Running a query fails with an error like:
Error 1735: Unable to connect to leaf @18.104.22.168:3306 with user root, using password NO:  Timed out reading from socket after 30 seconds
A MemSQL node is unable to connect to another MemSQL node. This may be because there is no network connectivity (such as a network problem or a firewall blocking connectivity), or because a node is overloaded with connection requests.
- Ensure that all nodes are able to connect to all other nodes on the configured port (default 3306). Make sure there is no firewall blocking connectivity.
- One way to verify connectivity is to run the MemSQL command on all MemSQL nodes. If this fails with the same error, then a node is unable to connect to another node.
- Note that some queries require different amounts of connectivity, e.g. some queries only require aggregator-leaf connections while others require aggregator-leaf as well as leaf-leaf connections. As a result, it is possible for some queries to succeed while others fail with this error.
- If all nodes are able to connect to all other nodes, the error is likely because your query or queries require opening too many connections at once. Run on all MemSQL nodes to pre-fill connection pools. If the connection pool size is too small for your workload, adjust the
max_pooled_connectionsconfiguration variable, which controls the number of pooled connections between each pair of nodes.