Generate short, random, textual IDs

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, write a set of functions that what is needed in reusable way.

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Waiting for 9.5 – TABLESAMPLE, SQL Standard and extensible

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 API.
Basic version follows SQLStandard exactly. Usable
concrete use cases for the sampling API follow in later
commits.
 
Petr Jelinek
 
Reviewed by Michael Paquier and Simon Riggs

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Explaining the unexplainable – part 5

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".

Continue reading Explaining the unexplainable – part 5