Insert

Insert rows into DuckDB through Diesel: single-row and batch inserts with value tuples or Insertable structs, affected-row counts, and pointers to RETURNING and ON CONFLICT upserts.

Writing rows with diesel::insert_into. This is Diesel’s portable insert builder on the DuckDB backend.

Single row

Pass a tuple of column.eq(value) assignments to .values(...):

use diesel::prelude::*;

diesel::insert_into(products::table)
    .values((products::id.eq(1), products::name.eq("widget"), products::price.eq(9.99)))
    .execute(&mut conn)?;

.execute returns the affected-row count as usize.

Batch insert

Pass a slice of value tuples. DuckDB inserts them in one statement:

let rows = vec![
    (products::id.eq(2), products::name.eq("gadget"), products::price.eq(4.99)),
    (products::id.eq(3), products::name.eq("gizmo"),  products::price.eq(14.0)),
];
let n = diesel::insert_into(products::table).values(&rows).execute(&mut conn)?; // n == 2

For very large bulk loads, the ORM insert path is not the fastest option. Drop to the core appender via conn.inner_mut() — it is purpose-built for high-throughput inserts.

Inserting structs

A #[derive(Insertable)] struct becomes a value set. Fields map to columns by name:

#[derive(Insertable)]
#[diesel(table_name = products)]
struct NewProduct<'a> {
    id: i32,
    name: &'a str,
    price: f64,
}

diesel::insert_into(products::table)
    .values(&NewProduct { id: 4, name: "doohickey", price: 1.0 })
    .execute(&mut conn)?;

// a Vec<NewProduct> inserts as a batch
diesel::insert_into(products::table).values(&many).execute(&mut conn)?;

See Schema for deriving Insertable.

Columns typed with a DuckDB-specific Duck* SQL type cannot be inserted through this typed builder — they bind via diesel::sql_query(...).bind::<DuckXxx, _>(value). See Type mapping.

Getting values back

To return server-generated or defaulted columns from an insert, chain .returning(...) and use get_result/get_results instead of execute:

let id: i32 = diesel::insert_into(products::table)
    .values((products::id.eq(5), products::name.eq("x"), products::price.eq(1.0)))
    .returning(products::id)
    .get_result(&mut conn)?;

Full details on the RETURNING page.

Handling conflicts

To make an insert idempotent or merge on a key collision, add .on_conflict(...). See Upsert (ON CONFLICT).

See also

RETURNING

Read columns back from a write.

Upsert

ON CONFLICT DO NOTHING / DO UPDATE.

Transactions

Group many writes atomically.

Appender (core)

The fast path for bulk inserts.