Move data with COPY

Data that changes infrequently can be easily imported into PostgresML (and any other Postgres database) using COPY. All you have to do is export your data as a file, create a table in Postgres to store it, and import it using the command line (or your IDE of choice).

Getting started

We'll be using CSV as our data format of choice. CSV is a supported mechanism for data transport in pretty much every database and system in existence, so you won't have any trouble finding the CSV export functionality in your current data store.

Let's use a simple CSV file with 3 columns as an example:

Column Data type Example data
name text John
age integer 30
is_paying_user boolean true

Export data

If you're using a Postgres database already, you can export any table as CSV with just one command:

content_copy link edit
psql \
postgres:// \
-c "\copy (SELECT * FROM users) TO '~/users.csv' CSV HEADER"

If you're using another data store, it will almost always provide a CSV export functionality.

Create table in PostgresML

Create a table in PostgresML with the correct schema:

content_copy link edit
name TEXT,
is_paying_user BOOLEAN

content_copy link edit

Data types should roughly match to what you have in your CSV file. If the data type is not known, you can always use TEXT and figure out what it is later with a few queries. Postgres also supports converting data types, as long as they are formatted correctly.

Import data

Once you have a table and your data exported as CSV, importing it can also be done with just one command:

content_copy link edit
psql \
postgres:// \
-c "\copy your_table FROM '~/your_table.csv' CSV HEADER"

We took our export command and changed TO to FROM, and that's it. Make sure you're connecting to your PostgresML database when importing data.

Refresh data

If your data changed, repeat this process again. To avoid duplicate entries in your table, you can truncate (or delete) all rows beforehand:

content_copy link edit
TRUNCATE your_table;