diff --git a/contrib/postgres_fdw/connection.c b/contrib/postgres_fdw/connection.c
index 6bac4ad23e..7d6a49be74 100644
--- a/contrib/postgres_fdw/connection.c
+++ b/contrib/postgres_fdw/connection.c
@@ -348,6 +348,7 @@ connect_pg_server(ForeignServer *server, UserMapping *user)
{
const char **keywords;
const char **values;
+ char *data = NULL;
int n;
/*
@@ -383,6 +384,36 @@ connect_pg_server(ForeignServer *server, UserMapping *user)
n++;
}
+ /*
+ * Search the parameter arrays to find application_name setting,
+ * and replace escape sequences in it with status information if found.
+ * The arrays are searched backwards because the last value
+ * is used if application_name is repeatedly set.
+ */
+ for (int i = n - 1; i >= 0; i--)
+ {
+ if (strcmp(keywords[i], "application_name") == 0)
+ {
+ data = process_pgfdw_appname(values[i]);
+
+ /* Use the string and break if it is valid */
+ if (data[0] != '\0')
+ {
+ values[i] = data;
+ break;
+ }
+
+ /*
+ * The parsing result became an empty string,
+ * and that means other "application_name" will be used
+ * for connecting to the remote server.
+ * So we must set values[i] to an empty string
+ * and search the array again.
+ */
+ values[i] = "";
+ }
+ }
+
/* Use "postgres_fdw" as fallback_application_name */
keywords[n] = "fallback_application_name";
values[n] = "postgres_fdw";
@@ -452,6 +483,8 @@ connect_pg_server(ForeignServer *server, UserMapping *user)
/* Prepare new session for use */
configure_remote_session(conn);
+ if (data != NULL)
+ pfree(data);
pfree(keywords);
pfree(values);
}
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index 5196e4797a..55441f8b40 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -10822,3 +10822,33 @@ ERROR: invalid value for integer option "batch_size": 100$%$#$#
ALTER FOREIGN DATA WRAPPER postgres_fdw OPTIONS (nonexistent 'fdw');
ERROR: invalid option "nonexistent"
HINT: There are no valid options in this context.
+-- ===================================================================
+-- test postgres_fdw.application_name GUC
+-- ===================================================================
+SET debug_discard_caches TO 0;
+-- Some escapes can be used for this GUC.
+SET postgres_fdw.application_name TO '%a%u%d%p%%';
+-- All escape candidates depend on the runtime environment
+-- and it causes some fails for this tests.
+-- Hence we just count number of rows here. It returns a row if works well.
+SELECT 1 FROM postgres_fdw_disconnect_all();
+ ?column?
+----------
+ 1
+(1 row)
+
+SELECT 1 FROM ft6 LIMIT 1;
+ ?column?
+----------
+ 1
+(1 row)
+
+SELECT COUNT(*) FROM pg_stat_activity WHERE application_name = current_setting('application_name') || current_user || current_database() || pg_backend_pid() || '%';
+ count
+-------
+ 1
+(1 row)
+
+--Clean up
+RESET postgres_fdw.application_name;
+RESET debug_discard_caches;
diff --git a/contrib/postgres_fdw/option.c b/contrib/postgres_fdw/option.c
index 48c7417e6e..a57de6903d 100644
--- a/contrib/postgres_fdw/option.c
+++ b/contrib/postgres_fdw/option.c
@@ -18,6 +18,9 @@
#include "catalog/pg_user_mapping.h"
#include "commands/defrem.h"
#include "commands/extension.h"
+#include "common/string.h"
+#include "lib/stringinfo.h"
+#include "libpq/libpq-be.h"
#include "postgres_fdw.h"
#include "utils/builtins.h"
#include "utils/guc.h"
@@ -445,6 +448,64 @@ ExtractExtensionList(const char *extensionsString, bool warnOnMissing)
return extensionOids;
}
+/*
+ * Replace escape sequences beginning with % character in the given
+ * application_name with status information, and return it.
+ */
+char *
+process_pgfdw_appname(const char *name)
+{
+ const char *p;
+ StringInfoData buf;
+
+ Assert(MyProcPort != NULL);
+ initStringInfo(&buf);
+
+
+ for(p = name; *p != '\0'; p++)
+ {
+ if (*p != '%')
+ {
+ /* literal char, just copy */
+ appendStringInfoChar(&buf, *p);
+ continue;
+ }
+
+ /* must be a '%', so skip to the next char */
+ p++;
+ if (*p == '\0')
+ break; /* format error - ignore it */
+ else if (*p == '%')
+ {
+ /* string contains %% */
+ appendStringInfoChar(&buf, '%');
+ continue;
+ }
+
+ /* process the option */
+ switch (*p)
+ {
+ case 'a':
+ appendStringInfoString(&buf, application_name);
+ break;
+ case 'u':
+ appendStringInfoString(&buf, MyProcPort->user_name);
+ break;
+ case 'd':
+ appendStringInfoString(&buf, MyProcPort->database_name);
+ break;
+ case 'p':
+ appendStringInfo(&buf, "%d", MyProcPid);
+ break;
+ default:
+ /* format error - ignore it */
+ break;
+ }
+ }
+
+ return buf.data;
+}
+
/*
* Module load callback
*/
diff --git a/contrib/postgres_fdw/postgres_fdw.h b/contrib/postgres_fdw/postgres_fdw.h
index 90b72e9ec5..584b87d96d 100644
--- a/contrib/postgres_fdw/postgres_fdw.h
+++ b/contrib/postgres_fdw/postgres_fdw.h
@@ -158,6 +158,7 @@ extern int ExtractConnectionOptions(List *defelems,
const char **values);
extern List *ExtractExtensionList(const char *extensionsString,
bool warnOnMissing);
+extern char *process_pgfdw_appname(const char *name);
extern char *pgfdw_application_name;
/* in deparse.c */
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 666d21962a..9ca5651483 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -3449,3 +3449,20 @@ CREATE FOREIGN TABLE inv_bsz (c1 int )
-- No option is allowed to be specified at foreign data wrapper level
ALTER FOREIGN DATA WRAPPER postgres_fdw OPTIONS (nonexistent 'fdw');
+
+-- ===================================================================
+-- test postgres_fdw.application_name GUC
+-- ===================================================================
+SET debug_discard_caches TO 0;
+-- Some escapes can be used for this GUC.
+SET postgres_fdw.application_name TO '%a%u%d%p%%';
+-- All escape candidates depend on the runtime environment
+-- and it causes some fails for this tests.
+-- Hence we just count number of rows here. It returns a row if works well.
+SELECT 1 FROM postgres_fdw_disconnect_all();
+SELECT 1 FROM ft6 LIMIT 1;
+SELECT COUNT(*) FROM pg_stat_activity WHERE application_name = current_setting('application_name') || current_user || current_database() || pg_backend_pid() || '%';
+
+--Clean up
+RESET postgres_fdw.application_name;
+RESET debug_discard_caches;
diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
index e71d2b4eea..7e39c93d02 100644
--- a/doc/src/sgml/postgres-fdw.sgml
+++ b/doc/src/sgml/postgres-fdw.sgml
@@ -180,6 +180,10 @@ OPTIONS (ADD password_required 'false');
relationship granted by authentication modes like peer
or ident authentication.
+
+ You can use escape sequences for application_name even if
+ it is set as a connection option. Please refer the later section.
+
@@ -920,7 +924,7 @@ postgres=# SELECT postgres_fdw_disconnect_all();
Configuration Parameters
-
+
postgres_fdw.application_name (string)
@@ -946,6 +950,58 @@ postgres=# SELECT postgres_fdw_disconnect_all();
Note that change of this parameter doesn't affect any existing
connections until they are re-established.
+
+
+ % characters begin escape sequences
+ that are replaced with status information as outlined below.
+ Unrecognized escapes are ignored. Other characters are copied straight
+ to the application name. Note that it's not allowed to specify a
+ plus/minus sign or a numeric literal after the %
+ and before the option, for alignment and padding.
+
+
+
+
+
+
+ Escape
+ Effect
+
+
+
+
+ %a
+ Application name
+
+
+ %u
+ Local user name
+
+
+ %d
+ Local database name
+
+
+ %p
+ Local backend process ID
+
+
+ %%
+ Liteal %
+
+
+
+
+
+
+ In the table above, the term "local" means information about a server
+ that uses postgres_fdw. For example, suppose you
+ connect to database template1 as user postgres and set
+ postgres_fdw.application_name
+ to "db=%d, user=%u". If you connect to a remote server with this
+ configuration, the application_name used is
+ "db=template1, user=postgres".
+