Re: [HACKERS] pg_upgrade failed if view contain natural left join condition

[Tom Lane]

"David G. Johnston"  writes:
> Per the docs:
> "If there are no common column names, NATURAL behaves like CROSS JOIN."

> I'm being a bit pedantic here but since NATURAL is a replacement for
> "ON/USING" it would seem more consistent to describe it, when no matching
> columns are found, as "behaves like specifying ON TRUE" instead.

Yeah, the analogy to CROSS JOIN falls down if it's an outer join.
I'll go fix that.

> I find it a bit strange, though not surprising, that it doesn't devolve to
> "ON FALSE".

No, it's normal that an AND of no conditions degenerates to TRUE.
It's like omitting a WHERE clause.

regards, tom lane


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Re: [HACKERS] pg_upgrade failed if view contain natural left join condition

[David G. Johnston]

On Thu, Jul 20, 2017 at 6:53 AM, Tom Lane  wrote:

> tushar  writes:
> > postgres=# create table t(n int);
> > CREATE TABLE
> > postgres=# create table t1(a int);
> > CREATE TABLE
> > postgres=# create view ttt1 as SELECT e.n FROM t e NATURAL LEFT JOIN t1
> d;
> > CREATE VIEW
>
> You realize of course that that's a pretty useless join definition.
> Still, yes, we do need to reverse-list the view with correct syntax.
> Probably t LEFT JOIN t1 ON TRUE would do it.
>

Per the docs:

"If there are no common column names, NATURAL behaves like CROSS JOIN."

I'm being a bit pedantic here but since NATURAL is a replacement for
"ON/USING" it would seem more consistent to describe it, when no matching
columns are found, as "behaves like specifying ON TRUE" instead.   Maybe
"behaves like specifying ON TRUE, causing a CROSS JOIN to occur instead."

I find it a bit strange, though not surprising, that it doesn't devolve to
"ON FALSE".

David J.

Re: [HACKERS] pg_upgrade failed if view contain natural left join condition

[Tom Lane]

tushar  writes:
> postgres=# create table t(n int);
> CREATE TABLE
> postgres=# create table t1(a int);
> CREATE TABLE
> postgres=# create view ttt1 as SELECT e.n FROM t e NATURAL LEFT JOIN t1 d;
> CREATE VIEW

You realize of course that that's a pretty useless join definition.
Still, yes, we do need to reverse-list the view with correct syntax.
Probably t LEFT JOIN t1 ON TRUE would do it.

> I think -this issue should be there in the older branches as well but 
> not checked that.

[experiments]  Seems to be wrong back to 9.3.  Although I have a feeling
this might be a mistake in a back-patched bug fix, so that it'd depend
on which 9.3.x you looked at.

regards, tom lane


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Re: [HACKERS] pg_upgrade failed if view contain natural left join condition

[Thom Brown]

On 20 July 2017 at 13:09, tushar  wrote:
> Steps to reproduce -
>
> v9.6
>
> postgres=# create table t(n int);
> CREATE TABLE
> postgres=# create table t1(a int);
> CREATE TABLE
> postgres=# create view ttt1 as SELECT e.n FROM t e NATURAL LEFT JOIN t1 d;
> CREATE VIEW
>
> v10 -
>
> run pg_upgrade -
>
> going to fail ,with this error -
>
> "
> pg_restore: creating TABLE "public.t"
> pg_restore: creating TABLE "public.t1"
> pg_restore: creating VIEW "public.ttt1"
> pg_restore: [archiver (db)] Error while PROCESSING TOC:
> pg_restore: [archiver (db)] Error from TOC entry 187; 1259 16390 VIEW ttt1
> edb
> pg_restore: [archiver (db)] could not execute query: ERROR:  syntax error at
> or near ")"
> LINE 16:  LEFT JOIN "t1" "d");
> ^
> Command was:
> -- For binary upgrade, must preserve pg_type oid
> SELECT
> pg_catalog.binary_upgrade_set_next_pg_type_oid('16392'::pg_catalog.oid);
>
>
> -- For binary upgrade, must preserve pg_type array oid
> SELECT
> pg_catalog.binary_upgrade_set_next_array_pg_type_oid('16391'::pg_catalog.oid);
>
>
> -- For binary upgrade, must preserve pg_class oids
> SELECT
> pg_catalog.binary_upgrade_set_next_heap_pg_class_oid('16390'::pg_catalog.oid);
>
> CREATE VIEW "ttt1" AS
>  SELECT "e"."n"
>FROM ("t" "e"
>  LEFT JOIN "t1" "d");
>
> "
> I think -this issue should be there in the older branches as well but not
> checked that.

I get the same result on 9.2 and 10 in pg_dump output.

Thom


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[HACKERS] pg_upgrade failed if view contain natural left join condition

[tushar]

Steps to reproduce -

v9.6

postgres=# create table t(n int);
CREATE TABLE
postgres=# create table t1(a int);
CREATE TABLE
postgres=# create view ttt1 as SELECT e.n FROM t e NATURAL LEFT JOIN t1 d;
CREATE VIEW

v10 -

run pg_upgrade -

going to fail ,with this error -

"
pg_restore: creating TABLE "public.t"
pg_restore: creating TABLE "public.t1"
pg_restore: creating VIEW "public.ttt1"
pg_restore: [archiver (db)] Error while PROCESSING TOC:
pg_restore: [archiver (db)] Error from TOC entry 187; 1259 16390 VIEW 
ttt1 edb
pg_restore: [archiver (db)] could not execute query: ERROR:  syntax 
error at or near ")"

LINE 16:  LEFT JOIN "t1" "d");
^
Command was:
-- For binary upgrade, must preserve pg_type oid
SELECT 
pg_catalog.binary_upgrade_set_next_pg_type_oid('16392'::pg_catalog.oid);



-- For binary upgrade, must preserve pg_type array oid
SELECT 
pg_catalog.binary_upgrade_set_next_array_pg_type_oid('16391'::pg_catalog.oid);



-- For binary upgrade, must preserve pg_class oids
SELECT 
pg_catalog.binary_upgrade_set_next_heap_pg_class_oid('16390'::pg_catalog.oid);


CREATE VIEW "ttt1" AS
 SELECT "e"."n"
   FROM ("t" "e"
 LEFT JOIN "t1" "d");

"
I think -this issue should be there in the older branches as well but 
not checked that.


--
regards,tushar
EnterpriseDB  https://www.enterprisedb.com/
The Enterprise PostgreSQL Company



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