Honor GUC settings specified in CREATE SUBSCRIPTION CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 568024ec9743ce7c973ffe74eb500052fb7011a3..743f951f3304d68935e0398cbe5905315f9f84df 100644 (file)
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -57,6 +57,8 @@ static void libpqrcv_get_senderinfo(WalReceiverConn *conn,
                                                                        char **sender_host, int *sender_port);
 static char *libpqrcv_identify_system(WalReceiverConn *conn,
                                                                          TimeLineID *primary_tli);
+static char *libpqrcv_get_option_from_conninfo(const char *connInfo,
+                                                                                          const char *keyword);
 static int     libpqrcv_server_version(WalReceiverConn *conn);
 static void libpqrcv_readtimelinehistoryfile(WalReceiverConn *conn,
                                                                                         TimeLineID tli, char **filename,
@@ -136,6 +138,7 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
        const char *keys[6];
        const char *vals[6];
        int                     i = 0;
+       char       *options_val = NULL;
 
        /*
         * Re-validate connection string. The validation already happened at DDL
@@ -167,6 +170,8 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
        vals[i] = appname;
        if (logical)
        {
+               char       *opt = NULL;
+
                /* Tell the publisher to translate to our encoding */
                keys[++i] = "client_encoding";
                vals[i] = GetDatabaseEncodingName();
@@ -179,8 +184,13 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
                 * the subscriber, such as triggers.)  This should match what pg_dump
                 * does.
                 */
+               opt = libpqrcv_get_option_from_conninfo(conninfo, "options");
+               options_val = psprintf("%s -c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3",
+                                                          (opt == NULL) ? "" : opt);
                keys[++i] = "options";
-               vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
+               vals[i] = options_val;
+               if (opt != NULL)
+                       pfree(opt);
        }
        keys[++i] = NULL;
        vals[i] = NULL;
@@ -232,6 +242,9 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
                        status = PQconnectPoll(conn->streamConn);
        } while (status != PGRES_POLLING_OK && status != PGRES_POLLING_FAILED);
 
+       if (options_val != NULL)
+               pfree(options_val);
+
        if (PQstatus(conn->streamConn) != CONNECTION_OK)
                goto bad_connection_errmsg;
 
@@ -434,6 +447,7 @@ libpqrcv_identify_system(WalReceiverConn *conn, TimeLineID *primary_tli)
                                                "the primary server: %s",
                                                pchomp(PQerrorMessage(conn->streamConn)))));
        }
+
        /*
         * IDENTIFY_SYSTEM returns 3 columns in 9.3 and earlier, and 4 columns in
         * 9.4 and onwards.
@@ -466,6 +480,51 @@ libpqrcv_server_version(WalReceiverConn *conn)
        return PQserverVersion(conn->streamConn);
 }
 
+/*
+ * Get the value of the option with the given keyword from the primary
+ * server's conninfo.
+ *
+ * If the option is not found in connInfo, return NULL value.
+ */
+static char *
+libpqrcv_get_option_from_conninfo(const char *connInfo, const char *keyword)
+{
+       PQconninfoOption *opts;
+       char       *option = NULL;
+       char       *err = NULL;
+
+       opts = PQconninfoParse(connInfo, &err);
+       if (opts == NULL)
+       {
+               /* The error string is malloc'd, so we must free it explicitly */
+               char       *errcopy = err ? pstrdup(err) : "out of memory";
+
+               PQfreemem(err);
+               ereport(ERROR,
+                               (errcode(ERRCODE_SYNTAX_ERROR),
+                                errmsg("invalid connection string syntax: %s", errcopy)));
+       }
+
+       for (PQconninfoOption *opt = opts; opt->keyword != NULL; ++opt)
+       {
+               /*
+                * If the same option appears multiple times, then the last one will
+                * be returned
+                */
+               if (strcmp(opt->keyword, keyword) == 0 && opt->val &&
+                       *opt->val)
+               {
+                       if (option)
+                               pfree(option);
+
+                       option = pstrdup(opt->val);
+               }
+       }
+
+       PQconninfoFree(opts);
+       return option;
+}
+
 /*
  * Start streaming WAL data from given streaming options.
  *