Tarantool 1.6 - let's get started

Not so long ago on Habré was published an article about the NoSQL database - "Tarantool 1.6 in the first person" . I am sure this database is well known in its circles and is already gaining popularity. I am also sure that there are those beginners, they did not reach the hands , who would like to try Tarantool in action. For those who wish, I will give a few simple examples to help you begin to get acquainted with this interesting product. As is clear from the title of the article - this is a version of Tarantool 1.6.

Install

The project site describes in detail installation options for different systems. For Ubuntu it looks like this:

wget http://tarantool.org/dist/public.key sudo apt-key add ./public.key release=`lsb_release -c -s` cat > /etc/apt/sources.list.d/tarantool.list <<- EOF deb http://tarantool.org/dist/master/ubuntu/ $release main deb-src http://tarantool.org/dist/master/ubuntu/ $release main EOF sudo apt-get update sudo apt-get install tarantool 

Hello world!

Tarantool uses Lua as an embedded language (Lua 5.1 based on on LuaJIT 2.0). The lua language is not difficult, you can quickly get acquainted with its basics here or on Habré in the publication “Lua in 15 minutes” . You can use Tarantool as a Lua interpreter.

 $ /usr/bin/tarantool /usr/bin/tarantool: version 1.6.4-509-ga4af00e type 'help' for interactive help tarantool> 2 + 3 --- - 5 ... tarantool> print ('Ola lua!') Ola lua! --- ... 

You can also write your logic using Lua scripts. Let's write the starting init.lua to run Tarantool and output the 'Hello world'.
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One of the main tarantool libraries is box . Using box.cfg (in lua {...} is a table) we create a launch configuration:

 box.cfg { listen = 3311, logger = 'tarantool.log', } 

Tarantool will be launched on port 3311 and will store logs in tarantool.log:

Create the hello () function

 local function hello() print ('Hello world!) end hello() 

Run and see:

 $ tarantool init.lua Hello world! 

Data base

In tarantool, tuples are stored in spaces (space) - some kind of analogue of a table.

Create a test space and a primary (primary) index in it (you can also build a secondary for all record fields), using the tree to store the indices:

 s = box.schema.space.create('test') p = s:create_index('primary', {type = 'tree', parts = {1, 'NUM'}}) 

Fill test records of the form {key, number}:

 for i = 1, 10 do s:insert({i, i}) end 

In this case, the object s is a reference to the box.space.test object. Accordingly, it was possible to write:

 box.space.test:insert({i, i}) 

By the way, you may encounter such an error when you restart tarantool:

 $ tarantool init.lua Hello world! main/101/init.lua F> Space 'test' already exists 

Tarantool stores all its data in RAM. For their safety Tarantool takes snapshots (snapshot) and binary logs (xlog). The error occurs due to the fact that at startup Tarantool loads data from the last use using the .snap files (snapshots) and .xlog files (by default in the working directory). Accordingly, your test space is already present in the database. You can delete .snap and .xlog each time you start it, or you can add a check for the existence of space.

 s = box.space.test if not s then s = box.schema.space.create('test') p = s:create_index('primary', {type = 'tree', parts = {1, 'NUM'}}) for i = 1, 10 do s:insert({i, i}) end end 

It would be very nice to check if our data is saved, our configuration in the running Tarantool. For this, a console for the administrator is provided. In general, in lua, the implementation of connecting various modules, embedded packages, other files with code occurs through the require mechanism.

 local console = require('console') console.listen(127.0.0.1:3312) 

After launching Tarantool, you can connect to the admin console on port 3312 using the nc / telnet and rlwrap utilities (for ease of operation). Once connected, you can work directly with Tarantool. Let's see, for example, the data of our test space:

 $ rlwrap nc 0 3312 Tarantool 1.6.4-509-ga4af00e (Lua console) type 'help' for interactive help box.space.test:select() --- - - [1, 1] - [2, 2] - [3, 3] - [4, 4] - [5, 5] - [6, 6] - [7, 7] - [8, 8] - [9, 9] - [10, 10] ... box.space.test:get(6) --- - [6, 6] ... 

Let's look at the configuration parameters of our Tarantool:


So, having created the space, we will perform the following task: in the records with the key> 5, we increase the value of the stored number by 10.
For the necessary sample we will use the box.index library.

 for k,v in box.space.test.index.primary:pairs(5, {iterator = box.index.GT}) do s:update(v[1], {{'=', 2, v[2] + 10}}) end 

box.space.index.primary - means working with the test space and its primary index.
pairs () is an iteration function that returns an iterator (variable k in a loop) and a table of values ​​(consists of a set of records v), accepts the key value (5) —the start of the iteration and the type of iterator.
iterator = box.index.GT - the GT (greater) iterator returns records with keys greater than the specified one.
update () - update of the record in the database, takes the value of the record key (v [1]),
{'=', 2, v [2] + 10} - indicates the update ('=') of the second value on v [2] + 10.

Let's see, using the admin console, the values ​​of our space:

 box.space.test:select() --- - - [1, 1] - [2, 2] - [3, 3] - [4, 4] - [5, 5] - [6, 16] - [7, 17] - [8, 18] - [9, 19] - [10, 20] ... 

Of course, to fully master Tarantool, to know its subtleties, you need to read the documentation on the project website. After all, apart from everything, Tarantool is not only a database, but also a lua application server. For example, there is an http server and queues . But the first step has been taken - you wrote your little script for Tarantool.

You can also read about Tarantool (in the examples there are older versions of the project) in other articles on Habré:
"We study Tarantool + Lua" ,
"Unique features Tarantool . "

Also, without any installation, you can try Tarantool on try.tarantool.org .