Skip to contents

Get Lineage for a Table

Source: R/query.R
datom_get_lineage.Rd

Reads lineage metadata for a table. Depending on depth, returns either the pre-computed transitive source list (source_lineage) or the immediate parent list (parents). Both fields are stored flat in the table's metadata – no walking or cross-project resolution is performed.

Usage

datom_get_lineage(conn, name, version = NULL, depth = c("source", "parents"))

Arguments

conn

A datom_conn object from datom_get_conn().

name

Table name.

version

Optional metadata_sha (datom version). If NULL, reads current metadata. If provided, fetches the versioned metadata snapshot.

depth

One of "source" (default) or "parents".

Value

For depth = "source": the table's recorded source_lineage – a list of source-table descriptors (each with project, table, version_sha), or NULL if the field is absent. For depth = "parents": list of parent entries (each with source, table, version, data_sha), or NULL if no lineage is recorded.

Details

The two fields answer different questions:

  • "source": "what raw datasets does this table ultimately depend on?" (audit, regulatory disclosure, reproducibility scope). Derived at write time as the deduplicated union of the parents' source_lineage fields.

  • "parents": "what did this table come from one step back?" (debugging, diff, replay). Equivalent to datom_get_parents().

See also

datom_get_parents() for a direct shorthand for the "parents" depth.

Examples

# Offline, self-contained: a bare git repo stands in for GitHub and a
# local directory for object storage.
if (requireNamespace("git2r", quietly = TRUE)) {
  tmp <- tempfile("datom-example-")
  remote <- file.path(tmp, "remote.git")
  dir.create(remote, recursive = TRUE)
  git2r::init(remote, bare = TRUE)

  store <- datom_store(
    data = datom_store_local(file.path(tmp, "storage")),
    github_pat = "example-token", # role selector; a local remote needs none
    data_repo_url = remote,
    validate = FALSE
  )
  datom_init_repo(file.path(tmp, "repo"), "example_project", store)
  conn <- datom_get_conn(file.path(tmp, "repo"), store)

  datom_write(conn, data = datom_example_data("dm"), name = "dm")
  print(datom_get_lineage(conn, "dm", depth = "parents"))
  print(datom_get_lineage(conn, "dm", depth = "source"))

  unlink(tmp, recursive = TRUE)
}
#> ℹ Created store directory /tmp/Rtmp0YCcPh/datom-example-1a3162efffbf/storage.
#> ✔ Initialized datom repository "example_project" at /tmp/Rtmp0YCcPh/datom-example-1a3162efffbf/repo
#> ✔ Wrote "dm" (full): "039f0c3f"
#> NULL
#> NULL