Wire telemetry tuning params from DSN through to telemetry client

ParseTelemetryConfig existed and was tested but was never called in
production — telemetry_batch_size and telemetry_flush_interval silently
fell into sessionParams (sent to the server) instead of tuning the
telemetry client. Fix by:

- Extracting telemetry_batch_size and telemetry_flush_interval in
  ParseDSN and storing them on UserConfig
- Adding batchSize/flushInterval params to InitializeForConnection and
  applying them over DefaultConfig()
- Passing c.cfg.TelemetryBatchSize/FlushInterval from connector.go

Also update .golangci.yml for golangci-lint v2 compatibility: add
required version field, move gofmt to formatters section, and remove
linters removed in v2 (deadcode, structcheck, varcheck, typecheck,
gosimple).

Co-authored-by: Isaac

Author: samikshya-db

.golangci.yml

@@ -1,24 +1,22 @@
+version: "2"
+
 linters:
   disable-all: true
   enable:
     - bodyclose
-    - deadcode
     - depguard
     - dogsled
     # - dupl
     - errcheck
-    # - exportloopref
     # - funlen
     # - gochecknoinits
     # - goconst
     # - gocritic
     # - gocyclo
-    - gofmt
     # - goimports
-    # - gomnd
+    # - mnd
     - goprintffuncname
     - gosec
-    - gosimple
     - govet
     - ineffassign
     # - lll
@@ -27,30 +25,28 @@ linters:
     # - noctx
     - nolintlint
     - staticcheck
-    - structcheck
     # - stylecheck
-    - typecheck
     # - unconvert
     # - unparam
     - unused
-    - varcheck
     # - whitespace
 
   # don't enable:
   # - asciicheck
-  # - scopelint
   # - gochecknoglobals
   # - gocognit
   # - godot
   # - godox
-  # - goerr113
-  # - interfacer
-  # - maligned
+  # - err113
+  # - ireturn
   # - nestif
-  # - prealloc
   # - testpackage
   # - revive
-  # - wsl
+
+formatters:
+  enable:
+    - gofmt
+    # - goimports
 
 linters-settings:
   depguard:

connector.go

@@ -87,6 +87,8 @@ func (c *connector) Connect(ctx context.Context) (driver.Conn, error) {
 		c.cfg.DriverVersion,
 		c.client,
 		c.cfg.EnableTelemetry,
+		c.cfg.TelemetryBatchSize,
+		c.cfg.TelemetryFlushInterval,
 	)
 	if conn.telemetry != nil {
 		log.Debug().Msg("telemetry initialized for connection")

internal/config/config.go

@@ -102,6 +102,8 @@ type UserConfig struct {
 	// Uses config overlay pattern: client > server > default.
 	// Unset = check server feature flag; explicitly true/false overrides the server.
 	EnableTelemetry          ConfigValue[bool]
+	TelemetryBatchSize       int           // 0 = use default (100)
+	TelemetryFlushInterval   time.Duration // 0 = use default (5s)
 	Transport                http.RoundTripper
 	UseLz4Compression        bool
 	EnableMetricViewMetadata bool
@@ -149,6 +151,8 @@ func (ucfg UserConfig) DeepCopy() UserConfig {
 		EnableMetricViewMetadata: ucfg.EnableMetricViewMetadata,
 		CloudFetchConfig:         ucfg.CloudFetchConfig,
 		EnableTelemetry:          ucfg.EnableTelemetry,
+		TelemetryBatchSize:       ucfg.TelemetryBatchSize,
+		TelemetryFlushInterval:   ucfg.TelemetryFlushInterval,
 	}
 }
 
@@ -297,6 +301,19 @@ func ParseDSN(dsn string) (UserConfig, error) {
 		}
 		ucfg.EnableTelemetry = NewConfigValue(enableTelemetry)
 	}
+	if batchSize, ok, err := params.extractAsInt("telemetry_batch_size"); ok {
+		if err != nil {
+			return UserConfig{}, err
+		}
+		if batchSize > 0 {
+			ucfg.TelemetryBatchSize = batchSize
+		}
+	}
+	if flushInterval, ok := params.extract("telemetry_flush_interval"); ok {
+		if d, err := time.ParseDuration(flushInterval); err == nil && d > 0 {
+			ucfg.TelemetryFlushInterval = d
+		}
+	}
 
 	// for timezone we do a case insensitive key match.
 	// We use getNoCase because we want to leave timezone in the params so that it will also

telemetry/driver_integration.go

@@ -3,6 +3,7 @@ package telemetry
 import (
 	"context"
 	"net/http"
+	"time"
 
 	"github.com/databricks/databricks-sql-go/internal/config"
 )
@@ -26,6 +27,8 @@ func InitializeForConnection(
 	driverVersion string,
 	httpClient *http.Client,
 	enableTelemetry config.ConfigValue[bool],
+	batchSize int,
+	flushInterval time.Duration,
 ) *Interceptor {
 	// Create telemetry config and apply client overlay.
 	// ConfigValue[bool] semantics:
@@ -38,6 +41,12 @@ func InitializeForConnection(
 	} else {
 		cfg.EnableTelemetry = true // Unset: default to enabled, server flag decides
 	}
+	if batchSize > 0 {
+		cfg.BatchSize = batchSize
+	}
+	if flushInterval > 0 {
+		cfg.FlushInterval = flushInterval
+	}
 
 	// Get feature flag cache context FIRST (for reference counting)
 	flagCache := getFeatureFlagCache()