bootstrap pipes action includes a setup wizard to guide you through the process of creating new pipes. In this tutorial, we'll be looking at the prompts you'll encounter to help you better understand what each question is asking.
🎦 Watch an Example
The below example demonstrates how to create a pipe from an existing SQL database table.
In this case, the remote table is called
weather_table and has a datetime column
timestamp and ID column
station. The pipe has the definition
SELECT * FROM weather_table.
To get started, run the following command:
--shell flag launches an interactive Meerschaum shell after executing the provided action. You can open the Meershaum shell with the
mrsm command or execute actions on the command line.
You will be asked for a pipe's three keys: a connector, metric, and location. For more information about how pipes are constructed, consult the pipes reference page.
The first question you will see is Where are the data coming from? along with a list of recognized connectors. A connector defines how Meerschaum interacts with other servers (e.g. username, password, host, etc.).
If you know what connector you need, go ahead and type its keys (type and label separated by a colon, like
sql:myserver), otherwise type 'New' to define a new connector. You can read more about how connectors work on the Connectors reference page.
If you chose
New to define a new connector, you'll be presented with a screen asking you to choose the connector's type. The type determines the protocol over which data will be transferred, so it's important to choose wisely! You can consult this Connectors Type table for the pros, cons, and use cases for each type of connector. The most common connectors are
api connectors, which correspond to your own SQL databases or Meerschaum instances.
After choosing the connector's type, you assign it a label. These two keys identify your connector and are represented with a colon, e.g.
sql:main for the default connector or
sql:local for the SQLite instance.
The metric is a label that describes the contents of a pipe. Pick something descriptive, such as
📍 Location (optional)
The location is an additional label you may assign to differentiate two pipes that share a connector and metric. If you omit the location, the location key will be
🕓 Datetime and ID columns¶
You will be prompted for the names of the datetime column and optionally an ID column. These columns will be used to index the pipe's table and are necessary for efficiently syncing new data. Consult your data source for the column names, and if you make a mistake, you can change the column names later with
If the ID is omitted, it is assumed that the pipe contains a single stream of data (i.e. datetimes are unique). The ID is used for partitioning and multiplexing sub-streams into a single pipe.
The last piece of metadata is the pipe's definition, the information needed to extract the data.
For a pipe with a
sql connector, your editor will open a
.sql file for a SQL query.
SQL definition caveats
The SQL query definition will not be executed directly but rather encased by a larger query via a
WITH clause. Therefore don't include
ORDER BY or other keywords which are disallowed in SQL views.
For a pipe with an
api connector, you will be prompted for the connector, metric, and location of the remote pipe.
For other types of connectors (like
plugin), your editor will open the pipe's attributes YAML file. Metadata needed for extracting data will fall under the
fetch: key (for example,
mqtt needs a
topic. Plugin pipes should not require anything specific).
📥 The First Sync¶
If you provided a definition and the correct index column names, you will be asked if you would like to sync new data into the pipe. When bootstrapping a new pipe, the definition will be executed, and the table will be created and indexed. Check out the syncing reference page for more information on how the syncing process works.
⤵️ Dropping Tables¶
If you want to drop a pipe's table without losing metadata, you can later execute the command
drop pipes. The command
delete pipes will drop pipes and remote registration information.