Apply R/S-Plus functions to remote groups of DBMS rows (experimental)

Applies R/S-Plus functions to groups of remote DBMS rows without bringing an entire result set all at once. The result set is expected to be sorted by the grouping field.

Methods

res

a PostgreSQL result set (see dbSendQuery).

...

any additional arguments to be passed to FUN.

References

See the Database Interface definition document DBI.pdf in the base directory of this package or https://cran.r-project.org/package=DBI.

See also

PostgreSQL postgresqlDBApply dbSendQuery fetch

Examples

if (FALSE) { # \dontrun{
## compute quanitiles for each network agent
con <- dbConnect(PostgreSQL(), user="user", password="passwd",dbname="dbname")
rs <- dbSendQuery(con, 
             "select Agent, ip_addr, DATA from pseudo_data order by Agent")
out <- dbApply(rs, INDEX = "Agent", 
        FUN = function(x, grp) quantile(x$DATA, names=FALSE))
} # }