perf(webapp): opt-in lazy materialization for the logs list query

Mono-RevId: b56b226a2b7a8428b9cfc6363f41cccf0564b173

Author: carderne

apps/webapp/app/env.server.ts

@@ -2300,6 +2300,10 @@ const EnvironmentSchema = z
       .int()
       .default(256_000_000),
     CLICKHOUSE_LOGS_LIST_MAX_THREADS: z.coerce.number().int().default(2),
+    // Logs list only: read the sort columns first and fetch the rest for the final page. Fewer
+    // column reads, which matters most on object storage. The settings exist from ClickHouse 25.4,
+    // but this query reads in sort order, which blocked lazy materialization until 25.8. Opt-in.
+    CLICKHOUSE_LOGS_LIST_LAZY_MATERIALIZATION: BoolEnv.default(false),
     // The HTTP request timeout is derived from this so ClickHouse gives up before the client does.
     CLICKHOUSE_LOGS_LIST_MAX_EXECUTION_TIME: z.coerce.number().int().default(15),
     // Bound read-in-order memory on object-storage reads: each part opens a per-column read

apps/webapp/app/presenters/v3/LogsListPresenter.server.ts

@@ -261,7 +261,16 @@ export class LogsListPresenter extends BasePresenter {
     // Run exactly one bounded query. Broadening a search window is an explicit user action;
     // silently rescanning the same recent rows makes absence queries needlessly expensive.
     const runQuery = () => {
-      const queryBuilder = this.clickhouse.taskEventsSearch.logsListQueryBuilder();
+      const queryBuilder = this.clickhouse.taskEventsSearch.logsListQueryBuilder({
+        // Scoped to this query rather than the logs client, which other pages share. ClickHouse
+        // skips lazy materialization when LIMIT exceeds the max, so pass this query's limit.
+        settings: env.CLICKHOUSE_LOGS_LIST_LAZY_MATERIALIZATION
+          ? {
+              query_plan_optimize_lazy_materialization: 1,
+              query_plan_max_limit_for_lazy_materialization: queryLimit,
+            }
+          : undefined,
+      });
 
       // The projector excludes events without a trace_id.
       queryBuilder.where("trace_id != ''");