Tsi1 strategy's upper/lower bound for using memory

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Hi there,
Considered our series cardinality is tend to infinity, I change in-mem indexing to tsi1 strategy in case of memory overload. However, I’m confusing that how many memory I can use for indexing, and is there an upper/lower bound I can set since I don’t want to sacrifice much more query performance.
Any suggestion would help. Thanks.