mirror of https://github.com/ClickHouse/ClickHouse.git synced 2024-10-14 12:30:49 +00:00

* CLICKHOUSE-4063: less manual html @ index.md

* CLICKHOUSE-4063: recommend markdown="1" in README.md

* CLICKHOUSE-4003: manually purge custom.css for now

* CLICKHOUSE-4064: expand <details> before any print (including to pdf)

* CLICKHOUSE-3927: rearrange interfaces/formats.md a bit

* CLICKHOUSE-3306: add few http headers

* Remove copy-paste introduced in #3392

* Hopefully better chinese fonts #3392

* get rid of tabs @ custom.css

* Apply comments and patch from #3384

* Add jdbc.md to ToC and some translation, though it still looks badly incomplete

* minor punctuation

* Add some backlinks to official website from mirrors that just blindly take markdown sources

* Do not make fonts extra light

* find . -name '*.md' -type f | xargs -I{} perl -pi -e 's//g' {}

* find . -name '*.md' -type f | xargs -I{} perl -pi -e 's/ sql/g' {}

* Remove outdated stuff from roadmap.md

* Not so light font on front page too

* Refactor Chinese formats.md to match recent changes in other languages

2018-10-16 13:47:17 +03:00

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GraphiteMergeTree

This engine is designed for rollup (thinning and aggregating/averaging) Graphite data. It may be helpful to developers who want to use ClickHouse as a data store for Graphite.

Graphite stores full data in ClickHouse, and data can be retrieved in the following ways:

Without thinning.

Uses the MergeTree engine.
With thinning.

Using the GraphiteMergeTree engine.

The engine inherits properties from MergeTree. The settings for thinning data are defined by the graphite_rollup parameter in the server configuration.

Using The Engine

The Graphite data table must contain the following fields at minimum:

Path – The metric name (Graphite sensor).
Time – The time for measuring the metric.
Value – The value of the metric at the time set in Time.
Version – Determines which value of the metric with the same Path and Time will remain in the database.

Rollup pattern:

pattern
    regexp
    function
    age -> precision
    ...
pattern
    ...
default
    function
       age -> precision
    ...

When processing a record, ClickHouse will check the rules in the patternclause. If the metric name matches the regexp, the rules from pattern are applied; otherwise, the rules from default are used.

Fields in the pattern.

age – The minimum age of the data in seconds.
function – The name of the aggregating function to apply to data whose age falls within the range [age, age + precision].
precision– How precisely to define the age of the data in seconds.
regexp– A pattern for the metric name.

Example of settings:

<graphite_rollup>
    <pattern>
        <regexp>click_cost</regexp>
        <function>any</function>
        <retention>
            <age>0</age>
            <precision>5</precision>
        </retention>
        <retention>
            <age>86400</age>
            <precision>60</precision>
        </retention>
    </pattern>
    <default>
        <function>max</function>
        <retention>
            <age>0</age>
            <precision>60</precision>
        </retention>
        <retention>
            <age>3600</age>
            <precision>300</precision>
        </retention>
        <retention>
            <age>86400</age>
            <precision>3600</precision>
        </retention>
    </default>
</graphite_rollup>

Original article

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GraphiteMergeTree

Using The Engine

2.6 KiB

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