DuckDB

Pro

DevDb opens DuckDB database files and data files. It reads Parquet, CSV, TSV, JSON and NDJSON files as tables.

Open a file

From the panel

1. Under Local Databases, select DuckDB Database File Picker.
2. Select a file:

Kind	Extensions
DuckDB database	.duckdb, .ddb, .db
Data file	.parquet, .csv, .tsv, .json, .ndjson

3. For a database file, select a mode:
   • Open read-only (recommended). DevDb does not lock the file. Other DuckDB processes keep access.
   • Open read-write. DevDb takes an exclusive write lock. Other DuckDB processes cannot open the file.

A data file shows as one table. The table name comes from the file name.

From .devdbrc

[
  {
    "type": "duckdb",
    "path": "/Users/me/data/analytics.duckdb",
    "readOnly": true
  }
]

readOnly is true by default. Set it to false only when you must change data. See the DuckDB reference.

Read-only by default

DevDb opens DuckDB files read-only by default:

• Your application or a notebook can use the same file while DevDb shows it.
• You cannot change data by mistake.

To edit data, open the file read-write. You can then edit values, set values to null and delete rows.

Sandbox

DevDb limits what a DuckDB query can do:

• No network access.
• No INSTALL or LOAD of extensions, and no automatic extension loading.
• No ATTACH of other databases, and no COPY to or from other files.
• DevDb can read only the file that you opened.

These limits also apply to queries from MCP clients.

SUMMARIZE

Click Summarize on a table to run DuckDB SUMMARIZE. DevDb shows these values for each column: type, min, max, approximate unique count, average, standard deviation, 25th, 50th and 75th percentiles, count and percentage of nulls.

• For a table with more than 5,000,000 rows, DevDb summarizes a sample of about 1,000,000 rows. The note column tells you when DevDb used a sample.
• If SUMMARIZE fails for the table (for example, an overflow in avg), DevDb summarizes each column alone. A column that still fails shows only min, max, approximate unique count, count and null percentage.
• You can cancel a running summary.

Data types

DevDb shows DECIMAL, UUID, DATE, TIMESTAMPTZ, MAP and BLOB values as readable text.

Limits

• Raw queries (for example from MCP) return at most 10,000 rows.
• DevDb lists tables in all schemas, not only main.

Platform support

DuckDB is available on:

• Windows x64 and arm64
• macOS x64 and arm64
• Linux x64 and arm64
• Alpine Linux x64 and arm64

DuckDB is not available on Linux armhf (ARMv7). There, DevDb shows "DuckDB is not supported on this platform".