As part of optimising scan execution by about 50% in MySQL
we made an effort to also write down a description of the scan protocol
locally within the LDM threads. This is documented in the source code of
MySQL Cluster 7.4 and here is an excerpt from the source code.
DBLQH controls the execution of scans on tables on behalf of DBTC and
DBSPJ. Here follows a signal overview of how a scan is performed within
one LDM instance. For a description of the global scan protocol
see DbtcMain.cpp as a comment before execSCAN_TABREQ.
DBLQH only controls execution of a …