(Baron Schwartz) One of the query optimization scenarios I’ve seen a lot over the years is finding something within some distance from a point. For example, finding people within some distance of yourself, apartments in a radius from a postal code, and so on.

(Shinguz) It is generally well known that indices help a lot to speed up database queries (especially SELECT but also UPDATE and DELETE). It is less known, that indices also have some disadvantages.

(Rob Gravelle) In the Web 2.0 world where smart phone and Web applications are competing to access terabytes of data, there is a new imperative for speeding up retrieval times as much as the technology permits.

(Pavel Stehule) PostgreSQL has a nice functions for operations over bitmapset. A bitmapset is set of positive integers. It should be smaller than array, and, what is important for me. it support very fast test if some value is in set or not. PostgreSQL internally use this functions, but there are no

(Mark Callaghan) MySQL development is on a roll so now is the time for me to request a fix for another obscure performance problem in InnoDB. The insert buffer is a feature that can make InnoDB much faster than you expect.

(Daniel Ehrenberg) On my computer, the callstack of a new process is around 10MB*. Modern operating system automatically reserve some amount of virtual memory and install protections on the page below the stack to create a segmentation fault on stack overflow. This ensures that a stack overflow won’

(Mark Callaghan) There are several types of performance monitoring. Some of them are made easier when workload metrics are summarized by database user, table and index.

(Leo Hsu and Regina Obe) Question: You have a table of people and a table that specifies the activities each person is involved in. You want to return a result that has one record per person and a column that has a listing of activities for each person separated by semicolons and alphabetically sort

(Mark Callaghan) How well do you understand InnoDB locking? The documentation is good but would benefit from a few examples. If you want to debug contention for InnoDB then you need to understand record, gap and next-key locks, the reasons for using next-key locks and the locks used by different sta

(Leo Hsu and Regina Obe) In Part 2 of PL/R we covered how to build PL/R functions that take arrays and output textual outputs of generated R objects. We then used this in an aggregate SQL query using array_agg. Often when you are building PL/R functions you’ll have R functions that you want to reuse