Telemetry events emitted by Blink, and a default logger built on them.

Attach the default logger in your seed script to get progress logging without writing any timing code:

Blink.Telemetry.attach_default_logger()
MyApp.Seeder.call()

Events

Build events

Table and context builders run when they are declared — with_table/2 and with_context/2 call your table/2 or context/2 clause immediately — so build time is reported per declaration, not as part of the run span below.

• [:blink, :build, :start] — emitted when a builder starts.
  • Measurements: :system_time, :monotonic_time
  • Metadata: :callback (:table or :context), :key (the declared name)
• [:blink, :build, :stop] — emitted when a builder returns.
  • Measurements: :duration, :monotonic_time
  • Metadata: as for :start
• [:blink, :build, :exception] — emitted when a builder raises.
  • Measurements: :duration, :monotonic_time
  • Metadata: as for :start, plus :kind, :reason, and :stacktrace of the error

A builder that returns a stream reports a near-zero duration here; its rows are produced during the copy instead.

Run events

A span around Blink.Seeder.run/3 — the copy phase of the seed.

• [:blink, :run, :start]
  • Measurements: :system_time, :monotonic_time
  • Metadata: :repo, :tables (declared names in insertion order), :atomic
• [:blink, :run, :stop]
  • Measurements: :duration, :monotonic_time
  • Metadata: as for :start
• [:blink, :run, :exception]
  • Measurements: :duration, :monotonic_time
  • Metadata: as for :start, plus :kind, :reason, :stacktrace

Copy events

Emitted by Blink.Adapter.Postgres for each table copied.

• [:blink, :copy, :start] — emitted once per table, before the first batch is written. A table whose builder returned no rows emits no copy events at all.
  • Measurements: :system_time
  • Metadata: :table_name, :batch_size, :concurrency, :timeout, :atomic, :truncate
• [:blink, :copy, :stop] — emitted when the table's copy — including its truncate (truncate: true) and its sequence reset (reset_sequences: true) — completes. In an atomic run the event fires inside the transaction, so a later table's failure can still roll the counted rows back — :stop reports a completed copy, not a commit.
  • Measurements: :duration, :row_count
  • Metadata: as for :start
• [:blink, :copy, :exception] — emitted when the table's copy (or its sequence reset) fails; the failed table emits no :stop. Inside Blink.Seeder.run/3 the [:blink, :run] span's :exception also fires — this event names the table, that one the seed. For a direct Blink.copy_to_table/4 call, where no run span fires, this event is the only failure signal besides the raised exception.
  • Measurements: :duration
  • Metadata: as for :start, plus :kind, :reason, :stacktrace

Durations are in :native time units; convert with System.convert_time_unit(duration, :native, :millisecond).

Default logger

attach_default_logger/1 logs seed progress from these events; its documentation lists which level each line uses:

[info] Seeding MyApp.Repo (3 tables)...
[debug] Copied 1000 rows into "users" in 12 ms
[info] Seeded MyApp.Repo (3 tables) in 87 ms