joekirincic/rhyper

A DBI-compliant interface to Tableau's Hyper Data Engine.

RHyper

A DBI-based interface to Tableau's Hyper Data Engine.

Installation

# Install the latest version using devtools:
# install.packages("devtools")
devtools::install_github("joekirincic/RHyper",)

# Or using remotes:
# install.packages("remotes")
remotes::install_github("joekirincic/RHyper")

Basic usage

library(DBI)
# Connect to a .hyper file.
hyper_file <- "mydb.hyper"
con <- dbConnect(RHyper::Hyper(), hyper_file)

dbListTables(con)
dbWriteTable(con, "mtcars", mtcars)
dbListTables(con)

dbListFields(con, "mtcars")
dbReadTable(con, "mtcars")

# You can fetch all results:
res <- dbSendQuery(con, "SELECT * FROM mtcars WHERE cyl = 4")
dbFetch(res)
dbClearResult(res)

# Or a chunk at a time
res <- dbSendQuery(con, "SELECT * FROM mtcars WHERE cyl = 4")
while(!dbHasCompleted(res)){
  chunk <- dbFetch(res, n = 5)
  print(nrow(chunk))
}
# Clear the result
dbClearResult(res)

# Disconnect from the database
dbDisconnect(con)

rhyper's Issues

Issue a warning when calling `dbConnect` on an invalid HyperConnection.

{DBItest} tests that calling dbConnect on an invalid connection results in a warning. A helper function (e.g. the accepted answer here) inside the disconnect function seems like an appropriate solution.

A warning should be issued when a `HyperConnection` is closed while a `HyperResult` is still open.

Issue warning when calling `dbDisconnect` on a closed HyperConnection.

{DBItest} tests that a warning is issued when dbConnect is called on a closed connection object. This test is satisfied by changing

void disconnect(SEXP connection_ptr){
  Rcpp::XPtr<HyperConnectionPtr> hc(connection_ptr);
  hc->get()->close();
}

to

void disconnect(SEXP connection_ptr){
  Rcpp::XPtr<HyperConnectionPtr> hc(connection_ptr);
  if(hc->get()->isOpen()){
    hc->get()->close();
    return;
  }
  Rcpp::warning("The connection is already closed.");
}

`dbSendQuery` should exit and issue an error when called on a closed HyperConnection.

Successive calls to `dbSendQuery` should invalidate previous `HyperResult` and issue a warning.

{DBItest} includes a test,send_query_only_one_result_set (details here), that {RHyper} doesn't pass. Packages {RPostgres} and {RSQLite} show two ways to address the issue (see here and here, resp.). Both involve bolting the DBIResult onto the DBIConnection object so the latter is always aware of the former's state.