abhishekrb19 opened a new pull request, #18993:
URL: https://github.com/apache/druid/pull/18993
Currently, when we use LoggingEmitter and/or LoggingRequestLogger, long,
complex SQL queries make up the majority of the log volume, so we truncate logs
to some extent. With these events, this can lead to the "value" part, timestamp
among other getting truncated since the map's ordering is arbitrary. So this
patch switches the EventMap to a LinkedHashMap so critical info (e.g., metric
name and value) are logged first, followed by fields like service dimensions,
user dimensions and the SQL query itself.
Same idea for the request logger: we log the query context before the SQL
query itself, which lets us preserve any useful/debuggable information
deterministically even under truncation.
Given these maps typically have at most ~20–30 key/value pairs, the
additional overhead of using a LinkedHashMap should be okay.
For example:
```
2026-02-06T21:43:41,033 DEBUG
[qtp1321214620-64[groupBy_[foo1]_379c91c7-40b1-4d40-b86f-340fcde5177b]]
org.apache.druid.java.util.emitter.core.LoggingEmitter - [metrics]
{"feed":"metrics","timestamp":"2026-02-06T21:43:41.033Z","metric":"query/bytes","value":138,"service":"druid/historical","host":"localhost:8083","version":"37.0.0-SNAPSHOT","context":{"applyLimitPushDown":true,"defaultTimeout":180000,"engine":"native","finalize":false,"fudgeTimestamp":"1454795020784","groupByOutermost":false,"maxQueuedBytes":5242880,"maxScatterGatherBytes":9223372036854775807,"queryFailTime":1770414400967,"queryId":"379c91c7-40b1-4d40-b86f-340fcde5177b","queryResourceId":"c5f4256c-f84f-40c4-964a-840f1505d9a3","resultAsArray":true,"sliceIndex":23,"sqlOuterLimit":1001,"sqlQueryId":"yay","sqlStringifyArrays":false,"timeout":179998},"dataSource":"foo1","duration":"PT2592000S","hasFilters":"false","id":"379c91c7-40b1-4d40-b86f-340fcde5177b","interval":["2025-09-01T00:00:00.000Z/2025-10-01T00:00:00.000Z"
],"numComplexMetrics":"0","numDimensions":"3","numMetrics":"0","remoteAddress":"127.0.0.1","statusCode":200,"success":"true","type":"groupBy"}
```
instead of
```
org.apache.druid.java.util.emitter.core.LoggingEmitter - [metrics]
{"server":"localhost:8083","numComplexMetrics":"0","type":"groupBy","version":"37.0.0-SNAPSHOT","duration":"PT2592000S","feed":"metrics","numDimensions":"3","metric":"query/node/ttfb","hasFilters":"false","service":"druid/broker","host":"localhost:8082","context":{"applyLimitPushDown":true,"defaultTimeout":180000,"engine":"native","finalize":false,"fudgeTimestamp":"1675477114564","groupByOutermost":false,"maxQueuedBytes":5242880,"maxScatterGatherBytes":9223372036854775807,"queryFailTime":1770171694634,"queryId":"51152d78-80c6-452b-ba1f-604c2edde74a","queryResourceId":"b5c87e25-8368-4c1c-b974-8fc6e272e54b","resultAsArray":true,"sliceIndex":23,"sqlOuterLimit":1001,"sqlQueryId":"foo","sqlStringifyArrays":false},"interval":["2025-09-01T00:00:00.000Z/2025-10-01T00:00:00.000Z"],"id":"51152d78-80c6-452b-ba1f-604c2edde74a","numMetrics":"0","value":17,"dataSource":"foo1","timestamp":"2026-02-06T02:18:34.654Z"}
```
This PR has:
- [x] been self-reviewed.
- [x] added unit tests or modified existing tests to cover new code paths,
ensuring the threshold for [code
coverage](https://github.com/apache/druid/blob/master/dev/code-review/code-coverage.md)
is met.
- [x] been tested in a test Druid cluster.
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