java PostgreSQL driver that would use the libpq
syntax, I can't see it being able to have any useful sort of
half-compatibility with JDBC, whether it mimics its interfaces or not. I'm
not sure it would be very useful at all, considering how much the existing
tooling the the Java world relies on JDBC.

This problem is also broader than JDBC: on top of the languages and
libraries already mentioned, it may affect ODBC, as Dave Cramer has just
said (I haven't tried).



Best wishes,

Bruno.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread Mike Blackwell

See for example
http://docs.oracle.com/cd/B19306_01/text.102/b14218/cqoper.htm#i997330,
Table 3-1, third row, showing the precedence of '?'.  Further down the
page, under Fuzzy see Backward Compatibility Syntax.


__
*Mike Blackwell | Technical Analyst, Distribution Services/Rollout
Management | RR Donnelley*
1750 Wallace Ave | St Charles, IL 60174-3401
Office: 630.313.7818
mike.blackw...@rrd.com
http://www.rrdonnelley.com


http://www.rrdonnelley.com/
* mike.blackw...@rrd.com*

On Tue, May 19, 2015 at 12:45 PM, Bruno Harbulot 
br...@distributedmatter.net wrote:



 On Tue, May 19, 2015 at 6:15 PM, Mike Blackwell mike.blackw...@rrd.com
 wrote:

 A Google search suggests Oracle 9.x supports a unary '?' operator (fuzzy
 match), so the use of '?' in an operator name is not without precedent.


 Interesting. Do you have any specific link? I'm probably not using the
 right Google search, but the nearest reference I've found is for Oracle 10,
 and it seems to use the tilde (~) operator for fuzzy matching:
 http://www.oracle.com/technetwork/search/oses/overview/new-query-features-in-10-1-8-2-1-132287.pdf

 Best wishes,

 Bruno.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On Tue, May 19, 2015 at 6:15 PM, Mike Blackwell mike.blackw...@rrd.com
wrote:

 A Google search suggests Oracle 9.x supports a unary '?' operator (fuzzy
 match), so the use of '?' in an operator name is not without precedent.


Interesting. Do you have any specific link? I'm probably not using the
right Google search, but the nearest reference I've found is for Oracle 10,
and it seems to use the tilde (~) operator for fuzzy matching:
http://www.oracle.com/technetwork/search/oses/overview/new-query-features-in-10-1-8-2-1-132287.pdf

Best wishes,

Bruno.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On Tue, May 19, 2015 at 7:51 PM, Greg Sabino Mullane g...@turnstep.com
wrote:


 -BEGIN PGP SIGNED MESSAGE-
 Hash: RIPEMD160


 Dave Cramer opined:
  It would seem that choosing ? for operators was ill advised; I'm not
  convinced that deprecating them is a bad idea. If we start now, in 5
 years
  they should be all but gone

 Ha ha ha ha ha! That's a good one. We still have clients on Postgres 7!
 Five years is way too short to replace something that major.


I think deprecation doesn't necessarily imply removal. It seems that the
two operators could exist together by creating a second operator with the
same characteristics as suggested by Frank Heikens in this post:
http://stackoverflow.com/questions/27573778/postgresql-jsonb-and-jdbc/27580137#27580137

This would also make it easier to backport these operators into existing
installations (even on 9.4), thereby making the transition easier.

I don't know enough about PostgreSQL's implementation, but I presume this
is effectively just giving an alias for the same operation, and hopefully,
the query engine could benefit from indices created using either notations
interchangeably. (This is probably the most important feature when changing
one notation for another.)


In addition, the argument regarding the time it can take users to upgrade
works both ways. If I understood correctly from your message yesterday,
you've only implemented the latest workaround using \? in DBD::Pg quite
recently, which would equally require users to be able to upgrade to a more
recent version of DBD::Pg (or PHP/PDO where the workaround doesn't seem to
be implemented at all yet). Admittedly, I guess it might often be easier to
upgrade the client side than the database server, but I'm not sure that is
always the case (some frontends can potentially be awkward to update,
whereas a database upgrade can be smoother... It varies...).


Best wishes,

Bruno.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On 19 May 2015 at 15:02, Tom Lane t...@sss.pgh.pa.us wrote:

 Greg Sabino Mullane g...@turnstep.com writes:
  Dave Cramer opined:
  It would seem that choosing ? for operators was ill advised; I'm not
  convinced that deprecating them is a bad idea. If we start now, in 5
 years
  they should be all but gone

  Ha ha ha ha ha! That's a good one. We still have clients on Postgres 7!
  Five years is way too short to replace something that major.

Yeah, that's a big problem for this line of thought.  Even if we had
 consensus today, the first release that would actually contain alternative
 operators would be 9.6, more than a year out (since 9.5 is past feature
 freeze now).  It would take several years after that before there would be
 any prospect of removing the old ones, and several years more before PG
 versions containing the old operators were out of support.

 Now there are different ways you could look at this.  From the perspective
 of a particular end user, you could imagine instituting a shop policy of
 not using the operators containing '?' as soon as you had a release where
 there were alternatives.  So in that context you might have a fix
 available as soon as 9.6 came out.  But from the perspective of a driver
 author who has to support queries written by other people, the problem
 would not be gone for at least ten years more.  Changing the driver's
 behavior sounds like a more practical solution.


The current JDBC driver doesn't really support anything beyond 8.4 except
for CRUD operations.

We are also are no longer supporting JVM's older than 1.6 in the current
driver.
People who insist on staying on old code get what they get. I don't see a
problem with saying after a certain date we just don't support it in the
current code.

After all I have heard rumblings about deprecating V2 protocol ?

FWIW, I was content to leave this alone. JDBC has a workable solution.
However I've not seen a good argument for continuing to use the ? operator
as it's conflicts with many clients and is apparently not in the SQL
standard.

Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread Greg Sabino Mullane


-BEGIN PGP SIGNED MESSAGE-
Hash: RIPEMD160


 I did find some alternatives discussed a couple of years back, like
 {postgres qm} and operator(?); the later simply being to allow the
 operator to be quoted inside operator()

Yes, we (DBD::Pg) looked at using at some of the JDBC-ish alternatives 
like the (very verbose) vendor escape clauses, but settled on the simplicity of 
a single backslash in the end. See part of the discussion here:

http://www.nntp.perl.org/group/perl.dbi.users/2014/12/msg37057.html

- -- 
Greg Sabino Mullane g...@turnstep.com
End Point Corporation http://www.endpoint.com/
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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On Tue, May 19, 2015 at 8:04 PM, Greg Sabino Mullane g...@turnstep.com
wrote:


 -BEGIN PGP SIGNED MESSAGE-
 Hash: RIPEMD160

 Bruno Harbulot asked for a devil's advocate by saying:
  My main point was that this is not specific to JDBC. Considering that
 even
  PostgreSQL's own ECPG is affected, the issue goes probably deeper than it
  seems. I'm just not convinced that passing the problem onto connectors,
  libraries and ultimately application developers is the right thing to do
  here.

 Well, one could argue that it *is* their problem, as they should be using
 the standard Postgres way for placeholders, which is $1, $2, $3...



As I was saying in another message on this thread a few hours ago, it
appears that ? is reserved for placeholders for Dynamic SQL according to
the SQL specifications, and that would be exactly what ECPG is using as far
as I understand.




  Recommending that all drivers implement \? as a semi-standard workaround
 is
  actually a much more difficult problem than it seems: it requires
 following
  the development of each project, making the case to each community
  (assuming they're all open source), and reasonable in-depth knowledge of
  their respective implementation, also assuming that \? won't cause
 further
  problems there (of course, all that is easier if you're already working
 on
  that particular project).

 That's actually where we are right now. And it's not really our job to
 make the case to each community - it is the responsibility of each project
 to solve the problem, presumably because of pressure from their users.


... except if those communities made the assumption that ? was indeed
reserved for placeholders according to the SQL specifications. (I might
have misinterpreted where that part of the spec is applicable, since I
can't claim I've absorbed the entire set of documents.)


  Even according to what you're saying this issue has required a first
  workaround back in 2008, and another one earlier this year, probably due
 to
  concerns that weren't spotted when implementing the first workaround
 (this
  also presumably requires users to run a fairly recent version of this
  connector now).

 True enough regarding the two changes. But the system worked well, in that
 someone had a problem, raised a bug, and it got fixed. I'm not sure I see
 the point about requiring recent versions of the connector - that's true
 for lots of bug fixes and features. This one at least is fairly optional
 with many existing workarounds (e.g. use $1, quote things in a different
 way).


This model of development also requires the users to be able to upgrade
their connectors to a recent release, which may also affect other
dependencies (depending on the complexity of the overall system).


Best wishes,

Bruno.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-19 Thread Jan de Visser

On May 19, 2015 07:04:56 PM Greg Sabino Mullane wrote:
 Bruno Harbulot asked for a devil's advocate by saying:
  My main point was that this is not specific to JDBC. Considering that even
  PostgreSQL's own ECPG is affected, the issue goes probably deeper than it
  seems. I'm just not convinced that passing the problem onto connectors,
  libraries and ultimately application developers is the right thing to do
  here.
 
 Well, one could argue that it *is* their problem, as they should be using
 the standard Postgres way for placeholders, which is $1, $2, $3...

Shirley you are joking: Many products use JDBC as an abstraction layer 
facilitating (mostly) seamless switching between databases. I know the product 
I worked on did. Are you advocating that every single statement should use 
SELECT * FROM foo WHERE bar = $1 on pg and SELECT * FROM foo WHERE bar = ? 
on every other database?

A database is only as valuable as the the part of the outside world it can 
interact with. Large parts of the data-consuming world are developed in java 
using JDBC. If your opinion is that JDBC developers should adapt themselves to 
pg then you instantaneously diminish the value of pg.

jan



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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-17 Thread Greg Sabino Mullane


-BEGIN PGP SIGNED MESSAGE-
Hash: RIPEMD160


Andrew Dunstan wrote:
 FTR, Perl's DBD::Pg lets you do this:
 $dbh-{pg_placeholder_dollaronly} = 1; # disable ? placeholders

You can also simply escape placeholders in DBD::Pg with a backslash:

$dbh-prepare(q{SELECT * FROM mytable WHERE lseg1 \?# lseg2 AND name = ?});

Dave Cramer wrote:
 Well our solution was to use ?? but that does mean we have to do some
 extra parsing which in a perfect world wouldn't be necessary.

That's not a good solution as '??' is a perfectly valid operator. ISTR 
seeing it used somewhere in the wild, but I could be wrong.

 In that case my vote is new operators. This has been a sore point for the
 JDBC driver

Um, no, new operators is a bad idea. Question marks are used by hstore, 
json, geometry, and who knows what else. I think the onus is solely on 
JDBC to solve this problem. DBD::Pg solved it in 2008 with 
the pg_placeholder_dollaronly solution, and earlier this year by allowing 
backslashes before the question mark (because other parts of the stack were 
not able to smoothly implement pg_placeholder_dollaronly.) I recommend 
all drivers implement \? as a semi-standard workaround.

See also:
http://blog.endpoint.com/2015/01/dbdpg-escaping-placeholders-with.html

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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-17 Thread David G. Johnston

On Sun, May 17, 2015 at 9:15 AM, Greg Sabino Mullane g...@turnstep.com
wrote:

 Dave Cramer wrote:
  Well our solution was to use ?? but that does mean we have to do some
  extra parsing which in a perfect world wouldn't be necessary.

 That's not a good solution as '??' is a perfectly valid operator. ISTR
 seeing it used somewhere in the wild, but I could be wrong.


It which case you would write (I think, not tested and not part of the
test suite that I can see...):

a  b ...

There was some discussion about ?? vs \?:

https://github.com/pgjdbc/pgjdbc/pull/187

I did find some alternatives discussed a couple of years back, like
{postgres qm} and operator(?); the later simply being to allow the
operator to be quoted inside operator()


http://postgresql.nabble.com/Alias-hstore-s-to-so-that-it-works-with-JDBC-td5743863i20.html

The commit that added ??:

https://github.com/pgjdbc/pgjdbc/pull/227

David J.

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-15 Thread Andrew Dunstan



On 05/15/2015 04:35 PM, Robert Haas wrote:

I guess JDBC has the same problem as Perl and JavaScript here: ?
signals a bind variable.  The next question is, why isn't there some
escaping mechanism for that, like writing ?? or \? or something?



FTR, Perl's DBD::Pg lets you do this:

   $dbh-{pg_placeholder_dollaronly} = 1; # disable ? placeholders
   $sth = $dbh-prepare(q{SELECT * FROM mytable WHERE lseg1 ?# lseg2
   AND name = $1});
   $sth-execute('segname');

cheers

andrew




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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

Not sure what the point of this is: as you indicated the ship has sailed so
to speak

Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

On 15 May 2015 at 15:14, Bruno Harbulot br...@distributedmatter.net wrote:

 Hello,

 I've been trying to use the new JSONB format using JDBC, and ran into
 trouble with the question mark operators (?, ?| and ?).
 I realise there has already been a discussion about this (actually, it was
 about hstore, not jsonb, but that's more or less the same problem):
 - http://www.postgresql.org/message-id/51114165.4070...@abshere.net
 -
 http://mail.openjdk.java.net/pipermail/jdbc-spec-discuss/2013-February/48.html


 From what I gather, the JDBC team seems to think that using ? in operators
 is not in line with the SQL standards, but the outcome on the PostgreSQL
 list team suggested that a fix could be implemented in the PostgreSQL JDBC
 driver anyway.

 I think this problem might actually affect a number of other places,
 unfortunately. I must admit I don't know the SQL specifications very well
 (a quick look at a draft seemed to suggest the question mark was indeed a
 reserved character, but this is probably out of context), and this isn't
 about finding out who is right or who is wrong, but from a practical point
 of view, this also seemed to affect other kinds of clients, for example:
 - Perl:
 http://blog.endpoint.com/2015/01/dbdpg-escaping-placeholders-with.html
 - JavaScript: https://github.com/tgriesser/knex/issues/519
 Of course, there can be workarounds in some cases, but even if they work,
 they can be quite awkward, especially if they differ from one language to
 another (in particular if you want to be able to re-use the same query from
 multiple languages).

 As far, as I can tell, question mark operators are also incompatible with
 PostgreSQL's ECPG when using dynamic SQL.
 http://www.postgresql.org/docs/current/static/ecpg-dynamic.html
 (I'm pasting an example at the end of this message, tried with a
 PostgreSQL 9.4 server.)

 I realise it's a bit late to raise this concern, considering that these
 operators have been around for a few versions now (at least as far as
 hstore), but wouldn't it be better to provide official alternative
 notations altogether, something that is less likely to conflict with most
 client implementations? Perhaps a function or a notation similar to what
 'CAST(x AS y)' is to 'x::y' would be suitable if other symbols aren't
 better (although I think a short operator would still be preferable).


 Best wishes,

 Bruno.




  ECPG test output:

 ** Using query: SELECT ('{key1:123,key2:Hello}'::jsonb -
 ?::text)::text

 Result should be 123 for 'key1': 123
 Result should be empty for 'key3':


 ** Using query: SELECT ('{key1:123,key2:Hello}'::jsonb ?
 ?::text)::text

 SQL error: syntax error at or near $1 on line 52
 SQL error: invalid statement name mystmt3 on line 55
 Result should be true for 'key1':
 SQL error: invalid statement name mystmt3 on line 59
 Result should be false for 'key3':
 SQL error: invalid statement name mystmt3 on line 62



  ECPG test code:


 #include stdio.h
 #include stdlib.h

 int main()
 {
 EXEC SQL BEGIN DECLARE SECTION;
 char* target = unix:postgresql://localhost/mydatabase;
 char result1[2048];
 int result1_ind;
 char *key1_str = key1;
 char *key3_str = key3;
 char *stmt2 = SELECT ('{\key1\:123,\key2\:\Hello\}'::jsonb
 - ?::text)::text;
 char *stmt3 = SELECT ('{\key1\:123,\key2\:\Hello\}'::jsonb
 ? ?::text)::text;
 EXEC SQL END DECLARE SECTION;

 EXEC SQL WHENEVER SQLWARNING SQLPRINT;
 EXEC SQL WHENEVER SQLERROR SQLPRINT;
 EXEC SQL CONNECT TO :target AS testdb;


 printf(\n\n** Using query: %s\n\n, stmt2);
 EXEC SQL PREPARE mystmt2 FROM :stmt2;

 result1[0] = 0;
 EXEC SQL EXECUTE mystmt2 INTO :result1 :result1_ind USING :key1_str;
 printf(Result should be 123 for 'key1': %s\n, result1);

 result1[0] = 0;
 EXEC SQL EXECUTE mystmt2 INTO :result1 :result1_ind USING :key3_str;
 printf(Result should be empty for 'key3': %s\n, result1);

 EXEC SQL DEALLOCATE PREPARE mystmt2;


 printf(\n\n** Using query: %s\n\n, stmt3);
 EXEC SQL PREPARE mystmt3 FROM :stmt3;

 result1[0] = 0;
 EXEC SQL EXECUTE mystmt3 INTO :result1_ind USING :key1_str;
 printf(Result should be true for 'key1': %s\n, result1);

 result1[0] = 0;
 EXEC SQL EXECUTE mystmt3 INTO :result1_ind USING :key3_str;
 printf(Result should be false for 'key3': %s\n, result1);

 EXEC SQL DEALLOCATE PREPARE mystmt3;

 EXEC SQL DISCONNECT ALL;

 return 0;
 }

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-15 Thread Robert Haas

On Fri, May 15, 2015 at 4:13 PM, Dave Cramer p...@fastcrypt.com wrote:
 Not sure what the point of this is: as you indicated the ship has sailed so
 to speak

Well, if we were to agree this was a problem, we could introduce new,
less-problematic operator names and then eventually deprecate the old
ones.  Personally, it wouldn't take a lot to convince me that if a
certain set of operator names is problematic for important connectors,
we should avoid using those and switch to other ones.  I expect others
on this mailing list to insist that if the connectors don't work,
that's the connector drivers fault for coding their connectors wrong.
And maybe that's the right answer, but on the other hand, maybe it's a
little myopic.  I think the discussion is worth having.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-15 Thread Michael Meskes

 As far, as I can tell, question mark operators are also incompatible
 with PostgreSQL's ECPG when using dynamic SQL.
 http://www.postgresql.org/docs/current/static/ecpg-dynamic.html
 (I'm pasting an example at the end of this message, tried with a
 PostgreSQL 9.4 server.)

Indeed it is. The question mark is used in ecpg to denote a variable to
be filled-in by the process. I'm not completely sure if this was in the
standard or only implemented because several (not sure if all) other
precompiler used it as well.

Michael
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Michael at Fam-Meskes dot De, Michael at Meskes dot (De|Com|Net|Org)
Meskes at (Debian|Postgresql) dot Org
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VfL Borussia! Força Barça! Go SF 49ers! Use Debian GNU/Linux, PostgreSQL


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On 15 May 2015 at 16:41, Robert Haas robertmh...@gmail.com wrote:

 On Fri, May 15, 2015 at 4:38 PM, Dave Cramer p...@fastcrypt.com wrote:
  I don't really want to take a violently strong position on this
  without understanding what's really going on here.
 
  Well our solution was to use ?? but that does mean we have to do some
 extra
  parsing which in a perfect world wouldn't be necessary.

 So what about strings quoted with '' or $$ or $something$ - how would
 you handle those?

 We parse for strings; the ?? just adds to the parsing load which we really
try to avoid.


Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On 15 May 2015 at 16:21, Robert Haas robertmh...@gmail.com wrote:

 On Fri, May 15, 2015 at 4:13 PM, Dave Cramer p...@fastcrypt.com wrote:
  Not sure what the point of this is: as you indicated the ship has sailed
 so
  to speak

 Well, if we were to agree this was a problem, we could introduce new,
 less-problematic operator names and then eventually deprecate the old
 ones.  Personally, it wouldn't take a lot to convince me that if a
 certain set of operator names is problematic for important connectors,
 we should avoid using those and switch to other ones.  I expect others
 on this mailing list to insist that if the connectors don't work,
 that's the connector drivers fault for coding their connectors wrong.
 And maybe that's the right answer, but on the other hand, maybe it's a
 little myopic.  I think the discussion is worth having.


In that case my vote is new operators. This has been a sore point for the
JDBC driver

Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-15 Thread Robert Haas

On Fri, May 15, 2015 at 4:23 PM, Dave Cramer p...@fastcrypt.com wrote:
 Well, if we were to agree this was a problem, we could introduce new,
 less-problematic operator names and then eventually deprecate the old
 ones.  Personally, it wouldn't take a lot to convince me that if a
 certain set of operator names is problematic for important connectors,
 we should avoid using those and switch to other ones.  I expect others
 on this mailing list to insist that if the connectors don't work,
 that's the connector drivers fault for coding their connectors wrong.
 And maybe that's the right answer, but on the other hand, maybe it's a
 little myopic.  I think the discussion is worth having.

 In that case my vote is new operators. This has been a sore point for the
 JDBC driver

I guess JDBC has the same problem as Perl and JavaScript here: ?
signals a bind variable.  The next question is, why isn't there some
escaping mechanism for that, like writing ?? or \? or something?

I ask because, you know, suppose you write this:

INSERT INTO foo VALUES ('How many pickled peppers did Peter Piper pick?');

Or alternatively this:

INSERT INTO foo VALUES ($$If Peter piper picked a peck of pickled
peppers, where's the peck of pickled peppers Peter Piper picked?$$);

Those have also got question marks in them.  Do they also get
interpreted as bind variables?

I don't really want to take a violently strong position on this
without understanding what's really going on here.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

On 15 May 2015 at 16:35, Robert Haas robertmh...@gmail.com wrote:

 On Fri, May 15, 2015 at 4:23 PM, Dave Cramer p...@fastcrypt.com wrote:
  Well, if we were to agree this was a problem, we could introduce new,
  less-problematic operator names and then eventually deprecate the old
  ones.  Personally, it wouldn't take a lot to convince me that if a
  certain set of operator names is problematic for important connectors,
  we should avoid using those and switch to other ones.  I expect others
  on this mailing list to insist that if the connectors don't work,
  that's the connector drivers fault for coding their connectors wrong.
  And maybe that's the right answer, but on the other hand, maybe it's a
  little myopic.  I think the discussion is worth having.
 
  In that case my vote is new operators. This has been a sore point for the
  JDBC driver

 I guess JDBC has the same problem as Perl and JavaScript here: ?
 signals a bind variable.  The next question is, why isn't there some
 escaping mechanism for that, like writing ?? or \? or something?

 I ask because, you know, suppose you write this:

 INSERT INTO foo VALUES ('How many pickled peppers did Peter Piper pick?');

 Or alternatively this:

 INSERT INTO foo VALUES ($$If Peter piper picked a peck of pickled
 peppers, where's the peck of pickled peppers Peter Piper picked?$$);

 Those have also got question marks in them.  Do they also get
 interpreted as bind variables?

 I don't really want to take a violently strong position on this
 without understanding what's really going on here.

 Well our solution was to use ?? but that does mean we have to do some
extra parsing which in a perfect world wouldn't be necessary.



Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)

2015-05-15 Thread Robert Haas

On Fri, May 15, 2015 at 4:38 PM, Dave Cramer p...@fastcrypt.com wrote:
 I don't really want to take a violently strong position on this
 without understanding what's really going on here.

 Well our solution was to use ?? but that does mean we have to do some extra
 parsing which in a perfect world wouldn't be necessary.

So what about strings quoted with '' or $$ or $something$ - how would
you handle those?

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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Re: [HACKERS] Problems with question marks in operators (JDBC, ECPG, ...)