[AshuSrv]

Description of the issue

PostgreSQL execution plans are never collected for Database Insights. The translator sets the per-interval explain budget to 0, and the receiver gates explain attempts on explained < maxExplainEachInterval, so that comparison is
never true. Every db.server.top_query event is emitted with an empty postgresql.query_plan attribute.

Description of changes

Set the per-interval explain budget to 1000 in the PostgreSQL receiver translator so execution plans are collected by default.

-cfg.MaxExplainEachInterval = 0
+cfg.MaxExplainEachInterval = 1000

The value is kept as an explicit assignment rather than removed so it remains easy to adjust.

The expected translator outputs under translator/tocwconfig/sampleConfig are updated to match, and a test assertion pins the value so it cannot silently regress to disabled.

1000 is the upstream default for this setting, so this restores upstream behaviour rather than introducing a value we would have to carry as a divergence.

The number is not the effective cap on work. The explain loop is bounded by top_n_query, which is 200, so at most 200 explains can be attempted in an interval regardless of this setting.

License

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Tests

Unit tests

go test ./translator/translate/otel/receiver/postgresql/... ./translator/tocwconfig/
ok  	github.com/aws/amazon-cloudwatch-agent/translator/translate/otel/receiver/postgresql
ok  	github.com/aws/amazon-cloudwatch-agent/translator/tocwconfig

make fmt, make fmt-sh and make lint are clean.

Verified on EC2 instance

Amazon Linux 2, PostgreSQL 14.23 with pg_stat_statements (track = all), a non-superuser role owning the workload tables, and a monitoring user granted pg_monitor plus SELECT on those tables.

Agent configuration used:

{
  "agent": { "region": "us-west-2" },
  "opentelemetry": {
    "collect": {
      "database_insights": {
        "postgresql": [
          {
            "endpoint": "localhost:5432",
            "instance_name": "explain-plans-test",
            "username": "cw_monitor",
            "password_file": "/opt/databaseinsights/.pgpass",
            "logs": { "file_path": "/var/log/postgresql/postgresql-*.log" }
          }
        ]
      }
    }
  }
}

The generated collector configuration now carries the budget:

top_query_collection:
    collection_interval: 1m0s
    max_explain_each_interval: 1000
    max_rows_per_query: 5000
    query_plan_cache_size: 1000
    query_plan_cache_ttl: 1h0m0s
    top_n_query: 200

Sample db.server.top_query record after the change, from
/aws/self-managed-database-insights/postgresql/raw-events:

"attributes": {
        "db.system.name": "postgresql",
        "db.namespace": "testdb",
        "db.query.text": "SELECT COALESCE ( ( SELECT extname FROM pg_extension WHERE extname = ? ) )",
        "postgresql.calls": 1,
        "postgresql.rows": 1,
         .
         .
         .
        "postgresql.query_plan": "[{\"Plan\":{\"Node Type\":\"Result\",\"Parallel Aware\":false,\"Async Capable\":false,\"Startup Cost\":1.01,\"Total Cost\":1.02,\"Plan Rows\":1,\"Plan Width\":64,\"Plans\":[{\"Node Type\":\"Seq Scan\",\"Parent Relationship\":\"InitPlan\",\"Subplan Name\":\"InitPlan 1 (returns $0)\",\"Parallel Aware\":false,\"Async Capable\":false,\"Relation Name\":\"pg_extension\",\"Alias\":\"pg_extension\",\"Startup Cost\":0.00,\"Total Cost\":1.01,\"Plan Rows\":1,\"Plan Width\":64,\"Filter\":\"( extname = ? )\"}]}}]"
    },

Requirements

• Run make fmt and make fmt-sh
• Run make lint

[github-actions]

Binary Size Report

linux/amd64

Binary	PR	vs main (5efb6c4)	vs v1.300070.0
amazon-cloudwatch-agent	193.3 MB	+0 B	${\color{green}▼}$ 38.0 MB (-16.4%)
amazon-cloudwatch-agent-config-wizard	2.0 MB	+0 B	${\color{red}▲}$ +86.0 KB (+4.5%)
config-downloader	2.0 MB	+0 B	${\color{red}▲}$ +86.0 KB (+4.5%)
config-translator	2.0 MB	+0 B	${\color{red}▲}$ +86.0 KB (+4.5%)
start-amazon-cloudwatch-agent	2.5 MB	+0 B	${\color{red}▲}$ +81.9 KB (+3.4%)
workload-discovery	3.0 MB	+0 B	${\color{red}▲}$ +94.2 KB (+3.2%)
Total	204.8 MB	+0 B	${\color{green}▼}$ 37.6 MB (-15.5%)

linux/amd64 amazon-cloudwatch-agent (last 9 main commits + this PR)

 193 ┤                                        
     ┤                            ███ ███ ███ 
     ┤                            ███ ███ ███ 
     ┤                            ███ ███ ███ 
     ┤                            ███ ███ ███ 
     ┤                            ███ ███ ███ 
     ┤                            ███ ███ ███ 
     ┤                            ███ ███ ███ 
 193 ┤▄▄▄ ▄▄▄ ▄▄▄ ▄▄▄ ▄▄▄ ▄▄▄ ▄▄▄ ███ ███ ███ 
 MB  └────────────────────────────────────────
      43f2526                             PR

linux/arm64

Binary	PR	vs main (5efb6c4)	vs v1.300070.0
amazon-cloudwatch-agent	177.1 MB	+0 B	${\color{green}▼}$ 34.4 MB (-16.3%)
amazon-cloudwatch-agent-config-wizard	2.0 MB	+0 B	${\color{green}▼}$ 22 B (-0.0%)
config-downloader	2.0 MB	+0 B	${\color{green}▼}$ 22 B (-0.0%)
config-translator	2.0 MB	+0 B	${\color{green}▼}$ 22 B (-0.0%)
start-amazon-cloudwatch-agent	2.4 MB	+0 B	${\color{red}▲}$ +65.5 KB (+2.8%)
workload-discovery	2.9 MB	+0 B	${\color{red}▲}$ +65.5 KB (+2.3%)
Total	188.4 MB	+0 B	${\color{green}▼}$ 34.3 MB (-15.4%)

windows/amd64

Binary	PR	vs main (5efb6c4)	vs v1.300070.0
amazon-cloudwatch-agent.exe	196.1 MB	${\color{red}▲}$ +6.1 KB (+0.0%)	${\color{green}▼}$ 38.1 MB (-16.3%)
amazon-cloudwatch-agent-config-wizard.exe	2.1 MB	+0 B	${\color{red}▲}$ +130.6 KB (+6.5%)
config-downloader.exe	2.1 MB	+0 B	${\color{red}▲}$ +130.0 KB (+6.5%)
config-translator.exe	2.1 MB	+0 B	${\color{red}▲}$ +130.6 KB (+6.5%)
start-amazon-cloudwatch-agent.exe	2.3 MB	+0 B	${\color{red}▲}$ +112.1 KB (+5.2%)
workload-discovery.exe	2.9 MB	+0 B	${\color{red}▲}$ +97.3 KB (+3.5%)
Total	207.7 MB	${\color{red}▲}$ +6.1 KB (+0.0%)	${\color{green}▼}$ 37.5 MB (-15.3%)

Investigating size changes

Use go-size-analyzer to compare binaries:

GOEXPERIMENT=jsonv2 go install github.com/Zxilly/go-size-analyzer/cmd/gsa@latest
gsa diff --old <baseline-binary> --new <new-binary>