Re: [sqlite] some questions about sqlite

2012-09-02 Thread Jay A. Kreibich 
On Sat, Sep 01, 2012 at 11:56:33PM -0700, J Decker scratched on the wall:
> On Sat, Sep 1, 2012 at 8:24 PM, Jay A. Kreibich  wrote:
> > On Sat, Sep 01, 2012 at 07:37:04PM -0700, J Decker scratched on the wall:
> >> On Sat, Sep 1, 2012 at 7:32 PM, Simon Slavin  wrote:
> >> > On 2 Sep 2012, at 3:13am, shuif...@mail.ustc.edu.cn wrote:
> >
> >> >> 2??how many user connections the sqlite can handler
> >> >
> >> > There is no limit in SQLite for connections.
> >>
> >> It is not advised to have multiple processes connect to same file. ..
> >> but in-process probably no limit of connections.
> >
> >   I'm not sure where this idea comes from, as it is perfectly
> >   acceptable to have multiple processes accessing the same database
> >   file.
> >
> >   SQLite makes very little distinction between different connections
> >   from the same process and different connections from different
> >   processes, so there isn't any significant limit that applies to one
> >   situation that doesn't apply to the other.
> >
> >   Concurrency is always an issue, and you don't want hundreds of
> >   connections banging on the same file, but that's true no matter if
> >   the connections come from the same process or not.

> the point would be 'and not have concurrancy issues that I'd have to
> solve myself...'

  SQLite uses file locks to control concurrent access between all
  the connections.  This is true if the connections come from the
  same process or different processes.  Accessing the same SQLite
  file from multiple connections/threads/processes is perfectly safe.

  About the only time you run into concurrent access issues is if you
  attempt to access an SQLite database on a network-based file system.
  Most network-based file systems don't do locks correctly (and
  definitely don't do distributed locks correctly), so there can be
  issues.  This case is well known and well documented and can be
  considered a bug in the network filesystem implementations.

   -j

-- 
Jay A. Kreibich < J A Y  @  K R E I B I.C H >

"Intelligence is like underwear: it is important that you have it,
 but showing it to the wrong people has the tendency to make them
 feel uncomfortable." -- Angela Johnson
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

Re: [sqlite] some questions about sqlite

2012-09-02 Thread Keith Medcalf 
> but about the second question，I write java code，and find if the connection
> exceeds 17990，then will throws exception
> SQLite.Exception: unknown error in open
>   at SQLite.Database._open4(Native Method)
>   at SQLite.Database.open(Database.java:37)
>   at SQLite.MyDay.main(MyDay.java:20)
> Exception in thread "main" java.lang.OutOfMemoryError: unable to get SQLite
   

Buy more memory.

---
()  ascii ribbon campaign against html e-mail
/\  www.asciiribbon.org



___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

Re: [sqlite] some questions about sqlite

2012-09-02 Thread Simon Slavin 

On 2 Sep 2012, at 7:56am, J Decker  wrote:

> the point would be 'and not have concurrancy issues that I'd have to
> solve myself...'

Apache runs one process for each request it's serving [1].  I have multiple 
Apache processes -- i.e. multiple web page requests -- accessing the same 
database (using the sqlite3 PHP library) at the same time.  I think I noticed a 
log last year which showed ten simultaneous processes all within the same 
second.  SQLite serialised the requests using locking and everything worked as 
designed.  Everyone got an acceptably fast response with no problems.  I wasn't 
even using any special compilation options or PRAGMAs.

Simon.

[1] Handwave here.  If you know the details you don't need me to explain them.
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

Re: [sqlite] some questions about sqlite

2012-09-02 Thread J Decker 
On Sat, Sep 1, 2012 at 8:24 PM, Jay A. Kreibich  wrote:
> On Sat, Sep 01, 2012 at 07:37:04PM -0700, J Decker scratched on the wall:
>> On Sat, Sep 1, 2012 at 7:32 PM, Simon Slavin  wrote:
>> > On 2 Sep 2012, at 3:13am, shuif...@mail.ustc.edu.cn wrote:
>
>> >> 2??how many user connections the sqlite can handler
>> >
>> > There is no limit in SQLite for connections.
>>
>> It is not advised to have multiple processes connect to same file. ..
>> but in-process probably no limit of connections.
>
>   I'm not sure where this idea comes from, as it is perfectly
>   acceptable to have multiple processes accessing the same database
>   file.
>
>   SQLite makes very little distinction between different connections
>   from the same process and different connections from different
>   processes, so there isn't any significant limit that applies to one
>   situation that doesn't apply to the other.
>
>   Concurrency is always an issue, and you don't want hundreds of
>   connections banging on the same file, but that's true no matter if
>   the connections come from the same process or not.
>

the point would be 'and not have concurrancy issues that I'd have to
solve myself...'

>-j
>
> --
> Jay A. Kreibich < J A Y  @  K R E I B I.C H >
>
> "Intelligence is like underwear: it is important that you have it,
>  but showing it to the wrong people has the tendency to make them
>  feel uncomfortable." -- Angela Johnson
> ___
> sqlite-users mailing list
> sqlite-users@sqlite.org
> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

Re: [sqlite] some questions about sqlite

2012-09-01 Thread Pavel Ivanov 
> thanks a lot，
> but about the second question，I write java code，and find if the connection 
> exceeds 17990，then will throws exception

This probably happened because your OS restricts number of open file
descriptors or something like that.

Pavel


On Sat, Sep 1, 2012 at 7:52 PM,  <shuif...@mail.ustc.edu.cn> wrote:
> thanks a lot，
> but about the second question，I write java code，and find if the connection 
> exceeds 17990，then will throws exception
> SQLite.Exception: unknown error in open
> at SQLite.Database._open4(Native Method)
> at SQLite.Database.open(Database.java:37)
> at SQLite.MyDay.main(MyDay.java:20)
> Exception in thread "main" java.lang.OutOfMemoryError: unable to get SQLite 
> handle
> at SQLite.Database._open4(Native Method)
> at SQLite.Database.open(Database.java:37)
> at SQLite.MyDay.main(MyDay.java:20)
>
> the source java code:
> public static void main(String[] args) {
> // TODO Auto-generated method stub
> int count=0;
>
> while(count<=17990){
> Database db = new Database();
>
> try {
> // open connection,but not close
> db.open("c:\\my1.db", 0666);
> count++;
> db.interrupt();
> db.busy_timeout(1000);
> db.busy_handler(null);
>
> } catch (Exception e) {
> e.printStackTrace();
> }
> }
>
> System.out.println(count);
> }
>
>
>> -Original E-mail-
>> From: "J Decker" <d3c...@gmail.com>
>> Sent Time: 2012-9-2 10:37:04
>> To: "General Discussion of SQLite Database" <sqlite-users@sqlite.org>
>> Cc:
>> Subject: Re: [sqlite] some questions about sqlite
>>
>> On Sat, Sep 1, 2012 at 7:32 PM, Simon Slavin <slav...@bigfraud.org> wrote:
>> >
>> > On 2 Sep 2012, at 3:13am, shuif...@mail.ustc.edu.cn wrote:
>> >
>> >> 1、Do the sqlite support job like oracle or sqlserver,such as
>> >>variable job1 number;
>> >>begin
>> >>sys.dbms_job.submit(job => :job,
>> >>what => 'prc_g_test;',
>> >> next_date => to_date('22-10-2008 10:06:41', 
>> >> 'dd-mm- hh24:mi:ss'),
>> >> interval => 
>> >> 'sysdate+1/1440');--每天1440分钟，即一分钟运行test过程一次
>> >> commit;
>> >>end;
>> >
>> > No.
>> >
>> >> 2、how many user connections the sqlite can handler
>> >
>> > There is no limit in SQLite for connections.
>>
>> It is not advised to have multiple processes connect to same file. ..
>> but in-process probably no limit of connections.
>>
>> >
>> > Simon.
>> > ___
>> > sqlite-users mailing list
>> > sqlite-users@sqlite.org
>> > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
>> ___
>> sqlite-users mailing list
>> sqlite-users@sqlite.org
>> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
>
> ___
> sqlite-users mailing list
> sqlite-users@sqlite.org
> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

Re: [sqlite] some questions about sqlite

2012-09-01 Thread Jay A. Kreibich 
On Sat, Sep 01, 2012 at 07:37:04PM -0700, J Decker scratched on the wall:
> On Sat, Sep 1, 2012 at 7:32 PM, Simon Slavin  wrote:
> > On 2 Sep 2012, at 3:13am, shuif...@mail.ustc.edu.cn wrote:

> >> 2??how many user connections the sqlite can handler
> >
> > There is no limit in SQLite for connections.
> 
> It is not advised to have multiple processes connect to same file. ..
> but in-process probably no limit of connections.

  I'm not sure where this idea comes from, as it is perfectly
  acceptable to have multiple processes accessing the same database
  file.

  SQLite makes very little distinction between different connections
  from the same process and different connections from different
  processes, so there isn't any significant limit that applies to one
  situation that doesn't apply to the other.

  Concurrency is always an issue, and you don't want hundreds of
  connections banging on the same file, but that's true no matter if
  the connections come from the same process or not.

   -j

-- 
Jay A. Kreibich < J A Y  @  K R E I B I.C H >

"Intelligence is like underwear: it is important that you have it,
 but showing it to the wrong people has the tendency to make them
 feel uncomfortable." -- Angela Johnson
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

Re: [sqlite] some questions about sqlite

2012-09-01 Thread shuifeng 
thanks a lot，
but about the second question，I write java code，and find if the connection 
exceeds 17990，then will throws exception
SQLite.Exception: unknown error in open
at SQLite.Database._open4(Native Method)
at SQLite.Database.open(Database.java:37)
at SQLite.MyDay.main(MyDay.java:20)
Exception in thread "main" java.lang.OutOfMemoryError: unable to get SQLite 
handle
at SQLite.Database._open4(Native Method)
at SQLite.Database.open(Database.java:37)
at SQLite.MyDay.main(MyDay.java:20)

the source java code:
public static void main(String[] args) {
// TODO Auto-generated method stub
int count=0;

while(count<=17990){
Database db = new Database();

try {
// open connection,but not close
db.open("c:\\my1.db", 0666);
count++;
db.interrupt();
db.busy_timeout(1000);
db.busy_handler(null);

} catch (Exception e) {
e.printStackTrace();
}
}

System.out.println(count);
}


> -Original E-mail-
> From: "J Decker" <d3c...@gmail.com>
> Sent Time: 2012-9-2 10:37:04
> To: "General Discussion of SQLite Database" <sqlite-users@sqlite.org>
> Cc: 
> Subject: Re: [sqlite] some questions about sqlite
> 
> On Sat, Sep 1, 2012 at 7:32 PM, Simon Slavin <slav...@bigfraud.org> wrote:
> >
> > On 2 Sep 2012, at 3:13am, shuif...@mail.ustc.edu.cn wrote:
> >
> >> 1、Do the sqlite support job like oracle or sqlserver,such as
> >>variable job1 number;
> >>begin
> >>sys.dbms_job.submit(job => :job,
> >>what => 'prc_g_test;',
> >> next_date => to_date('22-10-2008 10:06:41', 
> >> 'dd-mm- hh24:mi:ss'),
> >> interval => 
> >> 'sysdate+1/1440');--每天1440分钟，即一分钟运行test过程一次
> >> commit;
> >>end;
> >
> > No.
> >
> >> 2、how many user connections the sqlite can handler
> >
> > There is no limit in SQLite for connections.
> 
> It is not advised to have multiple processes connect to same file. ..
> but in-process probably no limit of connections.
> 
> >
> > Simon.
> > ___
> > sqlite-users mailing list
> > sqlite-users@sqlite.org
> > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
> ___
> sqlite-users mailing list
> sqlite-users@sqlite.org
> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

Re: [sqlite] some questions about sqlite

2012-09-01 Thread J Decker 
On Sat, Sep 1, 2012 at 7:32 PM, Simon Slavin  wrote:
>
> On 2 Sep 2012, at 3:13am, shuif...@mail.ustc.edu.cn wrote:
>
>> 1、Do the sqlite support job like oracle or sqlserver,such as
>>variable job1 number;
>>begin
>>sys.dbms_job.submit(job => :job,
>>what => 'prc_g_test;',
>> next_date => to_date('22-10-2008 10:06:41', 
>> 'dd-mm- hh24:mi:ss'),
>> interval => 
>> 'sysdate+1/1440');--每天1440分钟，即一分钟运行test过程一次
>> commit;
>>end;
>
> No.
>
>> 2、how many user connections the sqlite can handler
>
> There is no limit in SQLite for connections.

It is not advised to have multiple processes connect to same file. ..
but in-process probably no limit of connections.

>
> Simon.
> ___
> sqlite-users mailing list
> sqlite-users@sqlite.org
> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

Re: [sqlite] some questions about sqlite

2012-09-01 Thread Simon Slavin 

On 2 Sep 2012, at 3:13am, shuif...@mail.ustc.edu.cn wrote:

> 1、Do the sqlite support job like oracle or sqlserver,such as
>variable job1 number; 
>begin 
>sys.dbms_job.submit(job => :job, 
>what => 'prc_g_test;', 
> next_date => to_date('22-10-2008 10:06:41', 
> 'dd-mm- hh24:mi:ss'), 
> interval => 
> 'sysdate+1/1440');--每天1440分钟，即一分钟运行test过程一次 
> commit; 
>end; 

No.

> 2、how many user connections the sqlite can handler

There is no limit in SQLite for connections.

Simon.
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users