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The simplest is probably read committed especially if like many ETL jobs you are just going to grab stuff using one read for further processing. Another option, do a read committed and omit last 15 minutes of data if you are doing long running jobs to avoid churn at end of tables / logs.

I see folks doing serializable reads for historic ETL jobs with one read in the transaction - why? Is there some history / tool issue I'm not familiar with?

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For Aurora MySQL, the default for read-only replicas is repeatable read. As we mentioned towards the end of the post, read committed support appears to have been introduced to Aurora MySQL just last year. But you're right – now that it's supported, switching to read committed is by far the easiest fix.

No idea why people would be using serializable reads for ETL jobs though! :O

My own guess was that some ETL jobs were really data integrity jobs - in which case folks got used to higher levels of isolation being necessary across many reads to avoid false positives on their cross check stuff maybe.

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