examples

Writing Source Extractors

dlt sources are iterators or lists and writing them does not require any additional knowledge beyond basic python. dlt sources are also pythonic in nature: they are simple, can be chained, pipelined and composed like any other python iterator or a sequence.

Examples

1. quickstart loads a nested json document into duckdb and then queries it with built in sql_client demonstrating the parent-child table joins.

2. sql_query source and read_table example. This source iterates over any SELECT statement made against database system supported by SqlAlchemy. The example connects to Redshift and iterates a table containing Ethereum transactions. Shows the inferred schema (which nicely preserves typing). Mind that our source is a one-liner :)

3. rasa example and rasa_tracker_store source extracts rasa tracker store events to a set of inferred tables. It shows a few common patterns

• shows how to pipeline resources: it depends on a "head" resource that reads base data (ie. events from kafka/postgres/file). the dependent resource is called transformer
• it shows how to write stream resource which creates table schemas and sends data to those tables depending on the event type
• it stores last_timestamp_value in the state

1. singer_tap, stdout and singer_tap_example is fully functional wrapper for any singer/meltano source

• clones the desired tap, installs it and runs it in a virtual env
• passes the catalog and config files
• like rasa it is a transformer (on stdio pipe) and stream resource
• it stores singer state in dlt state

1. singer_tap_jsonl_example like the above but instead of process pipe it reads singer messages from file. it creates a huge hubspot schema.

2. google_sheets a source that returns values from specified sheet. The example takes a sheet, infers a schema, loads it to BigQuery/Redshift and displays inferred schema. it uses the secrets.toml to manage credentials and is an example of one-liner pipeline

3. chess an example of a pipeline project with its own config and credential files. it is also an example of how transformers are connected to resources and resource selection. it should be run from examples/chess` folder. It also shows: how to use retry decorator and how to run resources/transformers in parallel with a decorator

4. chess/chess_dbt.py: an example of a dbt transformations package working with a dataset loaded by dlt. The package is incrementally processing the loaded data following the new loaded packages stored in _dlt_loads table at the end of every pipeline run. Note the automatic usage of isolated virtual environment to run dbt and sharing of the credentials.

5. run_dbt_jaffle runs dbt's jaffle shop example taken directly from the github repo and queries the results with sql_client. duckdb database is used to load and transform the data. The database write access is passed from dlt to dbt and back.

Not yet ported:

1. discord_iterator an example that load example discord data (messages, channels) into warehouse from supplied files. Shows several auxiliary pipeline functions and an example of pipelining iterators (with map function). You can also see that produced schema is quite complicated due to several layers of nesting.

2. ethereum source shows that you can build highly scalable, parallel and robust sources as simple iterators.