If you are wondering why lemmy is moving away from offset pagination since 0.19, here is a nice article about it
Paywall.
https://ivopereira.net/efficient-pagination-dont-use-offset-limit
This seems to be the same article.
I have my doubts about the technique, but it could be useful in certain controlled situations.
Lemmy just implemented it for 0.19 and it makes a big difference on heavier queries like Scaled homepage.
It also has the advantage of your pagination not getting screwy if new content has been added between page 2 and 3 queries.
I was going to recommend looking at https://www.elastic.co/guide/en/elasticsearch/reference/current/paginate-search-results.html#scroll-search-results - but it looks like that method is now not advised- but if you read up above it it looks like there’s a search_after/PIT method described which sounds similar to the article.
This is all to say - I don’t think this is a one-off concept - it’s been around for a bit.
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Thanks! Agreed, it’s a very limited usecase.
I have my doubts about the technique, but it could be useful in certain controlled situations
This is completely uncontroversial advice and has been for 30 years. What are your doubts exactly?
I’d go further: if you see a query that uses “offset” on a non-trivial production DB something is very, very wrong.
Of course, the trick is that you need to make sure you have indexes for all sort orders you need to display, but that’s obvious.
Sorry, I updated the link
For the article-impaired,
Using OFFSET+LIMIT for pagination forces a full table scan, which in large databases is expensive.
The alternative proposed is a cursor+based navigation, which is ID+LIMIT and requires ID to be an orderable type with monotonically increasing value.
Which it almost never is.
Any data as simple as that is unlikely to reach a number of rows likely to cause an issue with performance.
Having said this, I’d say that OFFSET+LIMIT should never be used, not because of performance concerns, but because it is fundamentally broken.
If you have rows being posted frequently into a table and you try to go through them with OFFSET+LIMIT pagination, the output from a pagination will not correspond to the table’s contents. Fo each row that is appended to the table, your next pagination will include a repeated element from the tail of the previous pagination request.
Things get even messier once you try to page back your history, as now both the tip and the tail of each page will be messed up.
Cursor+based navigation ensures these conflicts do not happen, and also has the nice trait of being easily cacheable.
Account-wall. Please provide a link that doesn’t force me to make an account.
Sorry, link updated
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