About bitcoincore encryptwallet command.

BitcoinCore encryptwallet command is to prevent someone to access and steal private keys.

So I will encrypt my "wallet.dat" by using encryptwallet command.

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$ encryptwallet passphrase  interval
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But I doubt that how secure encryptwallet command is.

So I have two questions.

Q1.
Is it easy to decrypt encrypted wallet.dat by using random list attacking method or analyzing wallet.dat ?

In the past, have there been any cases where your passphrase has been decrypted ?

Q2,
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Arguments:
1. "passphrase"    (string) The pass phrase to encrypt the wallet with.
It must be at least 1 character, but should be long.
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What is the maximum passphrase length ?

I want to set my passphrase as long as possible.