[IMPROVED] Stream catchup with many deleted messages#7512
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Signed-off-by: Maurice van Veen <github@mauricevanveen.com>
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Stream catchup could be very slow if the stream contained many millions of deleted messages, but didn't pass the threshold of having more deletes than 10x the total messages. Generally
LoadMsgwill be faster thanLoadNextMsgif there are (nearly) no deleted messages, butLoadNextMsgbecomes faster the more deletes there are in the stream.Imagine a stream with 40 million messages and 90 million interior deletes. Under the old logic there would not be 400 million deletes, so we'd linearly scan through the whole stream whereas we could skip ahead way more effectively. This ratio is decreased to having 2x as many deletes as messages with an upper bound of 1 million deleted messages such that a stream with 40 million messages and the same amount of deletes would still use the optimized
LoadNextMsg.This PR also adds the time taken for the catchup to complete.
Signed-off-by: Maurice van Veen github@mauricevanveen.com