R/schemas.R

In sergeant: Tools to Transform and Query Data with Apache Drill

#' Returns a list of available schemas.
#'
#' @param drill_con drill server connection object setup by \code{drill_connection()}
#' @param .progress if \code{TRUE} (default if in an interactive session) then ask
#'                  \code{httr::RETRY} to display a progress bar
#' @references \href{https://drill.apache.org/docs/}{Drill documentation}
#' @family Dill direct REST API Interface
#' @export
drill_show_schemas <- function(drill_con, .progress=interactive()) {
  drill_query(drill_con, "SHOW SCHEMAS", .progress = .progress)
}

#' Change to a particular schema.
#'
#' @param drill_con drill server connection object setup by \code{drill_connection()}
#' @param schema_name A unique name for a Drill schema. A schema in Drill is a configured
#'                   storage plugin, such as hive, or a storage plugin and workspace.
#' @param .progress if \code{TRUE} (default if in an interactive session) then ask
#'                  \code{httr::RETRY} to display a progress bar
#' @references \href{https://drill.apache.org/docs/}{Drill documentation}
#' @family Dill direct REST API Interface
#' @export
drill_use <- function(drill_con, schema_name, .progress=interactive()) {
  query <- sprintf("USE `%s`", schema_name)
  out <- drill_query(drill_con, query, .progress = .progress)
  if (("errorMessage" %in% names(out))) message(str(out, 2))
  invisible(out)
}

#' Show files in a file system schema.
#'
#' @param drill_con drill server connection object setup by \code{drill_connection()}
#' @param schema_spec properly quoted "filesystem.directory_name" reference path
#' @param .progress if \code{TRUE} (default if in an interactive session) then ask
#'                  \code{httr::RETRY} to display a progress bar
#' @export
#' @references \href{https://drill.apache.org/docs/}{Drill documentation}
#' @family Dill direct REST API Interface
#' @examples
#' try({
#' drill_connection() %>% drill_show_files("dfs.tmp")
#' }, silent=TRUE)
drill_show_files <- function(drill_con, schema_spec, .progress=interactive()) {
  query <- sprintf("SHOW FILES IN %s", schema_spec)
  drill_query(drill_con, query, uplift=TRUE, .progress = .progress) %>%
    dplyr::select(name, isDirectory, permissions, dplyr::everything())
}