From a30bb5cc1f07ae31c00abe97e9a212bbc0d8999b Mon Sep 17 00:00:00 2001 From: Shubham Khanna Date: Wed, 22 Jan 2025 12:03:12 +0530 Subject: [PATCH v10] Enhance 'pg_createsubscriber' to fetch and append all databases This patch enhances the 'pg_createsubscriber' utility by adding the '--all-dbs' option. When '--all-dbs' is specified, the tool queries the source server (publisher) for all databases and creates subscriptions on the target server (subscriber) for databases with matching names. This simplifies the process of converting a physical standby to a logical subscriber, particularly during upgrades. The options '--database', '--publication', '--subscription', and '--replication-slot' cannot be used when '--all-dbs' is specified. --- doc/src/sgml/ref/pg_createsubscriber.sgml | 48 ++++++- src/bin/pg_basebackup/pg_createsubscriber.c | 92 +++++++++++- .../t/040_pg_createsubscriber.pl | 135 +++++++++++++++++- 3 files changed, 266 insertions(+), 9 deletions(-) diff --git a/doc/src/sgml/ref/pg_createsubscriber.sgml b/doc/src/sgml/ref/pg_createsubscriber.sgml index d56487fe2c..d87c814b25 100644 --- a/doc/src/sgml/ref/pg_createsubscriber.sgml +++ b/doc/src/sgml/ref/pg_createsubscriber.sgml @@ -20,6 +20,27 @@ PostgreSQL documentation + + pg_createsubscriber + option + + + + + + + + + + datadir + + + + + connstr + + + pg_createsubscriber option @@ -87,6 +108,22 @@ PostgreSQL documentation command-line arguments: + + + + + + For all source server non-template databases create subscriptions for + create subscriptions for databases with the same names on the + target server. + Subscription names, publication names, and replication slot names are + automatically generated. Cannot be used together with + , , + or . + + + + @@ -94,7 +131,7 @@ PostgreSQL documentation The name of the database in which to create a subscription. Multiple databases can be selected by writing multiple - switches. + switches. Cannot be used together with . @@ -214,7 +251,8 @@ PostgreSQL documentation names must match the number of specified databases, otherwise an error is reported. The order of the multiple publication name switches must match the order of database switches. If this option is not specified, - a generated name is assigned to the publication name. + a generated name is assigned to the publication name. Cannot be used + together with . @@ -230,7 +268,8 @@ PostgreSQL documentation otherwise an error is reported. The order of the multiple replication slot name switches must match the order of database switches. If this option is not specified, the subscription name is assigned to the - replication slot name. + replication slot name. Cannot be used together with + . @@ -245,7 +284,8 @@ PostgreSQL documentation names must match the number of specified databases, otherwise an error is reported. The order of the multiple subscription name switches must match the order of database switches. If this option is not specified, - a generated name is assigned to the subscription name. + a generated name is assigned to the subscription name. Cannot be used + together with . diff --git a/src/bin/pg_basebackup/pg_createsubscriber.c b/src/bin/pg_basebackup/pg_createsubscriber.c index 9fdf15e5ac..afe9f5cc81 100644 --- a/src/bin/pg_basebackup/pg_createsubscriber.c +++ b/src/bin/pg_basebackup/pg_createsubscriber.c @@ -43,6 +43,7 @@ struct CreateSubscriberOptions SimpleStringList sub_names; /* list of subscription names */ SimpleStringList replslot_names; /* list of replication slot names */ int recovery_timeout; /* stop recovery after this time */ + bool all_dbs; /* --all option was specified */ }; struct LogicalRepInfo @@ -106,6 +107,7 @@ static void check_and_drop_existing_subscriptions(PGconn *conn, const struct LogicalRepInfo *dbinfo); static void drop_existing_subscriptions(PGconn *conn, const char *subname, const char *dbname); +static void fetch_source_databases(struct CreateSubscriberOptions *opt); #define USEC_PER_SEC 1000000 #define WAIT_INTERVAL 1 /* 1 second */ @@ -220,6 +222,7 @@ usage(void) printf(_("Usage:\n")); printf(_(" %s [OPTION]...\n"), progname); printf(_("\nOptions:\n")); + printf(_(" -a, --all-dbs create subscriptions for all non-template source databases\n")); printf(_(" -d, --database=DBNAME database in which to create a subscription\n")); printf(_(" -D, --pgdata=DATADIR location for the subscriber data directory\n")); printf(_(" -n, --dry-run dry run, just show what would be done\n")); @@ -1883,11 +1886,60 @@ enable_subscription(PGconn *conn, const struct LogicalRepInfo *dbinfo) destroyPQExpBuffer(str); } +/* + * If --all is specified, fetch a list of all user-created databases from the + * source server. Internally, this is treated as if the user specified multiple + * --database options, one for each source database. + */ +static void +fetch_source_databases(struct CreateSubscriberOptions *opt) +{ + PGconn *conn; + PGresult *res; + + /* Establish a connection to the PostgreSQL server */ + conn = connect_database(opt->pub_conninfo_str, true); + + res = PQexec(conn, "SELECT datname FROM pg_database WHERE datistemplate = false AND datallowconn = true"); + + /* Check for errors during query execution */ + if (PQresultStatus(res) != PGRES_TUPLES_OK) + { + pg_log_error("could not obtain a list of databases: %s", PQresultErrorMessage(res)); + PQclear(res); + disconnect_database(conn, true); + } + + /* Process the query result */ + for (int i = 0; i < PQntuples(res); i++) + { + const char *dbname = PQgetvalue(res, i, 0); + + simple_string_list_append(&opt->database_names, dbname); + + /* Increment num_dbs to reflect multiple --database options */ + num_dbs++; + } + + /* Error if no databases were found on the source server */ + if (num_dbs == 0) + { + pg_log_error("no suitable databases found on the source server"); + pg_log_error_hint("Ensure that there are non-template and connectable databases on the source server."); + PQclear(res); + disconnect_database(conn, true); + } + + PQclear(res); + disconnect_database(conn, false); +} + int main(int argc, char **argv) { static struct option long_options[] = { + {"all-dbs", no_argument, NULL, 'a'}, {"database", required_argument, NULL, 'd'}, {"pgdata", required_argument, NULL, 'D'}, {"dry-run", no_argument, NULL, 'n'}, @@ -1955,6 +2007,7 @@ main(int argc, char **argv) 0 }; opt.recovery_timeout = 0; + opt.all_dbs = false; /* * Don't allow it to be run as root. It uses pg_ctl which does not allow @@ -1972,11 +2025,14 @@ main(int argc, char **argv) get_restricted_token(); - while ((c = getopt_long(argc, argv, "d:D:np:P:s:t:U:v", + while ((c = getopt_long(argc, argv, "ad:D:np:P:s:t:U:v", long_options, &option_index)) != -1) { switch (c) { + case 'a': + opt.all_dbs = true; + break; case 'd': if (!simple_string_list_member(&opt.database_names, optarg)) { @@ -2061,6 +2117,28 @@ main(int argc, char **argv) } } + /* Validate that --all-dbs is not used with incompatible options. */ + if (opt.all_dbs) + { + char *bad_switch = NULL; + + if (num_dbs > 0) + bad_switch = "--database"; + else if (num_pubs > 0) + bad_switch = "--publication"; + else if (num_replslots > 0) + bad_switch = "--replication-slot"; + else if (num_subs > 0) + bad_switch = "--subscription"; + + if (bad_switch) + { + pg_log_error("%s cannot be used with --all-dbs", bad_switch); + pg_log_error_hint("Try \"%s --help\" for more information.", progname); + exit(1); + } + } + /* Any non-option arguments? */ if (optind < argc) { @@ -2114,14 +2192,20 @@ main(int argc, char **argv) pg_log_info("validating subscriber connection string"); sub_base_conninfo = get_sub_conninfo(&opt); + /* + * Fetch all databases from the source (publisher) if --all is specified. + */ + if (opt.all_dbs) + fetch_source_databases(&opt); + if (opt.database_names.head == NULL) { pg_log_info("no database was specified"); /* - * If --database option is not provided, try to obtain the dbname from - * the publisher conninfo. If dbname parameter is not available, error - * out. + * If neither --database nor --all option is provided, try to obtain + * the dbname from the publisher conninfo. If dbname parameter is not + * available, error out. */ if (dbname_conninfo) { diff --git a/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl b/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl index c8dbdb7e9b..e3cdf1ea7d 100644 --- a/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl +++ b/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl @@ -371,6 +371,139 @@ command_ok( ], 'run pg_createsubscriber without --databases'); +# run pg_createsubscriber with '--all-dbs' and '--database' and verify the +# failure +command_fails_like( + [ + 'pg_createsubscriber', + '--verbose', + '--dry-run', + '--pgdata' => $node_s->data_dir, + '--publisher-server' => $node_p->connstr($db1), + '--socketdir' => $node_s->host, + '--subscriber-port' => $node_s->port, + '--all-dbs', + '--database' => $db1, + ], + qr/--database cannot be used with --all-dbs/, + 'fail if --database is used with --all-dbs'); + +# run pg_createsubscriber with '--database' and '--all-dbs' without '--dry-run' +# and verify the failure +command_fails_like( + [ + 'pg_createsubscriber', + '--verbose', + '--pgdata' => $node_s->data_dir, + '--publisher-server' => $node_p->connstr($db1), + '--socketdir' => $node_s->host, + '--subscriber-port' => $node_s->port, + '--database' => $db1, + '--all-dbs', + ], + qr/--database cannot be used with --all-dbs/, + 'fail if --database is used with --all-dbs'); + +# run pg_createsubscriber with '--publication' and '--all-dbs' and verify +# the failure +command_fails_like( + [ + 'pg_createsubscriber', + '--verbose', + '--dry-run', + '--pgdata' => $node_s->data_dir, + '--publisher-server' => $node_p->connstr($db1), + '--socketdir' => $node_s->host, + '--subscriber-port' => $node_s->port, + '--all-dbs', + '--publication' => 'pub1', + ], + qr/--publication cannot be used with --all-dbs/, + 'fail if --publication is used with --all-dbs'); + +# run pg_createsubscriber with '--replication-slot' and '--all-dbs' and +# verify the failure +command_fails_like( + [ + 'pg_createsubscriber', + '--verbose', + '--dry-run', + '--pgdata' => $node_s->data_dir, + '--publisher-server' => $node_p->connstr($db1), + '--socketdir' => $node_s->host, + '--subscriber-port' => $node_s->port, + '--replication-slot' => 'replslot1', + '--all-dbs', + ], + qr/--replication-slot cannot be used with --all-dbs/, + 'fail if --replication-slot is used with --all-dbs'); + +# run pg_createsubscriber with '--subscription' and '--all-dbs' and +# verify the failure +command_fails_like( + [ + 'pg_createsubscriber', + '--verbose', + '--dry-run', + '--pgdata' => $node_s->data_dir, + '--publisher-server' => $node_p->connstr($db1), + '--socketdir' => $node_s->host, + '--subscriber-port' => $node_s->port, + '--all-dbs', + '--subscription' => 'sub1', + ], + qr/--subscription cannot be used with --all-dbs/, + 'fail if --subscription is used with --all-dbs'); + +# run pg_createsubscriber with '--all-dbs' option +command_ok( + [ + 'pg_createsubscriber', + '--verbose', + '--dry-run', + '--pgdata' => $node_s->data_dir, + '--publisher-server' => $node_p->connstr($db1), + '--socketdir' => $node_s->host, + '--subscriber-port' => $node_s->port, + '--all-dbs', + ], + 'run pg_createsubscriber with --all-dbs'); + +# Set up node S2 as standby linking to node P +$node_p->backup('backup_3'); +my $node_s2 = PostgreSQL::Test::Cluster->new('node_s2'); +$node_s2->init_from_backup($node_p, 'backup_3', has_streaming => 1); +$node_s2->append_conf( + 'postgresql.conf', qq[ +primary_conninfo = '$pconnstr dbname=postgres' +hot_standby_feedback = on +]); +$node_s2->set_standby_mode(); + +# run pg_createsubscriber with '--all-dbs' option without '--dry-run' +command_ok( + [ + 'pg_createsubscriber', + '--verbose', + '--pgdata' => $node_s2->data_dir, + '--publisher-server' => $node_p->connstr($db1), + '--socketdir' => $node_s2->host, + '--subscriber-port' => $node_s2->port, + '--all-dbs', + ], + 'run pg_createsubscriber with --all-dbs'); + +$node_s2->start; + +# Verify that only user databases got subscriptions (not template databases) +my @user_dbs = ('postgres', $db1, $db2); +foreach my $dbname (@user_dbs) +{ + my $sub_exists = + $node_s2->safe_psql($dbname, "SELECT count(*) FROM pg_subscription;"); + is($sub_exists, '3', "Subscription created successfully for $dbname"); +} + # Run pg_createsubscriber on node S. --verbose is used twice # to show more information. command_ok( @@ -431,7 +564,7 @@ $result = $node_s->safe_psql($db1, is($result, qq(0), 'failover slot was removed'); # Check result in database $db1 -$result = $node_s->safe_psql($db1, 'SELECT * FROM tbl1'); +$result = $node_s->safe_psql($db1, 'SELECT * FROM tbl1 ORDER BY 1'); is( $result, qq(first row second row third row), -- 2.34.1