dbGetInfo,PrestoDriver-method {RPresto} | R Documentation |
Metadata about database objects
Description
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 signature 'PrestoDriver'
dbGetInfo(dbObj)
## S4 method for signature 'PrestoConnection'
dbGetInfo(dbObj)
## S4 method for signature '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
## 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)
[Package RPresto version 1.4.6 Index]