diff --git a/web/lib/groups.test.ts b/web/lib/groups.test.ts
index 602206c..bbbd0c2 100644
--- a/web/lib/groups.test.ts
+++ b/web/lib/groups.test.ts
@@ -321,10 +321,9 @@ describe.skipIf(!dockerAvailable())(
       expect(res.headers.get('cache-control')).toBeNull();
     });
 
-    it('treats legacy random-access rows without open_mode as hot access', async () => {
+    it('treats cached-only random-access rows as hot access', async () => {
       const pool = getPool();
       await pool.query("DELETE FROM random_access_times WHERE open_mode = 'reopen'");
-      await pool.query('ALTER TABLE random_access_times DROP COLUMN open_mode');
 
       const summary = await collectGroupSummary({ k: 'RandomAccessGroup' });
       if (summary === null || summary.type !== 'randomAccess') {
@@ -339,7 +338,7 @@ describe.skipIf(!dockerAvailable())(
 
       const group = expectDefined(
         await collectGroupCharts({ k: 'RandomAccessGroup' }, parseCommitWindow(null)),
-        'legacy random access group',
+        'cached-only random access group',
       );
       expect(Object.keys(group.charts[0].series).sort()).toEqual([
         'arrow-ipc:hot',
diff --git a/web/lib/queries.ts b/web/lib/queries.ts
index c8cdfe1..34b5d71 100644
--- a/web/lib/queries.ts
+++ b/web/lib/queries.ts
@@ -534,7 +534,7 @@ async function collectRandomAccessChart(
   const text = `
     SELECT r.commit_sha,
            r.format,
-           COALESCE(to_jsonb(r) ->> 'open_mode', 'cached') AS open_mode,
+           r.open_mode AS open_mode,
            r.value_ns::float8 AS value
       FROM random_access_times r
       JOIN commits c USING (commit_sha)
diff --git a/web/lib/summary.test.ts b/web/lib/summary.test.ts
index 7a2f57f..f563482 100644
--- a/web/lib/summary.test.ts
+++ b/web/lib/summary.test.ts
@@ -177,8 +177,10 @@ describe('compression summaries', () => {
     }
     expect(calls[0][0]).toContain('latest_uncompressed_sizes');
     for (const [text] of calls) {
-      expect(text).toContain("to_jsonb(s) ->> 'uncompressed_bytes'");
-      expect(text).not.toMatch(/\bs\.uncompressed_bytes\b/);
+      // Read the column directly: `to_jsonb(s)` serialized every row (a
+      // whole-table CPU cost on every summary) just to reach one field.
+      expect(text).toMatch(/\bs\.uncompressed_bytes\b/);
+      expect(text).not.toContain('to_jsonb(');
     }
     expect(calls[0][0]).toContain('LEFT JOIN latest_uncompressed_sizes');
     expect(calls[1][0]).toContain('latest_uncompressed_sizes');
@@ -268,8 +270,12 @@ describe('timing summaries (shared ranking model)', () => {
     const [text] = query.mock.calls[0] as [string, unknown[] | undefined];
     // Per-series freshness, not one global latest commit: a format that skipped
     // the newest commit stays on the card at its own last run.
-    expect(text).toContain("COALESCE(to_jsonb(r) ->> 'open_mode', 'cached')");
-    expect(text).not.toContain('r.open_mode');
+    // `open_mode` is read as a plain column. The previous `to_jsonb(r)` lookup
+    // serialized every row's `all_runtimes_ns` (tens of thousands of samples
+    // per random-access row), which is what pushed this statement past the
+    // server-side statement timeout in production.
+    expect(text).toContain('r.open_mode');
+    expect(text).not.toContain('to_jsonb(');
     expect(text).toContain('c.timestamp DESC');
     expect(text).not.toContain('MAX(c2.timestamp)');
   });
diff --git a/web/lib/summary.ts b/web/lib/summary.ts
index bf1bd66..6f53aca 100644
--- a/web/lib/summary.ts
+++ b/web/lib/summary.ts
@@ -410,28 +410,25 @@ function groupRandomAccessSamples(
  *    `lance`: a format that skipped the newest commit is compared as of when it
  *    last ran instead of vanishing from the card.
  *
- * After migration 010, `random_access_times` holds one row per
- * `(commit_sha, dataset, format, open_mode)`. Before that migration, the JSON
- * lookup returns NULL and the query treats every historical row as `cached`.
- * The table is small, so the per-series `DISTINCT ON` descent is cheap.
+ * Since migration 010, `random_access_times` holds one row per
+ * `(commit_sha, dataset, format, open_mode)`, with historical rows backfilled
+ * as `cached`. `open_mode` must be read as a plain column: an earlier
+ * `to_jsonb(r) ->> 'open_mode'` lookup serialized every row, including its
+ * `all_runtimes_ns` array of tens of thousands of samples, which made this
+ * statement exceed the server-side statement timeout in production. The
+ * table is small, so the per-series `DISTINCT ON` descent is cheap.
  */
 async function collectRandomAccessSummary(): Promise<Summary | null> {
   const text = `
-    SELECT DISTINCT ON (
-             r.dataset,
-             r.format,
-             COALESCE(to_jsonb(r) ->> 'open_mode', 'cached')
-           )
+    SELECT DISTINCT ON (r.dataset, r.format, r.open_mode)
            r.dataset AS bucket,
            r.format AS series,
-           COALESCE(to_jsonb(r) ->> 'open_mode', 'cached') AS open_mode,
+           r.open_mode AS open_mode,
            r.value_ns::float8 AS value
       FROM random_access_times r
       JOIN commits c USING (commit_sha)
      WHERE r.value_ns > 0
-     ORDER BY r.dataset,
-              r.format,
-              COALESCE(to_jsonb(r) ->> 'open_mode', 'cached'),
+     ORDER BY r.dataset, r.format, r.open_mode,
               c.timestamp DESC,
               r.commit_sha DESC
   `;
@@ -645,11 +642,11 @@ async function compressionSamples(): Promise<
     ), latest_uncompressed_sizes AS (
       SELECT DISTINCT ON (s.dataset, s.dataset_variant)
              s.dataset, s.dataset_variant,
-             (to_jsonb(s) ->> 'uncompressed_bytes')::float8 AS uncompressed_bytes
+             s.uncompressed_bytes::float8 AS uncompressed_bytes
         FROM compression_sizes s
         JOIN commits c ON c.commit_sha = s.commit_sha
        WHERE s.format = $4
-         AND (to_jsonb(s) ->> 'uncompressed_bytes')::float8 > 0
+         AND s.uncompressed_bytes::float8 > 0
          AND lower(s.dataset) NOT LIKE '%wide table%'
        ORDER BY s.dataset, s.dataset_variant NULLS FIRST,
                 c.timestamp DESC, s.commit_sha DESC
@@ -765,7 +762,7 @@ async function compressionSizeSamples(): Promise<
              c.timestamp AS ts,
              s.commit_sha AS commit_sha,
              s.value_bytes::float8 AS value_bytes,
-             (to_jsonb(s) ->> 'uncompressed_bytes')::float8 AS uncompressed_bytes,
+             s.uncompressed_bytes::float8 AS uncompressed_bytes,
              p.value_bytes::float8 AS parquet_bytes,
              s.dataset AS dataset,
              s.dataset_variant AS dataset_variant
@@ -818,11 +815,11 @@ async function compressionSizeSamples(): Promise<
     ), latest_uncompressed_sizes AS (
       SELECT DISTINCT ON (s.dataset, s.dataset_variant)
              s.dataset, s.dataset_variant,
-             (to_jsonb(s) ->> 'uncompressed_bytes')::float8 AS uncompressed_bytes
+             s.uncompressed_bytes::float8 AS uncompressed_bytes
         FROM compression_sizes s
         JOIN commits c ON c.commit_sha = s.commit_sha
        WHERE s.format = $4
-         AND (to_jsonb(s) ->> 'uncompressed_bytes')::float8 > 0
+         AND s.uncompressed_bytes::float8 > 0
          AND lower(s.dataset) NOT LIKE '%wide table%'
        ORDER BY s.dataset, s.dataset_variant NULLS FIRST,
                 c.timestamp DESC, s.commit_sha DESC