Documentation Home
MySQL 9.1 Reference Manual
Related Documentation Download this Manual
PDF (US Ltr) - 40.4Mb
PDF (A4) - 40.5Mb
Man Pages (TGZ) - 259.5Kb
Man Pages (Zip) - 366.7Kb
Info (Gzip) - 4.1Mb
Info (Zip) - 4.1Mb


MySQL 9.1 Reference Manual  / ...  / MySQL Performance Schema  / Performance Schema Table Descriptions  /  Performance Schema NDB Cluster Tables

29.12.12 Performance Schema NDB Cluster Tables

The following table shows all Performance Schema tables relating to theNDBCLUSTER storage engine.

Table 29.3 Performance Schema NDB Tables

Table NameDescription
ndb_replication_applier_statusNDB replication applier status information for each replication channel
ndb_sync_excluded_objectsNDB objects which cannot be synchronized
ndb_sync_pending_objectsNDB objects waiting for synchronization

Note

These tables are present only if MySQL has support enabled for theNDBCLUSTER storage engine.

Automatic synchronization inNDB attempts to detect and synchronize automatically all mismatches in metadata between the NDB Cluster's internal dictionary and the MySQL Server's datadictionary. This is done by default in the background at regular intervals as determined by thendb_metadata_check_interval system variable, unless disabled usingndb_metadata_check or overridden by settingndb_metadata_sync.

Information about the current state of automatic synchronization is exposed by a MySQL server acting as an SQL node in an NDB Cluster in these two Performance Schema tables:

  • ndb_sync_pending_objects: Displays information aboutNDB database objects for which mismatches have been detected between theNDB dictionary and the MySQL data dictionary. When attempting to synchronize such objects,NDB removes the object from the queue awaiting synchronization, and from this table, and tries to reconcile the mismatch. If synchronization of the object fails due to a temporary error, it is picked up and added back to the queue (and to this table) the next timeNDB performs mismatch detection; if the attempts fails due a permanent error, the object is added to thendb_sync_excluded_objects table.

  • ndb_sync_excluded_objects: Shows information aboutNDB database objects for which automatic synchronization has failed due to permanent errors resulting from mismatches which cannot be reconciled without manual intervention; these objects are blocklisted and not considered again for mismatch detection until this has been done.

These tables are described in more detail in the next two sections.

Historically, information about the state of theNDB replication applier was available only as a set of server status variables, which reflected the state of the default replication channel only. Thendb_replication_applier_status table provides this information for each active replication channel. SeeSection 29.12.12.3, “The ndb_replication_applier_status Table”, for a detailed description of this table and its columns.