Understanding Event Sequences in NDBCluster Using pollEvents2 Method (Doc ID 2215461.1)

Last updated on MARCH 08, 2017

Applies to:

MySQL Cluster - Version 7.4 and later
Information in this document applies to any platform.


On : 7.4 version, NDB API

27659 Query insert into TABLE_FOO values(1,0)
27659 Query delete from TABLE_BAR
27659 Query insert into TABLE_BAR values (100,'',0, 'stringvalue',1, 0, 0, 'n',100, 10, 'CHAR', 'example.domain.com',0, 0, 0, 1473303190)
27659 Query delete from TABLE_FOO
27659 Quit

An ndbapi script then does ndb->pollEvents2(_poll_wait_time) with the sequence sometimes like this
Had an Event = 2tab_ix=26 TABLE_BAR
Had an Event = 1tab_ix=26
Had an Event = 1tab_ix=27 TABLE_FOO
Had an Event = 2tab_ix=27

Other times like this
Had an Event = 2tab_ix=26
Had an Event = 1tab_ix=27
Had an Event = 1tab_ix=26
Had an Event = 2tab_ix=27

To have the event order be consistent.

The issue has the following business impact:
Due to this issue, users cannot understand the order of events in Cluster.


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