Re: psql and bytea
Sorry for my poor English.
First, postgresql is a beautiful DBMS !
I try to use bytea type with psql to store some files (i know, there are
\lo_*).
There are some informations in the man page of psql :
------------------------------------
Another possible use of this mechanism is to copy the contents of a file
into a field. First load the file into a variable and then proceed as
above.
testdb=> \set content ’\’’ ‘cat my_file.txt‘ ’\’’
testdb=> INSERT INTO my_table VALUES (:content);
One possible problem with this approach is that my_file.txt might
contain single quotes. These need to be escaped so that they don’t cause
a syntax error when the third line is processed. This could be done
with the program sed:
testdb=> \set content ’\’’ ‘sed -e "s/’/\\\\\\’/g" < my_file.txt‘ ’\’’
But this does not work with binary string (bytea) since i want to store
any kind of files.
------------------------------------
I check the documentation (really fantastic documentation ! Great job):
http://www.postgresql.org/docs/view.php?version=7.3&idoc=0&file=datatype-binary.html
I build two very simple tools to convert a binary stream to a bytea
stream.
------------------------------------
tobytea_sql.c :
/*
* convert a stream to bytea.
* The '\' is escaped, so it can be used in a SQL statement.
*/
#include <stdio.h>
int main(void) {
int c ;
while ((c = getchar()) != EOF) {
if ( c == '\'' || c == '\\' ||
c < 32 || c > 126 ) {
printf("\\\\%d%d%d",
(c % (8*8*8)) / (8*8),
(c % (8*8)) / 8,
c % 8) ;
}
else {
putchar(c) ;
}
}
return 0 ;
}
------------------------------------
/*
* convert a bytea stream
* This is not compatible with the output of tobytea_sql !
* tobytea_sql put two \ . frombytea espect only one !
*/
#include <stdio.h>
int main(void) {
int c ;
int car ;
while ((c = getchar()) != EOF) {
if ( c < 32 || c > 126) {
fprintf(stderr, "Char ignored\n") ;
break ;
}
if ( c == '\\' ) {
if ((c = getchar()) == EOF) return 0 ;
car = (c - '0') * 8 * 8 ;
if ((c = getchar()) == EOF) return 0 ;
car += (c - '0') * 8 ;
if ((c = getchar()) == EOF) return 0 ;
car += c - '0' ;
putchar(car) ;
}
else {
putchar(c) ;
}
}
return 0 ;
}
------------------------------------
How to use it ?
insert into a table :
$ psql
[...]
one=> create temp table tmp (data bytea) ;
CREATE TABLE
one=> -- push some data in a psql variable
one=> \set content '\''`tobytea_sql < data`'\''
one=> \echo :content
'o\\030\\251\\273C7\\266K\\331 ... [snip] ... \323W\\027\\256D'
one=> -- insert
one=> insert into tmp (data) values (:content) ;
INSERT 35042356 1
one=> -- vrite the content of temp.data to a file
one=> \a
Output format is unaligned.
one=> \t
Showing only tuples.
one=> \o | frombytea > data
one=> select data from tmp ;
one=> Char ignored -- psql send a CR at the end of the row
(frombytea drop it since CR = 10 and it is not a "normal" char for a
bytea stream).
Is there a bug in psql ? Check this :
WARNING : this example take a lot of memory !
Create a big file with some random data :
$ dd if=/dev/urandom bs=1M count=20 of=data
$ #the bytea stream is about 74 Mo !)
$ tobytea < data | wc
0 81574 74379444
$ psql
[...]
one=> \set content '\''`tobytea_sql < data`'\''
one=> insert into tmp (data) values(:content) ;
one'> -- Problem !
one'> ' -- try to continue
one(> ) ;
INSERT 35042373 1
one=> select length(data) from tmp ;
length
--
18924736
(1 row)
one=> -- this is not the original size (20M : 20971520).
I don't have any problems with smaller files (10Mo is always fine).
All of this is used with postgresql 7.3.2 shipped with Red Hat Linux 9 .
--
Féliciano Matias <feliciano.matias@free.fr>
Import Notes
Reply to msg id not found: 1052987079.17205.2.camel@one.myworldReference msg id not found: 1052987079.17205.2.camel@one.myworld
=?ISO-8859-1?Q?F=E9liciano?= Matias <feliciano.matias@free.fr> writes:
one=3D> -- this is not the original size (20M : 20971520).
I don't have any problems with smaller files (10Mo is always fine).
All of this is used with postgresql 7.3.2 shipped with Red Hat Linux 9 .
Hmm. There used to be some off-by-one type bugs in psql's
variable-substitution code, but those were fixed long before 7.3.2.
In any case, it's hard to see why such a problem would only arise
when you got past 10Mb string lengths.
I couldn't duplicate the problem here, so I'm going to suggest that
maybe you have a hardware problem? Perhaps there's a flaky RAM chip in
an area of memory that doesn't get used until you push up the size
of psql quite a bit. It'd be worth running memtest86 for awhile to
check.
regards, tom lane
Le jeu 15/05/2003 à 16:47, Tom Lane a écrit :
=?ISO-8859-1?Q?F=E9liciano?= Matias <feliciano.matias@free.fr> writes:
one=3D> -- this is not the original size (20M : 20971520).
I don't have any problems with smaller files (10Mo is always fine).
All of this is used with postgresql 7.3.2 shipped with Red Hat Linux 9 .Hmm. There used to be some off-by-one type bugs in psql's
variable-substitution code, but those were fixed long before 7.3.2.
In any case, it's hard to see why such a problem would only arise
when you got past 10Mb string lengths.
More then 10Mb string lengths :
$ tobytea < data | wc
0 81574 74379444 (71 Mo)
I couldn't duplicate the problem here,
It seems it's a bug in glibc-2.3.2-27.9.i686.rpm coming with RH9.
so I'm going to suggest that
maybe you have a hardware problem? Perhaps there's a flaky RAM chip in
an area of memory that doesn't get used until you push up the size
of psql quite a bit. It'd be worth running memtest86 for awhile to
check.
The hardware is ok.
I found the problem. It's bug in sprintf()
===============================================
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define SIZE (1024*70000)
int main(void) {
char * s = malloc(SIZE) ;
char * d = malloc(SIZE) ;
memset(s, 'a', SIZE-1) ;
d[SIZE-1] = '\0' ;
sprintf(d,"%s",s) ;
printf("%zi\n", strlen(d)) ;
return 0 ;
}
===============================================
$ ./a.out
67108863 (2^26-1)
My libc have a problem. I will fill a bug report to
http://bugzilla.redhat.com/ .
I apply this patch to the postgresql source :
===============================================
diff -urN postgresql-7.3.2.orig/src/bin/psql/mainloop.c postgresql-7.3.2/src/bin/psql/mainloop.c
--- postgresql-7.3.2.orig/src/bin/psql/mainloop.c 2002-10-13 01:09:34.000000000 +0200
+++ postgresql-7.3.2/src/bin/psql/mainloop.c 2003-05-16 04:46:03.000000000 +0200
@@ -389,8 +389,9 @@
exit(EXIT_FAILURE);
}- sprintf(new, "%.*s%s%s", i, line, value,
- &line[i + thislen + in_length]);
+ sprintf(new, "%.*s", i, line) ;
+ strcat(&new[i], value) ;
+ strcat(&new[i+out_length], &line[i + thislen + in_length]) ; free(line);
line = new;
===============================================
Also, i want to know if someone is interesting by tools such as
(to|from)bytea. I can put this little toys (with some enhancement.
"--help" :-) ) in contrib and update the man page of psql to show how
to use this tools to copy the content of a file (or stream) into a
field.
Since Postgresql have binary string, it is interesting and better than
\lo_* for little files (this use more memory than \lo_*).
By the way, i can add an option to psql that toggle the output of
carrier return at the end of each records. Perhaps this can be add to
\t.
regards, tom lane
--
Féliciano Matias <feliciano.matias@free.fr>
** Reply to message from Féliciano Matias <feliciano.matias@free.fr> on 16 May
2003 06:56:02 +0200
Hi,
I'm interested :)
Regards,
Wayne
Show quoted text
Le jeu 15/05/2003 à 16:47, Tom Lane a écrit :
=?ISO-8859-1?Q?F=E9liciano?= Matias <feliciano.matias@free.fr> writes:
one=3D> -- this is not the original size (20M : 20971520).
I don't have any problems with smaller files (10Mo is always fine).
All of this is used with postgresql 7.3.2 shipped with Red Hat Linux 9 .Hmm. There used to be some off-by-one type bugs in psql's
variable-substitution code, but those were fixed long before 7.3.2.
In any case, it's hard to see why such a problem would only arise
when you got past 10Mb string lengths.More then 10Mb string lengths :
$ tobytea < data | wc
0 81574 74379444 (71 Mo)I couldn't duplicate the problem here,
It seems it's a bug in glibc-2.3.2-27.9.i686.rpm coming with RH9.
so I'm going to suggest that
maybe you have a hardware problem? Perhaps there's a flaky RAM chip in
an area of memory that doesn't get used until you push up the size
of psql quite a bit. It'd be worth running memtest86 for awhile to
check.The hardware is ok.
I found the problem. It's bug in sprintf()
===============================================
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define SIZE (1024*70000)
int main(void) {
char * s = malloc(SIZE) ;
char * d = malloc(SIZE) ;
memset(s, 'a', SIZE-1) ;
d[SIZE-1] = '\0' ;
sprintf(d,"%s",s) ;
printf("%zi\n", strlen(d)) ;
return 0 ;
}
===============================================
$ ./a.out
67108863 (2^26-1)My libc have a problem. I will fill a bug report to
http://bugzilla.redhat.com/ .I apply this patch to the postgresql source : =============================================== diff -urN postgresql-7.3.2.orig/src/bin/psql/mainloop.c postgresql-7.3.2/src/bin/psql/mainloop.c --- postgresql-7.3.2.orig/src/bin/psql/mainloop.c 2002-10-13 01:09:34.000000000 +0200 +++ postgresql-7.3.2/src/bin/psql/mainloop.c 2003-05-16 04:46:03.000000000 +0200 @@ -389,8 +389,9 @@ exit(EXIT_FAILURE); }- sprintf(new, "%.*s%s%s", i, line, value, - &line[i + thislen + in_length]); + sprintf(new, "%.*s", i, line) ; + strcat(&new[i], value) ; + strcat(&new[i+out_length], &line[i + thislen + in_length]) ;free(line);
line = new;
===============================================Also, i want to know if someone is interesting by tools such as
(to|from)bytea. I can put this little toys (with some enhancement.
"--help" :-) ) in contrib and update the man page of psql to show how
to use this tools to copy the content of a file (or stream) into a
field.
Since Postgresql have binary string, it is interesting and better than
\lo_* for little files (this use more memory than \lo_*).By the way, i can add an option to psql that toggle the output of
carrier return at the end of each records. Perhaps this can be add to
\t.regards, tom lane
--
Féliciano Matias <feliciano.matias@free.fr>
My libc have a problem. I will fill a bug report to
http://bugzilla.redhat.com/ .
done :
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=90987
--
Féliciano Matias <feliciano.matias@free.fr>
Le ven 16/05/2003 à 06:56, Féliciano Matias a écrit :
All of this is used with postgresql 7.3.2 shipped with Red Hat Linux 9
[...]
I found the problem. It's bug in sprintf()
===============================================
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define SIZE (1024*70000)
int main(void) {
char * s = malloc(SIZE) ;
char * d = malloc(SIZE) ;
memset(s, 'a', SIZE-1) ;
d[SIZE-1] = '\0' ;
sprintf(d,"%s",s) ;
printf("%zi\n", strlen(d)) ;
return 0 ;
}
===============================================
$ ./a.out
67108863 (2^26-1)
from
bugzilla@redhat.com
------- Additional Comments From drepper@redhat.com 2003-06-09 23:22 -------
The current glibc CVS code has been changed to not have this liimtation anymore.
--
Féliciano Matias <feliciano.matias@free.fr>
I've seen that come up several times now.
Fï¿œliciano Matias wrote:
Show quoted text
Le ven 16/05/2003 ￜ 06:56, Fￜliciano Matias a ￜcrit :
All of this is used with postgresql 7.3.2 shipped with Red Hat Linux 9
[...]
I found the problem. It's bug in sprintf()
===============================================
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define SIZE (1024*70000)
int main(void) {
char * s = malloc(SIZE) ;
char * d = malloc(SIZE) ;
memset(s, 'a', SIZE-1) ;
d[SIZE-1] = '\0' ;
sprintf(d,"%s",s) ;
printf("%zi\n", strlen(d)) ;
return 0 ;
}
===============================================
$ ./a.out
67108863 (2^26-1)from
bugzilla@redhat.com
------- Additional Comments From drepper@redhat.com 2003-06-09 23:22 -------
The current glibc CVS code has been changed to not have this liimtation anymore.