Fetch rows from a Trino result

Pulls rows from the cursor, following Trino's nextUri chain as needed, and converts each column to its R type according to the column's declared Trino type and the connection's bigint setting.

Usage

# S4 method for class 'TrinoResult'
dbFetch(res, n = -1, ...)

Arguments

res

A TrinoResult object.

n

Number of rows to fetch. -1 or Inf (the default is -1) fetches every remaining row, paginating until the query finishes. A positive n returns at most that many rows, pulling as many pages as needed and keeping the remainder buffered on the cursor for the next call. 0 returns no rows but the result's columns, with their types.

...

Unused, for compatibility with the generic.

Value

A tibble. Once the result is exhausted, a zero-row tibble with the right columns and types.

Examples

if (FALSE) { # nzchar(Sys.getenv("RTRINO_TEST_URL"))
con <- DBI::dbConnect(RTrino::Trino(), host = Sys.getenv("RTRINO_TEST_URL"),
                      catalog = "tpch", schema = "tiny")
res <- DBI::dbSendQuery(con, "SELECT * FROM orders")
while (!DBI::dbHasCompleted(res)) {
  chunk <- DBI::dbFetch(res, n = 4000)
  # process chunk; here, just count its rows
  cat(nrow(chunk), "rows\n")
}
DBI::dbClearResult(res)
DBI::dbDisconnect(con)
}