Launching a function with a reload code

[creditskif]

Good afternoon, everyone! The idea is this, we have implemented a table in the database that stores asset data. How to force Dagster to unload data from a table only once, during "reload code"? Now this function is run 3 times when executing 1 asset

[cmpadden]

Hi @creditskif !

If the database query is happening at module import time or while defining the asset, it can run multiple times. Seeing it run 3 times during one asset execution can be expected depending on your deployment/processes.

The recommended pattern is to avoid doing database work during code loading. Instead:

• move the database query inside the asset body, so it only runs when the asset materializes
• or put the query behind a resource/client method and call it at execution time
• if you need to generate asset definitions from database rows, make that query cheap/idempotent, or cache the result somewhere outside the Dagster process

For example, avoid this:

rows = load_rows_from_db()  # runs during code load/reload

@asset
def my_asset():
    ...

Prefer this:

@asset
def my_asset(db):
    rows = db.load_rows()
    ...

If you can share a small snippet of where the table is being queried, folks can suggest the best Dagster pattern for your specific case.