Ivan’s posterous

Append only file is an alternative durability option for Redis. What this mean? Let's start with some fact:

• For default Redis saves snapshots of the dataset on disk, in a binary file called dump.rdb (by default at least). For instance you can configure Redis to save the dataset every 60 seconds if there are at least 100 changes in the dataset, or every 1000 seconds if there is at least a single change in the dataset. This is known as "Snapshotting".
• Snapshotting is not very durable. If your computer running Redis stops, your power line fails, or you write killall -9 redis-server for a mistake, the latest data written on Redis will get lost. There are applications where this is not a big deal. There are applications where this is not acceptable and Redis was not an option for this applications.

What is the solution? To use append only file as alternative to snapshotting. How it works?

• It is an 1.1 only feature.
• You have to turn it on editing the configuration file. Just make sure you have "appendonly yes" somewhere.
• Append only files work this way: every time Redis receive a command that changes the dataset (for instance a SET or LPUSH command) it appends this command in the append only file. When you restart Redis it will first re-play the append only file to rebuild the state.

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http://www.dilbert.com/blog/entry/the_bad_management_stimulus/

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http://bitbucket.org/will/epgsql/overview/

http://glozer.net/src/epgsql_pool/
(http://www.erlangatwork.com/2009/01/erlang-and-postgresql-redux.html)

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The University of New South Wales: Data Structures and Algorithms

http://techbytes360.blogspot.com/2009/11/free-algorithms-and-data-structures.html

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Ymacs is an Emacs-like editor that works in your browser. Which applies, at this state of affairs, only if your browser is Firefox. It looks pretty good with other browsers, but it seems to be almost impossible to catch all the required key bindings—only Firefox allows what we need.

http://www.ymacs.org/?re

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Picolisp is yet another dialect of the Lisp language, specially written to be radically practical and simple. The key features of PicoLisp are:

• It is an interpreter only. There is no compiler, not even an intermediate one.
• As a consequence, Pico Lisp is the most dynamic Lisp in existence today.
• But it is faster than some compiled Lisps.
• It uses exactly only one kind of memory structure: the cell. Upon that, everything is constructed.
• A cell is a cell in the same way it was with the original Lisp, consisting on a head and the rest, that is, a CAR part (which may be either a number, a symbol, or a pointer to another cell), and a CDR part (also a number, symbol or cell).
• As a consequence, it is incredibly memory efficient, and there is little to none memory fragmentation. Processors cache "loves" our interpreter.
• It can call C functions directly, no wrapper needed.
• It includes a database as part of the language itself, very scalable and incredibly fast even for databases of hundreds of gigabytes.
• It includes an HTTP server.
• It scales up to many servers and processors.
• It has the most advanced REPL of any lisp implementation in existence today. You can even develop application just with that and a small editor.
• You can use the REPL remotely.
• It is completely free software.
• It has a nice comunity.
• It is not a new thing, nor experimental, not something which has not been using in real life. PicoLisp has been used and developed since 1988.

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Some highlights:

• NIFs, write your own functions in C

• Builds and runs on Windows 7

• dialyzer can warn for some race conditions, and has a wx gui

• The -on_load() directive can be used to run a function when a module is loaded.

• Emacs erlang-mode improvements.

More: http://erlang.org/download/otp_src_R13B03.readme

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http://www.denao.com.br/blog/?p=124

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Materials from the Erlang User Conference 2009 and Tutorials Workshop at the EUC2009 are now available on our website:

- The presentation slides from the EUC2009 are available (http://www.erlang-factory.com/conference/ErlangUserConference2009/talks)
- The tutorial slides can be found (http://www.erlang-factory.com/conference/testingtutorialworkshop/talks)
- The photos taken at the EUC2009 are (http://www.erlang-factory.com/conference/ErlangUserConference2009#euc2009)
- The photos taken at the Tutorials Workshop are (http://www.erlang-factory.com/conference/testingtutorialworkshop#photos)

If you want to see more photos from the EUC2009 and previous Erlang User Conferences, they are all available on Flickr:  http://www.flickr.com/photos/erlang-consulting/

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