MySQL 5.6 Reference Manual Including MySQL NDB Cluster 7.3-7.4 Reference Guide
Querying this table provides information similar to that
provided by the ALL REPORT
MemoryUsage
command in the ndb_mgm
client, or logged by ALL DUMP
1000
.
The memoryusage
table contains the following
columns:
node_id
The node ID of this data node.
memory_type
One of Data memory
, Index
memory
, or Long message buffer
.
used
Number of bytes currently used for data memory or index memory by this data node.
used_pages
Number of pages currently used for data memory or index memory by this data node; see text.
total
Total number of bytes of data memory or index memory available for this data node; see text.
total_pages
Total number of memory pages available for data memory or index memory on this data node; see text.
The total
column represents the total amount
of memory in bytes available for the given resource (data memory
or index memory) on a particular data node. This number should
be approximately equal to the setting of the corresponding
configuration parameter in the config.ini
file.
Suppose that the cluster has 2 data nodes having node IDs
5
and 6
, and the
config.ini
file contains the following:
[ndbd default] DataMemory = 1G IndexMemory = 1G
Suppose also that the value of the
LongMessageBuffer
configuration parameter is allowed to assume its default (64 MB
in NDB 7.3.5 and later).
The following query shows approximately the same values:
mysql> SELECT node_id, memory_type, total > FROM ndbinfo.memoryusage; +---------+---------------------+------------+ | node_id | memory_type | total | +---------+---------------------+------------+ | 5 | Data memory | 1073741824 | | 5 | Index memory | 1074003968 | | 5 | Long message buffer | 67108864 | | 6 | Data memory | 1073741824 | | 6 | Index memory | 1074003968 | | 6 | Long message buffer | 67108864 | +---------+---------------------+------------+ 6 rows in set (0.00 sec)
In this case, the total
column values for
index memory are slightly higher than the value set of
IndexMemory
due to
internal rounding.
For the used_pages
and
total_pages
columns, resources are measured
in pages, which are 32K in size for
DataMemory
and 8K for
IndexMemory
. For long
message buffer memory, the page size is 256 bytes.
Long message buffer information can be found in this table beginning with NDB 7.3.5; in earlier versions of NDB Cluster, only data memory and index memory were included.