Thread: dblink versus long connection strings
This bug report: http://archives.postgresql.org/pgsql-bugs/2010-11/msg00139.php shows that this patch was ill-considered: http://archives.postgresql.org/pgsql-committers/2010-06/msg00013.php and this later attempt didn't fix it, because it still misbehaves in HEAD: http://archives.postgresql.org/pgsql-committers/2010-06/msg00070.php not to mention that that second patch didn't even touch pre-8.4 branches. I'm inclined to think that we should just change all the truncate_identifier calls to warn=false, and forget about providing identifier-truncated warnings here. It's too difficult to tell whether a string is really meant as an identifier. regards, tom lane
On Tue, Nov 23, 2010 at 01:27, Tom Lane <tgl@sss.pgh.pa.us> wrote: > This bug report: > http://archives.postgresql.org/pgsql-bugs/2010-11/msg00139.php > shows that this patch was ill-considered: > http://archives.postgresql.org/pgsql-committers/2010-06/msg00013.php > and this later attempt didn't fix it, because it still misbehaves in > HEAD: > http://archives.postgresql.org/pgsql-committers/2010-06/msg00070.php > not to mention that that second patch didn't even touch pre-8.4 > branches. > > I'm inclined to think that we should just change all the > truncate_identifier calls to warn=false, and forget about providing > identifier-truncated warnings here. It's too difficult to tell whether > a string is really meant as an identifier. It is not a truncated identifier, but I think the truncation is still worth warning because we cannot distinguish two connections that differ only >63 bytes. Do we need another logic to name non-named connections? For example, md5 hash of the connection string. -- Itagaki Takahiro
Itagaki Takahiro <itagaki.takahiro@gmail.com> writes:
> On Tue, Nov 23, 2010 at 01:27, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I'm inclined to think that we should just change all the
>> truncate_identifier calls to warn=false, and forget about providing
>> identifier-truncated warnings here. It's too difficult to tell whether
>> a string is really meant as an identifier.
> It is not a truncated identifier, but I think the truncation is still
> worth warning because we cannot distinguish two connections that
> differ only >63 bytes.
The problem is to not give a warning when the string isn't meant as a
connection name at all, but as a libpq conninfo string (which can
perfectly reasonably run to more than 63 characters). Most if not all
of the dblink functions will accept either.
Perhaps a reasonable compromise is to issue the truncation warnings when
an overlength name is being *entered* into the connection table, but not
for simple lookups.
regards, tom lane
On 11/22/2010 11:51 AM, Tom Lane wrote: > Itagaki Takahiro<itagaki.takahiro@gmail.com> writes: >> On Tue, Nov 23, 2010 at 01:27, Tom Lane<tgl@sss.pgh.pa.us> wrote: >>> I'm inclined to think that we should just change all the >>> truncate_identifier calls to warn=false, and forget about providing >>> identifier-truncated warnings here. Â It's too difficult to tell whether >>> a string is really meant as an identifier. >> It is not a truncated identifier, but I think the truncation is still >> worth warning because we cannot distinguish two connections that >> differ only>63 bytes. > The problem is to not give a warning when the string isn't meant as a > connection name at all, but as a libpq conninfo string (which can > perfectly reasonably run to more than 63 characters). Most if not all > of the dblink functions will accept either. > > Perhaps a reasonable compromise is to issue the truncation warnings when > an overlength name is being *entered* into the connection table, but not > for simple lookups. Can't we distinguish a name from a conninfo string by the presence of an = sign? cheers andrew
Andrew Dunstan <andrew@dunslane.net> writes:
> On 11/22/2010 11:51 AM, Tom Lane wrote:
>> Perhaps a reasonable compromise is to issue the truncation warnings when
>> an overlength name is being *entered* into the connection table, but not
>> for simple lookups.
> Can't we distinguish a name from a conninfo string by the presence of an
> = sign?
No, because = isn't disallowed in names ...
regards, tom lane
On 11/22/2010 12:08 PM, Tom Lane wrote: > Andrew Dunstan<andrew@dunslane.net> writes: >> On 11/22/2010 11:51 AM, Tom Lane wrote: >>> Perhaps a reasonable compromise is to issue the truncation warnings when >>> an overlength name is being *entered* into the connection table, but not >>> for simple lookups. >> Can't we distinguish a name from a conninfo string by the presence of an >> = sign? > No, because = isn't disallowed in names ... Ok, true, but it still might not be a bad heuristic to use for issuing a warning on lookup. cheers andrew
Andrew Dunstan <andrew@dunslane.net> writes:
> On 11/22/2010 12:08 PM, Tom Lane wrote:
>> No, because = isn't disallowed in names ...
> Ok, true, but it still might not be a bad heuristic to use for issuing a
> warning on lookup.
The fine manual says that using "=" in a connection name might be unwise
because of the risk of confusion. It doesn't say that you should expect
to get a NOTICE every single time you use the name. People have
complained of postmaster log bloat for lots less reason than this.
In any case I don't see an argument why warning on connection creation
isn't sufficient.
regards, tom lane
On 11/22/2010 12:21 PM, Tom Lane wrote: > Andrew Dunstan<andrew@dunslane.net> writes: >> On 11/22/2010 12:08 PM, Tom Lane wrote: >>> No, because = isn't disallowed in names ... >> Ok, true, but it still might not be a bad heuristic to use for issuing a >> warning on lookup. > The fine manual says that using "=" in a connection name might be unwise > because of the risk of confusion. It doesn't say that you should expect > to get a NOTICE every single time you use the name. People have > complained of postmaster log bloat for lots less reason than this. > > In any case I don't see an argument why warning on connection creation > isn't sufficient. OK. cheers andrew
On Tue, Nov 23, 2010 at 02:21, Tom Lane <tgl@sss.pgh.pa.us> wrote: > In any case I don't see an argument why warning on connection creation > isn't sufficient. I'll check all versions of dblink. truncate_identifier() will be called with warn=false in all cases except dblink_coneect() -> createNewConnection(). -- Itagaki Takahiro
I have views that use the dblink(connStr text, sql text) call. They cannot use a two-step process. So postgres 9.0 has broken all of those views. Is there a straightforward solution to this? -- View this message in context: http://postgresql.1045698.n5.nabble.com/dblink-versus-long-connection-strings-tp3275575p3284620.html Sent from the PostgreSQL - hackers mailing list archive at Nabble.com.
On Tue, Nov 30, 2010 at 01:01, queej <dqj@authentrics.com> wrote: > I have views that use the dblink(connStr text, sql text) call. They cannot > use a two-step process. So postgres 9.0 has broken all of those views. Is > there a straightforward solution to this? Could you explain your views? I cannot get any warnings from dblink(connStr text, sql text) with long connStr. Also, I wonder two things: * dblink(connStr text, sql text) never raises warning logs even without the recent fix, because they don't register connectionnames. * Connection names could be truncated, but connection strings are never truncated. I'm not sure why connection strings arelogged in your log. -- Itagaki Takahiro