Are LaminDB’s operations idempotent? (What happens if I save the same files & records twice?)#

LaminDB’s operations are idempotent. This is essential for two reasons:

  • Avoid that re-running a workflow errors.

  • Avoid that re-running a workflow inserts duplicated data.

Summary#

Metadata records#

If you try to create any metadata record (Registry) and upon_create_search_names is True (the default):

  1. LaminDB will warn you if a record with similar name exists and display a table of similar existing records.

  2. You can then decide whether you’d like to save a record to the database or rather query an existing one from the table.

  3. If a name already has an exact match in a registry, LaminDB will return it instead of creating a new record.

If you set upon_create_search_names to False, you’ll directly populate the DB.

Files#

If you try to create a File object from the same content, depending on upon_file_create_if_hash_exists,

  • you’ll get an existing object, if upon_file_create_if_hash_exists = "warn_return_existing" (the default)

  • you’ll get an error, if upon_file_create_if_hash_exists = "error"

  • you’ll get a warning and a new object, if upon_file_create_if_hash_exists = "warn_create_new"

Examples#

!lamin init --storage ./test-idempotency

✅ saved: User(id='DzTjkKse', handle='testuser1', email='testuser1@lamin.ai', name='Test User1', updated_at=2023-09-26 15:20:46)
✅ saved: Storage(id='0ZcAs8fO', root='/home/runner/work/lamindb/lamindb/docs/faq/test-idempotency', type='local', updated_at=2023-09-26 15:20:46, created_by_id='DzTjkKse')
💡 loaded instance: testuser1/test-idempotency
💡 did not register local instance on hub (if you want, call `lamin register`)


import lamindb as ln
import pytest

ln.settings.verbosity = "hint"

💡 loaded instance: testuser1/test-idempotency (lamindb 0.54.2)

Metadata records#

assert ln.settings.upon_create_search_names

Let us add a first record to the ULabel registry:

label = ln.ULabel(name="My project 1")
label.save()

If we create a new record, we’ll automatically get search results that give clues on whether we are prone to duplicating an entry:

label = ln.ULabel(name="My project 2")

❗ record with similar name exist! did you mean to load it?
id __ratio__
name
My project 1 Hv8YEhhK 91.666667 
label.save()

In case we match an existing name directly, we’ll get the existing object:

label = ln.ULabel(name="My project 1")

✅ loaded ULabel record with exact same name: 'My project 1'

If we save it again, it will not create a new entry in the registry:

label.save()

Now, if we create a third record, we’ll get two alternatives:

label = ln.ULabel(name="My project 3")

❗ records with similar names exist! did you mean to load one of them?
id __ratio__
name
My project 1 Hv8YEhhK 91.666667
My project 2 pvhTIXjQ 91.666667

If we prefer to not perform a search, e.g. for performance reasons or too noisy logging, we can switch it off.

ln.settings.upon_create_search_names = False

label = ln.ULabel(name="My project 3")

In this walkthrough, switch it back on:

ln.settings.upon_create_search_names = True

Data artifacts#

upon_file_create_if_hash_exists = "warn_return_existing"#

assert ln.settings.upon_file_create_if_hash_exists == "warn_return_existing"

filepath = ln.dev.datasets.file_fcs()

Create a File object.

file = ln.File(filepath, description="My fcs file")
file.save()

❗ no run & transform get linked, consider passing a `run` or calling ln.track()

💡 file will be copied to default storage upon `save()` with key `None` ('.lamindb/IWCgW1wljGH3TiNiaQIa.fcs')

✅ storing file 'IWCgW1wljGH3TiNiaQIa' at '.lamindb/IWCgW1wljGH3TiNiaQIa.fcs'
Hide code cell content 
assert file.hash == "KCEXRahJ-Ui9Y6nksQ8z1A"

Create a File object from the same path:

file2 = ln.File(filepath)

❗ no run & transform get linked, consider passing a `run` or calling ln.track()

❗ returning existing file with same hash: File(id='IWCgW1wljGH3TiNiaQIa', suffix='.fcs', description='My fcs file', size=6785467, hash='KCEXRahJ-Ui9Y6nksQ8z1A', hash_type='md5', updated_at=2023-09-26 15:20:48, storage_id='0ZcAs8fO', created_by_id='DzTjkKse')

It gives us the existing object:

assert file.id == file2.id

If you save it again, nothing will happen (the operation is idempotent):

file2.save()

upon_file_create_if_hash_exists = "error"#

ln.settings.upon_file_create_if_hash_exists = "error"

In this case, you’ll not be able to create an object from the same content:

with pytest.raises(RuntimeError):
    file3 = ln.File(filepath, description="My new fcs file")

❗ no run & transform get linked, consider passing a `run` or calling ln.track()

upon_file_create_if_hash_exists = "warn_create_new"#

ln.settings.upon_file_create_if_hash_exists = "warn_create_new"

In this case, you’ll create a new object:

file4 = ln.File(filepath, description="My new fcs file")
file4.save()

❗ no run & transform get linked, consider passing a `run` or calling ln.track()

❗ creating new File object despite existing file with same hash: File(id='IWCgW1wljGH3TiNiaQIa', suffix='.fcs', description='My fcs file', size=6785467, hash='KCEXRahJ-Ui9Y6nksQ8z1A', hash_type='md5', updated_at=2023-09-26 15:20:48, storage_id='0ZcAs8fO', created_by_id='DzTjkKse')

💡 file will be copied to default storage upon `save()` with key `None` ('.lamindb/dF9OI3drWNxJWiaqsNXg.fcs')

✅ storing file 'dF9OI3drWNxJWiaqsNXg' at '.lamindb/dF9OI3drWNxJWiaqsNXg.fcs'

You can verify that it’s a new entry by comparing the ids:

assert file4.id != file.id

file4.filter(hash="KCEXRahJ-Ui9Y6nksQ8z1A").df()
storage_id key suffix accessor description version size hash hash_type transform_id run_id initial_version_id updated_at created_by_id
id
IWCgW1wljGH3TiNiaQIa 0ZcAs8fO None .fcs None My fcs file None 6785467 KCEXRahJ-Ui9Y6nksQ8z1A md5 None None None 2023-09-26 15:20:48 DzTjkKse
dF9OI3drWNxJWiaqsNXg 0ZcAs8fO None .fcs None My new fcs file None 6785467 KCEXRahJ-Ui9Y6nksQ8z1A md5 None None None 2023-09-26 15:20:48 DzTjkKse
Hide code cell content 
assert len(file.filter(hash="KCEXRahJ-Ui9Y6nksQ8z1A").list()) == 2

!lamin delete --force test-idempotency
!rm -r test-idempotency

💡 deleting instance testuser1/test-idempotency
✅     deleted instance settings file: /home/runner/.lamin/instance--testuser1--test-idempotency.env

✅     instance cache deleted
✅     deleted '.lndb' sqlite file
❗     consider manually deleting your stored data: /home/runner/work/lamindb/lamindb/docs/faq/test-idempotency