R/delete.R

In vectra: Columnar Query Engine for Larger-than-RAM Data

#' Logically delete rows from a .vtr file
#'
#' Marks the specified 0-based physical row indices as deleted by writing (or
#' updating) a tombstone side file (`<path>.del`). The original `.vtr` file is
#' never modified. The next call to [tbl()] on the same path will automatically
#' exclude the deleted rows.
#'
#' Tombstone files are cumulative: calling `delete_vtr()` multiple times on the
#' same file merges all deletions (union, deduplicated). To undo deletions,
#' remove the `.del` file manually with `unlink(paste0(path, ".del"))`.
#'
#' @param path File path of the `.vtr` file to delete rows from.
#' @param row_ids A numeric vector of **0-based** physical row indices to
#'   delete. Out-of-range indices are silently ignored on read (they will
#'   never match a real row).
#'
#' @return Invisible `NULL`.
#'
#' @examples
#' f <- tempfile(fileext = ".vtr")
#' write_vtr(mtcars, f)
#'
#' # Delete the first and third rows (0-based indices 0 and 2)
#' delete_vtr(f, c(0, 2))
#'
#' result <- tbl(f) |> collect()
#' stopifnot(nrow(result) == nrow(mtcars) - 2L)
#'
#' unlink(c(f, paste0(f, ".del")))
#'
#' @export
delete_vtr <- function(path, row_ids) {
  check_scalar_string(path)
  if (!is.numeric(row_ids) && !is.integer(row_ids))
    stop("row_ids must be a numeric or integer vector of 0-based row indices")
  path <- normalizePath(path, mustWork = TRUE)
  .Call(C_delete_vtr, path, as.double(row_ids))
  invisible(NULL)
}