refactor(monitoring): replace SQL monitoring with DuckDB Parquet pipeline

[tlgimenes]

What is this contribution about?

Replaces the dual monitoring system (OTel for ops + monitoring_logs DB table for dashboards) with a unified pipeline: OTel instrumentation → Parquet files → DuckDB queries.

Key changes:

• DuckDB Foundation: DuckDBProvider wrapper around @duckdb/node-api, time-partitioned Parquet path utilities, schema constants, SQL injection safety validators
• ParquetSpanExporter: Custom OTel SpanExporter that buffers monitoring spans and flushes to ZSTD-compressed Parquet files via DuckDB COPY
• Span Enrichment: emitMonitoringSpan() shared utility replaces direct DB writes in both MonitoringTransport and proxy monitoring middleware
• DuckDBMonitoringStorage: Implements MonitoringStorage interface via read_parquet() with query, getStats, aggregate, countMatched, property filters, and date range glob narrowing
• Integration: ParquetSpanExporter wired into OTel SDK (local mode), DebugSampler fixed to always record monitoring spans, context factory switched to DuckDB storage
• Cleanup: Migration 036 drops monitoring_logs table, SqlMonitoringStorage deleted (-1146 lines), Parquet retention cleanup utility added

Architecture:

Tool Call → MonitoringTransport/proxy-monitoring
         → emitMonitoringSpan() (OTel span with mesh.monitoring.* attributes)
         → ParquetSpanExporter (buffers → DuckDB COPY → ZSTD Parquet)
         → DuckDBMonitoringStorage (read_parquet() for dashboard queries)

Screenshots/Demonstration

N/A — backend infrastructure change, no UI changes.

How to Test

1. Run the monitoring test suite:

   bun test apps/mesh/src/monitoring/ apps/mesh/src/api/routes/proxy-monitoring.test.ts

   Expected: 61 tests pass across 7 files

2. Run type checking:

   bun run check

   Expected: All workspaces pass

3. Run full test suite:

   bun test

   Expected: 967 pass, 32 skip (1 pre-existing e2e failure unrelated to this PR)

4. Verify Parquet writes (manual):

   • Start dev server with bun run dev
   • Make tool calls through an MCP connection
   • Check ./data/monitoring/YYYY/MM/DD/HH/ for .parquet files
   • Verify monitoring dashboard still shows tool call logs

Migration Notes

• Migration 036 drops the monitoring_logs table and its 6 indexes
• Data loss: Existing monitoring data in monitoring_logs will be lost. Export to Parquet before migrating if historical data is needed
• New dependency: @duckdb/node-api added to apps/mesh
• New env vars (optional):
  • MONITORING_PARQUET_PATH — override Parquet file location (default: ./data/monitoring)
  • When OTEL_EXPORTER_OTLP_ENDPOINT is set, ParquetSpanExporter is NOT added (cloud mode uses Collector)

Review Checklist

• PR title is clear and descriptive
• Changes are tested and working (61 tests)
• Documentation is updated (if needed)
• No breaking changes (MonitoringStorage interface preserved)

🤖 Generated with Claude Code

---

Summary by cubic

Replaces SQL-based monitoring with a unified OTel → Parquet → DuckDB pipeline for faster queries and lower DB load. Spans are enriched at source and written to time-partitioned Parquet files, which power the monitoring dashboard.

• Refactors

  • Added ParquetSpanExporter to buffer monitoring spans and write ZSTD Parquet on an hourly partitioned path.
  • Introduced emitMonitoringSpan used by MonitoringTransport and proxy middleware; DebugSampler always records these spans.
  • Implemented DuckDBMonitoringStorage (read_parquet with glob narrowing, property filters, aggregate/countMatched with limit and ordering).
  • Wired exporter in local mode and switched context to DuckDB storage; removed SqlMonitoringStorage and dropped DB writes.
  • Added Parquet retention cleanup utility.

• Migration

  • Drops monitoring_logs table and its indexes (migration 036).
  • Existing monitoring data will be lost; export to Parquet before migrating if needed.
  • New dependency: @duckdb/node-api. Optional env: MONITORING_PARQUET_PATH (default ./data/monitoring).
  • When OTLP endpoint is set, Parquet exporter is not enabled (cloud uses the OTel Collector).

^{Written for commit 576baaf. Summary will update on new commits.}

[github-actions]

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[github-actions]

Release Options

Should a new version be published when this PR is merged?

React with an emoji to vote on the release type:

Reaction	Type	Next Version
👍	Prerelease	2.139.4-alpha.1
🎉	Patch	2.139.4
❤️	Minor	2.140.0
🚀	Major	3.0.0

Current version: 2.139.3

Deployment

• Deploy to production (triggers ArgoCD sync after Docker image is published)

[cubic-dev-ai]

9 issues found across 33 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="apps/mesh/src/api/routes/proxy-monitoring.test.ts">

<violation number="1" location="apps/mesh/src/api/routes/proxy-monitoring.test.ts:116">
P3: Avoid fixed-time sleeps in async tests; this can cause flaky failures and unnecessary test latency.</violation>
</file>

<file name="apps/mesh/src/monitoring/parquet-span-exporter.test.ts">

<violation number="1" location="apps/mesh/src/monitoring/parquet-span-exporter.test.ts:142">
P2: The test relies on a fixed 200ms delay, which makes the async flush assertion timing-sensitive and flaky.</violation>
</file>

<file name="apps/mesh/src/monitoring/parquet-span-exporter.ts">

<violation number="1" location="apps/mesh/src/monitoring/parquet-span-exporter.ts:127">
P1: `forceFlush()` can return before an in-flight flush finishes, allowing shutdown to close DuckDB too early.</violation>

<violation number="2" location="apps/mesh/src/monitoring/parquet-span-exporter.ts:134">
P1: Flush errors are swallowed, causing export callbacks to report success even when Parquet writes fail.</violation>
</file>

<file name="apps/mesh/src/monitoring/duckdb-monitoring-storage.ts">

<violation number="1" location="apps/mesh/src/monitoring/duckdb-monitoring-storage.ts:51">
P2: The error catch in `safeQuery` is overly broad: `msg.includes("read_parquet")` will swallow any DuckDB error mentioning `read_parquet`, not just the "no files found" case. This could silently mask real query errors (type mismatches, permission issues, schema problems). Consider removing the `read_parquet` fallback and only catching the specific "No files found" message.</violation>

<violation number="2" location="apps/mesh/src/monitoring/duckdb-monitoring-storage.ts:522">
P1: The `queryTimeseriesGrouped` method silently discards the `groupByExpr` and `limit` parameters, falling back to ungrouped timeseries. Callers requesting grouped time-series aggregations will receive incorrect (ungrouped) results with no error or warning. At minimum, this should be documented with a TODO, or throw an unsupported-operation error so callers know the feature isn't implemented rather than returning misleading data.</violation>

<violation number="3" location="apps/mesh/src/monitoring/duckdb-monitoring-storage.ts:544">
P2: `"5m"` interval maps to `date_trunc('minute', ...)`, producing 1-minute buckets instead of 5-minute buckets. Consider using DuckDB's `time_bucket(INTERVAL '5 minutes', "timestamp")` for correct 5-minute bucketing.</violation>
</file>

<file name="apps/mesh/migrations/036-drop-monitoring-logs.ts">

<violation number="1" location="apps/mesh/migrations/036-drop-monitoring-logs.ts:8">
P2: Down migration is incomplete: three indexes dropped in `up()` are not recreated in `down()`, so rollback does not restore the original schema.</violation>
</file>

<file name="apps/mesh/src/monitoring/retention.ts">

<violation number="1" location="apps/mesh/src/monitoring/retention.ts:20">
P1: Retention comparison mixes local-time cutoff with UTC partition dates, which can delete data too early or too late depending on server timezone.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P1: forceFlush() can return before an in-flight flush finishes, allowing shutdown to close DuckDB too early.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At apps/mesh/src/monitoring/parquet-span-exporter.ts, line 127:

<comment>`forceFlush()` can return before an in-flight flush finishes, allowing shutdown to close DuckDB too early.</comment>

<file context>
@@ -0,0 +1,256 @@
+   * from corrupting the staging table.
+   */
+  private async flush(): Promise<void> {
+    if (this.buffer.length === 0) return;
+
+    // Take the current buffer and reset atomically
</file context>

[cubic-dev-ai]

P1: Flush errors are swallowed, causing export callbacks to report success even when Parquet writes fail.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At apps/mesh/src/monitoring/parquet-span-exporter.ts, line 134:

<comment>Flush errors are swallowed, causing export callbacks to report success even when Parquet writes fail.</comment>

<file context>
@@ -0,0 +1,256 @@
+    this.buffer = [];
+
+    // Chain onto the flush lock to serialize concurrent flushes
+    this.flushLock = this.flushLock
+      .then(() => this.doFlush(rows))
+      .catch((err) => {
</file context>

[cubic-dev-ai]

P1: The queryTimeseriesGrouped method silently discards the groupByExpr and limit parameters, falling back to ungrouped timeseries. Callers requesting grouped time-series aggregations will receive incorrect (ungrouped) results with no error or warning. At minimum, this should be documented with a TODO, or throw an unsupported-operation error so callers know the feature isn't implemented rather than returning misleading data.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At apps/mesh/src/monitoring/duckdb-monitoring-storage.ts, line 522:

<comment>The `queryTimeseriesGrouped` method silently discards the `groupByExpr` and `limit` parameters, falling back to ungrouped timeseries. Callers requesting grouped time-series aggregations will receive incorrect (ungrouped) results with no error or warning. At minimum, this should be documented with a TODO, or throw an unsupported-operation error so callers know the feature isn't implemented rather than returning misleading data.</comment>

<file context>
@@ -0,0 +1,591 @@
+    };
+  }
+
+  private async queryTimeseriesGrouped(
+    aggExpr: string,
+    _groupByExpr: string,
</file context>

[cubic-dev-ai]

P1: Retention comparison mixes local-time cutoff with UTC partition dates, which can delete data too early or too late depending on server timezone.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At apps/mesh/src/monitoring/retention.ts, line 20:

<comment>Retention comparison mixes local-time cutoff with UTC partition dates, which can delete data too early or too late depending on server timezone.</comment>

<file context>
@@ -0,0 +1,101 @@
+  retentionDays: number = 30,
+): Promise<number> {
+  const cutoff = new Date();
+  cutoff.setDate(cutoff.getDate() - retentionDays);
+  cutoff.setHours(0, 0, 0, 0);
+
</file context>

[cubic-dev-ai]

P2: The test relies on a fixed 200ms delay, which makes the async flush assertion timing-sensitive and flaky.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At apps/mesh/src/monitoring/parquet-span-exporter.test.ts, line 142:

<comment>The test relies on a fixed 200ms delay, which makes the async flush assertion timing-sensitive and flaky.</comment>

<file context>
@@ -0,0 +1,235 @@
+    expect(result).toBe(ExportResultCode.SUCCESS);
+
+    // Wait a tick for async flush
+    await new Promise((r) => setTimeout(r, 200));
+
+    const files = await findParquetFiles(basePath);
</file context>

[cubic-dev-ai]

P2: The error catch in safeQuery is overly broad: msg.includes("read_parquet") will swallow any DuckDB error mentioning read_parquet, not just the "no files found" case. This could silently mask real query errors (type mismatches, permission issues, schema problems). Consider removing the read_parquet fallback and only catching the specific "No files found" message.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At apps/mesh/src/monitoring/duckdb-monitoring-storage.ts, line 51:

<comment>The error catch in `safeQuery` is overly broad: `msg.includes("read_parquet")` will swallow any DuckDB error mentioning `read_parquet`, not just the "no files found" case. This could silently mask real query errors (type mismatches, permission issues, schema problems). Consider removing the `read_parquet` fallback and only catching the specific "No files found" message.</comment>

<file context>
@@ -0,0 +1,591 @@
+      return await this.duckdb.all<T>(sql, ...params);
+    } catch (err: unknown) {
+      const msg = err instanceof Error ? err.message : String(err);
+      if (msg.includes("No files found") || msg.includes("read_parquet")) {
+        return [];
+      }
</file context>

[cubic-dev-ai]

P2: "5m" interval maps to date_trunc('minute', ...), producing 1-minute buckets instead of 5-minute buckets. Consider using DuckDB's time_bucket(INTERVAL '5 minutes', "timestamp") for correct 5-minute bucketing.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At apps/mesh/src/monitoring/duckdb-monitoring-storage.ts, line 544:

<comment>`"5m"` interval maps to `date_trunc('minute', ...)`, producing 1-minute buckets instead of 5-minute buckets. Consider using DuckDB's `time_bucket(INTERVAL '5 minutes', "timestamp")` for correct 5-minute bucketing.</comment>

<file context>
@@ -0,0 +1,591 @@
+  private intervalToBucket(interval: string): string {
+    const map: Record<string, string> = {
+      "1m": "minute",
+      "5m": "minute",
+      "1h": "hour",
+      "1d": "day",
</file context>

[cubic-dev-ai]

P2: Down migration is incomplete: three indexes dropped in up() are not recreated in down(), so rollback does not restore the original schema.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At apps/mesh/migrations/036-drop-monitoring-logs.ts, line 8:

<comment>Down migration is incomplete: three indexes dropped in `up()` are not recreated in `down()`, so rollback does not restore the original schema.</comment>

<file context>
@@ -0,0 +1,71 @@
+  await db.schema
+    .dropIndex("monitoring_logs_org_timestamp")
+    .ifExists()
+    .execute();
+  await db.schema
+    .dropIndex("monitoring_logs_connection_timestamp")
</file context>

[cubic-dev-ai]

P3: Avoid fixed-time sleeps in async tests; this can cause flaky failures and unnecessary test latency.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At apps/mesh/src/api/routes/proxy-monitoring.test.ts, line 116:

<comment>Avoid fixed-time sleeps in async tests; this can cause flaky failures and unnecessary test latency.</comment>

<file context>
@@ -100,29 +107,23 @@ describe("proxy monitoring middleware", () => {
-    expect(event.output).toEqual({ error: "nope" });
-    // Verify new fields are logged
-    expect(event.userAgent).toBe("test-client/1.0");
+    await new Promise((r) => setTimeout(r, 50));
+    expect(startSpan).toHaveBeenCalledWith(MONITORING_SPAN_NAME);
+
</file context>