Environment

• Zabbix server and proxy 8.0.0 (c81e276), built from tag 8.0.0, using PostgreSQL
• ClickHouse 26.8.17.4, zabbix.otel_logs created with the official otel_logs_schema.sh, default TTL of 31 days
• OpenTelemetry Collector Contrib 0.164.0

Steps to reproduce

1. In a working server/proxy setup, configure an active proxy with Hostname=repro-proxy, APM TLS disabled and these parameters:

StartAPMCollector=1
TelemetryProvider=clickhouse;url=http://<clickhouse>:8123,db=zabbix

2. Register the proxy with APM collection enabled. For example, use these parameters for proxy.create:

{"name":"repro-proxy","operating_mode":0,"apm":{"data_collection_status":1}}

Wait until the proxy receives its configuration from the server.

3. Pause TTL merges so the inserted row can be inspected:

SYSTEM STOP TTL MERGES zabbix.otel_logs;

4. On the Collector host, write a log line without a timestamp:

echo "observed-only-test plain application log line without timestamp" > /tmp/app.log

5. Save the following configuration as /tmp/filelog-repro.yaml. Replace <proxy> with the proxy address. The Collector must be able to read /tmp/app.log.

receivers: 
  filelog: 
    include: [/tmp/app.log]
    start_at: beginning
processors: 
  resource: 
    attributes: 
      - key: service.name
        value: filelog-repro
        action: upsert
exporters: 
  otlp: 
    endpoint: <proxy>:4317
    tls: 
      insecure: true
  debug: 
    verbosity: detailed
service: 
  pipelines: 
    logs: 
      receivers: [filelog]
      processors: [resource]
      exporters: [otlp, debug]

Start the Collector:

otelcol-contrib --config=/tmp/filelog-repro.yaml

6. After the record is exported, check ClickHouse:

SELECT
    toUnixTimestamp64Nano(Timestamp) AS ns,
    _partition_id,
    Body
FROM zabbix.otel_logs
WHERE ServiceName = 'filelog-repro';

7. Resume TTL merges and repeat the SELECT to observe removal:

SYSTEM START TTL MERGES zabbix.otel_logs;

Result

Collector emits a record with no event timestamp and a valid observed timestamp:

ObservedTimestamp: 2026-11-07 03:47:20.034540741 +0000 UTC
Timestamp: 1970-01-01 00:00:00 +0000 UTC

The proxy stores it with Timestamp 0:

After TTL merges resume, ClickHouse removes the row.

Expected

When time_unix_nano is zero and observed_time_unix_nano is nonzero, the proxy should use the observed timestamp. The record should then be retained according to the configured TTL. Valid nonzero event timestamps should keep precedence.

OpenTelemetry Logs Data Model recommends the following when mapping logs to a format with one timestamp:

Use Timestamp if it is present, otherwise use ObservedTimestamp.

This affects records with an omitted or zero time_unix_nano and a nonzero observed_time_unix_nano. The filelog configuration above produces such records without any timestamp manipulation.