perf: optimise SQL query in observeRetrievalResultCodes (#316)

Rework `observeRetrievalResultCodes` to execute a single SQL query
to update all daily codes in one go.

Before this change, we would run ~1k individual queries, consume a lot
of CPU and trigger CPU throttling alert.

As part of this change, I am also adding a console log to tell us how
many rows - tuples (day, code) - we are updating in each loop iteration.

Signed-off-by: Miroslav Bajtoš <[email protected]>

observer/lib/observer.js

@@ -106,6 +106,7 @@ export const observeRetrievalResultCodes = async (pgPoolStats, influxQueryApi) =
   // Ref: https://github.com/filecoin-station/spark-stats/pull/244#discussion_r1824808007
   // Note: Having a bucket retention policy is important for this query not to
   // time out.
+  /** @type {{_time: string; _field: string; _value: number}[]} */
   const rows = await influxQueryApi.collectRows(`
     import "strings"
     from(bucket: "spark-evaluate")
@@ -116,16 +117,16 @@ export const observeRetrievalResultCodes = async (pgPoolStats, influxQueryApi) =
       |> keep(columns: ["_value", "_time", "_field"])
       |> map(fn: (r) => ({ r with _field: strings.replace(v: r._field, t: "result_rate_", u: "", i: 1) }))
   `)
-  for (const row of rows) {
-    await pgPoolStats.query(`
-      INSERT INTO daily_retrieval_result_codes
-      (day, code, rate)
-      VALUES ($1, $2, $3)
-      ON CONFLICT (day, code) DO UPDATE SET rate = EXCLUDED.rate
-    `, [
-      row._time,
-      row._field,
-      row._value
-    ])
-  }
+  console.log('Inserting %s rows to daily_retrieval_result_codes ', rows.length)
+
+  await pgPoolStats.query(`
+    INSERT INTO daily_retrieval_result_codes
+    (day, code, rate)
+    VALUES (unnest($1::DATE[]), unnest($2::TEXT[]), unnest($3::NUMERIC[]))
+    ON CONFLICT (day, code) DO UPDATE SET rate = EXCLUDED.rate
+  `, [
+    rows.map(r => r._time),
+    rows.map(r => r._field),
+    rows.map(r => r._value)
+  ])
 }