Blog: Optimizing promql queries #6697
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CharlieTLe
reviewed
Apr 26, 2025
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| This guide explains how Cortex evaluates PromQL queries, details how time series data is stored and retrieved, and offers strategies to write performant queries—particularly in high-cardinality environments. | ||
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| Note: If you are new to PromQL, it is recommended to with the [Querying basics documentation](https://prometheus.io/docs/prometheus/latest/querying/basics/). |
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| Note: If you are new to PromQL, it is recommended to with the [Querying basics documentation](https://prometheus.io/docs/prometheus/latest/querying/basics/). | |
| Note: If you are new to PromQL, it is recommended to first read the [Querying basics documentation](https://prometheus.io/docs/prometheus/latest/querying/basics/). |
CharlieTLe
reviewed
Apr 26, 2025
| Label matchers define the selection criteria for time series within the TSDB. Consider the following PromQL expression: | ||
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| ``` | ||
| sum(rate(http_requests_total{cluster="prod", job="envoy"}[5m])) |
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We can simplify to just the essential bits needed for the example.
Suggested change
| sum(rate(http_requests_total{cluster="prod", job="envoy"}[5m])) | |
| http_requests_total{cluster="prod", job="envoy"} |
CharlieTLe
reviewed
Apr 26, 2025
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| Cortex uses Prometheus's Time Series Database (TSDB) for storing time series data. The Prometheus TSDB is time partitioned into blocks. Each TSDB block is made up of the following files: | ||
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| * `ID` - ID of the block (ULID) |
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| * `ID` - ID of the block (ULID) | |
| * `ID` - ID of the block ([ULID](https://github.com/ulid/spec)) |
CharlieTLe
reviewed
Apr 26, 2025
| * `ID` - ID of the block (ULID) | ||
| * `meta.json` - Contains the metadata of the block | ||
| * `index` - A binary file that contains the index | ||
| * `chunks` - Directory containing the chunk segment files. |
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| * `chunks` - Directory containing the chunk segment files. | |
| * `chunks` - Directory containing the chunk segment files |
CharlieTLe
reviewed
Apr 26, 2025
| * `index` - A binary file that contains the index | ||
| * `chunks` - Directory containing the chunk segment files. | ||
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| More details: [TSDB format docs](https://github.com/prometheus/prometheus/blob/main/tsdb/docs/format/README.md) |
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| More details: [TSDB format docs](https://github.com/prometheus/prometheus/blob/main/tsdb/docs/format/README.md) | |
| More details: [TSDB format docs](https://github.com/prometheus/prometheus/blob/5630a3906ace8f2ecd16e7af7fb184e4f4dd853d/tsdb/docs/format/README.md) |
It's better to use a permalink in case files get moved around.
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Hi @harry671003, could you move docs/blog/optimizing-promql-queries.md under /website/content/en/blog/2025 after rebasing from the master branch? I've set up the blog with #6725. |
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What this PR does:
There has been some talk about creating a blog in Cortex.
#6471
This is my attempt at writing a blog post on optimizing PromQL queries with the audience being new users or Prometheus and Cortex.
Which issue(s) this PR fixes:
Fixes #
Checklist
CHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX]