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fix: Remove mutable OJS syntax causing runtime errors #42

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Merged
rdhyee merged 1 commit into from
Dec 5, 2025
Merged

fix: Remove mutable OJS syntax causing runtime errors #42

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30 changes: 5 additions & 25 deletions tutorials/narrow_vs_wide_performance.qmd
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Original file line number Diff line number Diff line change
Expand Up @@ -104,61 +104,41 @@ viewof runBenchmarks = Inputs.button("Run All Benchmarks", {
<div id="error_display" style="padding: 10px; background: #f8d7da; border-radius: 4px; color: #721c24; display: none;">
</div>

```{ojs}
//| echo: false
// Database initialization is lazy - only happens when button is clicked
// This is stored as a mutable to track state
mutable dbState = { narrow: null, wide: null, error: null, initialized: false }
```

```{ojs}
//| echo: false
// Initialize databases only when button is clicked (lazy loading)
// Returns { narrow, wide } or null if not yet clicked
initDatabases = {
// Only initialize when button is clicked
if (runBenchmarks < 1) return null;

// Return cached instances if already initialized
if (dbState.initialized && !dbState.error) {
return { narrow: dbState.narrow, wide: dbState.wide };
}

const loadingDiv = document.getElementById('loading_init');
const errorDiv = document.getElementById('error_display');

if (loadingDiv) loadingDiv.style.display = 'block';
if (errorDiv) errorDiv.style.display = 'none';

try {
// Initialize narrow database
const narrowDb = await DuckDBClient.of();
await narrowDb.query(`CREATE VIEW narrow AS SELECT * FROM read_parquet('${narrowUrl}')`);

// Initialize wide database
const wideDb = await DuckDBClient.of();
await wideDb.query(`CREATE VIEW wide AS SELECT * FROM read_parquet('${wideUrl}')`);

// Cache the instances
mutable dbState = { narrow: narrowDb, wide: wideDb, error: null, initialized: true };

if (loadingDiv) loadingDiv.style.display = 'none';
return { narrow: narrowDb, wide: wideDb };
} catch (e) {
const errorMsg = `Failed to initialize databases: ${e.message}. This may be due to network issues or CORS restrictions.`;
mutable dbState = { narrow: null, wide: null, error: errorMsg, initialized: false };

if (errorDiv) {
errorDiv.textContent = errorMsg;
errorDiv.style.display = 'block';
}
throw e;
} finally {
if (loadingDiv) loadingDiv.style.display = 'none';
return { error: errorMsg };
}
}

// Convenience accessors that wait for initialization
dbNarrow = initDatabases ? initDatabases.narrow : null
dbWide = initDatabases ? initDatabases.wide : null
dbNarrow = initDatabases && !initDatabases.error ? initDatabases.narrow : null
dbWide = initDatabases && !initDatabases.error ? initDatabases.wide : null
```

## Data Validity Check
Expand Down