Oracle 5.0, Reference Manual

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MySQL Cluster Log Messages
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Note
A single transaction may operate on data stored in multiple LQH blocks.
The
Operations
statistic provides the number of local operations performed by this LQH block in the
last reporting interval, and includes all types of read and write operations (insert, update, write, and
delete operations). This also includes operations used to replicate writes—for example, in a 2-replica
cluster, the write to the primary replica is recorded in the primary LQH, and the write to the backup
will be recorded in the backup LQH. Unique key operations may result in multiple local operations;
however, this does not include local operations generated as a result of a table scan or ordered index
scan, which are not counted.
Process scheduler statistics. In addition to the statistics reported by the transaction coordinator
and local query handler, each
ndbd
process has a scheduler which also provides useful metrics
relating to the performance of a MySQL Cluster. This scheduler runs in an infinite loop; during each
loop the scheduler performs the following tasks:
1. Read any incoming messages from sockets into a job buffer.
2. Check whether there are any timed messages to be executed; if so, put these into the job buffer as
well.
3. Execute (in a loop) any messages in the job buffer.
4. Send any distributed messages that were generated by executing the messages in the job buffer.
5. Wait for any new incoming messages.
Process scheduler statistics include the following:
•
Mean Loop Counter
. This is the number of loops executed in the third step from the preceding
list. This statistic increases in size as the utilization of the TCP/IP buffer improves. You can use this
to monitor changes in performance as you add new data node processes.
•
Mean send size
and
Mean receive size
. These statistics enable you to gauge the
efficiency of, respectively writes and reads between nodes. The values are given in bytes. Higher
values mean a lower cost per byte sent or received; the maximum value is 64K.
To cause all cluster log statistics to be logged, you can use the following command in the
NDB
management client:
ndb_mgm> ALL CLUSTERLOG STATISTICS=15
Note
Setting the threshold for
STATISTICS
to 15 causes the cluster log to become
very verbose, and to grow quite rapidly in size, in direct proportion to the
number of cluster nodes and the amount of activity in the MySQL Cluster.
For more information about MySQL Cluster management client commands relating to logging and
reporting, see
Section 17.5.6.1, “MySQL Cluster Logging Management Commands” .
17.5.7. MySQL Cluster Log Messages
This section contains information about the messages written to the cluster log in response to different
cluster log events. It provides additional, more specific information on
NDB
transporter errors.
17.5.7.1. MySQL Cluster: Messages in the Cluster Log
The following table lists the most common
NDB
cluster log messages. For information about the
cluster log, log events, and event types, see Section 17.5.6, “Event Reports Generated in MySQL