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# ######################################################################
# * General information *
# Instruments in the ndbcluster plugin uses the "ndbcluster"
# identifier plus a name which normally is the name of the
# object in the code. The prefix is decided by performance_schema and
# depends on the objects type.
# ie. <prefix>/ndbcluster/<variable_name>.
# All available instruments, their doc string etc are listed in the
# setup_instruments table.
# The system variables are prefixed with "ndb" and can be
# queried to see either global or session variables
SELECT COUNT(*) > 10 FROM performance_schema.global_variables
WHERE VARIABLE_NAME LIKE 'ndb%';
COUNT(*) > 10
1
SELECT * FROM performance_schema.session_variables
WHERE VARIABLE_NAME = 'ndb_use_copying_alter_table';
VARIABLE_NAME VARIABLE_VALUE
ndb_use_copying_alter_table OFF
# It's possible to see values of session variable for each thread
SELECT * FROM performance_schema.variables_by_thread
WHERE VARIABLE_NAME = 'ndb_use_transactions';
THREAD_ID VARIABLE_NAME VARIABLE_VALUE
<thread_id> ndb_use_transactions ON
# It's possible to query information about each variable
SELECT VARIABLE_NAME FROM performance_schema.variables_info
WHERE VARIABLE_NAME = 'ndb_version';
VARIABLE_NAME
ndb_version
# The status variables are prefixed with "Ndb" and can be
# queried to see either global or session status
SELECT COUNT(*) > 10 FROM performance_schema.global_status
WHERE VARIABLE_NAME LIKE 'Ndb%';
COUNT(*) > 10
1
SELECT * FROM performance_schema.session_status
WHERE VARIABLE_NAME = 'Ndb_replica_max_replicated_epoch';
VARIABLE_NAME VARIABLE_VALUE
Ndb_replica_max_replicated_epoch 0
# The threads created by the ndbcluster plugin can be queried, this
# provide a mapping to OS thread id
SELECT THREAD_ID, NAME, TYPE, THREAD_OS_ID FROM performance_schema.threads
WHERE NAME LIKE "thread/ndbcluster/%" ORDER BY NAME;
THREAD_ID NAME TYPE THREAD_OS_ID
<thread_id> thread/ndbcluster/ndb_binlog BACKGROUND <thread_os_id>
<thread_id> thread/ndbcluster/ndb_index_stat BACKGROUND <thread_os_id>
<thread_id> thread/ndbcluster/ndb_metadata BACKGROUND <thread_os_id>
<thread_id> thread/ndbcluster/ndb_purger BACKGROUND <thread_os_id>
# The threads created by the ndbcluster plugin can be used to query
# the amount of memory allocated by those from the mem_root arena
SELECT IF(PFS_MEM.SUM_NUMBER_OF_BYTES_ALLOC > 0, "true", "false") AS has_alloc_mem
FROM performance_schema.memory_summary_by_thread_by_event_name PFS_MEM
JOIN performance_schema.threads PFS_THR
ON PFS_MEM.THREAD_ID = PFS_THR.THREAD_ID
WHERE PFS_THR.name LIKE '%ndb_binlog%' AND EVENT_NAME LIKE '%THD::main_mem_root%';
has_alloc_mem
true
# The amount of memory used when accessing DD from ndbcluster plugin
# threads can be queried
SELECT IF(PFS_MEM.SUM_NUMBER_OF_BYTES_ALLOC > 0, "true", "false") AS has_alloc_mem
FROM performance_schema.memory_summary_by_thread_by_event_name PFS_MEM
JOIN performance_schema.threads PFS_THR
ON PFS_MEM.THREAD_ID = PFS_THR.THREAD_ID
WHERE PFS_THR.name LIKE '%ndb_binlog%' AND
EVENT_NAME LIKE '%Ndb_dd_client::dd_mem_root%';
has_alloc_mem
true
# The instrumented memory roots can be queried
SELECT EVENT_NAME
FROM performance_schema.memory_summary_by_thread_by_event_name
WHERE THREAD_ID = PS_CURRENT_THREAD_ID() AND
EVENT_NAME LIKE 'memory/ndbcluster/%';
EVENT_NAME
memory/ndbcluster/Thd_ndb::batch_mem_root
memory/ndbcluster/Ndb_dd_client::dd_mem_root
# Log messages written by ndbcluster plugin can be queried
# using the error_log table where the SUBSYSTEM column is
# set to "NDB"
SELECT THREAD_ID, PRIO, ERROR_CODE, SUBSYSTEM, DATA
FROM performance_schema.error_log
WHERE SUBSYSTEM = "NDB" AND
DATA LIKE "%all storage nodes connected%";
THREAD_ID 0
PRIO System
ERROR_CODE MY-010865
SUBSYSTEM NDB
DATA connection[0], NodeID: 49, all storage nodes connected
# Log messages written by ndbcluster plugin components that call into
# MySQL (need a THD) must have a thread_id (THD id) assigned
SELECT LEFT(DATA,LOCATE(':',DATA)-1) as component, IF(THREAD_ID > 0, "true", "false") AS has_thread_id
FROM performance_schema.error_log
WHERE SUBSYSTEM = "NDB" AND
DATA LIKE "%: Started%" ORDER BY DATA;
component Binlog
has_thread_id true
component Index Stat
has_thread_id false
component Metadata
has_thread_id true
component Purger
has_thread_id true
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