Compute the logical diff between two .vtr files

Streams both files and computes a set-level diff keyed on key_col. Returns a list with two elements:

Usage

diff_vtr(old_path, new_path, key_col)

Arguments

old_path: Path to the older .vtr file.
new_path: Path to the newer .vtr file.
key_col: Name of the column to use as the row key (must exist in both files with the same type).

Value

A named list with elements added (a vectra_node) and deleted (a vector of key values).

Details

added: a vectra_node (lazy tbl()) of rows present in new_path but not old_path (matched on key_col). Call collect() to materialise. The underlying temp file is deleted when the node is garbage-collected or when the calling R session ends via on.exit().
deleted: a vector of key values present in old_path but not new_path.

This is a logical diff (key-based set difference), not a binary file diff. Rows with the same key that have changed values are not reported as modified — use added and deleted together to detect updates (a key that appears in both means a row was replaced).

Examples

f1 <- tempfile(fileext = ".vtr")
f2 <- tempfile(fileext = ".vtr")
df1 <- data.frame(id = 1:5, val = letters[1:5], stringsAsFactors = FALSE)
df2 <- data.frame(id = c(3L, 4L, 5L, 6L, 7L),
                  val = c("C", "d", "e", "f", "g"),
                  stringsAsFactors = FALSE)
write_vtr(df1, f1)
write_vtr(df2, f2)

d <- diff_vtr(f1, f2, "id")
# Rows 1 and 2 deleted; rows 6 and 7 added
stopifnot(all(d$deleted %in% c(1, 2)))
stopifnot(all(collect(d$added)$id %in% c(6, 7)))

unlink(c(f1, f2))