db2env {filehash} | R Documentation |
Load entire database into an environment
db2env(db)
db |
database object |
db2env
is generic but there is a method for objects of class
"filehash"
.
db2env
loads the entire database db
into an environment
via calls to makeActiveBinding
. Therefore, the data themselves
are not stored in the environment, but a function pointing to the data
in the database is stored. When an element of the environment is
accessed, the function is called to retrieve the data from the
database. If the data in the database is changed, the changes will be
reflected in the environment.
The use of makeActiveBinding
allows for potentially large
databases to, at least conceptually, be used in R, as long as you
don't need simultaneous access to all of the elements in the
database.
An environment is returned, the elements of which are the keys of the database.
Roger D. Peng
dbCreate("myDB") db <- dbInitialize("myDB") dbInsert(db, "a", rnorm(100)) dbInsert(db, "b", 1:10) env <- db2env(db) ls(env) ## "a", "b" print(env$b) mean(env$a) env$a <- rnorm(100) mean(env$a) env$b[1:5] <- 5:1 print(env$b)