6.8.14SET MPI HINT

#Syntax

#Description

Set MPI hints⁵³ for accessing HDF5 files in an MPI environment. In other words, hints can be specified as key/value pairs to configure how files are created or used (i.e. opened) and are interpreted by the MPI environment (and not by HDFql/HDF5 library itself) to, e.g., increase performance. If using an HDFql non MPI-based distribution, an error is raised. In case the keyword DEFAULT is specified, the MPI hints are set to empty (i.e. nothing is passed to the MPI environment).

#Parameter(s)

hint_key – mandatory string that specifies the key of the hint to pass to the MPI environment.

hint_value – mandatory string that specifies the value (associated with the hint key) to pass to the MPI environment.

#Return

Nothing

#Example(s)

# set MPI hint "my_hint_key" to "my_hint_value" 
SET MPI HINT my_hint_key my_hint_value

# show (i.e. get) MPI hints (should return "my_hint_key", "my_hint_value") 
SHOW MPI HINT 

# set MPI hints to the default value (i.e. empty) 
SET MPI HINT DEFAULT

# show (i.e. get) MPI hints (should return nothing) 
SHOW MPI HINT 

# set MPI hints "striping_factor" to "4", "striping_unit" to "65536", and "cb_buffer_size" to "8388608"
SET MPI HINT striping_factor 4, striping_unit 65536, cb_buffer_size 8388608

# show (i.e. get) MPI hints (should return "striping_factor", "4", "striping_unit", "65536", "cb_buffer_size", and "8388608")
SHOW MPI HINT