[PECOBLR-1381][PECOBLR-1382] Implement telemetry Phase 6-7: Collection, Aggregation & Driver Integration

[samikshya-db]

Summary

This stacked PR builds on #319 and implements Phases 6-7 of the telemetry system, completing the full pipeline.

Stack: Part 2 of 2

• Base: [PECOBLR-1143] Implement telemetry Phase 4-5: Export infrastructure and opt-in configuration #319 (PECOBLR-1143 - Phases 4-5)
• This PR: PECOBLR-1381 + PECOBLR-1382 (Phases 6-7)

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Phase 6: Metric Collection & Aggregation ✅

New Files

errors.go (108 lines)

• ✅ isTerminalError() - Non-retryable error detection
• ✅ classifyError() - Error categorization
• ✅ HTTP error handling utilities

interceptor.go (146 lines)

• ✅ BeforeExecute() / AfterExecute() hooks
• ✅ Context-based metric tracking
• ✅ Latency measurement
• ✅ Tag collection
• ✅ Error swallowing

aggregator.go (242 lines)

• ✅ Statement-level aggregation
• ✅ Batch processing (size: 100)
• ✅ Background flush (interval: 5s)
• ✅ Thread-safe operations
• ✅ Immediate flush for terminal errors

client.go (updated)

• ✅ Full pipeline integration
• ✅ Graceful shutdown

---

Phase 7: Driver Integration ✅

Configuration Support

internal/config/config.go (+18 lines)

• ✅ EnableTelemetry field
• ✅ ForceEnableTelemetry field
• ✅ DSN parameter parsing
• ✅ DeepCopy() support

Connection Integration

connection.go, connector.go (+20 lines)

• ✅ Telemetry field in conn struct
• ✅ Initialization in Connect()
• ✅ Cleanup in Close()

Helper Module

driver_integration.go (59 lines)

• ✅ InitializeForConnection() - Setup
• ✅ ReleaseForConnection() - Cleanup
• ✅ Feature flag checking
• ✅ Resource management

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Integration Flow

DSN: "host:port/path?enableTelemetry=true"
    ↓
connector.Connect()
    ↓
telemetry.InitializeForConnection()
    ├─→ Feature flag check (5-level priority)
    ├─→ Get/Create telemetryClient (per host)
    └─→ Create Interceptor (per connection)
    ↓
conn.telemetry = Interceptor
    ↓
conn.Close()
    ├─→ Flush pending metrics
    └─→ Release resources

---

Changes

Total: +1,073 insertions, -48 deletions (13 files)

Phase 6:

• telemetry/errors.go (108 lines) - NEW
• telemetry/interceptor.go (146 lines) - NEW
• telemetry/aggregator.go (242 lines) - NEW
• telemetry/client.go (+27/-9) - MODIFIED

Phase 7:

• telemetry/driver_integration.go (59 lines) - NEW
• internal/config/config.go (+18) - MODIFIED
• connection.go (+10) - MODIFIED
• connector.go (+10) - MODIFIED
• telemetry/DESIGN.md - MODIFIED

---

Testing

All tests passing ✅

• ✅ 70+ telemetry tests (2.018s)
• ✅ No breaking changes
• ✅ Compilation verified
• ✅ Thread-safety verified

---

Usage Example

// Enable telemetry via DSN
dsn := "host:443/sql/1.0?enableTelemetry=true"
db, _ := sql.Open("databricks", dsn)

// Or force enable
dsn := "host:443/sql/1.0?forceEnableTelemetry=true"

---

Related Issues

• Builds on: [PECOBLR-1143] Implement telemetry Phase 4-5: Export infrastructure and opt-in configuration #319 (PECOBLR-1143)
• Implements: PECOBLR-1381 (Phase 6) ✅
• Implements: PECOBLR-1382 (Phase 7) ✅

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Checklist

• Phase 6: Collection & aggregation
• Phase 7: Driver integration
• Configuration support
• Resource management
• All tests passing
• No breaking changes
• DESIGN.md updated