Your first warehouse map

Start with a local DuckDB warehouse that contains deliberate data defects. By the end, you will have a map of its tables and evidence about a key and a join that cannot be trusted. You need a terminal and uv. Installation downloads packages; the demo and exploration run locally afterwards.

1. Install the CLI

uv tool install "exmergo-dex-core[duckdb]"
dex --help

Already using the Dex skills? Ask your agent to run the commands below through its installed wrapper. The wrapper and the CLI use the same engine.

2. Create the demo

Use a new directory outside an existing Dex project so the demo can create its own configuration.

mkdir dex-first-run
cd dex-first-run
dex demo

The command creates dex_demo.duckdb and .dex/config.yml. The warehouse has seven tables and 29,512 rows. It refuses to replace an existing warehouse file.

3. Map the warehouse

dex explore map

Read data.objects for each table’s grain, candidate key, and findings, then data.edges for the inferred joins. A candidate key is a measurement; a shared column name alone is not proof of a join. Every command prints a JSON envelope. Start with these fields:

Field	What to read
`status`	Whether the command succeeded, failed, or needs confirmation
`data`	The map, profile, or other result you asked for
`warnings`	Limits or qualifications that affect the result
`errors` and `reason`	Why a command could not finish

4. Investigate the findings

dex explore profile order_items products
dex explore relationships --verify

The demo’s order_item_id has duplicates, so it is not a valid grain. The web_events.customer_id join also fails verification: its values do not match the customer keys. These are intentional defects, not installation failures. To ask a data question, use Dex’s query command:

dex explore query "select count(*) as order_count from orders"

This returns 5,000 orders. Queries go through the same profiling and PII checks as the rest of exploration.

See how a PII refusal works

dex explore query "select email from customers"

This query is expected to be refused. The email column is flagged as personal data. Do not clear a flag just to make an example run; see the PII policy for how flags are reviewed.

Get started

Workflows

Tutorials and help

Your first warehouse map

1. Install the CLI

2. Create the demo

3. Map the warehouse

4. Investigate the findings

Next steps

Connect your own data

Explore with your agent

​1. Install the CLI

​2. Create the demo

​3. Map the warehouse

​4. Investigate the findings

​Next steps

Connect your own data

Explore with your agent

1. Install the CLI

2. Create the demo

3. Map the warehouse

4. Investigate the findings

Next steps