[PATCH] Tiny optmization or a bug?

Started by Ranier Vilelaabout 6 years ago3 messages
#1Ranier Vilela
ranier_gyn@hotmail.com
1 attachment(s)

Hi,
Hi,
Maybe this is a real bug.

The assignment has no effect, or forget dereferencing it?

Best regards.
Ranier Vilela

--- \dll\postgresql-12.0\a\backend\optimizer\plan\initsplan.c	Mon Sep 30 17:06:55 2019
+++ initsplan.c	Fri Nov 22 19:48:42 2019
@@ -1718,7 +1718,7 @@
 					relids =
 						get_relids_in_jointree((Node *) root->parse->jointree,
 											   false);
-					qualscope = bms_copy(relids);
+					bms_copy(relids);
 				}
 			}
 		}

Attachments:

initsplan.c.patchapplication/octet-stream; name=initsplan.c.patchDownload
--- \dll\postgresql-12.0\a\backend\optimizer\plan\initsplan.c	Mon Sep 30 17:06:55 2019
+++ initsplan.c	Fri Nov 22 19:48:42 2019
@@ -1718,7 +1718,7 @@
 					relids =
 						get_relids_in_jointree((Node *) root->parse->jointree,
 											   false);
-					qualscope = bms_copy(relids);
+					bms_copy(relids);
 				}
 			}
 		}
#2Tomas Vondra
tomas.vondra@2ndquadrant.com
In reply to: Ranier Vilela (#1)
Re: [PATCH] Tiny optmization or a bug?

On Fri, Nov 22, 2019 at 11:06:53PM +0000, Ranier Vilela wrote:

Hi,
Hi,
Maybe this is a real bug.

The assignment has no effect, or forget dereferencing it?

Best regards.
Ranier Vilela

--- \dll\postgresql-12.0\a\backend\optimizer\plan\initsplan.c	Mon Sep 30 17:06:55 2019
+++ initsplan.c	Fri Nov 22 19:48:42 2019
@@ -1718,7 +1718,7 @@
relids =
get_relids_in_jointree((Node *) root->parse->jointree,
false);
-					qualscope = bms_copy(relids);
+					bms_copy(relids);
}
}
}

Seriously, how are you searching for those "issues"?

1) We're using qualscope in an assert about 100 lines down, and as coded
we need a copy of relids because that may be mutated (and reallocated to
a different pointer). So no, the assignment *has* effect.

2) bms_copy(relids) on it's own is nonsensical, because it allocates a
copy but just throws the pointer away (why making the copy at all).

Have you tried modifying this code and running the regression tests? If
not, try it.

$ ./configure --enable-cassert
$ make
$ make check

Please, consider the suggestions from my previous response ...

regards

--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

#3Ranier Vilela
ranier_gyn@hotmail.com
In reply to: Tomas Vondra (#2)
RE: [PATCH] Tiny optmization or a bug?

Hi,
I just wanted to help a little bit, sorry for the out balls.

Maybe, I got one or two right.

Anyway, thank you very much for your attention and patience.

best regards.
Ranier Vilela

________________________________________
De: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Enviado: sexta-feira, 22 de novembro de 2019 23:25
Para: Ranier Vilela
Cc: pgsql-hackers@postgresql.org
Assunto: Re: [PATCH] Tiny optmization or a bug?

On Fri, Nov 22, 2019 at 11:06:53PM +0000, Ranier Vilela wrote:

Hi,
Hi,
Maybe this is a real bug.

The assignment has no effect, or forget dereferencing it?

Best regards.
Ranier Vilela

--- \dll\postgresql-12.0\a\backend\optimizer\plan\initsplan.c  Mon Sep 30 17:06:55 2019
+++ initsplan.c        Fri Nov 22 19:48:42 2019
@@ -1718,7 +1718,7 @@
relids =
get_relids_in_jointree((Node *) root->parse->jointree,
false);
-                                      qualscope = bms_copy(relids);
+                                      bms_copy(relids);
}
}
}

Seriously, how are you searching for those "issues"?

1) We're using qualscope in an assert about 100 lines down, and as coded
we need a copy of relids because that may be mutated (and reallocated to
a different pointer). So no, the assignment *has* effect.

2) bms_copy(relids) on it's own is nonsensical, because it allocates a
copy but just throws the pointer away (why making the copy at all).

Have you tried modifying this code and running the regression tests? If
not, try it.

$ ./configure --enable-cassert
$ make
$ make check

Please, consider the suggestions from my previous response ...

regards

--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services