dbGetInfo,PrestoDriver-method {RPresto} | R Documentation |
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.
## S4 method for signature 'PrestoDriver'
dbGetInfo(dbObj)
## S4 method for signature 'PrestoConnection'
dbGetInfo(dbObj)
## S4 method for signature 'PrestoResult'
dbGetInfo(dbObj)
dbObj |
A |
[PrestoResult] A list
with elements
The SQL sent to the database
Number of rows fetched so far
Whether all data has been fetched
Current stats on the query
## Not run:
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)
## End(Not run)