Couple of people asked, on irc, about how to generate unique, short, ids for rows. Since I wrote code for this for explain.depesz.com, I figured that instead of pointing to sources, and letting everyone to extract the functions, I will, instead, ...

On 15th of May, Simon Riggs committed patch: TABLESAMPLE, SQL Standard and extensible Add a TABLESAMPLE clause to SELECT statements that allows user to specify random BERNOULLI sampling or block level SYSTEM sampling. Implementation allows for extensible sampling functions to be written, using a standard ...

In previous posts in this series, I talked about how to read EXPLAIN output, and what each line (operation/node) means. Now, in the final post, I will try to explain how it happens that Pg chooses "Operation X" over "Operation Y".