box.schema.func.create()

box.schema.func.create(func-name[, {options-without-body}])¶

Create a function tuple without including the body option. For functions created with the body option, see box.schema.func.create(func-name [, {options-with-body}]).

This is called a «not persistent» function because functions without bodies are not persistent. This does not create the function itself – that is done with Lua – but if it is necessary to grant privileges for a function, box.schema.func.create must be done first. For explanation of how Tarantool maintains function data, see the reference for the box.space._func space.

Возможны следующие опции:

• if_not_exists = true|false (default = false) – true means there should be no error if the _func tuple already exists.

• setuid = true|false (default = false) – with true to make Tarantool treat the function’s caller as the function’s creator, with full privileges. Remember that SETUID works only over binary ports. SETUID doesn’t work if you invoke a function via an admin console or inside a Lua script.

• language = „LUA“|“C“ (default = „LUA“).

• (since version 2.10.0) takes_raw_args = true|false (default = false)— if set to true for a Lua function and the function is called via net.box (conn:call()) or by box.func.<func-name>:call(), the function arguments are passed being wrapped in a MsgPack object:

  local msgpack = require('msgpack')
  box.schema.func.create('my_func', {takes_raw_args = true})
  local my_func = function(mp)
      assert(msgpack.is_object(mp))
      local args = mp:decode() -- array of arguments
  end
  

  If a function forwards most of its arguments to another Tarantool instance or writes them to a database, the usage of this option can improve performance because it skips the MsgPack data decoding in Lua.

Параметры:	func-name (string) – имя функции, которое должно соответствовать правилам именования объектов options (table) – if_not_exists, setuid, language, takes_raw_args.
возвращает:	nil

These functions can be called with function-object:call(arguments); however, unlike the case with ordinary functions, array arguments will not be correctly recognized unless they are enclosed in braces.

Пример:

box.schema.func.create('calculate')
box.schema.func.create('calculate', {if_not_exists = false})
box.schema.func.create('calculate', {setuid = false})
box.schema.func.create('calculate', {language = 'LUA'})

box.schema.func.create(func-name[, {options-with-body}])

Create a function tuple. including the body option. (For functions created without the body option, see box.schema.func.create(func-name [, {options-without-body}]).

This is called a «persistent» function because only functions with bodies are persistent. This does create the function itself, the body is a function definition. For explanation of how Tarantool maintains function data, see the reference for the box.space._func space.

Возможны следующие опции:

• if_not_exists = true|false (default = false) - boolean; same as for box.schema.func.create(func-name [, {options-without-body}]).
• setuid = true|false (default = false) - boolean; same as for box.schema.func.create(func-name [, {options-without-body}]).
• language = „LUA“|“C“ (default = ‘LUA’) - string. same as for box.schema.func.create(func-name [, {options-without-body}]).
• is_sandboxed = true|false (default = false) - boolean; whether the function should be executed in a sandbox.
• is_deterministic = true|false (default = false) - boolean; true means that the function should be deterministic, false means that the function may or may not be deterministic.
• is_multikey = true|false (default = false)— if true is set in the function definition for a functional index, the function returns multiple keys. For details, see the example.
• body = function definition (default = nil) - string; the function definition.
• Additional options for SQL = See Calling Lua routines from SQL.
• takes_raw_args – see the option description in box.schema.func.create(func-name [, {options-with-body}]).

Параметры:	func-name (string) – имя функции, которое должно соответствовать правилам именования объектов options (table) – if_not_exists, setuid, language, is_sandboxed, is_deterministic, body.
возвращает:	nil

C functions are imported from .so files, Lua functions can be defined within body. We will only describe Lua functions in this section.

A function tuple with a body is «persistent» because the tuple is stored in a snapshot and is recoverable if the server restarts. All of the option values described in this section are visible in the box.space._func system space.

If is_sandboxed is true, then the function will be executed in an isolated environment: any operation that accesses the world outside the sandbox will be forbidden or will have no effect. Therefore a sandboxed function can only use modules and functions which cannot affect isolation: assert, error, ipairs, math.*, next, pairs, pcall, print, select, string.*, table.*, tonumber, tostring, type, unpack, utf8.*, xpcall. Also a sandboxed function cannot refer to global variables – they will be treated as local variables because the sandbox is established with setfenv. So a sandboxed function will happen to be stateless and deterministic.

If is_deterministic is true, there is no immediate effect. Tarantool plans to use the is_deterministic value in a future version. A function is deterministic if it always returns the same outputs given the same inputs. It is the function creator’s responsibility to ensure that a function is truly deterministic.

Using a persistent Lua function

After a persistent Lua function is created, it can be found in the box.space._func system space, and it can be shown with
box.func.func-name
and it can be invoked by any user with authorization to „execute“ it. The syntax for invoking is:
box.func.func-name:call([parameters])
or, if the connection is remote, the syntax is as in net_box:call().

Пример:

tarantool> lua_code = [[function(a, b) return a + b end]]
tarantool> box.schema.func.create('sum', {body = lua_code})

tarantool> box.func.sum
---
- is_sandboxed: false
  is_deterministic: false
  id: 2
  setuid: false
  body: function(a, b) return a + b end
  name: sum
  language: LUA
...

tarantool> box.func.sum:call({1, 2})
---
- 3
...