eG Monitoring
 

Measures reported by MySQLCluQueryTest

This test reports the performance statistics pertaining to the queries executed on each node in the target MySQL Cluster database server.

Outputs of the test : One set of results for each node in the target MySQL Cluster database server being monitored

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Query_rate Indicates the rate at which queries are sent to this node. Queries/Second This is an indicator of the workload on each node.
Slow_queries Indicates the number of queries that have taken more than the ‘long_query_time’ for execution on this node, during the last measurement period. Number This value should ideally be 0. If it remains consistently high, the administrator should look to identify and optimize the slow queries.

Compare the value of this measure across nodes to determine the node where too many queries are slow.
Handler_read_first Indicates the number of times the first entry was read from an index on this node during the last measurement period. Number If the value of this measure is high, it suggests that the server is doing a lot of full index scans.
Handler_read_key Indicates the number of requests that were received in the last measurement period, to read a row based on a key. Number If the value of this measure is high, it indicates that your queries and tables are properly indexed.
Handler_read_next Indicates the number of requests received in the last measurement period, to read the next row in the key order. Number This will be incremented if you are querying an index column with a range constraint. This will also be incremented if you are doing an index scan.
Handler_read_prev Indicates the number of requests received in the last measurement period, to read the previous row in the key order. Number This is mainly used to optimize ORDER BY... DESC.
Handler_read_rnd Indicates the number of requests received in the last measurement period, to read a row based on a fixed position. Number This will be high if you are executing a lot of queries that require sorting of the result. If the value of this measure is high, then you probably have a lot of queries that require MySQL cluster to scan whole tables or you have joins that do not use keys properly.
Handler_read_rnd_next Indicates the number of requests received in the last measurement period, to read the next row in the datafile. Number This will be high if you are performing a lot of table scans. Generally, this suggests that your tables are not properly indexed or that your queries are not written to use the indexes properly.