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Last active July 11, 2024 08:07
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AWS PostgreSQL max_connection per instance type
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aws_postgresql_max_connection.md

The default formula use by AWS RDS to calculate the max_connections parameter is: LEAST({DBInstanceClassMemory/9531392},5000)

But It's hard to find the exact value of DBInstanceClassMemory.

So, here are the values I got when I ran the SQL commmand: show max_connections; in some RDS instances:

Instance type RAM (GB) max_connections
db.t2.small 2 198
db.t2.medium 4 413
db.t2.large 8 856
db.m4.large 8 856
db.r4.large 15.25 1660

These are default values. You can always change the max_connections value in the parameters group of your DB.

@stafot
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stafot commented Nov 11, 2021

Does this LEAST({DBInstanceClassMemory/9531392},5000) apply to graviton instances too. As it seems they support more max connections than the others based on https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/AuroraPostgreSQL.Managing.html but doesn't have data for t4g family.

@ajhodgson
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Graviton - db.r6g.xlarge (32 GB) = 3484. Looks like the same formula.

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