Keyset pagination

In the past I have used the MySQL equivalent of pagination. In other words, the splitting up of a ResultSet into pages of a fixed number of entries, by means of using SQL¹.

It looks like the following:

SELECT * FROM tbl LIMIT 5,10;  # Retrieve rows 6-15

For compatibility with PostgreSQL, MySQL also supports the LIMIT row_count OFFSET offset syntax, which I've used in the past.

Performance

Performance is a key point here, as MySQL requires the retrieval of the results in order to determine where the offset starts.

If the table is large, retrieval of pages at the end of the table are going to be extremely slow.

Solution

A better way to deal with this, is to not use an offset, but use the key of the last row of the previous page, and use that in the query for the next page.

Obviously this only works if the resultset is sorted.

For more references that explain this a lot better, see [2] and [3].

References

[1] MySQL 5.7 - 14.2.9. SELECT Syntax

https://dev.mysql.com/doc/refman/5.7/en/select.html

[2] Use the Index, Luke! - We need tool support for keyset pagination

http://use-the-index-luke.com/no-offset

[3] Use the Index, Luke! - Paging Through Results

http://use-the-index-luke.com/sql/partial-results/fetch-next-page

Try Git

To anyone who is absolutely new to the exciting new world of Git¹.

There seems to be a little website where you can try Git², working in a (very very) limited sandbox environment.

What is Git?

If you wish to know what Git is, there are loads of interesting articles on teh interwebs that explain it very well.

But I did find the following explanation in the README provided with the source tar-ball:

The name "git" was given by Linus Torvalds when he wrote the very
first version. He described the tool as "the stupid content tracker"
and the name as (depending on your mood):

 - random three-letter combination that is pronounceable, and not
   actually used by any common UNIX command.  The fact that it is a
   mispronunciation of "get" may or may not be relevant.
 - stupid. contemptible and despicable. simple. Take your pick from the
   dictionary of slang.
 - "global information tracker": you're in a good mood, and it actually
   works for you. Angels sing, and a light suddenly fills the room.
 - "goddamn idiotic truckload of sh*t": when it breaks

References

[1] Git --distributed-is-the-new-centralized

https://git-scm.com/

[2] Try Git

https://try.github.io/