![cursor cat cursor cat](https://i2-prod.mirror.co.uk/incoming/article8754466.ece/ALTERNATES/s1200c/Girl-reunited-with-cat-after-it-went-missing-for-three-years.jpg)
That means it’s not just returning the next set of data you’re requesting, it’s scanning through all the previous data that comes before it. Until I investigated Facebook’s claim that cursors are the most efficient form of pagination.Īn offset is simply the number of records the database should skip before selecting records. Have you ever wondered how SQL’s built-in OFFSET clause works? Me neither. This is the worst-case scenario because it’s immediately apparent to the user that something is wrong, and your site will appear glitchy, when in fact, everything is working as expected (only it wasn’t expecting Sam to delete his photos). You’re just seeing duplicated displayed data caused by the fact that the second page should really be starting at an offset of 6 instead of 5, now that 1 new record has been added. Thank god.Īm I drunk now, too? Is Aunt Karen drunk? This way, it doesn’t matter that Sam deleted two embarrassing photos, we’d still get all the data previous to that timestamp including both cat photos. SELECT * FROM table WHERE cursor > timestamp ORDER BY timestamp LIMIT 5 For example, this cursor might be a timestamp that tells the database that the last record returned had a timestamp of September 12, 4:02 PM, and to return the next set of 5 items that happened before this timestamp. How cursor pagination works, is that rather than sending an offset parameter which acts like an index, it sends a cursor parameter which acts as a pointer to a specific record in the dataset to indicate where the last page left off. This means you may never get to see those awesome cat photos! And worse, you would have no way of knowing that you missed them. The database will get queried each time like this: SELECT * FROM table ORDER BY timestamp OFFSET 0 LIMIT 5 SELECT * FROM table ORDER BY timestamp OFFSET 5 LIMIT 5 SELECT * FROM table ORDER BY timestamp OFFSET 10 LIMIT 5 SELECT * FROM table ORDER BY timestamp OFFSET 15 LIMIT 5. It’s just querying the database for the next set of 5 which it still assumes will be located at an offset of 5. Unfortunately, offset pagination doesn’t care that the data has been modified.
![cursor cat cursor cat](http://www.draac.com/cursors/catdog1.gif)
If you were to load the next page of data, then you would expect to see some new posts load:
![cursor cat cursor cat](https://windows-cdn.softpedia.com/screenshots/thumbs/Cursor-Cat-thumb.png)
When you first land on the Facebook newsfeed, you immediately see the most recent 5 posts from your friends: Let’s take a look at a real-life example of data being skipped. Let’s explore both these points further… 2. With default offset pagination, if the data is not static, one of two things will happen: That is to say, new items or rows can be added or removed, and each new page will still load correctly.ĭue to the large wave of real-time applications in the past decade, cursor pagination has gained a lot of momentum. This is because cursors do not require the data to remain static. Perhaps the biggest advantage of cursor pagination is its ability to handle real-time data effectively. With the exception of "Editorial use only" photos (which can only be used in editorial projects and can't be modified), the possibilities are limitless.But just why are so many companies making the move from offset to cursors? The Benefits of Cursors 1.
Cursor cat free#
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