db.gpapply.md

In greenplum-db/GreenplumR: A Fast, Easy-to-Use Tool for Manipulating Tables in Databases

db.gpapply:

Apply a R function to every row of data of a data frame object.

Description

gpapply allows you to run a R function with input data frame in GPDB through PL/container or PL/R language. The R function will be parsed, then an UDF will be created in GPDB schema for execution. The calculation will be done in parallel with computing resources of GPDB segment hosts.

Usage

db.gpapply(X, FUN = NULL, output.name = NULL, output.signature = NULL,
            clear.existing = FALSE, case.sensitive = FALSE, output.distributeOn = NULL,
            debugger.mode = FALSE, runtime.id = "plc_r_shared", language = "plcontainer", input.signature = NULL, ...)

Arguments

Argument |Description ------------- |---------------- X | type must be db.data.frame, the first argument of FUN FUN | The function to apply each row of db.data.frame X MARGIN | padding argument, can be ignored output.name | The name of output table clear.existing | whether clear existing output table stored in GPD before executing the query output.signature | The signature of output table, can be a list or a function that takes no parameters. e.g. output.signature <- list(id = 'int', 'Sex' = 'text', 'Length' = 'float', height = 'float', shell = 'float') or output.signature <- function() list(id = 'int') case.sensitive | Bool. Whether output.name and the colume names of input tables are case sensitive or not output.distributeOn | Specify how output table is stored in database debugger.mode | TRUE to print the executed SQL internally. runtime.id | Used by "plcontainer" language only. The runtime id is set by plcontainer to specify a runtime cnofiguration. See plcontainer for more information. The argument type is string, e.g. "plc_r_shared" language | value should be "plcontainer" or "plr" input.signature | A list contains the name matching pattern between input table column name (i.e. parameter X) and apply function arugments if the type of apply function first parameter is not a data.frame. e.g. input.signature <- list('c1' = 'arg1')

Other parameters: if the function FUN has extra argument other than X, you can append them after all of the required arguments list.

Return Value

A data.frame that contains the result if the result is not empty. Otherwise, it returns a logical value, which indicates whether the SQL query has been sent to the database successfully.

Examples

r db.gptapply(X = dbDF, FUN = funcToRun, output.signature = list(id = 'int', 'Sex' = 'text'), clear.existing = FALSE, case.sensitive = FALSE, output.distributeOn = 'id', runtime.id = "plc_r_shared", language = "plcontainer", arg1OfFUN, arg2OfFUN)

greenplum-db/GreenplumR documentation built on Sept. 2, 2023, 8:09 a.m.