[API reference](https://evolu.dev/docs/api-reference) › [@evolu/sqlite-wasm](https://evolu.dev/docs/api-reference/sqlite-wasm) › [c-api](https://evolu.dev/docs/api-reference/sqlite-wasm/c-api) › sqlite3\_backup\_step

```ts
function sqlite3_backup_step(
  deps: SqliteWasmDep,
): (p: SqliteBackupPtr, nPage: number) => SqliteResultCode;
```

Defined in: [packages/sqlite-wasm/src/CApi.ts:1582](https://github.com/evoluhq/evolu/blob/bc4578a260dd15d5bbf94b83765ca05984d194cb/packages/sqlite-wasm/src/CApi.ts#L1582)

Copies up to nPage pages, or all that remain when nPage is negative. Returns
SQLITE_DONE once every page is copied, SQLITE_OK while pages remain,
SQLITE_BUSY or SQLITE_LOCKED when a lock prevents it for now, or another
error, after which only [sqlite3\_backup\_finish](https://evolu.dev/docs/api-reference/sqlite-wasm/c-api/functions/sqlite3_backup_finish) is useful.

Wasm type `i(ii)`. Signature `["sqlite3_backup_step", "int",
"sqlite3_backup*", "int"]` from SQLite's table.

See https://sqlite.org/c3ref/backup_finish.html.