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Add ALTER SYSTEM command to edit the server configuration file.
Patch contributed by Amit Kapila. Reviewed by Hari Babu, Masao Fujii, Boszormenyi Zoltan, Andres Freund, Greg Smith and others.
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‎doc/src/sgml/config.sgml

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@@ -158,6 +158,19 @@ SET ENABLE_SEQSCAN TO OFF;
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require superuser permission to change via <command>SET</command> or
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<command>ALTER</>.
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</para>
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<para>
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Another way to change configuration parameters persistently is by
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use of <xref linkend="SQL-ALTERSYSTEM">
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command, for example:
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<screen>
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ALTER SYSTEM SET checkpoint_timeout TO 600;
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</screen>
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This command will allow users to change values persistently
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through SQL command. The values will be effective after reload of server configuration
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(<acronym>SIGHUP</>) or server startup. The effect of this command is similar to when
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user manually changes values in <filename>postgresql.conf</filename>.
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</para>
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</sect2>
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<sect2 id="config-setting-examining">

‎doc/src/sgml/ref/allfiles.sgml

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@@ -30,6 +30,7 @@ Complete list of usable sgml source files in this directory.
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<!ENTITY alterSchema SYSTEM "alter_schema.sgml">
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<!ENTITY alterServer SYSTEM "alter_server.sgml">
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<!ENTITY alterSequence SYSTEM "alter_sequence.sgml">
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<!ENTITY alterSystem SYSTEM "alter_system.sgml">
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<!ENTITY alterTable SYSTEM "alter_table.sgml">
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<!ENTITY alterTableSpace SYSTEM "alter_tablespace.sgml">
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<!ENTITY alterTSConfig SYSTEM "alter_tsconfig.sgml">

‎doc/src/sgml/ref/alter_system.sgml

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@@ -0,0 +1,114 @@
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<!--
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doc/src/sgml/ref/alter_system.sgml
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PostgreSQL documentation
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-->
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<refentry id="SQL-ALTERSYSTEM">
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<refmeta>
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<refentrytitle>ALTER SYSTEM</refentrytitle>
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<manvolnum>7</manvolnum>
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<refmiscinfo>SQL - Language Statements</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>ALTER SYSTEM</refname>
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<refpurpose>change a server configuration parameter</refpurpose>
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</refnamediv>
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<indexterm zone="sql-altersystem">
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<primary>ALTER SYSTEM</primary>
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</indexterm>
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<refsynopsisdiv>
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<synopsis>
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ALTER SYSTEM SET <replaceable class="PARAMETER">configuration_parameter</replaceable> { TO | = } { <replaceable class="PARAMETER">value</replaceable> | '<replaceable class="PARAMETER">value</replaceable>' | DEFAULT }
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</synopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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<command>ALTER SYSTEM</command> writes the configuration parameter
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values to the <filename>postgresql.auto.conf</filename> file. With
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<literal>DEFAULT</literal>, it removes a configuration entry from
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<filename>postgresql.auto.conf</filename> file. The values will be
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effective after reload of server configuration (SIGHUP) or in next
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server start based on the type of configuration parameter modified.
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</para>
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<para>
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This command is not allowed inside transaction block or function.
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</para>
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<para>
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See <xref linkend="config-setting"> for other ways to set the parameters and
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how they become effective.
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</para>
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</refsect1>
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<refsect1>
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<title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><replaceable class="parameter">configuration_parameter</replaceable></term>
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<listitem>
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<para>
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Name of a settable run-time parameter. Available parameters are
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documented in <xref linkend="runtime-config">.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">value</replaceable></term>
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<listitem>
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<para>
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New value of parameter. Values can be specified as string
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constants, identifiers, numbers, or comma-separated lists of
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these, as appropriate for the particular parameter.
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<literal>DEFAULT</literal> can be written to specify to remove the
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parameter and its value from <filename>postgresql.auto.conf</filename>
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
80+
<title>Examples</title>
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<para>
83+
Set the <literal>wal_level</>:
84+
<programlisting>
85+
ALTER SYSTEM SET wal_level = hot_standby;
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</programlisting>
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</para>
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<para>
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Set the <literal>authentication_timeout</>:
91+
<programlisting>
92+
ALTER SYSTEM SET authentication_timeout = 10;
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</programlisting></para>
94+
</refsect1>
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<refsect1>
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<title>Compatibility</title>
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<para>
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The <command>ALTER SYSTEM</command> statement is a
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<productname>PostgreSQL</productname> extension.
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</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<simplelist type="inline">
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<member><xref linkend="SQL-SET"></member>
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<member><xref linkend="SQL-SHOW"></member>
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</simplelist>
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</refsect1>
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</refentry>

‎doc/src/sgml/reference.sgml

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@@ -58,6 +58,7 @@
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&alterSchema;
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&alterSequence;
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&alterServer;
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&alterSystem;
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&alterTable;
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&alterTableSpace;
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&alterTSConfig;

‎doc/src/sgml/storage.sgml

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@@ -125,6 +125,12 @@ Item
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<entry>Subdirectory containing WAL (Write Ahead Log) files</entry>
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</row>
127127

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<row>
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<entry><filename>postgresql.auto.conf</></entry>
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<entry>A file used for storing configuration parameters that are set by
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<command>ALTER SYSTEM</command></entry>
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</row>
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<row>
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<entry><filename>postmaster.opts</></entry>
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<entry>A file recording the command-line options the server was

‎src/backend/nodes/copyfuncs.c

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@@ -3292,6 +3292,16 @@ _copyReplicaIdentityStmt(const ReplicaIdentityStmt *from)
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return newnode;
32933293
}
32943294

3295+
static AlterSystemStmt *
3296+
_copyAlterSystemStmt(const AlterSystemStmt * from)
3297+
{
3298+
AlterSystemStmt *newnode = makeNode(AlterSystemStmt);
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3300+
COPY_NODE_FIELD(setstmt);
3301+
3302+
return newnode;
3303+
}
3304+
32953305
static CreateSeqStmt *
32963306
_copyCreateSeqStmt(const CreateSeqStmt *from)
32973307
{
@@ -4368,6 +4378,9 @@ copyObject(const void *from)
43684378
case T_ReplicaIdentityStmt:
43694379
retval = _copyReplicaIdentityStmt(from);
43704380
break;
4381+
case T_AlterSystemStmt:
4382+
retval = _copyAlterSystemStmt(from);
4383+
break;
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case T_CreateSeqStmt:
43724385
retval = _copyCreateSeqStmt(from);
43734386
break;

‎src/backend/nodes/equalfuncs.c

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@@ -1546,6 +1546,15 @@ _equalReplicaIdentityStmt(const ReplicaIdentityStmt *a, const ReplicaIdentityStm
15461546
return true;
15471547
}
15481548

1549+
static bool
1550+
_equalAlterSystemStmt(const AlterSystemStmt * a, const AlterSystemStmt * b)
1551+
{
1552+
COMPARE_NODE_FIELD(setstmt);
1553+
1554+
return true;
1555+
}
1556+
1557+
15491558
static bool
15501559
_equalCreateSeqStmt(const CreateSeqStmt *a, const CreateSeqStmt *b)
15511560
{
@@ -2838,6 +2847,9 @@ equal(const void *a, const void *b)
28382847
case T_ReplicaIdentityStmt:
28392848
retval = _equalReplicaIdentityStmt(a, b);
28402849
break;
2850+
case T_AlterSystemStmt:
2851+
retval = _equalAlterSystemStmt(a, b);
2852+
break;
28412853
case T_CreateSeqStmt:
28422854
retval = _equalCreateSeqStmt(a, b);
28432855
break;

‎src/backend/parser/gram.y

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@@ -216,7 +216,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
216216
AlterEventTrigStmt
217217
AlterDatabaseStmt AlterDatabaseSetStmt AlterDomainStmt AlterEnumStmt
218218
AlterFdwStmt AlterForeignServerStmt AlterGroupStmt
219-
AlterObjectSchemaStmt AlterOwnerStmt AlterSeqStmt AlterTableStmt
219+
AlterObjectSchemaStmt AlterOwnerStmt AlterSeqStmt AlterSystemStmt AlterTableStmt
220220
AlterExtensionStmt AlterExtensionContentsStmt AlterForeignTableStmt
221221
AlterCompositeTypeStmt AlterUserStmt AlterUserMappingStmt AlterUserSetStmt
222222
AlterRoleStmt AlterRoleSetStmt
@@ -397,7 +397,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
397397

398398
%type <istmt> insert_rest
399399

400-
%type <vsetstmt> set_rest set_rest_more SetResetClause FunctionSetResetClause
400+
%type <vsetstmt> generic_set set_rest set_rest_more SetResetClause FunctionSetResetClause
401401

402402
%type <node> TableElement TypedTableElement ConstraintElem TableFuncElement
403403
%type <node> columnDef columnOptions
@@ -724,6 +724,7 @@ stmt :
724724
| AlterObjectSchemaStmt
725725
| AlterOwnerStmt
726726
| AlterSeqStmt
727+
| AlterSystemStmt
727728
| AlterTableStmt
728729
| AlterCompositeTypeStmt
729730
| AlterRoleSetStmt
@@ -1333,7 +1334,7 @@ set_rest:
13331334
| set_rest_more
13341335
;
13351336

1336-
set_rest_more: /* Generic SET syntaxes: */
1337+
generic_set:
13371338
var_name TO var_list
13381339
{
13391340
VariableSetStmt *n = makeNode(VariableSetStmt);
@@ -1364,6 +1365,9 @@ set_rest_more: /* Generic SET syntaxes: */
13641365
n->name = $1;
13651366
$$ = n;
13661367
}
1368+
1369+
set_rest_more: /* Generic SET syntaxes: */
1370+
generic_set {$$ = $1;}
13671371
| var_name FROM CURRENT_P
13681372
{
13691373
VariableSetStmt *n = makeNode(VariableSetStmt);
@@ -8310,6 +8314,23 @@ DropdbStmt: DROP DATABASE database_name
83108314
;
83118315

83128316

8317+
/*****************************************************************************
8318+
*
8319+
* ALTER SYSTEM SET
8320+
*
8321+
* This is used to change configuration parameters persistently.
8322+
*****************************************************************************/
8323+
8324+
AlterSystemStmt:
8325+
ALTER SYSTEM_P SET generic_set
8326+
{
8327+
AlterSystemStmt *n = makeNode(AlterSystemStmt);
8328+
n->setstmt = $4;
8329+
$$ = (Node *)n;
8330+
}
8331+
;
8332+
8333+
83138334
/*****************************************************************************
83148335
*
83158336
* Manipulate a domain

‎src/backend/replication/basebackup.c

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@@ -811,6 +811,13 @@ sendDir(char *path, int basepathlen, bool sizeonly)
811811
strlen(PG_TEMP_FILE_PREFIX)) == 0)
812812
continue;
813813

814+
/* skip auto conf temporary file */
815+
if (strncmp(de->d_name,
816+
PG_AUTOCONF_FILENAME ".temp",
817+
sizeof(PG_AUTOCONF_FILENAME) + 4) == 0)
818+
continue;
819+
820+
814821
/*
815822
* If there's a backup_label file, it belongs to a backup started by
816823
* the user with pg_start_backup(). It is *not* correct for this

‎src/backend/tcop/utility.c

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@@ -687,6 +687,11 @@ standard_ProcessUtility(Node *parsetree,
687687
ExplainQuery((ExplainStmt *) parsetree, queryString, params, dest);
688688
break;
689689

690+
case T_AlterSystemStmt:
691+
PreventTransactionChain(isTopLevel, "ALTER SYSTEM");
692+
AlterSystemSetConfigFile((AlterSystemStmt *) parsetree);
693+
break;
694+
690695
case T_VariableSetStmt:
691696
ExecSetVariableStmt((VariableSetStmt *) parsetree, isTopLevel);
692697
break;
@@ -2157,6 +2162,10 @@ CreateCommandTag(Node *parsetree)
21572162
tag = "REFRESH MATERIALIZED VIEW";
21582163
break;
21592164

2165+
case T_AlterSystemStmt:
2166+
tag = "ALTER SYSTEM";
2167+
break;
2168+
21602169
case T_VariableSetStmt:
21612170
switch (((VariableSetStmt *) parsetree)->kind)
21622171
{
@@ -2726,6 +2735,10 @@ GetCommandLogLevel(Node *parsetree)
27262735
lev = LOGSTMT_DDL;
27272736
break;
27282737

2738+
case T_AlterSystemStmt:
2739+
lev = LOGSTMT_ALL;
2740+
break;
2741+
27292742
case T_VariableSetStmt:
27302743
lev = LOGSTMT_ALL;
27312744
break;

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