[exporter/clickhouse] Incorrect ServiceName set for Logs Records

[Fiery-Fenix]

Component(s)

exporter/clickhouse

What happened?

Description

In some corner cases, for Log Records clickhouseexporter inserts incorrect ServiceName value
For example, clickhouseexporter receives 2 Log Records in this order:

• First record with Resource Attribute service.name is equal to someservice
• Second record - without Resource Attribute service.name
  In this case - both records will be written to ClickHouse with ServiceName = someservice
  That is happened because of this line: https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/exporter/clickhouseexporter/exporter_logs.go#L74
  Variable serviceName defined outside of the loop and keep last value between loops
  This variable should be defined inside of the loop to keep data only for current Resource Log
  Traces part is already have correct code - see https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/exporter/clickhouseexporter/exporter_traces.go#L78
  Metrics part is also unaffected - for example see https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/exporter/clickhouseexporter/internal/gauge_metrics.go#L112

Steps to Reproduce

Feed to clickhouseexporter 2 Log Records:

• First record with Resource Attribute service.name is equal to someservice
• Second record - without Resource Attribute service.name

Expected Result

Written data should have following values in ServiceName field of otel_logs table:

• someservice
• Empty string

Actual Result

Actual written data have following values in ServiceName field of otel_logs table:

• someservice
• someservice

Collector version

v0.113.0

Environment information

Environment

OS: (e.g., "Ubuntu 20.04")
Compiler(if manually compiled): (e.g., "go 14.2")

OpenTelemetry Collector configuration

No response

Log output

No response

Additional context

No response

[github-actions]

Pinging code owners:

• exporter/clickhouse: @hanjm @dmitryax @Frapschen @SpencerTorres

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[VihasMakwana]

Removing triage label as this looks like a valid bug and has a bugfix PR linked