dplyr (version 0.5.0)

compute: Compute a lazy tbl.

Description

compute forces computation of lazy tbls, leaving data in the remote source. collect also forces computation, but will bring data back into an R data.frame (stored in a tbl_df). collapse doesn't force computation, but collapses a complex tbl into a form that additional restrictions can be placed on.

Usage

compute(x, name = random_table_name(), ...)
collect(x, ...)
collapse(x, ...)
# S3 method for tbl_sql
compute(x, name = random_table_name(), temporary = TRUE,
  unique_indexes = list(), indexes = list(), ...)

Arguments

x

a data tbl

name

name of temporary table on database.

...

other arguments passed on to methods

temporary

if TRUE, will create a temporary table that is local to this connection and will be automatically deleted when the connection expires

unique_indexes

a list of character vectors. Each element of the list will create a new unique index over the specified column(s). Duplicate rows will result in failure.

indexes

a list of character vectors. Each element of the list will create a new index.

Grouping

compute and collect preserve grouping, collapse drops it.

See Also

copy_to which is the conceptual opposite: it takes a local data frame and makes it available to the remote source.

Examples

if (require("RSQLite") && has_lahman("sqlite")) {
  batting <- tbl(lahman_sqlite(), "Batting")
  remote <- select(filter(batting, yearID > 2010 && stint == 1), playerID:H)
  remote2 <- collapse(remote)
  cached <- compute(remote)
  local  <- collect(remote)
}