Thread: CALL stmt, ERROR: unrecognized node type: 113 bug
Hi
I am playing with procedures little bitcreate procedure test(a int)
postgres=# call test((select 10));
ERROR: unrecognized node type: 113
postgres=# \sf test
ERROR: cache lookup failed for type 0
On Thu, Feb 01, 2018 at 05:33:54PM +0100, Pavel Stehule wrote: > I am playing with procedures little bit > > I found few bugs > > create procedure test(a int) > as $$ > begin > raise notice '>>>%<<<', a; > end; > $$ language plpgsql; > > call test(10); -- ok > > postgres=# call test((select 10)); > ERROR: unrecognized node type: 113 > > postgres=# \sf test > ERROR: cache lookup failed for type 0 Peter, Andrew, this is missing some bits related to the conversion of SubLink nodes to SubPlan nodes for procedures when used as argument of a procedure as only the latter can be executed after the former is processed by the latter (see SS_process_sublinks). -- Michael
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On Fri, Feb 02, 2018 at 04:01:13PM +0900, Michael Paquier wrote: > Peter, Andrew, this is missing some bits related to the conversion of > SubLink nodes to SubPlan nodes for procedures when used as argument of > a procedure as only the latter can be executed after the former is > processed by the latter (see SS_process_sublinks). Meh-to-self. You need to read that as "only a SubPlan can be executed after a SubLink has been processed by the planner", so please replace the last "latter" by "planner". -- Michael
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On Fri, Feb 02, 2018 at 04:07:28PM +0900, Michael Paquier wrote: > You need to read that as "only a SubPlan can be executed after a SubLink > has been processed by the planner", so please replace the last "latter" > by "planner". (I forgot to add Peter and Andrew in CC: previously, so done now.) e4128ee7 is making is clear that SubLink are authorized when transforming it in transformSubLink(), however I cannot think about a use case so should we just forbid them, and this is actually untested. So the patch attached does so. The second problem involves a cache lookup failure for a type when trying to use pg_get_functiondef on a procedure. Luckily, it is possible to make the difference between a procedure and a function by checking if prorettype is InvalidOid or not. There is room for a new patch which supports pg_get_proceduredef() to generate the definition of a procedure, with perhaps a dedicated psql shortcut, but that could always be done later on. -- Michael
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Hi
2018-02-09 7:56 GMT+01:00 Michael Paquier <michael@paquier.xyz>:
On Fri, Feb 02, 2018 at 04:07:28PM +0900, Michael Paquier wrote:
> You need to read that as "only a SubPlan can be executed after a SubLink
> has been processed by the planner", so please replace the last "latter"
> by "planner".
(I forgot to add Peter and Andrew in CC: previously, so done now.)
e4128ee7 is making is clear that SubLink are authorized when
transforming it in transformSubLink(), however I cannot think about a
use case so should we just forbid them, and this is actually untested.
So the patch attached does so.
The second problem involves a cache lookup failure for a type when
trying to use pg_get_functiondef on a procedure. Luckily, it is
possible to make the difference between a procedure and a function by
checking if prorettype is InvalidOid or not. There is room for a new
patch which supports pg_get_proceduredef() to generate the definition of
a procedure, with perhaps a dedicated psql shortcut, but that could
always be done later on.
Blocking subqueries in CALL parameters is possible solution. But blocking func def for procedures without any substitution doesn't look correct for me.
Regards
Pavel
--
Michael
On Fri, Feb 09, 2018 at 12:02:57PM +0100, Pavel Stehule wrote: > 2018-02-09 7:56 GMT+01:00 Michael Paquier <michael@paquier.xyz>: > > The second problem involves a cache lookup failure for a type when > > trying to use pg_get_functiondef on a procedure. Luckily, it is > > possible to make the difference between a procedure and a function by > > checking if prorettype is InvalidOid or not. There is room for a new > > patch which supports pg_get_proceduredef() to generate the definition of > > a procedure, with perhaps a dedicated psql shortcut, but that could > > always be done later on. > > Blocking subqueries in CALL parameters is possible solution. ExecuteCallStmt has visibly been written so as it is able to handle the input set of arguments with a minimal infrastructure in place. SubLink nodes require more advanced handling as those need to go through the planner. There is also additional processing in the rewriter. At the end I tend to think that any user would just turn their back on calling a function for such cases anyway, so it seems to me that the potential benefits are not worth the code complexity. > But blocking > func def for procedures without any substitution doesn't look correct for > me. I don't disagree with you here, there is room for such a function, but on the other side not having it does not make the existing feature less useful. As it is Peter's and Andrew's feature, the last word should come from them. Here is my opinion for what it's worth: - Procedures are not functions, the code is pretty clear about that, so a system function to generate the definition of a procedure should not happen with pg_get_functiondef(). They share a lot of infrastructure so you can reuse a lot of the code present. - A different psql shortcut should be used, and I would assume that \sp is adapted. - Aggregates are also in pg_proc, we generate an error on them because they are of different type, so an error for procedures when trying to fetch a functoin definition looks like the good answer. If folks feel that having a way to retrieve the procedure definition easily via ruleutils.c is a must-have, then we have material for a good open item :) -- Michael
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On Fri, Feb 09, 2018 at 12:02:57PM +0100, Pavel Stehule wrote:
> 2018-02-09 7:56 GMT+01:00 Michael Paquier <michael@paquier.xyz>:
> > The second problem involves a cache lookup failure for a type when
> > trying to use pg_get_functiondef on a procedure. Luckily, it is
> > possible to make the difference between a procedure and a function by
> > checking if prorettype is InvalidOid or not. There is room for a new
> > patch which supports pg_get_proceduredef() to generate the definition of
> > a procedure, with perhaps a dedicated psql shortcut, but that could
> > always be done later on.
>
> Blocking subqueries in CALL parameters is possible solution.
ExecuteCallStmt has visibly been written so as it is able to handle the
input set of arguments with a minimal infrastructure in place. SubLink
nodes require more advanced handling as those need to go through the
planner. There is also additional processing in the rewriter. At the
end I tend to think that any user would just turn their back on calling
a function for such cases anyway, so it seems to me that the potential
benefits are not worth the code complexity.
CALL is not just a different syntax for function invocation - if you want the properties of CALL then falling back to SELECT function() is not a valid alternative.
To me this feels like an interaction between two features that users are going to expect to just work. Current discussions lead me to think that is something we strive to provide unless a strong argument against is provided. I'm not sure added code complexity here is going to make the grade even if I cannot reasonably judge just how much complexity is involved.
David J.
2018-02-09 15:15 GMT+01:00 David G. Johnston <david.g.johnston@gmail.com>:
+1
On Fri, Feb 09, 2018 at 12:02:57PM +0100, Pavel Stehule wrote:
> 2018-02-09 7:56 GMT+01:00 Michael Paquier <michael@paquier.xyz>:
> > The second problem involves a cache lookup failure for a type when
> > trying to use pg_get_functiondef on a procedure. Luckily, it is
> > possible to make the difference between a procedure and a function by
> > checking if prorettype is InvalidOid or not. There is room for a new
> > patch which supports pg_get_proceduredef() to generate the definition of
> > a procedure, with perhaps a dedicated psql shortcut, but that could
> > always be done later on.
>
> Blocking subqueries in CALL parameters is possible solution.
ExecuteCallStmt has visibly been written so as it is able to handle the
input set of arguments with a minimal infrastructure in place. SubLink
nodes require more advanced handling as those need to go through the
planner. There is also additional processing in the rewriter. At the
end I tend to think that any user would just turn their back on calling
a function for such cases anyway, so it seems to me that the potential
benefits are not worth the code complexity.CALL is not just a different syntax for function invocation - if you want the properties of CALL then falling back to SELECT function() is not a valid alternative.
+1
To me this feels like an interaction between two features that users are going to expect to just work. Current discussions lead me to think that is something we strive to provide unless a strong argument against is provided. I'm not sure added code complexity here is going to make the grade even if I cannot reasonably judge just how much complexity is involved.
when some procedure can do transaction control, or can returns possible set or multirecord set (in future), then 100% agree, so it is different creature then function. But if not, then it should be specified why it is different from void function.
I don't understand, why we should to prohibit subqueries as procedure params - with some limits. I can understand to requirement to not change any data.
Regards
Pavel
David J.
"David G. Johnston" <david.g.johnston@gmail.com> writes: > On Fri, Feb 9, 2018 at 6:23 AM, Michael Paquier <michael@paquier.xyz> wrote: >> On Fri, Feb 09, 2018 at 12:02:57PM +0100, Pavel Stehule wrote: >>> Blocking subqueries in CALL parameters is possible solution. > To me this feels like an interaction between two features that users are > going to expect to just work. Meh. It doesn't look significantly different to me than the restriction that you can't have sub-selects in CHECK expressions, index expressions, etc. Obviously we need a clean failure like you get for those cases. But otherwise it's an OK restriction that stems from exactly the same cause: we do not want to invoke the full planner in this context (and even if we did, we don't want to use the full executor to execute the result). regards, tom lane
"David G. Johnston" <david.g.johnston@gmail.com> writes:
> On Fri, Feb 9, 2018 at 6:23 AM, Michael Paquier <michael@paquier.xyz> wrote:
>> On Fri, Feb 09, 2018 at 12:02:57PM +0100, Pavel Stehule wrote:
>>> Blocking subqueries in CALL parameters is possible solution.
> To me this feels like an interaction between two features that users are
> going to expect to just work.
Meh. It doesn't look significantly different to me than the restriction
that you can't have sub-selects in CHECK expressions, index expressions,
etc. Obviously we need a clean failure like you get for those cases.
But otherwise it's an OK restriction that stems from exactly the same
cause: we do not want to invoke the full planner in this context (and
even if we did, we don't want to use the full executor to execute the
result).
Does/Should:
CALL test(func(10)); --with or without an extra set of parentheses
work here too?
David J.
On 2018-02-09 09:42:41 -0500, Tom Lane wrote: > It doesn't look significantly different to me than the restriction > that you can't have sub-selects in CHECK expressions, index > expressions, etc. Obviously we need a clean failure like you get for > those cases. But otherwise it's an OK restriction that stems from > exactly the same cause: we do not want to invoke the full planner in > this context (and even if we did, we don't want to use the full > executor to execute the result). +1
On Fri, Feb 09, 2018 at 08:30:49AM -0800, Andres Freund wrote: > On 2018-02-09 09:42:41 -0500, Tom Lane wrote: >> It doesn't look significantly different to me than the restriction >> that you can't have sub-selects in CHECK expressions, index >> expressions, etc. Obviously we need a clean failure like you get for >> those cases. But otherwise it's an OK restriction that stems from >> exactly the same cause: we do not want to invoke the full planner in >> this context (and even if we did, we don't want to use the full >> executor to execute the result). > > +1 +1. -- Michael
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Michael Paquier <michael@paquier.xyz> writes: > On Fri, Feb 09, 2018 at 08:30:49AM -0800, Andres Freund wrote: >> On 2018-02-09 09:42:41 -0500, Tom Lane wrote: >>> ... But otherwise it's an OK restriction that stems from >>> exactly the same cause: we do not want to invoke the full planner in >>> this context (and even if we did, we don't want to use the full >>> executor to execute the result). So I idly looked at ExecuteCallStmt to see how, in fact, it is executing these things, and I was right to guess that it couldn't possibly support a sub-select, since it's just using ExecEvalExprSwitchContext. So we need to go teach transformSubLink that EXPR_KIND_CALL is *not* okay, which is simple enough. However, I also wondered how ExecuteCallStmt works at all for pass-by- reference datatypes, since it immediately destroys the execution context for each expression. And the answer is that it doesn't, as proven here: regression=# create procedure myp(f1 text) as $$begin regression$# raise notice 'f1 = %', f1; regression$# end$$ language plpgsql; CREATE PROCEDURE regression=# call myp('xyzzy'); NOTICE: f1 = xyzzy CALL regression=# call myp('xyzzy' || 'x'); NOTICE: f1 = CALL The call with a literal constant accidentally seems to work, because the returned Datum is actually pointing into the original expression tree. But if you have the expression do any actual work, then not so much. I think this could be fixed by evaluating all the arguments in a single execution context that is not destroyed till after the call finishes (using a separate one for each argument seems pretty silly anyway). However, the code could do with more than zero commentary about how come this is safe at all --- even if we keep the execution context, it's still a child of whatever random memory context ExecuteCallStmt was called in, and it's not very clear that that context will survive a transaction commit. This does not leave me with a warm feeling about either the amount of testing the procedure feature has gotten, or the state of its internal documentation. regards, tom lane
I wrote: > However, I also wondered how ExecuteCallStmt works at all for pass-by- > reference datatypes, since it immediately destroys the execution context > for each expression. And the answer is that it doesn't, as proven here: On closer inspection, there are actually three sub-cases involved. It accidentally works for simple constant arguments, because the passed Datum will point at a Const node generated during transformExpr. And it works for fully run-time-evaluated arguments, because those end up in memory belonging to the standalone ExprContext(s), which ExecuteCallStmt never bothers to free at all. (Which is a bug in itself, although possibly one that wouldn't be exposed in practice given that we disallow SRFs here; I don't know if there are any other cases that would expect ExprContext cleanup hooks to get invoked.) Where it doesn't work is for expressions that are const-folded during ExecPrepareExpr, because then the values are in Const nodes that live in the EState's per-query context, and the code is throwing that away too soon. I pushed a fix for all that. The failure in pg_get_functiondef() is still there. While the immediate answer probably is to teach that function to emit correct CREATE PROCEDURE syntax, I continue to think that it's a bad idea to be putting zeroes into pg_proc.prorettype. regards, tom lane
On Sat, Feb 10, 2018 at 01:46:40PM -0500, Tom Lane wrote: > I pushed a fix for all that. Shouldn't there be a test case as well? The patch I sent upthread was doing the whole set, except that I did not bother > The failure in pg_get_functiondef() is still there. While the immediate > answer probably is to teach that function to emit correct CREATE PROCEDURE > syntax, I continue to think that it's a bad idea to be putting zeroes into > pg_proc.prorettype. Yeah, or an error with a new function dedicated to procedures. I also finc confusing the use of prorettype to track this object type. This brings the amount of objects stored in pg_proc to four. Perhaps it would be time to bring more clarity in pg_proc by introducing a prokind column for functions, aggregates, window functions and procedures? I don't feel really hot for an extra boolean column like proisproc. -- Michael
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On Sun, Feb 11, 2018 at 08:17:55AM +0900, Michael Paquier wrote: > On Sat, Feb 10, 2018 at 01:46:40PM -0500, Tom Lane wrote: >> I pushed a fix for all that. > > Shouldn't there be a test case as well? The patch I sent upthread was > doing the whole set, except that I did not bother ... Rename EXPR_KIND_CALL to something else. This was missing the last part of the sentence. -- Michael
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Michael Paquier <michael@paquier.xyz> writes: > On Sat, Feb 10, 2018 at 01:46:40PM -0500, Tom Lane wrote: >> I pushed a fix for all that. > Shouldn't there be a test case as well? There was one for the premature-free issue in d02d4a6d4. I didn't really see a need for an explicit test for the subselect issue. > This brings the amount of objects stored in pg_proc to four. Perhaps it > would be time to bring more clarity in pg_proc by introducing a prokind > column for functions, aggregates, window functions and procedures? Yeah. I was under the impression that Peter was looking into that ... [ digs... ] see https://www.postgresql.org/message-id/80ee1f5c-fa9d-7285-ed07-cff53d4f4858@2ndquadrant.com regards, tom lane
On 2/9/18 09:42, Tom Lane wrote: > Meh. It doesn't look significantly different to me than the restriction > that you can't have sub-selects in CHECK expressions, index expressions, > etc. Obviously we need a clean failure like you get for those cases. > But otherwise it's an OK restriction that stems from exactly the same > cause: we do not want to invoke the full planner in this context (and > even if we did, we don't want to use the full executor to execute the > result). A close analogy is that EXECUTE parameters also don't accept subqueries. It would perhaps be nice if that could be made to work, but as discussed it would require a bunch more work. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
2018-02-12 18:17 GMT+01:00 Peter Eisentraut <peter.eisentraut@2ndquadrant.com>:
On 2/9/18 09:42, Tom Lane wrote:
> Meh. It doesn't look significantly different to me than the restriction
> that you can't have sub-selects in CHECK expressions, index expressions,
> etc. Obviously we need a clean failure like you get for those cases.
> But otherwise it's an OK restriction that stems from exactly the same
> cause: we do not want to invoke the full planner in this context (and
> even if we did, we don't want to use the full executor to execute the
> result).
A close analogy is that EXECUTE parameters also don't accept subqueries.
It would perhaps be nice if that could be made to work, but as
discussed it would require a bunch more work.
I can live with it. Should be well documented and explained.
Regards
Pavel
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
On 2/1/18 11:33, Pavel Stehule wrote: > postgres=# \sf test > ERROR: cache lookup failed for type 0 Here is a patch set that adds procedure support to \ef and \sf. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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On 2/11/18 01:10, Tom Lane wrote: >> This brings the amount of objects stored in pg_proc to four. Perhaps it >> would be time to bring more clarity in pg_proc by introducing a prokind >> column for functions, aggregates, window functions and procedures? > > Yeah. I was under the impression that Peter was looking into that ... > [ digs... ] see > https://www.postgresql.org/message-id/80ee1f5c-fa9d-7285-ed07-cff53d4f4858@2ndquadrant.com Yeah that's still pending, but there wasn't a whole lot of reaction in that thread. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
Peter Eisentraut <peter.eisentraut@2ndquadrant.com> writes: > On 2/11/18 01:10, Tom Lane wrote: >> Yeah. I was under the impression that Peter was looking into that ... >> [ digs... ] see >> https://www.postgresql.org/message-id/80ee1f5c-fa9d-7285-ed07-cff53d4f4858@2ndquadrant.com > Yeah that's still pending, but there wasn't a whole lot of reaction in > that thread. I think it's probably a good idea, but you hadn't finished the client end of the patch. Since the main argument against doing this would probably be about client-side breakage, we need to see how big that impact will be before we make a final decision. regards, tom lane
Peter Eisentraut <peter.eisentraut@2ndquadrant.com> writes: > On 2/1/18 11:33, Pavel Stehule wrote: >> postgres=# \sf test >> ERROR: cache lookup failed for type 0 > Here is a patch set that adds procedure support to \ef and \sf. I've not read in detail, but it looks reasonable offhand, modulo that I still don't like prorettype == 0 ;-). I did notice a tiny typo: - * with. Hence prefer "$function$", but extend if needed. + * with. Hence prefer "$function$"/"$procedure", but extend if needed. I think you want + * with. Hence prefer "$function$"/"$procedure$", but extend if needed. regards, tom lane
On Mon, Feb 12, 2018 at 03:19:27PM -0500, Tom Lane wrote: > I've not read in detail, but it looks reasonable offhand, modulo > that I still don't like prorettype == 0 ;-). > > I did notice a tiny typo: > > - * with. Hence prefer "$function$", but extend if needed. > + * with. Hence prefer "$function$"/"$procedure", but extend if needed. > > I think you want > > + * with. Hence prefer "$function$"/"$procedure$", but extend if needed. 0001 and 0002 are welcome. I have a small comment on top of Tom's for 0003. + appendStringInfoString(&buf, ")\n"); + if (proc->prorettype) + { + appendStringInfoString(&buf, " RETURNS "); + print_function_rettype(&buf, proctup); + appendStringInfoChar(&buf, '\n'); + } Could you use a separate boolean variable which is set as OidIsValid(prorettype), say called isfunction? The goal is to avoid the check on prorettype in more than one place. If pg_proc's shape is changed depending on the discussion, the current patch is a recipy to forget updating all those places. A comment in pg_get_function_result to mention that prorettype = InvalidOid is here to track that the call involves a procedure would be nice. Should the documentation of pg_function_is_visible also mention procedures? -- Michael
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On 2/13/18 03:57, Michael Paquier wrote: > On Mon, Feb 12, 2018 at 03:19:27PM -0500, Tom Lane wrote: >> I've not read in detail, but it looks reasonable offhand, modulo >> that I still don't like prorettype == 0 ;-). >> >> I did notice a tiny typo: >> >> - * with. Hence prefer "$function$", but extend if needed. >> + * with. Hence prefer "$function$"/"$procedure", but extend if needed. >> >> I think you want >> >> + * with. Hence prefer "$function$"/"$procedure$", but extend if needed. done > 0001 and 0002 are welcome. I have a small comment on top of Tom's for 0003. > > + appendStringInfoString(&buf, ")\n"); > + if (proc->prorettype) > + { > + appendStringInfoString(&buf, " RETURNS "); > + print_function_rettype(&buf, proctup); > + appendStringInfoChar(&buf, '\n'); > + } > Could you use a separate boolean variable which is set as > OidIsValid(prorettype), say called isfunction? done > Should the documentation of pg_function_is_visible also mention > procedures? done and committed -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
On Mon, Feb 12, 2018 at 3:19 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote: > modulo that I still don't like prorettype == 0 ;-). +1. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
On Tue, Feb 13, 2018 at 03:26:20PM -0500, Peter Eisentraut wrote: > and committed Thanks, those changes are fine for me. Perhaps you want to have print_function_rettype() drop a elog(ERROR) if called with an invalid prorettype? I tend to be allergic to Asserts in ruleutils.c since 0daeba0e... -- Michael