<!--

$PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.40 2005/12/23 00:38:03 momjian Exp $

$PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.41 2005/12/27 23:54:01 adunstan Exp $

-->

<chapter Id="runtime-config">

<title>Server Configuration</title>

<listitem>

<para>

Sets the number of shared memory buffers used by the database

server. The default is typically1000, but may be less if your

server. The default is typically4000, but may be less if your

kernel settings will not support it (as determined during

<application>initdb</>). Each buffer is 8192 bytes, unless a

different value of <symbol>BLCKSZ</symbol> was chosen when building

Sets the maximum number of disk pages for which free space will

be tracked in the shared free-space map. Six bytes of shared memory

are consumed for each page slot. This setting must be more than

16 * <varname>max_fsm_relations</varname>. The default is 20000.

This option can only be set at server start.

16 * <varname>max_fsm_relations</varname>. The default is 20000,

but <application>initdb</> will try to set it as close as possible

to 200000, depending on the amount of available memory.

This option can only be set at server start.

</para>

</listitem>

</varlistentry>

staticintn_connections=10;

staticintn_buffers=50;

staticintn_fsm_pages=20000;

}

}

#defineTEST_FSM(x) ( (x) > 1000 ? 50 * (x) : 20000 )

for (i=0;i<len;i++)

{

inttest_buffs=conns[i]*5;

inttest_max_fsm=TEST_FSM(test_buffs);

snprintf(cmd,sizeof(cmd),

"< \"%s\" > \"%s\" 2>&1%s",

SYSTEMQUOTE,backend_exec,boot_options,

conns[i]*5,conns[i],

test_max_fsm,

test_buffs,conns[i],

DEVNULL,DEVNULL,SYSTEMQUOTE);

status=system(cmd);

if (status==0)

test_buffers(void)

{

charcmd[MAXPGPATH];

staticconstintbufs[]= {1000,900,800,700,600,500,

400,300,200,100,50};

staticconstintbufs[]= {

4000,3500,3000,2500,2000,1500,

1000,900,800,700,600,500,

400,300,200,100,50

};

staticconstintlen=sizeof(bufs) /sizeof(int);

inti,

status;

status,

test_max_fsm_pages;

printf(_("selecting default shared_buffers ... "));

printf(_("selecting default shared_buffers/max_fsm_pages ... "));

fflush(stdout);

for (i=0;i<len;i++)

{

test_max_fsm_pages=TEST_FSM(bufs[i]);

snprintf(cmd,sizeof(cmd),

"< \"%s\" > \"%s\" 2>&1%s",

SYSTEMQUOTE,backend_exec,boot_options,

test_max_fsm_pages,

bufs[i],n_connections,

DEVNULL,DEVNULL,SYSTEMQUOTE);

status=system(cmd);

if (i >=len)

i=len-1;

n_buffers=bufs[i];

n_fsm_pages=test_max_fsm_pages;

printf("%d\n",n_buffers);

printf("%d/%d\n",n_buffers,n_fsm_pages);

}

snprintf(repltok,sizeof(repltok),"shared_buffers = %d",n_buffers);

conflines=replace_token(conflines,"#shared_buffers = 1000",repltok);

snprintf(repltok,sizeof(repltok),"max_fsm_pages = %d",n_fsm_pages);

conflines=replace_token(conflines,"#max_fsm_pages = 20000",repltok);

snprintf(repltok,sizeof(repltok),"#port = %d",DEF_PGPORT);

conflines=replace_token(conflines,"#port = 5432",repltok);