Metadata about database objects

For the PrestoResult object, the implementation returns the additional stats field which can be used to implement things like progress bars. See the examples section.

Usage

# S4 method for PrestoDriver
dbGetInfo(dbObj)

# S4 method for PrestoConnection
dbGetInfo(dbObj)

# S4 method for PrestoResult
dbGetInfo(dbObj)

Arguments

dbObj: A PrestoDriver, PrestoConnection or PrestoResult object

Value

PrestoResult A list() with elements

statement: The SQL sent to the database
row.count: Number of rows fetched so far
has.completed: Whether all data has been fetched
stats: Current stats on the query

Examples

if (FALSE) {
conn <- dbConnect(Presto(), "localhost", 7777, "onur", "datascience")
result <- dbSendQuery(conn, "SELECT * FROM jonchang_iris")
iris <- data.frame()
progress.bar <- NULL
while (!dbHasCompleted(result)) {
  chunk <- dbFetch(result)
  if (!NROW(iris)) {
    iris <- chunk
  } else if (NROW(chunk)) {
    iris <- rbind(iris, chunk)
  }
  stats <- dbGetInfo(result)[["stats"]]
  if (is.null(progress.bar)) {
    progress.bar <- txtProgressBar(0, stats[["totalSplits"]], style = 3)
  } else {
    setTxtProgressBar(progress.bar, stats[["completedSplits"]])
  }
}
close(progress.bar)
}