Re: Truncate logs by max_log_size

On Fri, Nov 29, 2024 at 3:24 AM Jim Jones <jim(dot)jones(at)uni-muenster(dot)de> wrote:

>
>
> On 28.11.24 20:20, Kirill Gavrilov wrote:
> > Here is version 3 of this patch. I found another place where this
> > setting can be applied.
> > Also added some documentation and specified that this setting
> > truncates queries by size in bytes.
>
> Thanks. It is now possible to change the parameter using SET
>
> postgres=# SET max_log_size TO 15;
> SET
> postgres=# SHOW max_log_size ;
> max_log_size
> --------------
> 15
> (1 row)
>

> In the postgresql.conf the default value is set to 0
>
> #max_log_size = 0
>
> But if we take a look at the parameter it shows something else
>
> postgres=# SHOW max_log_size ;
> max_log_size
> --------------
> 5242880
> (1 row)
>
> Perhaps it would be best to keep the default value in the
> postgresql.conf consistent with the documentation and the actual
> max_log_size value. IMHO 0 (or -1) should disable it.
>
> There are also several compilation issues:
>
> postgres.c: In function ‘exec_simple_query’:
> postgres.c:1040:9: warning: ISO C90 forbids mixed declarations and code
> [-Wdeclaration-after-statement]
> 1040 | bool copied = false;
> | ^~~~
> elog.c: In function ‘EmitErrorReport’:
> elog.c:1697:9: warning: ISO C90 forbids mixed declarations and code
> [-Wdeclaration-after-statement]
> 1697 | const char* old_query_string = debug_query_string;
> | ^~~~~
> elog.c:1744:23: warning: passing argument 1 of ‘pfree’ discards ‘const’
> qualifier from pointer target type [-Wdiscarded-qualifiers]
> 1744 | pfree(debug_query_string);
> | ^~~~~~~~~~~~~~~~~~
> In file included from ../../../../src/include/postgres.h:47,
> from elog.c:55:
> ../../../../src/include/utils/palloc.h:86:25: note: expected ‘void *’
> but argument is of type ‘const char *’
> 86 | extern void pfree(void *pointer);
> | ~~~~~~^~~~~~~
> elog.c: In function ‘build_query_log’:
> elog.c:3798:9: warning: ISO C90 forbids mixed declarations and code
> [-Wdeclaration-after-statement]
> 3798 | size_t query_len = strlen(query);
> | ^~~~~~
> elog.c:3801:24: warning: return discards ‘const’ qualifier from pointer
> target type [-Wdiscarded-qualifiers]
> 3801 | return query;
> | ^~~~~
> elog.c:3805:9: warning: ISO C90 forbids mixed declarations and code
> [-Wdeclaration-after-statement]
> 3805 | size_t query_log_len = pg_mbcliplen(query, query_len,
> max_log_size);
> | ^~~~~~
>
> and there is a trailing whitespace at:
>
> + * If query needs to be truncated, copied will be set to true
>
>
> /home/jim/patches/max_log_query/V3-0001-parameter-max_log_size-to-truncate-logs.patch:141:
> trailing whitespace.
> * If query needs to be truncated, copied will be set to true
> Checking patch doc/src/sgml/config.sgml...
> Hunk #1 succeeded at 7865 (offset -48 lines).
> Checking patch src/backend/tcop/postgres.c...
> Hunk #1 succeeded at 71 (offset 1 line).
> Hunk #2 succeeded at 1031 (offset 1 line).
> Hunk #3 succeeded at 1083 (offset 1 line).
> Hunk #4 succeeded at 1382 (offset 1 line).
> Hunk #5 succeeded at 1393 (offset 1 line).
> Checking patch src/backend/utils/error/elog.c...
> Hunk #4 succeeded at 3781 (offset -3 lines).
> Checking patch src/backend/utils/misc/guc_tables.c...
> Hunk #1 succeeded at 3714 (offset -10 lines).
> Checking patch src/backend/utils/misc/postgresql.conf.sample...
> Hunk #1 succeeded at 615 (offset -2 lines).
> Checking patch src/bin/pg_ctl/t/004_logrotate.pl...
> Checking patch src/include/utils/elog.h...
> Applied patch doc/src/sgml/config.sgml cleanly.
> Applied patch src/backend/tcop/postgres.c cleanly.
> Applied patch src/backend/utils/error/elog.c cleanly.
> Applied patch src/backend/utils/misc/guc_tables.c cleanly.
> Applied patch src/backend/utils/misc/postgresql.conf.sample cleanly.
> Applied patch src/bin/pg_ctl/t/004_logrotate.pl cleanly.
> Applied patch src/include/utils/elog.h cleanly.
> warning: 1 line adds whitespace errors.
>
> --
> Jim
>
>
Thanks for spotting mistakes.
Setting max_log_size to 0 already disables truncation.
I changed guc units to bytes, just to make it more human-friendly. Did
some refactoring and fixed all warnings. Set default value in
postgresql.conf.