Update Cesium demos to use Cloudflare R2 URLs for Zenodo parquet files

- narrow_vs_wide_performance.qmd: Update to use full iSamples dataset
  on R2 (844MB narrow, 282MB wide - all 4 sources)
- parquet_cesium_isamples_wide.qmd: Update URL to January 2026 wide file
  which fixes issue #8 ([null] array bug)

R2 URLs:
- Narrow: https://pub-a18234d962364c22a50c787b7ca09fa5.r2.dev/isamples_202512_narrow.parquet
- Wide: https://pub-a18234d962364c22a50c787b7ca09fa5.r2.dev/isamples_202601_wide.parquet

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: rdhyee

tutorials/narrow_vs_wide_performance.qmd

@@ -16,12 +16,14 @@ This page benchmarks the performance difference between **narrow** and **wide**
 
 The iSamples property graph data can be serialized in two different parquet formats:
 
-| Format | Description | File Size | Row Count |
-|--------|-------------|-----------|-----------|
-| **Narrow** | Stores relationships as separate edge rows (`otype='_edge_'`) | 691 MB | ~11.6M rows |
-| **Wide** | Stores relationships as `p__*` columns on entity rows | 275 MB | ~2.5M rows |
+| Format | Description | File Size | Row Count | Sources |
+|--------|-------------|-----------|-----------|---------|
+| **Narrow** | Stores relationships as separate edge rows (`otype='_edge_'`) | 844 MB | ~106M rows | All 4 sources |
+| **Wide** | Stores relationships as `p__*` columns on entity rows | 282 MB | ~20M rows | All 4 sources |
 
-Both formats represent the **same underlying data** with identical semantics, but the wide format is optimized for analytical queries by eliminating edge rows.
+Both formats represent the **same underlying data** (SESAR, OpenContext, GEOME, Smithsonian) with identical semantics, but the wide format is optimized for analytical queries by eliminating edge rows.
+
+**Data source**: Cloudflare R2 (updated January 2026)
 
 ### Why Performance Matters
 
@@ -57,9 +59,10 @@ import { DuckDBClient } from "https://cdn.jsdelivr.net/npm/@observablehq/duckdb@
 
 ```{ojs}
 //| echo: false
-// Define parquet URLs
-narrowUrl = "https://storage.googleapis.com/opencontext-parquet/oc_isamples_pqg.parquet"
-wideUrl = "https://storage.googleapis.com/opencontext-parquet/oc_isamples_pqg_wide.parquet"
+// Define parquet URLs - iSamples full dataset on Cloudflare R2 (all sources)
+// Updated 2026-01-14: Using Zenodo narrow/wide files on Cloudflare R2
+narrowUrl = "https://pub-a18234d962364c22a50c787b7ca09fa5.r2.dev/isamples_202512_narrow.parquet"
+wideUrl = "https://pub-a18234d962364c22a50c787b7ca09fa5.r2.dev/isamples_202601_wide.parquet"
 ```
 
 ### Environment Info

tutorials/parquet_cesium_isamples_wide.qmd

@@ -44,7 +44,7 @@ Cesium.Ion.defaultAccessToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJqdGkiOi
 //| echo: false
 viewof parquet_path = Inputs.text({
   label:"Source (iSamples Wide Format)",
-  value:"https://pub-a18234d962364c22a50c787b7ca09fa5.r2.dev/isamples_202512_wide.parquet",
+  value:"https://pub-a18234d962364c22a50c787b7ca09fa5.r2.dev/isamples_202601_wide.parquet",
   placeholder: "URL or file:///path/to/file.parquet",
   width:"100%",
   submit:true
@@ -94,13 +94,13 @@ Download the file locally, then serve it:
 
 ```bash
 # Download the wide parquet file (~242MB)
-curl -O https://pub-a18234d962364c22a50c787b7ca09fa5.r2.dev/isamples_202512_wide.parquet
+curl -O https://pub-a18234d962364c22a50c787b7ca09fa5.r2.dev/isamples_202601_wide.parquet
 
 # Serve it locally
 python3 -m http.server 8000
 ```
 
-Then use: `http://localhost:8000/isamples_202512_wide.parquet`
+Then use: `http://localhost:8000/isamples_202601_wide.parquet`
 
 **Benefits of wide format file:**
 - 66% smaller than narrow format (242 MB vs 709 MB)