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Restart Type 

N (NDB 8.0.13) 

This parameter is present beginning in NDB 8.0.20, but has no effect prior to NDB 8.0.24. It provides a simple interface to control adaptive spinning on data nodes, with four possible values furnishing presets for spin parameter values, as shown in the following list: 

1. StaticSpinning  (default): Sets EnableAdaptiveSpinning  to false  and SchedulerSpinTimer  to 0. ( SetAllowedSpinOverhead  is not relevant in this case.) 

2. CostBasedSpinning : Sets EnableAdaptiveSpinning  to true , SchedulerSpinTimer  to 100, and SetAllowedSpinOverhead  to 200. 

3. LatencyOptimisedSpinning : Sets EnableAdaptiveSpinning  to true , SchedulerSpinTimer  to 200, and SetAllowedSpinOverhead  to 1000. 

4. DatabaseMachineSpinning : Sets EnableAdaptiveSpinning  to true , SchedulerSpinTimer  to 500, and SetAllowedSpinOverhead  to 10000. This is intended for use in cases where threads own their own CPUs. 

The spin parameters modified by SpinMethod  are described in the following list: 

• SchedulerSpinTimer : This is the same as the data node configuration parameter of that name. The setting applied to this parameter by SpinMethod  overrides any value set in the config.ini  file. 

• EnableAdaptiveSpinning : Enables or disables adaptive spinning. Disabling it causes spinning to be performed without making any checks for CPU resources. This parameter cannot be set directly in the cluster configuration file, and under most circumstances should not need to be, but can be enabled directly using DUMP 104004 1  or disabled with DUMP 104004 0  in the ndb_mgm  management client. 

• SetAllowedSpinOverhead : Sets the amount of CPU time to allow for gaining latency. This parameter cannot be set directly in the config.ini  file. In most cases, the setting applied by SpinMethod should be satisfactory, but if it is necessary to change it directly, you can use DUMP 104002 overhead  to do so, where overhead  is a value ranging from 0 to 10000, inclusive; see the description of the indicated DUMP  command for details. 

On platforms lacking usable spin instructions, such as PowerPC and some SPARC platforms, spin time is set to 0 in all situations, and values for SpinMethod  other than StaticSpinning  are ignored. 

• TwoPassInitialNodeRestartCopy 

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Multithreaded building of ordered indexes can be enabled for initial restarts of data nodes by setting this configuration parameter to true  (the default value), which enables two-pass copying of data during initial node restarts. 

You must also set BuildIndexThreads  to a nonzero value. 

