Summary

When using SQLRooms with DuckDB-WASM to display query results from Parquet files, DATE and DECIMAL columns are not rendered correctly:

• DATE columns display as Date32<DAY> instead of a formatted date string
• DECIMAL columns display as raw scaled integers (e.g., 15130000000 instead of 1.513) unless castDecimalToDouble is enabled, which then causes floating-point precision issues (e.g., 1.6700000000000002 instead of 1.67)

Environment

• @sqlrooms/sql-editor: 0.26.0
• @sqlrooms/data-table: 0.26.0
• @sqlrooms/duckdb: 0.26.0
• @duckdb/duckdb-wasm: 1.30.0
• Browser: Chrome

Steps to Reproduce

1. Create a DuckDB connector with type casting options:

const duckDbConnector = createWasmDuckDbConnector({
  query: {
    castDecimalToDouble: true,
    castTimestampToDate: true,
    castBigIntToDouble: true,
  },
});

2. Load a Parquet file with DATE and DECIMAL columns
3. Query the table and view results in QueryResultPanel

Expected vs Actual Behavior

Root Cause

DATE Issue: In useArrowDataTable.js, the DATE handling assumes the value is already a JavaScript Date instance:

if (arrow.DataType.isDate(type)) {
    if (value instanceof Date) {  // <-- This check fails for Arrow Date32
        return value.toISOString();
    }
}
return String(value);  // Falls through, showing "Date32<DAY>"

DuckDB-WASM's castTimestampToDate only affects TIMESTAMP, not DATE. The Arrow Date32 value is an integer (days since epoch), not a Date instance.

Related Issues

• duckdb/duckdb-wasm#393
• apache/arrow-js#77