fix: replace PostgreSQL aggregate functions with ClickHouse -Merge combinators

RouteCatalogController, RouteMetricsController, AgentRegistrationController
all had inline SQL using SUM() on AggregateFunction columns from stats_1m_*
AggregatingMergeTree tables. Replace with countMerge/countIfMerge/sumMerge.
Also fix time_bucket() → toStartOfInterval() and ::double → toFloat64().

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/AgentRegistrationController.java

@@ -255,13 +255,15 @@ public class AgentRegistrationController {
         Instant now = Instant.now();
         Instant from1m = now.minus(1, ChronoUnit.MINUTES);
         try {
+            // Literal SQL — ClickHouse JDBC driver wraps prepared statements in sub-queries
+            // that strip AggregateFunction column types, breaking -Merge combinators
             jdbc.query(
                     "SELECT application_name, " +
-                            "SUM(total_count) AS total, " +
+                            "countMerge(total_count) AS total, " +
-                            "SUM(failed_count) AS failed, " +
+                            "countIfMerge(failed_count) AS failed, " +
                             "COUNT(DISTINCT route_id) AS active_routes " +
-                            "FROM stats_1m_route WHERE bucket >= ? AND bucket < ? " +
+                            "FROM stats_1m_route WHERE bucket >= " + lit(from1m) + " AND bucket < " + lit(now) +
-                            "GROUP BY application_name",
+                            " GROUP BY application_name",
                     rs -> {
                         long total = rs.getLong("total");
                         long failed = rs.getLong("failed");
@@ -269,11 +271,18 @@ public class AgentRegistrationController {
                         double errorRate = total > 0 ? (double) failed / total : 0.0;
                         int activeRoutes = rs.getInt("active_routes");
                         result.put(rs.getString("application_name"), new double[]{tps, errorRate, activeRoutes});
-                    },
+                    });
-                    Timestamp.from(from1m), Timestamp.from(now));
         } catch (Exception e) {
             log.debug("Could not query agent metrics: {}", e.getMessage());
         }
         return result;
     }
+
+    /** Format an Instant as a ClickHouse DateTime literal. */
+    private static String lit(Instant instant) {
+        Instant truncated = instant.truncatedTo(ChronoUnit.SECONDS);
+        String ts = new Timestamp(truncated.toEpochMilli()).toString();
+        if (ts.endsWith(".0")) ts = ts.substring(0, ts.length() - 2);
+        return "'" + ts + "'";
+    }
 }

cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/RouteCatalogController.java

@@ -78,38 +78,37 @@ public class RouteCatalogController {
         Instant rangeTo = to != null ? Instant.parse(to) : now;
         Instant from1m = now.minus(1, ChronoUnit.MINUTES);
 
-        // Route exchange counts from continuous aggregate
+        // Route exchange counts from AggregatingMergeTree (literal SQL — ClickHouse JDBC driver
+        // wraps prepared statements in sub-queries that strip AggregateFunction column types)
         Map<String, Long> routeExchangeCounts = new LinkedHashMap<>();
         Map<String, Instant> routeLastSeen = new LinkedHashMap<>();
         try {
             jdbc.query(
-                    "SELECT application_name, route_id, SUM(total_count) AS cnt, MAX(bucket) AS last_seen " +
+                    "SELECT application_name, route_id, countMerge(total_count) AS cnt, MAX(bucket) AS last_seen " +
-                            "FROM stats_1m_route WHERE bucket >= ? AND bucket < ? " +
+                            "FROM stats_1m_route WHERE bucket >= " + lit(rangeFrom) + " AND bucket < " + lit(rangeTo) +
-                            "GROUP BY application_name, route_id",
+                            " GROUP BY application_name, route_id",
                     rs -> {
                         String key = rs.getString("application_name") + "/" + rs.getString("route_id");
                         routeExchangeCounts.put(key, rs.getLong("cnt"));
                         Timestamp ts = rs.getTimestamp("last_seen");
                         if (ts != null) routeLastSeen.put(key, ts.toInstant());
-                    },
+                    });
-                    Timestamp.from(rangeFrom), Timestamp.from(rangeTo));
         } catch (Exception e) {
-            // Continuous aggregate may not exist yet
+            // AggregatingMergeTree table may not exist yet
         }
 
         // Per-agent TPS from the last minute
         Map<String, Double> agentTps = new LinkedHashMap<>();
         try {
             jdbc.query(
-                    "SELECT application_name, SUM(total_count) AS cnt " +
+                    "SELECT application_name, countMerge(total_count) AS cnt " +
-                            "FROM stats_1m_route WHERE bucket >= ? AND bucket < ? " +
+                            "FROM stats_1m_route WHERE bucket >= " + lit(from1m) + " AND bucket < " + lit(now) +
-                            "GROUP BY application_name",
+                            " GROUP BY application_name",
                     rs -> {
                         // This gives per-app TPS; we'll distribute among agents below
-                    },
+                    });
-                    Timestamp.from(from1m), Timestamp.from(now));
         } catch (Exception e) {
-            // Continuous aggregate may not exist yet
+            // AggregatingMergeTree table may not exist yet
         }
 
         // Build catalog entries
@@ -158,6 +157,14 @@ public class RouteCatalogController {
                 .orElse(null);
     }
 
+    /** Format an Instant as a ClickHouse DateTime literal. */
+    private static String lit(Instant instant) {
+        Instant truncated = instant.truncatedTo(ChronoUnit.SECONDS);
+        String ts = new Timestamp(truncated.toEpochMilli()).toString();
+        if (ts.endsWith(".0")) ts = ts.substring(0, ts.length() - 2);
+        return "'" + ts + "'";
+    }
+
     private String computeWorstHealth(List<AgentInfo> agents) {
         boolean hasDead = false;
         boolean hasStale = false;

cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/RouteMetricsController.java

@@ -52,20 +52,18 @@ public class RouteMetricsController {
         Instant fromInstant = from != null ? Instant.parse(from) : toInstant.minus(24, ChronoUnit.HOURS);
         long windowSeconds = Duration.between(fromInstant, toInstant).toSeconds();
 
+        // Literal SQL — ClickHouse JDBC driver wraps prepared statements in sub-queries
+        // that strip AggregateFunction column types, breaking -Merge combinators
         var sql = new StringBuilder(
                 "SELECT application_name, route_id, " +
-                "SUM(total_count) AS total, " +
+                "countMerge(total_count) AS total, " +
-                "SUM(failed_count) AS failed, " +
+                "countIfMerge(failed_count) AS failed, " +
-                "CASE WHEN SUM(total_count) > 0 THEN SUM(duration_sum) / SUM(total_count) ELSE 0 END AS avg_dur, " +
+                "CASE WHEN countMerge(total_count) > 0 THEN toFloat64(sumMerge(duration_sum)) / countMerge(total_count) ELSE 0 END AS avg_dur, " +
-                "COALESCE(MAX(p99_duration), 0) AS p99_dur " +
+                "COALESCE(quantileMerge(0.99)(p99_duration), 0) AS p99_dur " +
-                "FROM stats_1m_route WHERE bucket >= ? AND bucket < ?");
+                "FROM stats_1m_route WHERE bucket >= " + lit(fromInstant) + " AND bucket < " + lit(toInstant));
-        var params = new ArrayList<Object>();
-        params.add(Timestamp.from(fromInstant));
-        params.add(Timestamp.from(toInstant));
 
         if (appId != null) {
-            sql.append(" AND application_name = ?");
+            sql.append(" AND application_name = " + lit(appId));
-            params.add(appId);
         }
         sql.append(" GROUP BY application_name, route_id ORDER BY application_name, route_id");
 
@@ -88,7 +86,7 @@ public class RouteMetricsController {
             routeKeys.add(new RouteKey(applicationName, routeId));
             return new RouteMetrics(routeId, applicationName, total, successRate,
                     avgDur, p99Dur, errorRate, tps, List.of(), -1.0);
-        }, params.toArray());
+        });
 
         // Fetch sparklines (12 buckets over the time window)
         if (!metrics.isEmpty()) {
@@ -98,15 +96,13 @@ public class RouteMetricsController {
             for (int i = 0; i < metrics.size(); i++) {
                 RouteMetrics m = metrics.get(i);
                 try {
-                    List<Double> sparkline = jdbc.query(
+                    String sparkSql = "SELECT toStartOfInterval(bucket, toIntervalSecond(" + bucketSeconds + ")) AS period, " +
-                            "SELECT time_bucket(? * INTERVAL '1 second', bucket) AS period, " +
+                            "COALESCE(countMerge(total_count), 0) AS cnt " +
-                                    "COALESCE(SUM(total_count), 0) AS cnt " +
+                            "FROM stats_1m_route WHERE bucket >= " + lit(fromInstant) + " AND bucket < " + lit(toInstant) +
-                                    "FROM stats_1m_route WHERE bucket >= ? AND bucket < ? " +
+                            " AND application_name = " + lit(m.appId()) + " AND route_id = " + lit(m.routeId()) +
-                                    "AND application_name = ? AND route_id = ? " +
+                            " GROUP BY period ORDER BY period";
-                                    "GROUP BY period ORDER BY period",
+                    List<Double> sparkline = jdbc.query(sparkSql,
-                            (rs, rowNum) -> rs.getDouble("cnt"),
+                            (rs, rowNum) -> rs.getDouble("cnt"));
-                            bucketSeconds, Timestamp.from(fromInstant), Timestamp.from(toInstant),
-                            m.appId(), m.routeId());
                     metrics.set(i, new RouteMetrics(m.routeId(), m.appId(), m.exchangeCount(),
                             m.successRate(), m.avgDurationMs(), m.p99DurationMs(),
                             m.errorRate(), m.throughputPerSec(), sparkline, m.slaCompliance()));
@@ -153,25 +149,22 @@ public class RouteMetricsController {
         Instant toInstant = to != null ? to : Instant.now();
         Instant fromInstant = from != null ? from : toInstant.minus(24, ChronoUnit.HOURS);
 
+        // Literal SQL for AggregatingMergeTree -Merge combinators
         var sql = new StringBuilder(
                 "SELECT processor_id, processor_type, route_id, application_name, " +
-                "SUM(total_count) AS total_count, " +
+                "countMerge(total_count) AS total_count, " +
-                "SUM(failed_count) AS failed_count, " +
+                "countIfMerge(failed_count) AS failed_count, " +
-                "CASE WHEN SUM(total_count) > 0 THEN SUM(duration_sum)::double precision / SUM(total_count) ELSE 0 END AS avg_duration_ms, " +
+                "CASE WHEN countMerge(total_count) > 0 THEN toFloat64(sumMerge(duration_sum)) / countMerge(total_count) ELSE 0 END AS avg_duration_ms, " +
-                "MAX(p99_duration) AS p99_duration_ms " +
+                "quantileMerge(0.99)(p99_duration) AS p99_duration_ms " +
                 "FROM stats_1m_processor_detail " +
-                "WHERE bucket >= ? AND bucket < ? AND route_id = ?");
+                "WHERE bucket >= " + lit(fromInstant) + " AND bucket < " + lit(toInstant) +
-        var params = new ArrayList<Object>();
+                " AND route_id = " + lit(routeId));
-        params.add(Timestamp.from(fromInstant));
-        params.add(Timestamp.from(toInstant));
-        params.add(routeId);
 
         if (appId != null) {
-            sql.append(" AND application_name = ?");
+            sql.append(" AND application_name = " + lit(appId));
-            params.add(appId);
         }
         sql.append(" GROUP BY processor_id, processor_type, route_id, application_name");
-        sql.append(" ORDER BY SUM(total_count) DESC");
+        sql.append(" ORDER BY countMerge(total_count) DESC");
 
         List<ProcessorMetrics> metrics = jdbc.query(sql.toString(), (rs, rowNum) -> {
             long totalCount = rs.getLong("total_count");
@@ -187,8 +180,21 @@ public class RouteMetricsController {
                     rs.getDouble("avg_duration_ms"),
                     rs.getDouble("p99_duration_ms"),
                     errorRate);
-        }, params.toArray());
+        });
 
         return ResponseEntity.ok(metrics);
     }
+
+    /** Format an Instant as a ClickHouse DateTime literal. */
+    private static String lit(Instant instant) {
+        Instant truncated = instant.truncatedTo(ChronoUnit.SECONDS);
+        String ts = new Timestamp(truncated.toEpochMilli()).toString();
+        if (ts.endsWith(".0")) ts = ts.substring(0, ts.length() - 2);
+        return "'" + ts + "'";
+    }
+
+    /** Format a string as a SQL literal with single-quote escaping. */
+    private static String lit(String value) {
+        return "'" + value.replace("'", "\\'") + "'";
+    }
 }