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replikativ / datahike-postgres

Datahike with Postgres as data storage
Eclipse Public License 1.0
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Relationship between row counts and entities #10

Open Folcon opened 4 years ago

Folcon commented 4 years ago

Hi, I'm looking to test datahike on a small heroku postgres app and I'm wondering if there's a relationship between entity count and row's created?

The reason I'm asking is heroku's basic databases have row limits and I just don't want to just hit them.

whilo commented 4 years ago

There is a weak relationship. We store binary blobs of the hitchhiker-tree in postgres, which typically have a few hundred Datoms (facts) in them. This means the number of keys in Heroku is approximately #entities * #datoms per entity / #datoms per node in the hitchhiker-tree.

In general that means you can have many more entities than the row limit, but it also depends on the history feature and your write granularity. Please report back when you hit problems, we want to support Heroku well.