rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
postgresql/src/bin/pg_basebackup/pg_createsubscriber.c

2150 lines
61 KiB
C
Raw Permalink Blame History

/*-------------------------------------------------------------------------
*
* pg_createsubscriber.c
* Create a new logical replica from a standby server
*
* Copyright (C) 2024, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/bin/pg_basebackup/pg_createsubscriber.c
*
*-------------------------------------------------------------------------
*/
#include "postgres_fe.h"
#include <sys/time.h>
#include <sys/wait.h>
#include <time.h>
#include "catalog/pg_authid_d.h"
#include "common/connect.h"
#include "common/controldata_utils.h"
#include "common/file_perm.h"
#include "common/logging.h"
#include "common/pg_prng.h"
#include "common/restricted_token.h"
#include "fe_utils/recovery_gen.h"
#include "fe_utils/simple_list.h"
#include "getopt_long.h"
#define DEFAULT_SUB_PORT "50432"
/* Command-line options */
struct CreateSubscriberOptions
{
char *config_file; /* configuration file */
char *pub_conninfo_str; /* publisher connection string */
char *socket_dir; /* directory for Unix-domain socket, if any */
char *sub_port; /* subscriber port number */
const char *sub_username; /* subscriber username */
SimpleStringList database_names; /* list of database names */
SimpleStringList pub_names; /* list of publication names */
SimpleStringList sub_names; /* list of subscription names */
SimpleStringList replslot_names; /* list of replication slot names */
int recovery_timeout; /* stop recovery after this time */
};
struct LogicalRepInfo
{
Oid oid; /* database OID */
char *dbname; /* database name */
char *pubconninfo; /* publisher connection string */
char *subconninfo; /* subscriber connection string */
char *pubname; /* publication name */
char *subname; /* subscription name */
char *replslotname; /* replication slot name */
bool made_replslot; /* replication slot was created */
bool made_publication; /* publication was created */
};
static void cleanup_objects_atexit(void);
static void usage();
static char *get_base_conninfo(const char *conninfo, char **dbname);
static char *get_sub_conninfo(const struct CreateSubscriberOptions *opt);
static char *get_exec_path(const char *argv0, const char *progname);
static void check_data_directory(const char *datadir);
static char *concat_conninfo_dbname(const char *conninfo, const char *dbname);
static struct LogicalRepInfo *store_pub_sub_info(const struct CreateSubscriberOptions *opt,
const char *pub_base_conninfo,
const char *sub_base_conninfo);
static PGconn *connect_database(const char *conninfo, bool exit_on_error);
static void disconnect_database(PGconn *conn, bool exit_on_error);
static uint64 get_primary_sysid(const char *conninfo);
static uint64 get_standby_sysid(const char *datadir);
static void modify_subscriber_sysid(const struct CreateSubscriberOptions *opt);
static bool server_is_in_recovery(PGconn *conn);
static char *generate_object_name(PGconn *conn);
static void check_publisher(const struct LogicalRepInfo *dbinfo);
static char *setup_publisher(struct LogicalRepInfo *dbinfo);
static void check_subscriber(const struct LogicalRepInfo *dbinfo);
static void setup_subscriber(struct LogicalRepInfo *dbinfo,
const char *consistent_lsn);
static void setup_recovery(const struct LogicalRepInfo *dbinfo, const char *datadir,
const char *lsn);
static void drop_primary_replication_slot(struct LogicalRepInfo *dbinfo,
const char *slotname);
static char *create_logical_replication_slot(PGconn *conn,
struct LogicalRepInfo *dbinfo);
static void drop_replication_slot(PGconn *conn, struct LogicalRepInfo *dbinfo,
const char *slot_name);
static void pg_ctl_status(const char *pg_ctl_cmd, int rc);
static void start_standby_server(const struct CreateSubscriberOptions *opt,
bool restricted_access);
static void stop_standby_server(const char *datadir);
static void wait_for_end_recovery(const char *conninfo,
const struct CreateSubscriberOptions *opt);
static void create_publication(PGconn *conn, struct LogicalRepInfo *dbinfo);
static void drop_publication(PGconn *conn, struct LogicalRepInfo *dbinfo);
static void create_subscription(PGconn *conn, const struct LogicalRepInfo *dbinfo);
static void set_replication_progress(PGconn *conn, const struct LogicalRepInfo *dbinfo,
const char *lsn);
static void enable_subscription(PGconn *conn, const struct LogicalRepInfo *dbinfo);
#define USEC_PER_SEC 1000000
#define WAIT_INTERVAL 1 /* 1 second */
static const char *progname;
static char *primary_slot_name = NULL;
static bool dry_run = false;
static bool success = false;
static struct LogicalRepInfo *dbinfo;
static int num_dbs = 0; /* number of specified databases */
static int num_pubs = 0; /* number of specified publications */
static int num_subs = 0; /* number of specified subscriptions */
static int num_replslots = 0; /* number of specified replication slots */
static pg_prng_state prng_state;
static char *pg_ctl_path = NULL;
static char *pg_resetwal_path = NULL;
/* standby / subscriber data directory */
static char *subscriber_dir = NULL;
static bool recovery_ended = false;
static bool standby_running = false;
enum WaitPMResult
{
POSTMASTER_READY,
POSTMASTER_STILL_STARTING
};
/*
* Cleanup objects that were created by pg_createsubscriber if there is an
* error.
*
* Publications and replication slots are created on primary. Depending on the
* step it failed, it should remove the already created objects if it is
* possible (sometimes it won't work due to a connection issue).
* There is no cleanup on the target server. The steps on the target server are
* executed *after* promotion, hence, at this point, a failure means recreate
* the physical replica and start again.
*/
static void
cleanup_objects_atexit(void)
{
if (success)
return;
/*
* If the server is promoted, there is no way to use the current setup
* again. Warn the user that a new replication setup should be done before
* trying again.
*/
if (recovery_ended)
{
pg_log_warning("failed after the end of recovery");
pg_log_warning_hint("The target server cannot be used as a physical replica anymore. "
"You must recreate the physical replica before continuing.");
}
for (int i = 0; i < num_dbs; i++)
{
if (dbinfo[i].made_publication || dbinfo[i].made_replslot)
{
PGconn *conn;
conn = connect_database(dbinfo[i].pubconninfo, false);
if (conn != NULL)
{
if (dbinfo[i].made_publication)
drop_publication(conn, &dbinfo[i]);
if (dbinfo[i].made_replslot)
drop_replication_slot(conn, &dbinfo[i], dbinfo[i].replslotname);
disconnect_database(conn, false);
}
else
{
/*
* If a connection could not be established, inform the user
* that some objects were left on primary and should be
* removed before trying again.
*/
if (dbinfo[i].made_publication)
{
pg_log_warning("publication \"%s\" in database \"%s\" on primary might be left behind",
dbinfo[i].pubname, dbinfo[i].dbname);
pg_log_warning_hint("Consider dropping this publication before trying again.");
}
if (dbinfo[i].made_replslot)
{
pg_log_warning("replication slot \"%s\" in database \"%s\" on primary might be left behind",
dbinfo[i].replslotname, dbinfo[i].dbname);
pg_log_warning_hint("Drop this replication slot soon to avoid retention of WAL files.");
}
}
}
}
if (standby_running)
stop_standby_server(subscriber_dir);
}
static void
usage(void)
{
printf(_("%s creates a new logical replica from a standby server.\n\n"),
progname);
printf(_("Usage:\n"));
printf(_(" %s [OPTION]...\n"), progname);
printf(_("\nOptions:\n"));
printf(_(" -d, --database=DBNAME database 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"));
printf(_(" -p, --subscriber-port=PORT subscriber port number (default %s)\n"), DEFAULT_SUB_PORT);
printf(_(" -P, --publisher-server=CONNSTR publisher connection string\n"));
printf(_(" -s, --socket-directory=DIR socket directory to use (default current directory)\n"));
printf(_(" -t, --recovery-timeout=SECS seconds to wait for recovery to end\n"));
printf(_(" -U, --subscriber-username=NAME subscriber username\n"));
printf(_(" -v, --verbose output verbose messages\n"));
printf(_(" --config-file=FILENAME use specified main server configuration\n"
" file when running target cluster\n"));
printf(_(" --publication=NAME publication name\n"));
printf(_(" --replication-slot=NAME replication slot name\n"));
printf(_(" --subscription=NAME subscription name\n"));
printf(_(" -V, --version output version information, then exit\n"));
printf(_(" -?, --help show this help, then exit\n"));
printf(_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
}
/*
* Validate a connection string. Returns a base connection string that is a
* connection string without a database name.
*
* Since we might process multiple databases, each database name will be
* appended to this base connection string to provide a final connection
* string. If the second argument (dbname) is not null, returns dbname if the
* provided connection string contains it. If option --database is not
* provided, uses dbname as the only database to setup the logical replica.
*
* It is the caller's responsibility to free the returned connection string and
* dbname.
*/
static char *
get_base_conninfo(const char *conninfo, char **dbname)
{
PQExpBuffer buf;
PQconninfoOption *conn_opts;
PQconninfoOption *conn_opt;
char *errmsg = NULL;
char *ret;
int i;
conn_opts = PQconninfoParse(conninfo, &errmsg);
if (conn_opts == NULL)
{
pg_log_error("could not parse connection string: %s", errmsg);
PQfreemem(errmsg);
return NULL;
}
buf = createPQExpBuffer();
i = 0;
for (conn_opt = conn_opts; conn_opt->keyword != NULL; conn_opt++)
{
if (strcmp(conn_opt->keyword, "dbname") == 0 && conn_opt->val != NULL)
{
if (dbname)
*dbname = pg_strdup(conn_opt->val);
continue;
}
if (conn_opt->val != NULL && conn_opt->val[0] != '\0')
{
if (i > 0)
appendPQExpBufferChar(buf, ' ');
appendPQExpBuffer(buf, "%s=%s", conn_opt->keyword, conn_opt->val);
i++;
}
}
ret = pg_strdup(buf->data);
destroyPQExpBuffer(buf);
PQconninfoFree(conn_opts);
return ret;
}
/*
* Build a subscriber connection string. Only a few parameters are supported
* since it starts a server with restricted access.
*/
static char *
get_sub_conninfo(const struct CreateSubscriberOptions *opt)
{
PQExpBuffer buf = createPQExpBuffer();
char *ret;
appendPQExpBuffer(buf, "port=%s", opt->sub_port);
#if !defined(WIN32)
appendPQExpBuffer(buf, " host=%s", opt->socket_dir);
#endif
if (opt->sub_username != NULL)
appendPQExpBuffer(buf, " user=%s", opt->sub_username);
appendPQExpBuffer(buf, " fallback_application_name=%s", progname);
ret = pg_strdup(buf->data);
destroyPQExpBuffer(buf);
return ret;
}
/*
* Verify if a PostgreSQL binary (progname) is available in the same directory as
* pg_createsubscriber and it has the same version. It returns the absolute
* path of the progname.
*/
static char *
get_exec_path(const char *argv0, const char *progname)
{
char *versionstr;
char *exec_path;
int ret;
versionstr = psprintf("%s (PostgreSQL) %s\n", progname, PG_VERSION);
exec_path = pg_malloc(MAXPGPATH);
ret = find_other_exec(argv0, progname, versionstr, exec_path);
if (ret < 0)
{
char full_path[MAXPGPATH];
if (find_my_exec(argv0, full_path) < 0)
strlcpy(full_path, progname, sizeof(full_path));
if (ret == -1)
pg_fatal("program \"%s\" is needed by %s but was not found in the same directory as \"%s\"",
progname, "pg_createsubscriber", full_path);
else
pg_fatal("program \"%s\" was found by \"%s\" but was not the same version as %s",
progname, full_path, "pg_createsubscriber");
}
pg_log_debug("%s path is: %s", progname, exec_path);
return exec_path;
}
/*
* Is it a cluster directory? These are preliminary checks. It is far from
* making an accurate check. If it is not a clone from the publisher, it will
* eventually fail in a future step.
*/
static void
check_data_directory(const char *datadir)
{
struct stat statbuf;
char versionfile[MAXPGPATH];
pg_log_info("checking if directory \"%s\" is a cluster data directory",
datadir);
if (stat(datadir, &statbuf) != 0)
{
if (errno == ENOENT)
pg_fatal("data directory \"%s\" does not exist", datadir);
else
pg_fatal("could not access directory \"%s\": %m", datadir);
}
snprintf(versionfile, MAXPGPATH, "%s/PG_VERSION", datadir);
if (stat(versionfile, &statbuf) != 0 && errno == ENOENT)
{
pg_fatal("directory \"%s\" is not a database cluster directory",
datadir);
}
}
/*
* Append database name into a base connection string.
*
* dbname is the only parameter that changes so it is not included in the base
* connection string. This function concatenates dbname to build a "real"
* connection string.
*/
static char *
concat_conninfo_dbname(const char *conninfo, const char *dbname)
{
PQExpBuffer buf = createPQExpBuffer();
char *ret;
Assert(conninfo != NULL);
appendPQExpBufferStr(buf, conninfo);
appendPQExpBuffer(buf, " dbname=%s", dbname);
ret = pg_strdup(buf->data);
destroyPQExpBuffer(buf);
return ret;
}
/*
* Store publication and subscription information.
*
* If publication, replication slot and subscription names were specified,
* store it here. Otherwise, a generated name will be assigned to the object in
* setup_publisher().
*/
static struct LogicalRepInfo *
store_pub_sub_info(const struct CreateSubscriberOptions *opt,
const char *pub_base_conninfo,
const char *sub_base_conninfo)
{
struct LogicalRepInfo *dbinfo;
SimpleStringListCell *pubcell = NULL;
SimpleStringListCell *subcell = NULL;
SimpleStringListCell *replslotcell = NULL;
int i = 0;
dbinfo = pg_malloc_array(struct LogicalRepInfo, num_dbs);
if (num_pubs > 0)
pubcell = opt->pub_names.head;
if (num_subs > 0)
subcell = opt->sub_names.head;
if (num_replslots > 0)
replslotcell = opt->replslot_names.head;
for (SimpleStringListCell *cell = opt->database_names.head; cell; cell = cell->next)
{
char *conninfo;
/* Fill publisher attributes */
conninfo = concat_conninfo_dbname(pub_base_conninfo, cell->val);
dbinfo[i].pubconninfo = conninfo;
dbinfo[i].dbname = cell->val;
if (num_pubs > 0)
dbinfo[i].pubname = pubcell->val;
else
dbinfo[i].pubname = NULL;
if (num_replslots > 0)
dbinfo[i].replslotname = replslotcell->val;
else
dbinfo[i].replslotname = NULL;
dbinfo[i].made_replslot = false;
dbinfo[i].made_publication = false;
/* Fill subscriber attributes */
conninfo = concat_conninfo_dbname(sub_base_conninfo, cell->val);
dbinfo[i].subconninfo = conninfo;
if (num_subs > 0)
dbinfo[i].subname = subcell->val;
else
dbinfo[i].subname = NULL;
/* Other fields will be filled later */
pg_log_debug("publisher(%d): publication: %s ; replication slot: %s ; connection string: %s", i,
dbinfo[i].pubname ? dbinfo[i].pubname : "(auto)",
dbinfo[i].replslotname ? dbinfo[i].replslotname : "(auto)",
dbinfo[i].pubconninfo);
pg_log_debug("subscriber(%d): subscription: %s ; connection string: %s", i,
dbinfo[i].subname ? dbinfo[i].subname : "(auto)",
dbinfo[i].subconninfo);
if (num_pubs > 0)
pubcell = pubcell->next;
if (num_subs > 0)
subcell = subcell->next;
if (num_replslots > 0)
replslotcell = replslotcell->next;
i++;
}
return dbinfo;
}
/*
* Open a new connection. If exit_on_error is true, it has an undesired
* condition and it should exit immediately.
*/
static PGconn *
connect_database(const char *conninfo, bool exit_on_error)
{
PGconn *conn;
PGresult *res;
conn = PQconnectdb(conninfo);
if (PQstatus(conn) != CONNECTION_OK)
{
pg_log_error("connection to database failed: %s",
PQerrorMessage(conn));
PQfinish(conn);
if (exit_on_error)
exit(1);
return NULL;
}
/* Secure search_path */
res = PQexec(conn, ALWAYS_SECURE_SEARCH_PATH_SQL);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not clear search_path: %s",
PQresultErrorMessage(res));
PQclear(res);
PQfinish(conn);
if (exit_on_error)
exit(1);
return NULL;
}
PQclear(res);
return conn;
}
/*
* Close the connection. If exit_on_error is true, it has an undesired
* condition and it should exit immediately.
*/
static void
disconnect_database(PGconn *conn, bool exit_on_error)
{
Assert(conn != NULL);
PQfinish(conn);
if (exit_on_error)
exit(1);
}
/*
* Obtain the system identifier using the provided connection. It will be used
* to compare if a data directory is a clone of another one.
*/
static uint64
get_primary_sysid(const char *conninfo)
{
PGconn *conn;
PGresult *res;
uint64 sysid;
pg_log_info("getting system identifier from publisher");
conn = connect_database(conninfo, true);
res = PQexec(conn, "SELECT system_identifier FROM pg_catalog.pg_control_system()");
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not get system identifier: %s",
PQresultErrorMessage(res));
disconnect_database(conn, true);
}
if (PQntuples(res) != 1)
{
pg_log_error("could not get system identifier: got %d rows, expected %d row",
PQntuples(res), 1);
disconnect_database(conn, true);
}
sysid = strtou64(PQgetvalue(res, 0, 0), NULL, 10);
pg_log_info("system identifier is %llu on publisher",
(unsigned long long) sysid);
PQclear(res);
disconnect_database(conn, false);
return sysid;
}
/*
* Obtain the system identifier from control file. It will be used to compare
* if a data directory is a clone of another one. This routine is used locally
* and avoids a connection.
*/
static uint64
get_standby_sysid(const char *datadir)
{
ControlFileData *cf;
bool crc_ok;
uint64 sysid;
pg_log_info("getting system identifier from subscriber");
cf = get_controlfile(datadir, &crc_ok);
if (!crc_ok)
pg_fatal("control file appears to be corrupt");
sysid = cf->system_identifier;
pg_log_info("system identifier is %llu on subscriber",
(unsigned long long) sysid);
pg_free(cf);
return sysid;
}
/*
* Modify the system identifier. Since a standby server preserves the system
* identifier, it makes sense to change it to avoid situations in which WAL
* files from one of the systems might be used in the other one.
*/
static void
modify_subscriber_sysid(const struct CreateSubscriberOptions *opt)
{
ControlFileData *cf;
bool crc_ok;
struct timeval tv;
char *cmd_str;
pg_log_info("modifying system identifier of subscriber");
cf = get_controlfile(subscriber_dir, &crc_ok);
if (!crc_ok)
pg_fatal("control file appears to be corrupt");
/*
* Select a new system identifier.
*
* XXX this code was extracted from BootStrapXLOG().
*/
gettimeofday(&tv, NULL);
cf->system_identifier = ((uint64) tv.tv_sec) << 32;
cf->system_identifier |= ((uint64) tv.tv_usec) << 12;
cf->system_identifier |= getpid() & 0xFFF;
if (!dry_run)
update_controlfile(subscriber_dir, cf, true);
pg_log_info("system identifier is %llu on subscriber",
(unsigned long long) cf->system_identifier);
pg_log_info("running pg_resetwal on the subscriber");
cmd_str = psprintf("\"%s\" -D \"%s\" > \"%s\"", pg_resetwal_path,
subscriber_dir, DEVNULL);
pg_log_debug("pg_resetwal command is: %s", cmd_str);
if (!dry_run)
{
int rc = system(cmd_str);
if (rc == 0)
pg_log_info("subscriber successfully changed the system identifier");
else
pg_fatal("subscriber failed to change system identifier: exit code: %d", rc);
}
pg_free(cf);
}
/*
* Generate an object name using a prefix, database oid and a random integer.
* It is used in case the user does not specify an object name (publication,
* subscription, replication slot).
*/
static char *
generate_object_name(PGconn *conn)
{
PGresult *res;
Oid oid;
uint32 rand;
char *objname;
res = PQexec(conn,
"SELECT oid FROM pg_catalog.pg_database "
"WHERE datname = pg_catalog.current_database()");
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not obtain database OID: %s",
PQresultErrorMessage(res));
disconnect_database(conn, true);
}
if (PQntuples(res) != 1)
{
pg_log_error("could not obtain database OID: got %d rows, expected %d row",
PQntuples(res), 1);
disconnect_database(conn, true);
}
/* Database OID */
oid = strtoul(PQgetvalue(res, 0, 0), NULL, 10);
PQclear(res);
/* Random unsigned integer */
rand = pg_prng_uint32(&prng_state);
/*
* Build the object name. The name must not exceed NAMEDATALEN - 1. This
* current schema uses a maximum of 40 characters (20 + 10 + 1 + 8 +
* '\0').
*/
objname = psprintf("pg_createsubscriber_%u_%x", oid, rand);
return objname;
}
/*
* Create the publications and replication slots in preparation for logical
* replication. Returns the LSN from latest replication slot. It will be the
* replication start point that is used to adjust the subscriptions (see
* set_replication_progress).
*/
static char *
setup_publisher(struct LogicalRepInfo *dbinfo)
{
char *lsn = NULL;
pg_prng_seed(&prng_state, (uint64) (getpid() ^ time(NULL)));
for (int i = 0; i < num_dbs; i++)
{
PGconn *conn;
char *genname = NULL;
conn = connect_database(dbinfo[i].pubconninfo, true);
/*
* If an object name was not specified as command-line options, assign
* a generated object name. The replication slot has a different rule.
* The subscription name is assigned to the replication slot name if
* no replication slot is specified. It follows the same rule as
* CREATE SUBSCRIPTION.
*/
if (num_pubs == 0 || num_subs == 0 || num_replslots == 0)
genname = generate_object_name(conn);
if (num_pubs == 0)
dbinfo[i].pubname = pg_strdup(genname);
if (num_subs == 0)
dbinfo[i].subname = pg_strdup(genname);
if (num_replslots == 0)
dbinfo[i].replslotname = pg_strdup(dbinfo[i].subname);
/*
* Create publication on publisher. This step should be executed
* *before* promoting the subscriber to avoid any transactions between
* consistent LSN and the new publication rows (such transactions
* wouldn't see the new publication rows resulting in an error).
*/
create_publication(conn, &dbinfo[i]);
/* Create replication slot on publisher */
if (lsn)
pg_free(lsn);
lsn = create_logical_replication_slot(conn, &dbinfo[i]);
if (lsn != NULL || dry_run)
pg_log_info("create replication slot \"%s\" on publisher",
dbinfo[i].replslotname);
else
exit(1);
disconnect_database(conn, false);
}
return lsn;
}
/*
* Is recovery still in progress?
*/
static bool
server_is_in_recovery(PGconn *conn)
{
PGresult *res;
int ret;
res = PQexec(conn, "SELECT pg_catalog.pg_is_in_recovery()");
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not obtain recovery progress: %s",
PQresultErrorMessage(res));
disconnect_database(conn, true);
}
ret = strcmp("t", PQgetvalue(res, 0, 0));
PQclear(res);
return ret == 0;
}
/*
* Is the primary server ready for logical replication?
*
* XXX Does it not allow a synchronous replica?
*/
static void
check_publisher(const struct LogicalRepInfo *dbinfo)
{
PGconn *conn;
PGresult *res;
bool failed = false;
char *wal_level;
int max_repslots;
int cur_repslots;
int max_walsenders;
int cur_walsenders;
pg_log_info("checking settings on publisher");
conn = connect_database(dbinfo[0].pubconninfo, true);
/*
* If the primary server is in recovery (i.e. cascading replication),
* objects (publication) cannot be created because it is read only.
*/
if (server_is_in_recovery(conn))
{
pg_log_error("primary server cannot be in recovery");
disconnect_database(conn, true);
}
/*------------------------------------------------------------------------
* Logical replication requires a few parameters to be set on publisher.
* Since these parameters are not a requirement for physical replication,
* we should check it to make sure it won't fail.
*
* - wal_level = logical
* - max_replication_slots >= current + number of dbs to be converted
* - max_wal_senders >= current + number of dbs to be converted
* -----------------------------------------------------------------------
*/
res = PQexec(conn,
"WITH wl AS "
"(SELECT setting AS wallevel FROM pg_catalog.pg_settings "
"WHERE name = 'wal_level'), "
"total_mrs AS "
"(SELECT setting AS tmrs FROM pg_catalog.pg_settings "
"WHERE name = 'max_replication_slots'), "
"cur_mrs AS "
"(SELECT count(*) AS cmrs "
"FROM pg_catalog.pg_replication_slots), "
"total_mws AS "
"(SELECT setting AS tmws FROM pg_catalog.pg_settings "
"WHERE name = 'max_wal_senders'), "
"cur_mws AS "
"(SELECT count(*) AS cmws FROM pg_catalog.pg_stat_activity "
"WHERE backend_type = 'walsender') "
"SELECT wallevel, tmrs, cmrs, tmws, cmws "
"FROM wl, total_mrs, cur_mrs, total_mws, cur_mws");
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not obtain publisher settings: %s",
PQresultErrorMessage(res));
disconnect_database(conn, true);
}
wal_level = pg_strdup(PQgetvalue(res, 0, 0));
max_repslots = atoi(PQgetvalue(res, 0, 1));
cur_repslots = atoi(PQgetvalue(res, 0, 2));
max_walsenders = atoi(PQgetvalue(res, 0, 3));
cur_walsenders = atoi(PQgetvalue(res, 0, 4));
PQclear(res);
pg_log_debug("publisher: wal_level: %s", wal_level);
pg_log_debug("publisher: max_replication_slots: %d", max_repslots);
pg_log_debug("publisher: current replication slots: %d", cur_repslots);
pg_log_debug("publisher: max_wal_senders: %d", max_walsenders);
pg_log_debug("publisher: current wal senders: %d", cur_walsenders);
/*
* If standby sets primary_slot_name, check if this replication slot is in
* use on primary for WAL retention purposes. This replication slot has no
* use after the transformation, hence, it will be removed at the end of
* this process.
*/
if (primary_slot_name)
{
PQExpBuffer str = createPQExpBuffer();
char *psn_esc = PQescapeLiteral(conn, primary_slot_name, strlen(primary_slot_name));
appendPQExpBuffer(str,
"SELECT 1 FROM pg_catalog.pg_replication_slots "
"WHERE active AND slot_name = %s",
psn_esc);
pg_free(psn_esc);
pg_log_debug("command is: %s", str->data);
res = PQexec(conn, str->data);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not obtain replication slot information: %s",
PQresultErrorMessage(res));
disconnect_database(conn, true);
}
if (PQntuples(res) != 1)
{
pg_log_error("could not obtain replication slot information: got %d rows, expected %d row",
PQntuples(res), 1);
disconnect_database(conn, true);
}
else
pg_log_info("primary has replication slot \"%s\"",
primary_slot_name);
PQclear(res);
}
disconnect_database(conn, false);
if (strcmp(wal_level, "logical") != 0)
{
pg_log_error("publisher requires wal_level >= \"logical\"");
failed = true;
}
if (max_repslots - cur_repslots < num_dbs)
{
pg_log_error("publisher requires %d replication slots, but only %d remain",
num_dbs, max_repslots - cur_repslots);
pg_log_error_hint("Consider increasing max_replication_slots to at least %d.",
cur_repslots + num_dbs);
failed = true;
}
if (max_walsenders - cur_walsenders < num_dbs)
{
pg_log_error("publisher requires %d wal sender processes, but only %d remain",
num_dbs, max_walsenders - cur_walsenders);
pg_log_error_hint("Consider increasing max_wal_senders to at least %d.",
cur_walsenders + num_dbs);
failed = true;
}
pg_free(wal_level);
if (failed)
exit(1);
}
/*
* Is the standby server ready for logical replication?
*
* XXX Does it not allow a time-delayed replica?
*
* XXX In a cascaded replication scenario (P -> S -> C), if the target server
* is S, it cannot detect there is a replica (server C) because server S starts
* accepting only local connections and server C cannot connect to it. Hence,
* there is not a reliable way to provide a suitable error saying the server C
* will be broken at the end of this process (due to pg_resetwal).
*/
static void
check_subscriber(const struct LogicalRepInfo *dbinfo)
{
PGconn *conn;
PGresult *res;
bool failed = false;
int max_lrworkers;
int max_repslots;
int max_wprocs;
pg_log_info("checking settings on subscriber");
conn = connect_database(dbinfo[0].subconninfo, true);
/* The target server must be a standby */
if (!server_is_in_recovery(conn))
{
pg_log_error("target server must be a standby");
disconnect_database(conn, true);
}
/*------------------------------------------------------------------------
* Logical replication requires a few parameters to be set on subscriber.
* Since these parameters are not a requirement for physical replication,
* we should check it to make sure it won't fail.
*
* - max_replication_slots >= number of dbs to be converted
* - max_logical_replication_workers >= number of dbs to be converted
* - max_worker_processes >= 1 + number of dbs to be converted
*------------------------------------------------------------------------
*/
res = PQexec(conn,
"SELECT setting FROM pg_catalog.pg_settings WHERE name IN ("
"'max_logical_replication_workers', "
"'max_replication_slots', "
"'max_worker_processes', "
"'primary_slot_name') "
"ORDER BY name");
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not obtain subscriber settings: %s",
PQresultErrorMessage(res));
disconnect_database(conn, true);
}
max_lrworkers = atoi(PQgetvalue(res, 0, 0));
max_repslots = atoi(PQgetvalue(res, 1, 0));
max_wprocs = atoi(PQgetvalue(res, 2, 0));
if (strcmp(PQgetvalue(res, 3, 0), "") != 0)
primary_slot_name = pg_strdup(PQgetvalue(res, 3, 0));
pg_log_debug("subscriber: max_logical_replication_workers: %d",
max_lrworkers);
pg_log_debug("subscriber: max_replication_slots: %d", max_repslots);
pg_log_debug("subscriber: max_worker_processes: %d", max_wprocs);
if (primary_slot_name)
pg_log_debug("subscriber: primary_slot_name: %s", primary_slot_name);
PQclear(res);
disconnect_database(conn, false);
if (max_repslots < num_dbs)
{
pg_log_error("subscriber requires %d replication slots, but only %d remain",
num_dbs, max_repslots);
pg_log_error_hint("Consider increasing max_replication_slots to at least %d.",
num_dbs);
failed = true;
}
if (max_lrworkers < num_dbs)
{
pg_log_error("subscriber requires %d logical replication workers, but only %d remain",
num_dbs, max_lrworkers);
pg_log_error_hint("Consider increasing max_logical_replication_workers to at least %d.",
num_dbs);
failed = true;
}
if (max_wprocs < num_dbs + 1)
{
pg_log_error("subscriber requires %d worker processes, but only %d remain",
num_dbs + 1, max_wprocs);
pg_log_error_hint("Consider increasing max_worker_processes to at least %d.",
num_dbs + 1);
failed = true;
}
if (failed)
exit(1);
}
/*
* Create the subscriptions, adjust the initial location for logical
* replication and enable the subscriptions. That's the last step for logical
* replication setup.
*/
static void
setup_subscriber(struct LogicalRepInfo *dbinfo, const char *consistent_lsn)
{
for (int i = 0; i < num_dbs; i++)
{
PGconn *conn;
/* Connect to subscriber. */
conn = connect_database(dbinfo[i].subconninfo, true);
/*
* Since the publication was created before the consistent LSN, it is
* available on the subscriber when the physical replica is promoted.
* Remove publications from the subscriber because it has no use.
*/
drop_publication(conn, &dbinfo[i]);
create_subscription(conn, &dbinfo[i]);
/* Set the replication progress to the correct LSN */
set_replication_progress(conn, &dbinfo[i], consistent_lsn);
/* Enable subscription */
enable_subscription(conn, &dbinfo[i]);
disconnect_database(conn, false);
}
}
/*
* Write the required recovery parameters.
*/
static void
setup_recovery(const struct LogicalRepInfo *dbinfo, const char *datadir, const char *lsn)
{
PGconn *conn;
PQExpBuffer recoveryconfcontents;
/*
* Despite of the recovery parameters will be written to the subscriber,
* use a publisher connection. The primary_conninfo is generated using the
* connection settings.
*/
conn = connect_database(dbinfo[0].pubconninfo, true);
/*
* Write recovery parameters.
*
* The subscriber is not running yet. In dry run mode, the recovery
* parameters *won't* be written. An invalid LSN is used for printing
* purposes. Additional recovery parameters are added here. It avoids
* unexpected behavior such as end of recovery as soon as a consistent
* state is reached (recovery_target) and failure due to multiple recovery
* targets (name, time, xid, LSN).
*/
recoveryconfcontents = GenerateRecoveryConfig(conn, NULL, NULL);
appendPQExpBuffer(recoveryconfcontents, "recovery_target = ''\n");
appendPQExpBuffer(recoveryconfcontents,
"recovery_target_timeline = 'latest'\n");
appendPQExpBuffer(recoveryconfcontents,
"recovery_target_inclusive = true\n");
appendPQExpBuffer(recoveryconfcontents,
"recovery_target_action = promote\n");
appendPQExpBuffer(recoveryconfcontents, "recovery_target_name = ''\n");
appendPQExpBuffer(recoveryconfcontents, "recovery_target_time = ''\n");
appendPQExpBuffer(recoveryconfcontents, "recovery_target_xid = ''\n");
if (dry_run)
{
appendPQExpBuffer(recoveryconfcontents, "# dry run mode");
appendPQExpBuffer(recoveryconfcontents,
"recovery_target_lsn = '%X/%X'\n",
LSN_FORMAT_ARGS((XLogRecPtr) InvalidXLogRecPtr));
}
else
{
appendPQExpBuffer(recoveryconfcontents, "recovery_target_lsn = '%s'\n",
lsn);
WriteRecoveryConfig(conn, datadir, recoveryconfcontents);
}
disconnect_database(conn, false);
pg_log_debug("recovery parameters:\n%s", recoveryconfcontents->data);
}
/*
* Drop physical replication slot on primary if the standby was using it. After
* the transformation, it has no use.
*
* XXX we might not fail here. Instead, we provide a warning so the user
* eventually drops this replication slot later.
*/
static void
drop_primary_replication_slot(struct LogicalRepInfo *dbinfo, const char *slotname)
{
PGconn *conn;
/* Replication slot does not exist, do nothing */
if (!primary_slot_name)
return;
conn = connect_database(dbinfo[0].pubconninfo, false);
if (conn != NULL)
{
drop_replication_slot(conn, &dbinfo[0], slotname);
disconnect_database(conn, false);
}
else
{
pg_log_warning("could not drop replication slot \"%s\" on primary",
slotname);
pg_log_warning_hint("Drop this replication slot soon to avoid retention of WAL files.");
}
}
/*
* Create a logical replication slot and returns a LSN.
*
* CreateReplicationSlot() is not used because it does not provide the one-row
* result set that contains the LSN.
*/
static char *
create_logical_replication_slot(PGconn *conn, struct LogicalRepInfo *dbinfo)
{
PQExpBuffer str = createPQExpBuffer();
PGresult *res = NULL;
const char *slot_name = dbinfo->replslotname;
char *slot_name_esc;
char *lsn = NULL;
Assert(conn != NULL);
pg_log_info("creating the replication slot \"%s\" on database \"%s\"",
slot_name, dbinfo->dbname);
slot_name_esc = PQescapeLiteral(conn, slot_name, strlen(slot_name));
appendPQExpBuffer(str,
"SELECT lsn FROM pg_catalog.pg_create_logical_replication_slot(%s, 'pgoutput', false, false, false)",
slot_name_esc);
pg_free(slot_name_esc);
pg_log_debug("command is: %s", str->data);
if (!dry_run)
{
res = PQexec(conn, str->data);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not create replication slot \"%s\" on database \"%s\": %s",
slot_name, dbinfo->dbname,
PQresultErrorMessage(res));
PQclear(res);
destroyPQExpBuffer(str);
return NULL;
}
lsn = pg_strdup(PQgetvalue(res, 0, 0));
PQclear(res);
}
/* For cleanup purposes */
dbinfo->made_replslot = true;
destroyPQExpBuffer(str);
return lsn;
}
static void
drop_replication_slot(PGconn *conn, struct LogicalRepInfo *dbinfo,
const char *slot_name)
{
PQExpBuffer str = createPQExpBuffer();
char *slot_name_esc;
PGresult *res;
Assert(conn != NULL);
pg_log_info("dropping the replication slot \"%s\" on database \"%s\"",
slot_name, dbinfo->dbname);
slot_name_esc = PQescapeLiteral(conn, slot_name, strlen(slot_name));
appendPQExpBuffer(str, "SELECT pg_catalog.pg_drop_replication_slot(%s)", slot_name_esc);
pg_free(slot_name_esc);
pg_log_debug("command is: %s", str->data);
if (!dry_run)
{
res = PQexec(conn, str->data);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not drop replication slot \"%s\" on database \"%s\": %s",
slot_name, dbinfo->dbname, PQresultErrorMessage(res));
dbinfo->made_replslot = false; /* don't try again. */
}
PQclear(res);
}
destroyPQExpBuffer(str);
}
/*
* Reports a suitable message if pg_ctl fails.
*/
static void
pg_ctl_status(const char *pg_ctl_cmd, int rc)
{
if (rc != 0)
{
if (WIFEXITED(rc))
{
pg_log_error("pg_ctl failed with exit code %d", WEXITSTATUS(rc));
}
else if (WIFSIGNALED(rc))
{
#if defined(WIN32)
pg_log_error("pg_ctl was terminated by exception 0x%X",
WTERMSIG(rc));
pg_log_error_detail("See C include file \"ntstatus.h\" for a description of the hexadecimal value.");
#else
pg_log_error("pg_ctl was terminated by signal %d: %s",
WTERMSIG(rc), pg_strsignal(WTERMSIG(rc)));
#endif
}
else
{
pg_log_error("pg_ctl exited with unrecognized status %d", rc);
}
pg_log_error_detail("The failed command was: %s", pg_ctl_cmd);
exit(1);
}
}
static void
start_standby_server(const struct CreateSubscriberOptions *opt, bool restricted_access)
{
PQExpBuffer pg_ctl_cmd = createPQExpBuffer();
int rc;
appendPQExpBuffer(pg_ctl_cmd, "\"%s\" start -D \"%s\" -s",
pg_ctl_path, subscriber_dir);
if (restricted_access)
{
appendPQExpBuffer(pg_ctl_cmd, " -o \"-p %s\"", opt->sub_port);
#if !defined(WIN32)
/*
* An empty listen_addresses list means the server does not listen on
* any IP interfaces; only Unix-domain sockets can be used to connect
* to the server. Prevent external connections to minimize the chance
* of failure.
*/
appendPQExpBufferStr(pg_ctl_cmd, " -o \"-c listen_addresses='' -c unix_socket_permissions=0700");
if (opt->socket_dir)
appendPQExpBuffer(pg_ctl_cmd, " -c unix_socket_directories='%s'",
opt->socket_dir);
appendPQExpBufferChar(pg_ctl_cmd, '"');
#endif
}
if (opt->config_file != NULL)
appendPQExpBuffer(pg_ctl_cmd, " -o \"-c config_file=%s\"",
opt->config_file);
pg_log_debug("pg_ctl command is: %s", pg_ctl_cmd->data);
rc = system(pg_ctl_cmd->data);
pg_ctl_status(pg_ctl_cmd->data, rc);
standby_running = true;
destroyPQExpBuffer(pg_ctl_cmd);
pg_log_info("server was started");
}
static void
stop_standby_server(const char *datadir)
{
char *pg_ctl_cmd;
int rc;
pg_ctl_cmd = psprintf("\"%s\" stop -D \"%s\" -s", pg_ctl_path,
datadir);
pg_log_debug("pg_ctl command is: %s", pg_ctl_cmd);
rc = system(pg_ctl_cmd);
pg_ctl_status(pg_ctl_cmd, rc);
standby_running = false;
pg_log_info("server was stopped");
}
/*
* Returns after the server finishes the recovery process.
*
* If recovery_timeout option is set, terminate abnormally without finishing
* the recovery process. By default, it waits forever.
*/
static void
wait_for_end_recovery(const char *conninfo, const struct CreateSubscriberOptions *opt)
{
PGconn *conn;
int status = POSTMASTER_STILL_STARTING;
int timer = 0;
int count = 0; /* number of consecutive connection attempts */
#define NUM_CONN_ATTEMPTS 10
pg_log_info("waiting for the target server to reach the consistent state");
conn = connect_database(conninfo, true);
for (;;)
{
PGresult *res;
bool in_recovery = server_is_in_recovery(conn);
/*
* Does the recovery process finish? In dry run mode, there is no
* recovery mode. Bail out as the recovery process has ended.
*/
if (!in_recovery || dry_run)
{
status = POSTMASTER_READY;
recovery_ended = true;
break;
}
/*
* If it is still in recovery, make sure the target server is
* connected to the primary so it can receive the required WAL to
* finish the recovery process. If it is disconnected try
* NUM_CONN_ATTEMPTS in a row and bail out if not succeed.
*/
res = PQexec(conn,
"SELECT 1 FROM pg_catalog.pg_stat_wal_receiver");
if (PQntuples(res) == 0)
{
if (++count > NUM_CONN_ATTEMPTS)
{
stop_standby_server(subscriber_dir);
pg_log_error("standby server disconnected from the primary");
break;
}
}
else
count = 0; /* reset counter if it connects again */
PQclear(res);
/* Bail out after recovery_timeout seconds if this option is set */
if (opt->recovery_timeout > 0 && timer >= opt->recovery_timeout)
{
stop_standby_server(subscriber_dir);
pg_log_error("recovery timed out");
disconnect_database(conn, true);
}
/* Keep waiting */
pg_usleep(WAIT_INTERVAL * USEC_PER_SEC);
timer += WAIT_INTERVAL;
}
disconnect_database(conn, false);
if (status == POSTMASTER_STILL_STARTING)
pg_fatal("server did not end recovery");
pg_log_info("target server reached the consistent state");
pg_log_info_hint("If pg_createsubscriber fails after this point, you must recreate the physical replica before continuing.");
}
/*
* Create a publication that includes all tables in the database.
*/
static void
create_publication(PGconn *conn, struct LogicalRepInfo *dbinfo)
{
PQExpBuffer str = createPQExpBuffer();
PGresult *res;
char *ipubname_esc;
char *spubname_esc;
Assert(conn != NULL);
ipubname_esc = PQescapeIdentifier(conn, dbinfo->pubname, strlen(dbinfo->pubname));
spubname_esc = PQescapeLiteral(conn, dbinfo->pubname, strlen(dbinfo->pubname));
/* Check if the publication already exists */
appendPQExpBuffer(str,
"SELECT 1 FROM pg_catalog.pg_publication "
"WHERE pubname = %s",
spubname_esc);
res = PQexec(conn, str->data);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not obtain publication information: %s",
PQresultErrorMessage(res));
disconnect_database(conn, true);
}
if (PQntuples(res) == 1)
{
/*
* Unfortunately, if it reaches this code path, it will always fail
* (unless you decide to change the existing publication name). That's
* bad but it is very unlikely that the user will choose a name with
* pg_createsubscriber_ prefix followed by the exact database oid and
* a random number.
*/
pg_log_error("publication \"%s\" already exists", dbinfo->pubname);
pg_log_error_hint("Consider renaming this publication before continuing.");
disconnect_database(conn, true);
}
PQclear(res);
resetPQExpBuffer(str);
pg_log_info("creating publication \"%s\" on database \"%s\"",
dbinfo->pubname, dbinfo->dbname);
appendPQExpBuffer(str, "CREATE PUBLICATION %s FOR ALL TABLES",
ipubname_esc);
pg_log_debug("command is: %s", str->data);
if (!dry_run)
{
res = PQexec(conn, str->data);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
pg_log_error("could not create publication \"%s\" on database \"%s\": %s",
dbinfo->pubname, dbinfo->dbname, PQresultErrorMessage(res));
disconnect_database(conn, true);
}
PQclear(res);
}
/* For cleanup purposes */
dbinfo->made_publication = true;
pg_free(ipubname_esc);
pg_free(spubname_esc);
destroyPQExpBuffer(str);
}
/*
* Remove publication if it couldn't finish all steps.
*/
static void
drop_publication(PGconn *conn, struct LogicalRepInfo *dbinfo)
{
PQExpBuffer str = createPQExpBuffer();
PGresult *res;
char *pubname_esc;
Assert(conn != NULL);
pubname_esc = PQescapeIdentifier(conn, dbinfo->pubname, strlen(dbinfo->pubname));
pg_log_info("dropping publication \"%s\" on database \"%s\"",
dbinfo->pubname, dbinfo->dbname);
appendPQExpBuffer(str, "DROP PUBLICATION %s", pubname_esc);
pg_free(pubname_esc);
pg_log_debug("command is: %s", str->data);
if (!dry_run)
{
res = PQexec(conn, str->data);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
pg_log_error("could not drop publication \"%s\" on database \"%s\": %s",
dbinfo->pubname, dbinfo->dbname, PQresultErrorMessage(res));
dbinfo->made_publication = false; /* don't try again. */
/*
* Don't disconnect and exit here. This routine is used by primary
* (cleanup publication / replication slot due to an error) and
* subscriber (remove the replicated publications). In both cases,
* it can continue and provide instructions for the user to remove
* it later if cleanup fails.
*/
}
PQclear(res);
}
destroyPQExpBuffer(str);
}
/*
* Create a subscription with some predefined options.
*
* A replication slot was already created in a previous step. Let's use it. It
* is not required to copy data. The subscription will be created but it will
* not be enabled now. That's because the replication progress must be set and
* the replication origin name (one of the function arguments) contains the
* subscription OID in its name. Once the subscription is created,
* set_replication_progress() can obtain the chosen origin name and set up its
* initial location.
*/
static void
create_subscription(PGconn *conn, const struct LogicalRepInfo *dbinfo)
{
PQExpBuffer str = createPQExpBuffer();
PGresult *res;
char *pubname_esc;
char *subname_esc;
char *pubconninfo_esc;
char *replslotname_esc;
Assert(conn != NULL);
pubname_esc = PQescapeIdentifier(conn, dbinfo->pubname, strlen(dbinfo->pubname));
subname_esc = PQescapeIdentifier(conn, dbinfo->subname, strlen(dbinfo->subname));
pubconninfo_esc = PQescapeLiteral(conn, dbinfo->pubconninfo, strlen(dbinfo->pubconninfo));
replslotname_esc = PQescapeLiteral(conn, dbinfo->replslotname, strlen(dbinfo->replslotname));
pg_log_info("creating subscription \"%s\" on database \"%s\"",
dbinfo->subname, dbinfo->dbname);
appendPQExpBuffer(str,
"CREATE SUBSCRIPTION %s CONNECTION %s PUBLICATION %s "
"WITH (create_slot = false, enabled = false, "
"slot_name = %s, copy_data = false)",
subname_esc, pubconninfo_esc, pubname_esc, replslotname_esc);
pg_free(pubname_esc);
pg_free(subname_esc);
pg_free(pubconninfo_esc);
pg_free(replslotname_esc);
pg_log_debug("command is: %s", str->data);
if (!dry_run)
{
res = PQexec(conn, str->data);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
pg_log_error("could not create subscription \"%s\" on database \"%s\": %s",
dbinfo->subname, dbinfo->dbname, PQresultErrorMessage(res));
disconnect_database(conn, true);
}
PQclear(res);
}
destroyPQExpBuffer(str);
}
/*
* Sets the replication progress to the consistent LSN.
*
* The subscriber caught up to the consistent LSN provided by the last
* replication slot that was created. The goal is to set up the initial
* location for the logical replication that is the exact LSN that the
* subscriber was promoted. Once the subscription is enabled it will start
* streaming from that location onwards. In dry run mode, the subscription OID
* and LSN are set to invalid values for printing purposes.
*/
static void
set_replication_progress(PGconn *conn, const struct LogicalRepInfo *dbinfo, const char *lsn)
{
PQExpBuffer str = createPQExpBuffer();
PGresult *res;
Oid suboid;
char *subname;
char *dbname;
char *originname;
char *lsnstr;
Assert(conn != NULL);
subname = PQescapeLiteral(conn, dbinfo->subname, strlen(dbinfo->subname));
dbname = PQescapeLiteral(conn, dbinfo->dbname, strlen(dbinfo->dbname));
appendPQExpBuffer(str,
"SELECT s.oid FROM pg_catalog.pg_subscription s "
"INNER JOIN pg_catalog.pg_database d ON (s.subdbid = d.oid) "
"WHERE s.subname = %s AND d.datname = %s",
subname, dbname);
res = PQexec(conn, str->data);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not obtain subscription OID: %s",
PQresultErrorMessage(res));
disconnect_database(conn, true);
}
if (PQntuples(res) != 1 && !dry_run)
{
pg_log_error("could not obtain subscription OID: got %d rows, expected %d row",
PQntuples(res), 1);
disconnect_database(conn, true);
}
if (dry_run)
{
suboid = InvalidOid;
lsnstr = psprintf("%X/%X", LSN_FORMAT_ARGS((XLogRecPtr) InvalidXLogRecPtr));
}
else
{
suboid = strtoul(PQgetvalue(res, 0, 0), NULL, 10);
lsnstr = psprintf("%s", lsn);
}
PQclear(res);
/*
* The origin name is defined as pg_%u. %u is the subscription OID. See
* ApplyWorkerMain().
*/
originname = psprintf("pg_%u", suboid);
pg_log_info("setting the replication progress (node name \"%s\" ; LSN %s) on database \"%s\"",
originname, lsnstr, dbinfo->dbname);
resetPQExpBuffer(str);
appendPQExpBuffer(str,
"SELECT pg_catalog.pg_replication_origin_advance('%s', '%s')",
originname, lsnstr);
pg_log_debug("command is: %s", str->data);
if (!dry_run)
{
res = PQexec(conn, str->data);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not set replication progress for the subscription \"%s\": %s",
dbinfo->subname, PQresultErrorMessage(res));
disconnect_database(conn, true);
}
PQclear(res);
}
pg_free(subname);
pg_free(dbname);
pg_free(originname);
pg_free(lsnstr);
destroyPQExpBuffer(str);
}
/*
* Enables the subscription.
*
* The subscription was created in a previous step but it was disabled. After
* adjusting the initial logical replication location, enable the subscription.
*/
static void
enable_subscription(PGconn *conn, const struct LogicalRepInfo *dbinfo)
{
PQExpBuffer str = createPQExpBuffer();
PGresult *res;
char *subname;
Assert(conn != NULL);
subname = PQescapeIdentifier(conn, dbinfo->subname, strlen(dbinfo->subname));
pg_log_info("enabling subscription \"%s\" on database \"%s\"",
dbinfo->subname, dbinfo->dbname);
appendPQExpBuffer(str, "ALTER SUBSCRIPTION %s ENABLE", subname);
pg_log_debug("command is: %s", str->data);
if (!dry_run)
{
res = PQexec(conn, str->data);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
pg_log_error("could not enable subscription \"%s\": %s",
dbinfo->subname, PQresultErrorMessage(res));
disconnect_database(conn, true);
}
PQclear(res);
}
pg_free(subname);
destroyPQExpBuffer(str);
}
int
main(int argc, char **argv)
{
static struct option long_options[] =
{
{"database", required_argument, NULL, 'd'},
{"pgdata", required_argument, NULL, 'D'},
{"dry-run", no_argument, NULL, 'n'},
{"subscriber-port", required_argument, NULL, 'p'},
{"publisher-server", required_argument, NULL, 'P'},
{"socket-directory", required_argument, NULL, 's'},
{"recovery-timeout", required_argument, NULL, 't'},
{"subscriber-username", required_argument, NULL, 'U'},
{"verbose", no_argument, NULL, 'v'},
{"version", no_argument, NULL, 'V'},
{"help", no_argument, NULL, '?'},
{"config-file", required_argument, NULL, 1},
{"publication", required_argument, NULL, 2},
{"replication-slot", required_argument, NULL, 3},
{"subscription", required_argument, NULL, 4},
{NULL, 0, NULL, 0}
};
struct CreateSubscriberOptions opt = {0};
int c;
int option_index;
char *pub_base_conninfo;
char *sub_base_conninfo;
char *dbname_conninfo = NULL;
uint64 pub_sysid;
uint64 sub_sysid;
struct stat statbuf;
char *consistent_lsn;
char pidfile[MAXPGPATH];
pg_logging_init(argv[0]);
pg_logging_set_level(PG_LOG_WARNING);
progname = get_progname(argv[0]);
set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_createsubscriber"));
if (argc > 1)
{
if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
{
usage();
exit(0);
}
else if (strcmp(argv[1], "-V") == 0
|| strcmp(argv[1], "--version") == 0)
{
puts("pg_createsubscriber (PostgreSQL) " PG_VERSION);
exit(0);
}
}
/* Default settings */
subscriber_dir = NULL;
opt.config_file = NULL;
opt.pub_conninfo_str = NULL;
opt.socket_dir = NULL;
opt.sub_port = DEFAULT_SUB_PORT;
opt.sub_username = NULL;
opt.database_names = (SimpleStringList)
{
0
};
opt.recovery_timeout = 0;
/*
* Don't allow it to be run as root. It uses pg_ctl which does not allow
* it either.
*/
#ifndef WIN32
if (geteuid() == 0)
{
pg_log_error("cannot be executed by \"root\"");
pg_log_error_hint("You must run %s as the PostgreSQL superuser.",
progname);
exit(1);
}
#endif
get_restricted_token();
while ((c = getopt_long(argc, argv, "d:D:np:P:s:t:U:v",
long_options, &option_index)) != -1)
{
switch (c)
{
case 'd':
if (!simple_string_list_member(&opt.database_names, optarg))
{
simple_string_list_append(&opt.database_names, optarg);
num_dbs++;
}
else
{
pg_log_error("duplicate database \"%s\"", optarg);
exit(1);
}
break;
case 'D':
subscriber_dir = pg_strdup(optarg);
canonicalize_path(subscriber_dir);
break;
case 'n':
dry_run = true;
break;
case 'p':
opt.sub_port = pg_strdup(optarg);
break;
case 'P':
opt.pub_conninfo_str = pg_strdup(optarg);
break;
case 's':
opt.socket_dir = pg_strdup(optarg);
canonicalize_path(opt.socket_dir);
break;
case 't':
opt.recovery_timeout = atoi(optarg);
break;
case 'U':
opt.sub_username = pg_strdup(optarg);
break;
case 'v':
pg_logging_increase_verbosity();
break;
case 1:
opt.config_file = pg_strdup(optarg);
break;
case 2:
if (!simple_string_list_member(&opt.pub_names, optarg))
{
simple_string_list_append(&opt.pub_names, optarg);
num_pubs++;
}
else
{
pg_log_error("duplicate publication \"%s\"", optarg);
exit(1);
}
break;
case 3:
if (!simple_string_list_member(&opt.replslot_names, optarg))
{
simple_string_list_append(&opt.replslot_names, optarg);
num_replslots++;
}
else
{
pg_log_error("duplicate replication slot \"%s\"", optarg);
exit(1);
}
break;
case 4:
if (!simple_string_list_member(&opt.sub_names, optarg))
{
simple_string_list_append(&opt.sub_names, optarg);
num_subs++;
}
else
{
pg_log_error("duplicate subscription \"%s\"", optarg);
exit(1);
}
break;
default:
/* getopt_long already emitted a complaint */
pg_log_error_hint("Try \"%s --help\" for more information.", progname);
exit(1);
}
}
/* Any non-option arguments? */
if (optind < argc)
{
pg_log_error("too many command-line arguments (first is \"%s\")",
argv[optind]);
pg_log_error_hint("Try \"%s --help\" for more information.", progname);
exit(1);
}
/* Required arguments */
if (subscriber_dir == NULL)
{
pg_log_error("no subscriber data directory specified");
pg_log_error_hint("Try \"%s --help\" for more information.", progname);
exit(1);
}
/* If socket directory is not provided, use the current directory */
if (opt.socket_dir == NULL)
{
char cwd[MAXPGPATH];
if (!getcwd(cwd, MAXPGPATH))
pg_fatal("could not determine current directory");
opt.socket_dir = pg_strdup(cwd);
canonicalize_path(opt.socket_dir);
}
/*
* Parse connection string. Build a base connection string that might be
* reused by multiple databases.
*/
if (opt.pub_conninfo_str == NULL)
{
/*
* TODO use primary_conninfo (if available) from subscriber and
* extract publisher connection string. Assume that there are
* identical entries for physical and logical replication. If there is
* not, we would fail anyway.
*/
pg_log_error("no publisher connection string specified");
pg_log_error_hint("Try \"%s --help\" for more information.", progname);
exit(1);
}
pg_log_info("validating connection string on publisher");
pub_base_conninfo = get_base_conninfo(opt.pub_conninfo_str,
&dbname_conninfo);
if (pub_base_conninfo == NULL)
exit(1);
pg_log_info("validating connection string on subscriber");
sub_base_conninfo = get_sub_conninfo(&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 (dbname_conninfo)
{
simple_string_list_append(&opt.database_names, dbname_conninfo);
num_dbs++;
pg_log_info("database \"%s\" was extracted from the publisher connection string",
dbname_conninfo);
}
else
{
pg_log_error("no database name specified");
pg_log_error_hint("Try \"%s --help\" for more information.",
progname);
exit(1);
}
}
/* Number of object names must match number of databases */
if (num_pubs > 0 && num_pubs != num_dbs)
{
pg_log_error("wrong number of publication names");
pg_log_error_hint("Number of publication names (%d) must match number of database names (%d).",
num_pubs, num_dbs);
exit(1);
}
if (num_subs > 0 && num_subs != num_dbs)
{
pg_log_error("wrong number of subscription names");
pg_log_error_hint("Number of subscription names (%d) must match number of database names (%d).",
num_subs, num_dbs);
exit(1);
}
if (num_replslots > 0 && num_replslots != num_dbs)
{
pg_log_error("wrong number of replication slot names");
pg_log_error_hint("Number of replication slot names (%d) must match number of database names (%d).",
num_replslots, num_dbs);
exit(1);
}
/* Get the absolute path of pg_ctl and pg_resetwal on the subscriber */
pg_ctl_path = get_exec_path(argv[0], "pg_ctl");
pg_resetwal_path = get_exec_path(argv[0], "pg_resetwal");
/* Rudimentary check for a data directory */
check_data_directory(subscriber_dir);
/*
* Store database information for publisher and subscriber. It should be
* called before atexit() because its return is used in the
* cleanup_objects_atexit().
*/
dbinfo = store_pub_sub_info(&opt, pub_base_conninfo, sub_base_conninfo);
/* Register a function to clean up objects in case of failure */
atexit(cleanup_objects_atexit);
/*
* Check if the subscriber data directory has the same system identifier
* than the publisher data directory.
*/
pub_sysid = get_primary_sysid(dbinfo[0].pubconninfo);
sub_sysid = get_standby_sysid(subscriber_dir);
if (pub_sysid != sub_sysid)
pg_fatal("subscriber data directory is not a copy of the source database cluster");
/* Subscriber PID file */
snprintf(pidfile, MAXPGPATH, "%s/postmaster.pid", subscriber_dir);
/*
* The standby server must not be running. If the server is started under
* service manager and pg_createsubscriber stops it, the service manager
* might react to this action and start the server again. Therefore,
* refuse to proceed if the server is running to avoid possible failures.
*/
if (stat(pidfile, &statbuf) == 0)
{
pg_log_error("standby is up and running");
pg_log_error_hint("Stop the standby and try again.");
exit(1);
}
/*
* Start a short-lived standby server with temporary parameters (provided
* by command-line options). The goal is to avoid connections during the
* transformation steps.
*/
pg_log_info("starting the standby with command-line options");
start_standby_server(&opt, true);
/* Check if the standby server is ready for logical replication */
check_subscriber(dbinfo);
/*
* Check if the primary server is ready for logical replication. This
* routine checks if a replication slot is in use on primary so it relies
* on check_subscriber() to obtain the primary_slot_name. That's why it is
* called after it.
*/
check_publisher(dbinfo);
/*
* Stop the target server. The recovery process requires that the server
* reaches a consistent state before targeting the recovery stop point.
* Make sure a consistent state is reached (stop the target server
* guarantees it) *before* creating the replication slots in
* setup_publisher().
*/
pg_log_info("stopping the subscriber");
stop_standby_server(subscriber_dir);
/*
* Create the required objects for each database on publisher. This step
* is here mainly because if we stop the standby we cannot verify if the
* primary slot is in use. We could use an extra connection for it but it
* doesn't seem worth.
*/
consistent_lsn = setup_publisher(dbinfo);
/* Write the required recovery parameters */
setup_recovery(dbinfo, subscriber_dir, consistent_lsn);
/*
* Start subscriber so the recovery parameters will take effect. Wait
* until accepting connections.
*/
pg_log_info("starting the subscriber");
start_standby_server(&opt, true);
/* Waiting the subscriber to be promoted */
wait_for_end_recovery(dbinfo[0].subconninfo, &opt);
/*
* Create the subscription for each database on subscriber. It does not
* enable it immediately because it needs to adjust the replication start
* point to the LSN reported by setup_publisher(). It also cleans up
* publications created by this tool and replication to the standby.
*/
setup_subscriber(dbinfo, consistent_lsn);
/* Remove primary_slot_name if it exists on primary */
drop_primary_replication_slot(dbinfo, primary_slot_name);
/* Stop the subscriber */
pg_log_info("stopping the subscriber");
stop_standby_server(subscriber_dir);
/* Change system identifier from subscriber */
modify_subscriber_sysid(&opt);
success = true;
pg_log_info("Done!");
return 0;
}
Reference in New Issue View Git Blame Copy Permalink