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repmgrd: skip LSN checks of 0 priority node

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The node will never become a candidate so we can save the round trip
to fetch its LSN.
This commit is contained in:
Ian Barwick
2019-02-06 14:25:57 +09:00
parent 984ce7420b
commit b9cd321aed
1 changed files with 47 additions and 40 deletions
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87
repmgrd-physical.c
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@@ -3072,6 +3072,8 @@ _print_election_result(ElectionResult result)
/* /*
* Failover decision for nodes attached to the current primary.
*
* NB: this function sets standby_nodes; caller (do_primary_failover) * NB: this function sets standby_nodes; caller (do_primary_failover)
* expects to be able to read this list * expects to be able to read this list
*/ */
@@ -3221,61 +3223,66 @@ do_election(void)
log_debug("node %i is witness, not querying state", cell->node_info->node_id); log_debug("node %i is witness, not querying state", cell->node_info->node_id);
continue; continue;
} }
/* XXX don't check 0-priority nodes */ /* don't check 0-priority nodes */
if (cell->node_info->priority == 0)
/* get node's LSN - if "higher" than current winner, current node is candidate */
cell->node_info->last_wal_receive_lsn = get_last_wal_receive_location(cell->node_info->conn);
log_verbose(LOG_DEBUG, "node %i's last receive LSN is: %X/%X",
cell->node_info->node_id,
format_lsn(cell->node_info->last_wal_receive_lsn));
/* compare LSN */
if (cell->node_info->last_wal_receive_lsn > candidate_node->last_wal_receive_lsn)
{ {
/* other node is ahead */ log_debug("node %i has priority of 0, skipping",
log_verbose(LOG_DEBUG, "node %i is ahead of current candidate %i", cell->node_info->node_id);
cell->node_info->node_id,
candidate_node->node_id);
candidate_node = cell->node_info;
} }
/* LSN is same - tiebreak on priority, then node_id */ else
else if (cell->node_info->last_wal_receive_lsn == candidate_node->last_wal_receive_lsn)
{ {
log_verbose(LOG_DEBUG, "node %i has same LSN as current candidate %i", /* get node's last receive LSN - if "higher" than current winner, current node is candidate */
cell->node_info->last_wal_receive_lsn = get_last_wal_receive_location(cell->node_info->conn);
log_verbose(LOG_DEBUG, "node %i's last receive LSN is: %X/%X",
cell->node_info->node_id, cell->node_info->node_id,
candidate_node->node_id); format_lsn(cell->node_info->last_wal_receive_lsn));
if (cell->node_info->priority > candidate_node->priority)
/* compare LSN */
if (cell->node_info->last_wal_receive_lsn > candidate_node->last_wal_receive_lsn)
{ {
log_verbose(LOG_DEBUG, "node %i has higher priority (%i) than current candidate %i (%i)", /* other node is ahead */
log_verbose(LOG_DEBUG, "node %i is ahead of current candidate %i",
cell->node_info->node_id, cell->node_info->node_id,
cell->node_info->priority, candidate_node->node_id);
candidate_node->node_id,
candidate_node->priority);
candidate_node = cell->node_info; candidate_node = cell->node_info;
} }
else if (cell->node_info->priority == candidate_node->priority) /* LSN is same - tiebreak on priority, then node_id */
else if (cell->node_info->last_wal_receive_lsn == candidate_node->last_wal_receive_lsn)
{ {
if (cell->node_info->node_id < candidate_node->node_id) log_verbose(LOG_DEBUG, "node %i has same LSN as current candidate %i",
cell->node_info->node_id,
candidate_node->node_id);
if (cell->node_info->priority > candidate_node->priority)
{ {
log_verbose(LOG_DEBUG, "node %i has same priority but lower node_id than current candidate %i", log_verbose(LOG_DEBUG, "node %i has higher priority (%i) than current candidate %i (%i)",
cell->node_info->node_id, cell->node_info->node_id,
candidate_node->node_id); cell->node_info->priority,
candidate_node->node_id,
candidate_node->priority);
candidate_node = cell->node_info; candidate_node = cell->node_info;
} }
} else if (cell->node_info->priority == candidate_node->priority)
else {
{ if (cell->node_info->node_id < candidate_node->node_id)
log_verbose(LOG_DEBUG, "node %i has lower priority (%i) than current candidate %i (%i)", {
cell->node_info->node_id, log_verbose(LOG_DEBUG, "node %i has same priority but lower node_id than current candidate %i",
cell->node_info->priority, cell->node_info->node_id,
candidate_node->node_id, candidate_node->node_id);
candidate_node->priority); candidate_node = cell->node_info;
}
}
else
{
log_verbose(LOG_DEBUG, "node %i has lower priority (%i) than current candidate %i (%i)",
cell->node_info->node_id,
cell->node_info->priority,
candidate_node->node_id,
candidate_node->priority);
}
} }
} }
} }
if (primary_location_seen == false) if (primary_location_seen == false)