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If you’re looking for inspiration, Impala has a very active JIRA instance. We have labelled some JIRA tickets ‘newbie’ - these are ideal for someone who is looking to learn the codebase. If you find one you like, feel free to email dev@impala.apache.org to discuss it, or dig right in. Before you start, though, register on the Apache JIRA system and ask someone on dev@ to assign the ticket to you. That way you don't end up in a race condition with another new contributor!
Impala is extremely actively developed, and all parts of the code are changing quickly as we work to meet Impala’s roadmap and provide the features our customers need. We are therefore very unlikely to be able to accept large, unsolicited patches into the codebase. If you are considering undertaking a substantial piece of work, please be forewarned: we cannot guarantee that we will be able to accept it, or that we will have the time to review it. If you are unsure, please ask before you start work.
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