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Remove high cardinality tags from Data Streams hashes #10287

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Merged
piochelepiotr merged 2 commits into from
Jan 5, 2026
Merged

Remove high cardinality tags from Data Streams hashes #10287

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1728796
fix high cardinality hashes
piochelepiotr Jan 2, 2026
a96d252
Add unit tests
piochelepiotr Jan 5, 2026
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28 changes: 15 additions & 13 deletions internal-api/src/main/java/datadog/trace/api/datastreams/DataStreamsTags.java
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Original file line number Diff line number Diff line change
Expand Up @@ -334,7 +334,7 @@ public DataStreamsTags(
}
}

// hashable tags are 0-4
// hashable tags are 0-6: bus, direction, exchange, topic, type, subscription, kafkaClusterId
for (int i = 0; i < 7; i++) {
String tag = this.tagByIndex(i);
if (tag != null) {
Expand All @@ -343,9 +343,9 @@ public DataStreamsTags(
}
}

// aggregation tags are 5-7
// aggregation tags are 7-11: datasetName, datasetNamespace, isManual, group, consumerGroup
this.aggregationHash = this.hash;
for (int i = 7; i < 10; i++) {
for (int i = 7; i < 12; i++) {
String tag = this.tagByIndex(i);
if (tag != null) {
this.nonNullSize++;
Expand All @@ -354,9 +354,9 @@ public DataStreamsTags(
}
}

// the rest are values
// values are 12-13: partition, hasRoutingKey
this.completeHash = aggregationHash;
for (int i = 10; i < this.size(); i++) {
for (int i = 12; i < this.size(); i++) {
String tag = this.tagByIndex(i);
if (tag != null) {
this.nonNullSize++;
Expand All @@ -370,6 +370,8 @@ public int size() {
return 14;
}

// WARNING: DO NOT REORDER! Indices 0-6 are hash tags, 7-11 are aggregation tags, 12-13 are
// values. Reordering breaks hashing!
public String tagByIndex(int index) {
switch (index) {
case 0:
Expand All @@ -385,21 +387,21 @@ public String tagByIndex(int index) {
case 5:
return this.subscription;
case 6:
return this.datasetName;
return this.kafkaClusterId;
case 7:
return this.datasetNamespace;
return this.datasetName;
case 8:
return this.isManual;
return this.datasetNamespace;
case 9:
return this.group;
return this.isManual;
case 10:
return this.consumerGroup;
return this.group;
case 11:
return this.hasRoutingKey;
return this.consumerGroup;
case 12:
return this.kafkaClusterId;
case 13:
return this.partition;
case 13:
return this.hasRoutingKey;
default:
return null;
}
Expand Down