scidb (version 1.2-0)

persist: persist

Description

Mark a scidb or scidbdf object and any SciDB arrays in its dependency graph persistent.

Usage

persist(x, remove = FALSE, ...)

Arguments

x

A scidb or scidbdf object

remove

A logical value. See details.

...

Optional arguments not used by the default method, but reserved for future use.

Value

NULL is invisibly returned. Use this function for its side effects.

Details

Most scidb objects are ephemeral unless the gc=FALSE option is explicitly selected. Use the persist function with remove=FALSE to mark an array and all of its dependencies persistent. This is useful when you want to save a scidb object to an R data file and make sure its data is there when re-loaded.

Specify remove=TRUE to 'unpersist' an object and all of its dependencies.

See Also

scidb

Examples

## Not run: 
# x <- as.scidb(iris)
# y <- unique(x$Species)
# persist(y)
# save(y, file="y.rdata")
# 
# # Now, *both* x and y can be removed without deleting the backing SciDB
# # array. Without persist or setting gc=FALSE on x, the array would have
# # been removed.
# rm(x,y)
# gc()
# 
# # Since the array is still there, we can get it back.
# load("y.rdata")
# y[]
# ## End(Not run)