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Improve node metadata and upstream connecting mechanism

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To handle cascaded replication we're going to have to keep track
of each node's upstream node. Also enumerate the node type
("primary", "standby" or "witness") and mark if active.
This commit is contained in:
Ian Barwick
2015-01-16 10:27:44 +09:00
parent 4b6c097a3e
commit a82d37e48a
4 changed files with 117 additions and 58 deletions
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91
dbutils.c
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@@ -145,11 +145,13 @@ is_witness(PGconn *conn, char *cluster, int node_id)
int result = 0;
char sqlquery[QUERY_STR_LEN];
// ZZZ witness
sqlquery_snprintf(sqlquery,
"SELECT witness "
"SELECT TRUE "
" FROM %s.repl_nodes "
" WHERE cluster = '%s' "
" AND id = %d ",
" AND id = %d "
" AND type = 'witness' ",
get_repmgr_schema_quoted(conn),
cluster,
node_id);
@@ -224,6 +226,50 @@ is_pgup(PGconn *conn, int timeout)
return true;
}
/*
* Return the id of the active primary node, or -1 if no
* record available.
*
* This reports the value stored in the database only and
* does not verify whether the node is actually available
*/
int
get_primary_node_id(PGconn *conn, char *cluster)
{
char sqlquery[QUERY_STR_LEN];
PGresult *res;
int retval;
sqlquery_snprintf(sqlquery,
"SELECT id "
" FROM %s.repl_nodes "
" WHERE cluster = '%s' "
" AND type = 'primary' "
" AND active IS TRUE ",
get_repmgr_schema_quoted(conn),
cluster);
res = PQexec(conn, sqlquery);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
log_err(_("get_primary_node_id(): query failed\n%s\n"),
PQerrorMessage(conn));
retval = -1;
}
else if (PQntuples(res) == 0)
{
log_warning(_("get_primary_node_id(): no active primary found\n"));
retval = -1;
}
else
{
retval = atoi(PQgetvalue(res, 0, 0));
}
PQclear(res);
return retval;
}
/*
* Return the server version number for the connection provided
@@ -393,8 +439,8 @@ get_pg_setting(PGconn *conn, const char *setting, char *output)
PGconn *
get_upstream_connection(PGconn *standby_conn, char *cluster,
int *upstream_node_id, char *upstream_conninfo_out)
get_upstream_connection(PGconn *standby_conn, char *cluster, int node_id,
int *upstream_node_id_ptr, char *upstream_conninfo_out)
{
PGconn *upstream_conn = NULL;
PGresult *res;
@@ -409,23 +455,17 @@ get_upstream_connection(PGconn *standby_conn, char *cluster,
if (upstream_conninfo_out != NULL)
upstream_conninfo = upstream_conninfo_out;
/* hacky query */
sqlquery_snprintf(sqlquery,
"WITH i AS ( "
" WITH p AS ( "
" SELECT repmgr_get_primary_conninfo() AS conninfo "
" )"
" SELECT p.conninfo, "
" unnest(regexp_matches(conninfo,'application_name=(\\S+)')) AS name "
" FROM p "
") "
" SELECT rn.conninfo, i.name, rn.id "
" FROM i "
"INNER JOIN %s.repl_nodes rn "
" ON rn.name = i.name "
" WHERE cluster = '%s' ",
" SELECT un.conninfo, un.name, un.id "
" FROM %s.repl_nodes un "
"INNER JOIN %s.repl_nodes n "
" ON (un.id = n.upstream_node_id AND un.cluster = n.cluster)"
" WHERE n.cluster = '%s' "
" AND n.id = %i ",
get_repmgr_schema_quoted(standby_conn),
cluster);
get_repmgr_schema_quoted(standby_conn),
cluster,
node_id);
log_debug("%s", sqlquery);
@@ -439,20 +479,19 @@ get_upstream_connection(PGconn *standby_conn, char *cluster,
return NULL;
}
// ZZZ check for empty result
// maybe modify function to return NULL
strncpy(upstream_conninfo, PQgetvalue(res, 0, 0), MAXCONNINFO);
*upstream_node_id = atoi(PQgetvalue(res, 0, 1));
if(upstream_node_id_ptr != NULL)
*upstream_node_id_ptr = atoi(PQgetvalue(res, 0, 1));
PQclear(res);
log_debug("conninfo is: '%s'", upstream_conninfo);
log_debug("conninfo is: '%s'\n", upstream_conninfo);
upstream_conn = establish_db_connection(upstream_conninfo, false);
if (PQstatus(upstream_conn) != CONNECTION_OK)
{
log_err(_("Unable to connect to upstream server: %s\n"),
log_err(_("Unable to connect to upstream node: %s\n"),
PQerrorMessage(upstream_conn));
return NULL;
}
@@ -494,7 +533,7 @@ get_master_connection(PGconn *standby_conn, char *cluster,
"SELECT id, conninfo "
" FROM %s.repl_nodes "
" WHERE cluster = '%s' "
" AND NOT witness ",
" AND type != 'witness' ",
get_repmgr_schema_quoted(standby_conn),
cluster);