I have a large S3 bucket with around 200 million objects, and I've set up a daily inventory that writes to a different bucket. I've created an Athena table for this inventory data, partitioned by inventory date (DT). However, when I try to query the most recent inventory, it takes a long time to complete. For instance, even a straightforward query like `select max(DT) from inventory_table` takes about 50 seconds. I'm looking for optimization tips to speed up these queries, particularly to only focus on the most recent inventory. What can I do?
4 Answers
To make Athena queries faster, you should restrict the number of files it scans. Consider partitioning by year/month/day, so your queries only focus on relevant directories. For instance, you could add a WHERE clause that filters by year and month, which should speed things up significantly.
Do some quick tests! Check the query times for `max(DT)` versus using an actual DT value in your WHERE clause. You might find that specifying a direct value runs much faster than calculating the max.
Are you utilizing partitions in your setup?
Just a heads-up, if you're using CSV files for your inventory, think about switching to Parquet. Parquet files, especially when compressed, generally perform better in queries compared to CSVs.
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