Question 1

Why does the `julianday` function work in Source Queries but not in Inline Queries in Evidence?

Accepted Answer

Inline Queries use DuckDB syntax (executed in-browser via WebAssembly), not your database's native SQL dialect. `julianday` is a SQLite function and not part of DuckDB. To use it, switch to a Source Query, which runs against your actual database (e.g., SQLite). No code change is needed in the query itself—just use a Source Query block instead of an inline SQL fenced code block.

Question 2

Why does the Evidence Dropdown component sort values alphabetically instead of preserving query order?

Accepted Answer

The Evidence Dropdown component sorts option labels by ascending alphabetical order by default, not following the original query row order. To control the order, add an explicit order column to your query and reference it via the `order` prop.

Example:

```sql
SELECT value, ROW_NUMBER() OVER() AS sort_col
FROM your_table
ORDER BY sort_col
```

Then in the component:
`<Dropdown data={data} name=name value=value order=sort_col />`

This behavior was clarified in the documentation after version 4.7.2. There is an open issue for a possible prop to override the default sorting.

Question 3

Why does `npm run sources` fail with 'Invalid argument error: Need at least 1 bytes for bitmap' when using boolean columns with all NULLs?

Accepted Answer

This error occurs due to a bug in the underlying Arrow library (arrow-rs) when creating Parquet files from queries containing boolean columns where all values are NULL. The immediate workaround is to exclude such columns from your SQL query, as they contain no information. For example, avoid `SELECT null::bool AS mycol ...`. If you must keep the column, cast it to a non-boolean type (e.g., `null::int`). Track the upstream fix at https://github.com/apache/arrow-js/issues/68.

Question 4

Why does npm install take 30 minutes and create 2.4 GB node_modules when using @evidence-dev/duckdb?

Accepted Answer

This happens when DuckDB compiles from source because no pre-compiled binary is available for your platform. In GitHub Actions on `ubuntu-latest`, a pre-compiled binary should exist. To avoid the long install every time, use npm caching in your workflow:

```yaml
- name: Install Node.js
  uses: actions/setup-node@v4
  with:
    node-version: 20
    cache: npm
```

This reuses `node_modules` if `package-lock.json` hasn’t changed, reducing install time dramatically. If the build still occurs, check [DuckDB releases](https://github.com/duckdb/duckdb/releases) for a binary matching your runner’s OS and architecture. System-installed DuckDB cannot currently be used with Evidence without custom configuration.

Question 5

Why is the Evidence Docker dev environment no longer maintained and how can I use Docker now?

Accepted Answer

The official Evidence Docker dev environment is not actively maintained as of the latest update. The maintainers have removed it from the documentation and are not prioritizing fixes. To continue using Docker, fork the repository and build your own images. You can also contribute by submitting a pull request to improve the Docker setup.

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