fix: PR compress benchmarks (#2419)

PR compression benchmarks fail because the PR results do not have a
"storage" key. They indeed do not use any hard drive or object storage.
Moreover, those benchmarks don't use our `QueryMeasurement` /
`GenericMeasurement` structs, so they don't get a `null` storage key.

This ensures that if _either_ the PR results or the base results are
missing a storage key, we treat it as NA.

If we try to compare results from before the "storage" key to after the
"storage" key, this will not error but the right join will only include
the PR's results. The table will look very similar to the one I'm
removing here.

Author: danking

scripts/compare-benchmark-jsons.py

@@ -21,22 +21,17 @@
 pr_commit_id = next(iter(pr_commit_id))
 
 if "storage" not in base:
-    # This means the base commit was generated in the pre-object-store days. We cannot give a true
-    # diff because we're comparing different storage systems.
-    pr
-    print(
-        pd.DataFrame(
-            {
-                "name": pr["name"],
-                f"PR {pr_commit_id[:8]}": pr["value"],
-                f"base {base_commit_id[:8]} (no S3 results found)": pd.NA,
-                "ratio (PR/base)": pd.NA,
-                "unit": pr["unit"],
-            }
-        ).to_markdown(index=False)
-    )
-    sys.exit(0)
+    # For whatever reason, the base lacks storage. Might be an old database of results. Might be a
+    # database of results without any storage fields.
+    base["storage"] = pd.NA
 
+if "storage" not in pr:
+    # Not all benchmarks have a "storage" key. If none of the JSON objects in the PR results file
+    # had a "storage" key, then the PR DataFrame will lack that key and the join will fail.
+    pr["storage"] = pd.NA
+
+# NB: `pd.merge` considers two null key values to be equal, so benchmarks without storage keys will
+# match.
 df3 = pd.merge(base, pr, on=["name", "storage"], how="right", suffixes=("_base", "_pr"))
 
 assert df3["unit_base"].equals(df3["unit_pr"]), (df3["unit_base"], df3["unit_pr"])