Plan the number of tables and databases ​

Do not plan capacity from an undocumented maximum object count. Coordinator DB exposes managed database and table inventories, while practical limits depend on the workload and resources available to your deployment. A successful CREATE alone does not prove that a very large catalog meets your latency goals.

SELECT database, count(*) AS objects
FROM system.tables
WHERE schema_name = 'main'
GROUP BY database
ORDER BY database
FORMAT csv;

Choose a useful object boundary ​

A table should represent a meaningful schema and access pattern. Avoid creating one table per event, customer or time bucket solely to imitate a partition feature. A shared table with explicit identifiers can make application queries and schema changes easier to manage, provided it matches the required data contract.

Measure catalog growth ​

Test the expected number of databases and tables in a nonproduction environment. Include startup, metadata discovery, ordinary queries and the schema changes your application performs. Record resource usage and client-visible duration as the catalog grows.

Use system.databases, system.tables and system.columns to confirm what actually exists. Filter by database and namespace when identical table names are intentional. Do not treat a table-size estimate as an exact count of its rows.

See database inventory, table inventory and schema design.