Schema Introspection

List the tables in the main schema, inspect a table’s columns, and read a query’s EXPLAIN plan — three read-only commands backed by information_schema.

Three read commands let the webview inspect schema and query plans without hand-writing information_schema queries: tables, columns, and explain. All three return arrays of JSON row objects.

tables

List the tables in the main schema, ordered by name.

const tables = await db.tables<{ table_name: string }>()
// [{ table_name: 'events' }, { table_name: 'users' }]

• Signature: tables<T = Record<string, unknown>>(): Promise<T[]>.

• Backed by:

  SELECT table_name FROM information_schema.tables
  WHERE table_schema = 'main' ORDER BY table_name
  

columns

List a table’s columns with their type and nullability, in ordinal order.

const cols = await db.columns<{
  column_name: string
  data_type: string
  is_nullable: string
}>('events')
// [{ column_name: 'id', data_type: 'INTEGER', is_nullable: 'YES' }, …]

• Signature: columns<T = Record<string, unknown>>(table: string): Promise<T[]>.

• Backed by (the table name is passed as a bound parameter, not interpolated):

  SELECT column_name, data_type, is_nullable FROM information_schema.columns
  WHERE table_name = $1 ORDER BY ordinal_position
  

is_nullable is the SQL-standard 'YES'/'NO' string from information_schema, not a boolean.

explain

Return the query plan rows for a statement (DuckDB EXPLAIN).

const plan = await db.explain('SELECT * FROM events WHERE id > 1')
// rows describing the physical plan; render plan.length / the plan text

• Signature: explain<T = Record<string, unknown>>(query: string): Promise<T[]>.
• The backend runs EXPLAIN <query> and returns the resulting rows.

explain passes query through the deny_risky_statements filter (on the leading keyword), so with that policy enabled you cannot explain an ATTACH/COPY/… form. It does not require write permission.

Permissions

Each has its own permission: better-duck-tauri:allow-tables, allow-columns, allow-explain. None are in the default set, so grant the ones your UI needs. See Capabilities & permissions.

See also

• Query & execute — run the queries you discover here.
• Connections, Database & Config — the main schema and catalog model.