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A comment on Making Postgres Bloom. Parent comment

Re:Making Postgres Bloom by usman-m on Thursday July 30, 2015 @04:48PM (#9977966)
It probably uses a HyperLogLog--the 2% error rate kind of gives it away. Bloom filters approximate set membership queries, HyperLogLogs approximate set cardinality queries. COUNT DISTINCT is a set cardinality query.

We actually support a HyperLogLog backed COUNT DISTINCT aggregate too: http://docs.pipelinedb.com/aggregates.html#general-aggregate...

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Re:Making Postgres Bloom by striking on Thursday July 30, 2015 @05:35PM (#9978325)
Consider my metaphorical hat eaten. Thanks for the cool tools! I'm currently working with Postgres and this looks like a great thing to add to the mix.
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Re:Making Postgres Bloom by anarazel on Thursday July 30, 2015 @10:48PM (#9979656)
There's a postgres extension that implements hll for postgres. Rather useful: https://github.com/aggregateknowledge/postgresql-hll
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