On 7th of December, Simon Riggs committed patch:
Event Trigger for table_rewrite Generate a table_rewrite event when ALTER TABLE attempts to rewrite a table. Provide helper functions to identify table and reason. Intended use case is to help assess or to react to schema changes that might hold exclusive locks for long periods. Dimitri Fontaine, triggering an edit by Simon Riggs Reviewed in detail by Michael Paquier
The general knowledge is that numerics are slower than integers/float, but offer precision and ranges that are better.
While I understand what is slow, I don't really know how much slower numerics are. So let's test it.
During my time with PostgreSQL I found some things that I love. I found some things that I hate (very little of them). And some things that I would like to get, but, so far, I don't have them.
Of course, PostgreSQL being Open Source, I could add it myself, if only I would know some (real) C and had necessary skills. Which I don't. But anyway, decided to write my personal wishlist for PostgreSQL – maybe someone will say “hey, that would be cool, and I know how to write it"
On 25th of November, Tom Lane committed patch:
Support arrays as input to array_agg() and ARRAY(SELECT ...). These cases formerly failed with errors about "could not find array type for data type". Now they yield arrays of the same element type and one higher dimension. The implementation involves creating functions with API similar to the existing accumArrayResult() family. I (tgl) also extended the base family by adding an initArrayResult() function, which allows callers to avoid special-casing the zero-inputs case if they just want an empty array as result. (Not all do, so the previous calling convention remains valid.) This allowed simplifying some existing code in xml.c and plperl.c. Ali Akbar, reviewed by Pavel Stehule, significantly modified by me
On 7th of November, Alvaro Herrera committed patch:
BRIN is a new index access method intended to accelerate scans of very large tables, without the maintenance overhead of btrees or other traditional indexes. They work by maintaining "summary" data about block ranges. Bitmap index scans work by reading each summary tuple and comparing them with the query quals; all pages in the range are returned in a lossy TID bitmap if the quals are consistent with the values in the summary tuple, otherwise not. Normal index scans are not supported because these indexes do not store TIDs. As new tuples are added into the index, the summary information is updated (if the block range in which the tuple is added is already summarized) or not; in the latter case, a subsequent pass of VACUUM or the brin_summarize_new_values() function will create the summary information. For data types with natural 1-D sort orders, the summary info consists of the maximum and the minimum values of each indexed column within each page range. This type of operator class we call "Minmax", and we supply a bunch of them for most data types with B-tree opclasses. Since the BRIN code is generalized, other approaches are possible for things such as arrays, geometric types, ranges, etc; even for things such as enum types we could do something different than minmax with better results. In this commit I only include minmax. Catalog version bumped due to new builtin catalog entries. There's more that could be done here, but this is a good step forwards. Loosely based on ideas from Simon Riggs; code mostly by Álvaro Herrera, with contribution by Heikki Linnakangas. Patch reviewed by: Amit Kapila, Heikki Linnakangas, Robert Haas. Testing help from Jeff Janes, Erik Rijkers, Emanuel Calvo. PS: The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 318633.
There are some cases where you might want to get your own copy of explain.depesz.com. You might not trust me with your explains. You might want to use it without internet access. Or you just want to play with it, and have total control over the site.
Installing, while obvious to me, and recently described by John Poole, is not always 100% clear. So, I decided to write about how to set it up, from scratch.
Uploaded new version to the server – straight from GitHub. There are two changes – one visible, and one not really.
The invisible change, first, is one for people hosting explain.depesz.com on their own. As you perhaps know you can get sources of explain.depesz.com and install it on any box you want (as log as you can get there PostgreSQL, Perl, and some perl modules). While working on it on my own, I figured I could use a way to tell which version of module-xxx the site is running right now. So I build /info page (which is inaccessible to everyone, but manually-marked admins), which lists versions and interesting paths.
The second change – the one visible to users, is that I made explain.depesz.com commify numbers. Sometimes it can be hard to read value like 12325563, but now it will be displayed as 12,325,563 making is simpler to grasp.
This second change was suggested by Jacek Wielemborek, so if you hate it – blame him. Of course if you love the change – it's all on me
Hope you'll find it helpful.