This is the archive of the old blog hosted on blogger.
The old blog is still available on the url https://4thdoctordba.blogspot.com
With the revolutionary PostgreSQL 8.0 were introduced a different memory manager, the two queues.
This algorithm uses three list of buffer page pointers called cache directory blocks (CDB). The lists T1,T2 are actually pointing buffered pages. B1 lists pages been recently in the shared buffer.
The list T1 is used as LRU for the pages loaded from disk. The list T2 is used as LRU list for pages already cached and evicted from the list T1.
I’m not dead yeat. Just hard days.
However, I’ll talk at the Skiff in the sunny Brighton about PostgreSQL, the big the fast and the (NOSQL on) ACID.
If you are around we should kick in the talk at 19.00 BST.
This talk is part of the SANE meetings happening on a monthly basis.
More informations about the Skiff there.
http://www.theskiff.org/ Here the slides
PostgreSQL, the big the fast and the (NOSQL on) Acid from Federico Campoli
3.1.1 PostgreSQL 7.4, the LRU list In PostgreSQL 7.4 the free space in the shared buffer was managed using a simple last recently used list. When a page is first request from disk the buffer manager puts it into the first buffer in the free LRU list. If the first buffer is used by another page the list is shifted by one unity and the eventual last page in the list is discarded.
The PostgreSQL Global Development Group has released an important update with fixes for multiple security issues to all supported versions of the PostgreSQL database system, which includes minor versions 9.4.1, 9.3.6, 9.2.10, 9.1.15, and 9.0.19. This update includes both security fixes and fixes for issues discovered since the last release. In particular for the 9.4 update, there is a change to the way unicode strings are escaped for the JSON and JSONB data types.
The PostgreSQL memory at first sight looks simple. If compared with the complex structures implemented in the other DBMS to a careless reader could seem rudimentary. However, the memory and in particular the shared buffers implementation is complex and sophisticated. This chapter will dig down deep into the PostgreSQL’s memory.
3.1 The shared buffer The shared buffer is a segment allocated at cluster’s startup. Its size is determined by the GUC parameter shared_buffers and the size can be changed only restarting the cluster.
