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Initial switchover implementation

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The repmgr3 implementation required the promotion candidate (standby)
to directly work with the demotion candidate's data directory,
directly execute server control commands etc.

Here we delegated a lot more of that work to the repmgr on the
demotion candidate, which reduces the amount of back-and-forth
over SSH and generally makes things cleaner and smoother.

In particular the repmgr on the demotion candidate will carry
out a thorough check that the node is shut down and report
the last checkpoint LSN to the promotion candidate; this
can then be used to determine whether pg_rewind needs to be
executed on the demoted primary before reintegrating it back
into the cluster (todo).

Also implement "--dry-run" for this action, which will sanity-check the
nodes as far as possible without executing the switchover.

Additionally some of the new repmgr node commands (or command options)
introduced for this can be also executed by the user to obtain
additional information about the status of each node.
This commit is contained in:
Ian Barwick
2017-08-03 16:38:37 +09:00
parent c67aa15581
commit 112ca6321a
15 changed files with 1024 additions and 102 deletions
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57
dbutils.c
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@@ -1036,7 +1036,7 @@ _get_primary_connection(PGconn *conn,
}
/* find all registered nodes */
log_info(_("retrieving node list"));
log_verbose(LOG_INFO, _("retrieving node list"));
initPQExpBuffer(&query);
appendPQExpBuffer(&query,
@@ -1182,6 +1182,9 @@ get_replication_info(PGconn *conn, ReplInfo *replication_info)
PQExpBufferData query;
PGresult *res;
if (server_version_num == UNKNOWN_SERVER_VERSION_NUM)
server_version_num = get_server_version(conn, NULL);
initPQExpBuffer(&query);
appendPQExpBuffer(
&query,
@@ -1297,6 +1300,28 @@ get_repmgr_extension_status(PGconn *conn)
return REPMGR_AVAILABLE;
}
/* ========================= */
/* node management functions */
/* ========================= */
/* assumes superuser connection */
void
checkpoint(PGconn *conn)
{
PGresult *res;
res = PQexec(conn, "CHECKPOINT");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
log_error(_("unable to execute CHECKPOINT"));
log_detail("%s", PQerrorMessage(conn));
}
PQclear(res);
return;
}
/* ===================== */
/* Node record functions */
@@ -1819,7 +1844,7 @@ _create_update_node_record(PGconn *conn, char *action, t_node_info *node_info)
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
log_error(_("unable to %s node record:\n %s"),
action,
@@ -1854,7 +1879,7 @@ update_node_record_set_active(PGconn *conn, int this_node_id, bool active)
res = PQexec(conn, query.data);
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
log_error(_("unable to update node record:\n %s"),
PQerrorMessage(conn));
@@ -2065,7 +2090,7 @@ delete_node_record(PGconn *conn, int node)
res = PQexec(conn, query.data);
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
log_error(_("unable to delete node record:\n %s"),
PQerrorMessage(conn));
@@ -2478,7 +2503,7 @@ _create_event(PGconn *conn, t_configuration_options *options, int node_id, char
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
/* we don't treat this as an error */
log_warning(_("unable to create event record:\n %s"),
@@ -2717,7 +2742,7 @@ create_replication_slot(PGconn *conn, char *slot_name, int server_version_num, P
res = PQexec(conn, query.data);
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
appendPQExpBuffer(error_msg,
_("unable to create slot '%s' on the upstream node: %s\n"),
@@ -2750,7 +2775,7 @@ drop_replication_slot(PGconn *conn, char *slot_name)
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_error(_("unable to drop replication slot \"%s\":\n %s"),
slot_name,
@@ -2786,7 +2811,7 @@ get_slot_record(PGconn *conn, char *slot_name, t_replication_slot *record)
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_error(_("unable to query pg_replication_slots:\n %s"),
PQerrorMessage(conn));
@@ -2991,7 +3016,7 @@ get_voting_status(PGconn *conn)
res = PQexec(conn, "SELECT repmgr.get_voting_status()");
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_error(_("unable to query repmgr.get_voting_status():\n %s"),
PQerrorMessage(conn));
@@ -3169,7 +3194,7 @@ notify_follow_primary(PGconn *conn, int primary_node_id)
res = PQexec(conn, query.data);
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_error(_("unable to execute repmgr.notify_follow_primary():\n %s"),
PQerrorMessage(conn));
@@ -3228,7 +3253,7 @@ reset_voting_status(PGconn *conn)
termPQExpBuffer(&query);
// COMMAND_OK?
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_error(_("unable to execute repmgr.reset_voting_status():\n %s"),
PQerrorMessage(conn));
@@ -3448,7 +3473,7 @@ add_table_to_bdr_replication_set(PGconn *conn, const char *tablename, const char
res = PQexec(conn, query.data);
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_error(_("unable to add table 'repmgr.%s' to replication set '%s':\n %s"),
tablename,
@@ -3485,7 +3510,7 @@ bdr_node_exists(PGconn *conn, const char *node_name)
res = PQexec(conn, query.data);
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
node_exists = false;
}
@@ -3524,7 +3549,7 @@ get_bdr_node_replication_slot_status(PGconn *conn, const char *node_name)
res = PQexec(conn, query.data);
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
status = SLOT_UNKNOWN;
}
@@ -3596,7 +3621,7 @@ add_extension_tables_to_bdr_replication_set(PGconn *conn)
res = PQexec(conn, query.data);
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
//
}
@@ -3679,7 +3704,7 @@ get_bdr_node_record_by_name(PGconn *conn, const char *node_name, t_bdr_node_info
res = PQexec(conn, query.data);
termPQExpBuffer(&query);
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_error(_("unable to retrieve BDR node record for \"%s\":\n %s"),
node_name,