Add support for ExponentialHistogram

[srikanthccv]

So there can be at least some non-trivial stuff in launch week.

It is built on top of SigNoz/ch-go#1 and SigNoz/clickhouse-go#1. The detail of the sketch is too broad to put into the PR description. If you want to test it out, please run https://gist.github.com/srikanthccv/d046e2b677a5c03c29782cc9f8e179f1.

SELECT arrayMap(a -> round(a, 2), (quantilesDDMerge(0.01, 0.42, 0.69, 0.75, 0.9, 0.95, 0.99)(sketch)))
FROM signoz_metrics.exp_hist
WHERE unix_milli <= toUnixTimestamp(now() - INTERVAL 1 MINUTE) * 1000

Summary by CodeRabbit

• New Features
  • Introduced support for exponential histogram metrics, including complex data processing and storage.
  • Added new tables for storing exponential histogram metrics, enhancing the app's data handling capabilities.
• Improvements
  • Improved handling and processing of exponential histogram data points, ensuring accurate and efficient data representation.
• Database Changes
  • Implemented new SQL migrations for creating and dropping tables related to exponential histogram metrics.

[coderabbitai]

Walkthrough

The recent changes introduce enhanced support for exponential histograms in the ClickHouse metrics exporter. Key updates include the ability to process and write complex exponential histogram data to new tables, improved handling of metric types, and the addition of specific SQL migrations for managing the necessary database schema changes. This update aims at better data representation and processing efficiency for exponential histograms within the metrics system.

Changes

Files	Summary
.../clickhouse.go	Added chproto import, a new constant, and functionality for writing to DISTRIBUTED_EXP_HIST_TABLE.
.../exporter.go	Introduced support for MetricTypeExponentialHistogram, handling its aggregation and data points processing.
.../helper.go	Added functions for exponential histogram handling and processing, with enhanced logic and calculations.
.../metrics/migrations/000007_exp_hist.down.sql .../metrics/migrations/000007_exp_hist.up.sql	SQL migrations for creating and dropping exp_hist and distributed_exp_hist tables.

🐇✨
In a land of data, vast and wide,
A rabbit hopped with a skilled stride.
Histograms exponential, now neatly stored,
Through tables and metrics, our data soared.
🎉📊

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[srikanthccv]

Once this is merged, I will add the instrumentation for signoz_latency with this new type and test the effectiveness. The fixed bucket histogram will still be there.

[coderabbitai]

Review Status

Actionable comments generated: 0

Configuration used: CodeRabbit UI

Commits

Files that changed from the base of the PR and between adb5367 and ca7495e.

Files ignored due to path filters (2)

• go.mod is excluded by: !**/*.mod
• go.sum is excluded by: !**/*.sum

Files selected for processing (5)

• exporter/clickhousemetricsexporter/clickhouse.go (3 hunks)
• exporter/clickhousemetricsexporter/exporter.go (2 hunks)
• exporter/clickhousemetricsexporter/helper.go (1 hunks)
• migrationmanager/migrators/metrics/migrations/000007_exp_hist.down.sql (1 hunks)
• migrationmanager/migrators/metrics/migrations/000007_exp_hist.up.sql (1 hunks)

Additional comments: 8

migrationmanager/migrators/metrics/migrations/000007_exp_hist.down.sql (1)

• 1-3: LGTM.

migrationmanager/migrators/metrics/migrations/000007_exp_hist.up.sql (1)

• 1-19: LGTM.

exporter/clickhousemetricsexporter/exporter.go (2)

• 189-190: LGTM.
• 261-276: LGTM.

exporter/clickhousemetricsexporter/clickhouse.go (2)

• 55-55: LGTM.
• 496-576: LGTM.

exporter/clickhousemetricsexporter/helper.go (2)

• 489-510: LGTM.
• 512-553: LGTM.

[srikanthccv]

I am going to merge this since there is less context known to the reviewer. The tl;dr version is that the sketch maintains a maximum of 1024 buckets with bins/buckets laid out in such a way that relative error is honoured. The buckets are multiples of powers of 2, and that makes it possible to merge the sketches by reducing the scale of high precision sketch to low precision sketch. I will be happy to answer questions anytime https://www.vldb.org/pvldb/vol12/p2195-masson.pdf