Save (or load) allocation size default preference in an optional config file

Usage

save_allocation_size_preference(value)

get_allocation_size_preference()

set_allocation_size_preference(value)

Arguments

value

A numeric value with the desired allocation size (in bytes).

Value

For the setter, TRUE is returned invisibly but the function is invoked for the side effect of storing the value. For the getters, the value as a numeric.

Details

When retrieving data from sparse arrays, allocation sizes cannot be determined ex ante as the degree of sparsity is unknown. A configuration value can aide in providing an allocation size value. These functions let the user store such a value for retrieval by their package or script code. The preference will be encoded in a configuration file as R (version 4.0.0 or later) allows a user- and package specific configuration files. These helper functions sets and retrieve the value, respectively, or retrieve the cached value from the package environment where is it set at package load.

The value will be stored as a character value and reparsed so ‘1e6’ and ‘1000000’ are equivalent, and the fixed (but adjustable) number of digits for numerical precision use for formatting will impact the writing. This should have no effect on standard allocation sizes.

The value is used as a limit per column so total memory use per query will a multiple of this value, and increasing in dimension and attribute count.

A fallback value of 10 mb is used if no user value is set.

Note

This function requires R version 4.0.0 or later to utilise the per-user config directory accessor function. For older R versions, a fallback from the TileDB configuration object is used.