[erlang-questions] Retrieving "semi-constant" data from a function versus Mnesia ( corrected line-breaks ! )

Peter Johansson flexchap@REDACTED
Sat May 9 14:55:43 CEST 2015

2015-05-09 14:35 GMT+02:00 Peter Johansson <flexchap@REDACTED>:

> Hi to all fellow Erlang-users out there !
> I'm working with a web-application prototype, powered by Erlang, at the
> current time ..... and is for the moment preoccupied with the choose of a
> suitable implementation regarding in-memory storage of shared/"top-level"
> configuration-data terms.
> This configuration-data terms holds ejson-structures ( typically 5KB -
> 15KB in size ) and will be consulted by the majority of the request-related
> processes based on cookie-association & parameters.
> Since this configuration-data relatively rarely will undergo updates but
> still be read by almost every request-process I consider it's in-memory
> storage implementation as highly significant for the process-efficiency
> over time & shifting payload-situations.
> In the case of Mnesia the configuration-terms have to be retrieved by the
> means of transactions of table-records into the different process-heaps,
> that means in-memory copy-operations which obviously will cause some
> overhead in the environment during the occurrence of peak-like situations.
> The other case (the function case) is to template the updated
> ejson-structures (as the sole "return"-structures) into dedicated
> function-definitions, each definition hold in it's own module, and then
> recompile & reload those modules programmatically via special
> update-functions. The up to date configuration-data can then be retrieved
> by common processes as simple function-calls returning fixed data.
> I assume/expect these sole ejson/"return"-structures to be stored into the
> constant-pools of the modules when these becomes loaded in memory. In such
> case the call to any such function into a variable-bound should result in
> the creation of a memory-reference for that variable pointing to the fixed
> structure in the module's constant-pool.
> Retrieving the configuration-data in this later manner must be
> significantly more efficient compare to the case of transactions from
> Mnesia if considering both the sizes of the data-structures & the frequency
> under which they will be consulted/read.
> Is this assumption of mine correct/true or have I missed/overlooked
> something in my assessment of the situation ?
> Sending my best regards to you erlangers reading this !  / Peter
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