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62 lines
2.2 KiB
Markdown
62 lines
2.2 KiB
Markdown
Room and User Statistics
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========================
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Synapse maintains room and user statistics (as well as a cache of room state),
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in various tables. These can be used for administrative purposes but are also
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used when generating the public room directory.
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# Synapse Developer Documentation
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## High-Level Concepts
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### Definitions
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* **subject**: Something we are tracking stats about – currently a room or user.
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* **current row**: An entry for a subject in the appropriate current statistics
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table. Each subject can have only one.
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* **historical row**: An entry for a subject in the appropriate historical
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statistics table. Each subject can have any number of these.
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### Overview
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Stats are maintained as time series. There are two kinds of column:
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* absolute columns – where the value is correct for the time given by `end_ts`
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in the stats row. (Imagine a line graph for these values)
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* They can also be thought of as 'gauges' in Prometheus, if you are familiar.
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* per-slice columns – where the value corresponds to how many of the occurrences
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occurred within the time slice given by `(end_ts − bucket_size)…end_ts`
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or `start_ts…end_ts`. (Imagine a histogram for these values)
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Stats are maintained in two tables (for each type): current and historical.
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Current stats correspond to the present values. Each subject can only have one
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entry.
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Historical stats correspond to values in the past. Subjects may have multiple
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entries.
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## Concepts around the management of stats
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### Current rows
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Current rows contain the most up-to-date statistics for a room.
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They only contain absolute columns
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### Historical rows
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Historical rows can always be considered to be valid for the time slice and
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end time specified.
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* historical rows will not exist for every time slice – they will be omitted
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if there were no changes. In this case, the following assumptions can be
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made to interpolate/recreate missing rows:
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- absolute fields have the same values as in the preceding row
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- per-slice fields are zero (`0`)
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* historical rows will not be retained forever – rows older than a configurable
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time will be purged.
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#### Purge
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The purging of historical rows is not yet implemented.
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