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tarantool / crud

Easy assess to data stored in vshard cluster
BSD 2-Clause "Simplified" License
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CRUD

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The CRUD module allows to perform CRUD operations on the cluster. It also provides the crud-storage and crud-router roles for Tarantool Cartridge.

Table of Contents

Quickstart

First, install Tarantool.

Install

Manual install

To try crud in your application, you may install it manually fron web with tt rocks rock management tool.

tt rocks install crud

Application dependency

To use crud in your application, set it as a rockspec dependency.

package = 'myapp'

version = 'scm-1'

source  = {
    url = '/dev/null',
}

dependencies = {
    'tarantool >= 3.1.0',
    'crud == <the-latest-tag>-1',
}

build = {
    type = 'none';
}

Repository clone

You can also clone the repository to explore crud and try it inside a sandbox.

git clone https://github.com/tarantool/crud.git
cd crud
tt rocks make

Usage

For Tarantool 3.x, enable crud roles on your application instances in a configuration (see Tarantool 3 roles section). Roles support Tarantool 3.0.2, Tarantool 3.1.0 and newer. Older versions are not supported due to tarantool/tarantool#9643 and tarantool/tarantool#9649 issues.

For Tarantool 1.10 and 2.x, add crud roles into dependencies of your roles (see Cartridge roles section).

For Tarantool 1.10, 2.x and 3.x you can also manually call the crud initialization code on VShard router and storage instances.

Sandbox

The repository provide a simple sandbox application with a test dataset on a single instance.

./doc/playground.lua
tarantool> crud.select('customers', {{'<=', 'age', 35}}, {first = 10})
tarantool> crud.select('developers', nil, {first = 6})

API

The CRUD operations should be called from router.

All VShard storages should call crud.init_storage() after vshard.storage.cfg() (or enable the roles.crud-storage role for Tarantool 3 or the crud-storage role for Cartridge) first to initialize storage-side functions that are used to manipulate data across the cluster. The storage-side functions have the same access as a user calling crud.init_storage(). Therefore, if crud do not have enough access to modify some space, then you need to give access to the user.

You can call crud.init_storage{async = true} to bootstrap procedures grants asynchronously. It is useful in case your application master instances may start in ro mode (for example, if you use Tarantool 3.x). By default, asynchronous bootstrap is used for Tarantool 3.x and synchronous bootstrap is used for Tarantool 1.10 and 2.x.

All VShard routers should call crud.init_router() after vshard.router.cfg() (or enable the roles.crud-storage role for Tarantool 3 or the crud-router role for Cartridge) to make crud functions callable via net.box. If a user is allowed to execute crud functions on the router-side then the user does not need additional access on storages.

You can check out an example of the configuration for local development (a single instance that combines router and storage) in playground.lua.

All operations return a table that contains rows (tuples) and metadata (space format). It can be used to convert received tuples to objects via crud.unflatten_rows function.

For example:

res, err = crud.select('customers', nil, {first = 2})
res
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [1, 12477, 'Elizabeth', 12]
  - [2, 21401, 'David', 33]
...
crud.unflatten_rows(res.rows, res.metadata)
---
- - bucket_id: 12477
    age: 12
    name: Elizabeth
    id: 1
  - bucket_id: 21401
    age: 33
    name: David
    id: 2
...

Notes:

Sharding key and bucket id calculation

Sharding key is a set of tuple field values used for calculation bucket ID. Sharding key definition is a set of tuple field names that describe what tuple field should be a part of sharding key. Bucket ID determines which replicaset stores certain data. Function that used for bucket ID calculation is named sharding function.

By default CRUD calculates bucket ID using primary key and a function vshard.router.bucket_id_strcrc32(key), it happen automatically and doesn't require any actions from user side. However, for operations that accepts tuple/object bucket ID can be specified as tuple/object field as well as opts.bucket_id value.

Starting from 0.10.0 users who don't want to use primary key as a sharding key may set custom sharding key definition as a part of DDL schema or insert manually to the space _ddl_sharding_key (for both cases consider a DDL module documentation). As soon as sharding key for a certain space is available in _ddl_sharding_key space CRUD will use it for bucket ID calculation automatically. Note that CRUD methods delete(), get() and update() requires that sharding key must be a part of primary key.

Starting from 0.11.0 you can specify sharding function to calculate bucket_id with sharding func definition as a part of DDL schema or insert manually to the space _ddl_sharding_func.

Automatic sharding key and function reload is supported since version 0.11.0. Version 0.11.0 contains critical bug that causes some CRUD methods to fail with "Sharding hash mismatch" error if ddl is set and bucket_id is provided explicitly (#278). Please, upgrade to 0.11.1 instead.

CRUD uses strcrc32 as sharding function by default. The reason why using of strcrc32 is undesirable is that this sharding function is not consistent for cdata numbers. In particular, it returns 3 different values for normal Lua numbers like 123, for unsigned long long cdata (like 123ULL, or ffi.cast('unsigned long long', 123)), and for signed long long cdata (like 123LL, or ffi.cast('long long', 123)).

We cannot change default sharding function strcrc32 due to backward compatibility concerns, but please consider using better alternatives for sharding function. mpcrc32 is one of them.

Table below describe what operations supports custom sharding key:

CRUD method Sharding key support
get() Yes
insert() / insert_object() Yes
delete() Yes
replace() / replace_object() Yes
upsert() / upsert_object() Yes
select() / pairs() Yes
count() Yes
update() Yes
min() / max() No (not required)
cut_rows() / cut_objects() No (not required)
truncate() No (not required)
len() No (not required)

Current limitations for using custom sharding key:

Package info

tarantool> require('crud')._VERSION
---
- 1.1.0
...

Use _VERSION handle to check installed module version. The handle was introduced in 1.1.0. If installed from master, _VERSION shows last tagged version.

Insert

-- Insert tuple
local result, err = crud.insert(space_name, tuple, opts)
-- Insert object
local result, err = crud.insert_object(space_name, object, opts)

where:

Returns metadata and array contains one inserted row, error.

Example:

crud.insert('customers', {1, box.NULL, 'Elizabeth', 23})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [1, 477, 'Elizabeth', 23]
...
crud.insert_object('customers', {
    id = 2, name = 'Elizabeth', age = 24,
})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [2, 401, 'Elizabeth', 24]
...

Insert many

-- Insert batch of tuples
local result, err = crud.insert_many(space_name, tuples, opts)
-- Insert batch of objects
local result, err = crud.insert_object_many(space_name, objects, opts)

where:

Returns metadata and array with inserted rows, array of errors. Each error object can contain field operation_data.

operation_data field can contain:

Right now CRUD cannot provide batch insert with full consistency. CRUD offers batch insert with partial consistency. That means that full consistency can be provided only on single replicaset using box transactions.

Example:

crud.insert_many('customers', {
  {1, box.NULL, 'Elizabeth', 23},
  {2, box.NULL, 'Anastasia', 22},
})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [1, 477, 'Elizabeth', 23]
  - [2, 401, 'Anastasia', 22]
...
crud.insert_object_many('customers', {
    {id = 3, name = 'Elizabeth', age = 24},
    {id = 10, name = 'Anastasia', age = 21},
})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [3, 2804, 'Elizabeth', 24]
  - [10, 569, 'Anastasia', 21]

-- Partial success
local res, errs = crud.insert_object_many('customers', {
    {id = 22, name = 'Alex', age = 34},
    {id = 3, name = 'Anastasia', age = 22},
    {id = 5, name = 'Sergey', age = 25},
})
---
res
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [5, 1172, 'Sergey', 25],
  - [22, 655, 'Alex', 34],

#errs                  -- 1
errs[1].class_name     -- BatchInsertError
errs[1].err            -- 'Duplicate key exists <...>'
errs[1].operation_data -- {3, 2804, 'Anastasia', 22}
...

-- Partial success with stop and rollback on error
-- stop_on_error = true, rollback_on_error = true
-- two error on one storage with rollback, inserts
-- stop by error on this storage inserts before
-- error are rollback
local res, errs =  crud.insert_object_many('customers', {
    {id = 6, name = 'Alex', age = 34},
    {id = 92, name = 'Artur', age = 29},
    {id = 3, name = 'Anastasia', age = 22},
    {id = 4, name = 'Sergey', age = 25},
    {id = 9, name = 'Anna', age = 30},
    {id = 71, name = 'Oksana', age = 29},
}, {
    stop_on_error = true,
    rollback_on_error  = true,
})
---
res
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [4, 1161, 'Sergey', 25],
  - [6, 1064, 'Alex', 34],
#errs                  -- 4
errs[1].class_name     -- InsertManyError
errs[1].err            -- 'Duplicate key exists <...>'
errs[1].operation_data -- {3, 2804, 'Anastasia', 22}

errs[2].class_name     -- NotPerformedError
errs[2].err            -- 'Operation with tuple was not performed'
errs[2].operation_data -- {9, 1644, "Anna", 30}

errs[3].class_name     -- NotPerformedError
errs[3].err            -- 'Operation with tuple was not performed'
errs[3].operation_data -- {71, 1802, "Oksana", 29}

errs[4].class_name     -- NotPerformedError
errs[4].err            -- 'Operation with tuple was rollback'
errs[4].operation_data -- {92, 2040, "Artur", 29}

Get

local result, err = crud.get(space_name, key, opts)

where:

Returns metadata and array contains one row, error.

Example:

crud.get('customers', 1)
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [1, 477, 'Elizabeth', 23]
...

Update

local result, err = crud.update(space_name, key, operations, opts)

where:

Returns metadata and array contains one updated row, error.

Example:

crud.update('customers', 1, {{'+', 'age', 1}})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [1, 477, 'Elizabeth', 24]
...

Delete

local result, err = crud.delete(space_name, key, opts)

where:

Returns metadata and array contains one deleted row (empty for vinyl), error.

Example:

crud.delete('customers', 1)
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [1, 477, 'Elizabeth', 24]

Replace

-- Replace tuple
local result, err = crud.replace(space_name, tuple, opts)
-- Replace object
local result, err = crud.replace_object(space_name, object, opts)

where:

Returns inserted or replaced rows and metadata or nil with error.

Example:

crud.replace('customers', {1, box.NULL, 'Alice', 22})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [1, 477, 'Alice', 22]
...
crud.replace_object('customers', {
    id = 1, name = 'Alice', age = 22,
})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [1, 477, 'Alice', 22]
...

Replace many

-- Replace batch of tuples
local result, err = crud.replace_many(space_name, tuples, opts)
-- Replace batch of objects
local result, err = crud.replace_object_many(space_name, objects, opts)

where:

Returns metadata and array with inserted/replaced rows, array of errors. Each error object can contain field operation_data.

operation_data field can contain:

Right now CRUD cannot provide batch replace with full consistency. CRUD offers batch replace with partial consistency. That means that full consistency can be provided only on single replicaset using box transactions.

Example:

crud.replace_many('developers', {
  {1, box.NULL, 'Elizabeth', 'lizaaa'},
  {2, box.NULL, 'Anastasia', 'iamnewdeveloper'},
})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'login', 'type': 'string'}
  rows:
  - [1, 477, 'Elizabeth', 'lizaaa']
  - [2, 401, 'Anastasia', 'iamnewdeveloper']
...
crud.replace_object_many('developers', {
    {id = 1, name = 'Inga', login = 'mylogin'},
    {id = 10, name = 'Anastasia', login = 'qwerty'},
})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [1, 477, 'Inga', 'mylogin']
  - [10, 569, 'Anastasia', 'qwerty']

-- Partial success
-- Let's say login has unique secondary index
local res, errs = crud.replace_object_many('developers', {
    {id = 22, name = 'Alex', login = 'pushkinn'},
    {id = 3, name = 'Anastasia', login = 'qwerty'},
    {id = 5, name = 'Sergey', login = 's.petrenko'},
})
---
res
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [5, 1172, 'Sergey', 's.petrenko'],
  - [22, 655, 'Alex', 'pushkinn'],

#errs                  -- 1
errs[1].class_name     -- ReplaceManyError
errs[1].err            -- 'Duplicate key exists <...>'
errs[1].operation_data -- {3, 2804, 'Anastasia', 'qwerty'}

-- Partial success with stop and rollback on error
-- stop_on_error = true, rollback_on_error = true
-- two error on one storage with rollback, inserts stop by error on this storage
-- inserts before error are rollback
local res, crud.replace_object_many('developers', {
    {id = 6, name = 'Alex', login = 'alexpushkin'},
    {id = 92, name = 'Artur', login = 'AGolden'},
    {id = 11, name = 'Anastasia', login = 'qwerty'},
    {id = 4, name = 'Sergey', login = 's.smirnov'},
    {id = 9, name = 'Anna', login = 'AnnaBlack'},
    {id = 17, name = 'Oksana', login = 'OKonov'},
}, {
    stop_on_error = true,
    rollback_on_error  = true,
})
res
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [4, 1161, 'Sergey', 's.smirnov'],
  - [6, 1064, 'Alex', 'alexpushkin'],
#errs                  -- 4
errs[1].class_name     -- ReplaceManyError
errs[1].err            -- 'Duplicate key exists <...>'
errs[1].operation_data -- {11, 2652, "Anastasia", "qwerty"}

errs[2].class_name     -- NotPerformedError
errs[2].err            -- 'Operation with tuple was not performed'
errs[2].operation_data -- {9, 1644, "Anna", "AnnaBlack"}

errs[3].class_name     -- NotPerformedError
errs[3].err            -- 'Operation with tuple was not performed'
errs[3].operation_data -- {17, 2900, "Oksana", "OKonov"}

errs[4].class_name     -- NotPerformedError
errs[4].err            -- 'Operation with tuple was rollback'
errs[4].operation_data -- {92, 2040, "Artur", "AGolden"}
...

Upsert

-- Upsert tuple
local result, err = crud.upsert(space_name, tuple, operations, opts)
-- Upsert object
local result, err = crud.upsert_object(space_name, tuple, operations, opts)

where:

Returns metadata and empty array of rows or nil, error.

Example:

crud.upsert('customers',
    {1, box.NULL, 'Alice', 22},
    {{'+', 'age', 1}})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows: []
...
crud.upsert_object('customers',
    {id = 1, name = 'Alice', age = 22},
    {{'+', 'age', 1}})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows: []
...

Upsert many

-- Upsert batch of tuples
local result, err = crud.upsert_many(space_name, tuples_operation_data, opts)
-- Upsert batch of objects
local result, err = crud.upsert_object_many(space_name, objects_operation_data, opts)

where:

Returns metadata and array of errors. Each error object can contain field operation_data.

operation_data field can contain:

Right now CRUD cannot provide batch upsert with full consistency. CRUD offers batch upsert with partial consistency. That means that full consistency can be provided only on single replicaset using box transactions.

Example:

crud.upsert_many('customers', {
    {{1, box.NULL, 'Elizabeth', 23}, {{'+', 'age', 1}}},
    {{2, box.NULL, 'Anastasia', 22}, {{'+', 'age', 2}, {'=', 'name', 'Oleg'}}}
})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}

...
crud.upsert_object_many('customers', {
    {{id = 3, name = 'Elizabeth', age = 24}, {{'+', 'age', 1}}},
    {{id = 10, name = 'Anastasia', age = 21}, {{'+', 'age', 2}}}
})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}

-- Partial success
local res, errs = crud.upsert_object_many('customers', {
    {{id = 22, name = 'Alex', age = 34}, {{'+', 'age', 12}}},
    {{id = 3, name = 'Anastasia', age = 22}, {{'=', 'age', 'invalid type'}}},
    {{id = 5, name = 'Sergey', age = 25}, {{'+', 'age', 10}}}
})
---
res
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}

#errs                  -- 1
errs[1].class_name     -- BatchUpsertError
errs[1].err            -- 'Tuple field 4 (age) type does not match one required by operation <...>'
errs[1].operation_data -- {3, 2804, 'Anastasia', 22}
...
-- Partial success success with stop and rollback on error
-- stop_on_error = true, rollback_on_error = true
-- two error on one storage with rollback,
-- inserts stop by error on this storage
-- inserts before error are rollback
local res, errs = crud.upsert_object_many('customers', {
    {{id = 6, name = 'Alex', age = 34}, {{'+', 'age', 1}}},
    {{id = 92, name = 'Artur', age = 29}, {{'+', 'age', 2}}},
    {{id = 3, name = 'Anastasia', age = 22}, {{'+', 'age', '3'}}},
    {{id = 4, name = 'Sergey', age = 25}, {{'+', 'age', 4}}},
    {{id = 9, name = 'Anna', age = 30}, {{'+', 'age', 5}}},
    {{id = 71, name = 'Oksana', age = 29}, {{'+', 'age', '6'}}},
}, {
    stop_on_error = true,
    rollback_on_error  = true,
})
res
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
#errs                  -- 4
errs[1].class_name     -- UpsertManyError
errs[1].err            -- 'Duplicate key exists <...>'
errs[1].operation_data -- {3, 2804, 'Anastasia', 22}

errs[2].class_name     -- NotPerformedError
errs[2].err            -- 'Operation with tuple was not performed'
errs[2].operation_data -- {9, 1644, "Anna", 30}

errs[3].class_name     -- NotPerformedError
errs[3].err            -- 'Operation with tuple was not performed'
errs[3].operation_data -- {71, 1802, "Oksana", 29}

errs[4].class_name     -- NotPerformedError
errs[4].err            -- 'Operation with tuple was rollback'
errs[4].operation_data -- {92, 2040, "Artur", 29}

Select

CRUD supports multi-conditional selects, treating a cluster as a single space. The conditions may include field names, as well as index names. (Refer to #352 for field number.) The recommended first condition is a TREE index; this helps reducing the number of tuples to scan. Otherwise a full scan is performed.

local result, err = crud.select(space_name, conditions, opts)

where:

Returns metadata and array of rows, error.

Select conditions

Select conditions are very similar to Tarantool update operations.

Each condition is a table {operator, field-identifier, value}:

Example:

crud.select('customers', {{'<=', 'age', 35}}, {first = 10})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [5, 1172, 'Jack', 35]
  - [3, 2804, 'David', 33]
  - [6, 1064, 'William', 25]
  - [7, 693, 'Elizabeth', 18]
  - [1, 477, 'Elizabeth', 12]
...

Note: tuples are sorted by age because space has index age. Otherwise, tuples are sorted by primary key.

See more examples of select queries here.

Pairs

You can iterate across a distributed space using the crud.pairs function. Its arguments are the same as crud.select arguments except fullscan (it does not exist because crud.pairs does not generate a critical log entry on potentially long requests) and negative first values aren't allowed. User could pass use_tomap flag (false by default) to iterate over flat tuples or objects.

Example:

local tuples = {}
for _, tuple in crud.pairs('customers', {{'<=', 'age', 35}}, {use_tomap = false}) do
    -- {5, 1172, 'Jack', 35}
    table.insert(tuples, tuple)
end

local objects = {}
for _, object in crud.pairs('customers', {{'<=', 'age', 35}}, {use_tomap = true}) do
    -- {id = 5, name = 'Jack', bucket_id = 1172, age = 35}
    table.insert(objects, object)
end

See more examples of pairs queries here.

Min and max

CRUD supports operations to get the minimum (maximum) object from the space index

local result, err = crud.min(space_name, index_id, opts)
local result, err = crud.max(space_name, index_id, opts)

where:

-- Find the minimum value in the specified index
local result, err = crud.min('customers', 'age')
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [1, 477, 'Elizabeth', 12]

-- Find the maximum value in the specified index
local result, err = crud.max('customers', 'age')
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [5, 1172, 'Jack', 35]

Cut extra rows

You could use crud.cut_rows function to cut off scan key and primary key values that were merged to the select/pairs partial result (select/pairs with fields option).

local res, err = crud.cut_rows(rows, metadata, fields)

where:

Returns metadata and array of rows, error.

See more examples of crud.cut_rows usage here and here.

Cut extra objects

If you use pairs with use_tomap flag and you need to cut off scan key and primary key values that were merged to the pairs partial result (pairs with fields option) you should use crud.cut_objects.

local new_objects = crud.cut_objects(objects, fields)

where:

Returns array of objects.

See more examples of crud.cut_objects usage here.

Truncate

-- Truncate space
local result, err = crud.truncate(space_name, opts)

where:

Returns true or nil with error.

Example:

#crud.select('customers', {{'<=', 'age', 35}}, {first = 10})
---
- 1
...
crud.truncate('customers', {timeout = 2})
---
- true
...
#crud.select('customers', {{'<=', 'age', 35}}, {first = 10})
---
- 0
...

Len

-- Calculates the number of tuples in the space for memtx engine
-- Calculates the maximum approximate number of tuples in the space for vinyl engine
local result, err = crud.len(space_name, opts)

where:

Returns number or nil with error.

Using space id instead of space name is also possible, but deprecated and will be removed in future releases.

Using space id in crud.len and custom vshard_router is not supported by statistics: space labels may be inconsistent.

Example:

Using memtx:

#crud.select('customers', nil, {fullscan = true})
---
- 5
...
crud.len('customers', {timeout = 2})
---
- 5
...

Using vinyl:

crud.len('customers')
---
- 0
...
crud.delete('customers', 1)
---
...
crud.len('customers')
---
- 1
...

Storage info

-- Get storages status
local result, err = crud.storage_info(opts)

where:

Returns storages status table by instance UUID or nil with error. Status table fields:

Example:

crud.storage_info()
---
- fe1b5bd9-42d4-4955-816c-3aa015e0eb81:
    status: running
    is_master: true
  a1eefe51-9869-4c4c-9676-76431b08c97a:
    status: running
    is_master: true
  777415f4-d656-440e-8834-7124b7267b6d:
    status: uninitialized
    is_master: false
  e1b2e202-b0f7-49cd-b0a2-6b3a584f995e:
    status: error
    message: 'connect, called on fd 36, aka 127.0.0.1:49762: Connection refused'
    is_master: false
...

Count

CRUD supports multi-conditional count, treating a cluster as a single space. The same as with select() the conditions may include field names or numbers, as well as index names. The recommended first condition is a TREE index; this helps to reduce the number of tuples to scan. Otherwise a full scan is performed. If compared with len(), count() method scans the entire space to count the tuples according user conditions. This method does yield that's why result may be approximate. Number of tuples before next yield() is under control with option yield_every.

local result, err = crud.count(space_name, conditions, opts)

where:

crud.count('customers', {{'==', 'age', 35}})
---
- 1
...

Call options for crud methods

Combinations of mode, prefer_replica and balance options lead to:

Statistics

crud routers can provide statistics on called operations.

-- Enable statistics collect.
crud.cfg{ stats = true }

-- Returns table with statistics information.
crud.stats()

-- Returns table with statistics information for specific space.
crud.stats('my_space')

-- Disables statistics collect and destroys all collectors.
crud.cfg{ stats = false }

-- Destroys all statistics collectors and creates them again.
crud.reset_stats()

If metrics 0.10.0 or greater found, metrics collectors will be used by default to store statistics instead of local collectors. Quantiles in metrics summary collections are disabled by default. You can manually choose driver and enable quantiles.

-- Use simple local collectors (default if no required metrics version found).
crud.cfg{ stats = true, stats_driver = 'local' }

-- Use metrics collectors (default if metrics rock found).
crud.cfg{ stats = true, stats_driver = 'metrics' }

-- Use metrics collectors with 0.99 quantiles.
crud.cfg{ stats = true, stats_driver = 'metrics', stats_quantiles = true }

You can use crud.cfg to check current stats state.

crud.cfg
---
- stats_quantiles: true
  stats: true
  stats_driver: metrics
...

Performance overhead is 3-10% in case of local driver and 5-15% in case of metrics driver, up to 20% for metrics with quantiles.

Beware that iterating through crud.cfg with pairs is not supported yet, refer to tarantool/crud#265.

Format is as follows.

crud.stats()
---
- spaces:
    my_space:
      insert:
        ok:
          latency: 0.0015
          latency_average: 0.002
          latency_quantile_recent: 0.0015
          count: 19800
          time: 39.6
        error:
          latency: 0.0000008
          latency_average: 0.000001
          latency_quantile_recent: 0.0000008
          count: 4
          time: 0.000004
...
crud.stats('my_space')
---
- insert:
    ok:
      latency: 0.0015
      latency_average: 0.002
      latency_quantile_recent: 0.0015
      count: 19800
      time: 39.6
    error:
      latency: 0.0000008
      latency_average: 0.000001
      latency_quantile_recent: 0.0000008
      count: 4
      time: 0.000004
...

spaces section contains statistics for each observed space. If operation has never been called for a space, the corresponding field will be empty. If no requests has been called for a space, it will not be represented. Space data is based on client requests rather than storages schema, so requests for non-existing spaces are also collected.

Possible statistics operation labels are insert (for insert and insert_object calls), get, replace (for replace and replace_object calls), update, upsert (for upsert and upsert_object calls), delete, select (for select and pairs calls), truncate, len, count and borders (for min and max calls).

Each operation section consists of different collectors for success calls and error (both error throw and nil, err) returns. count is the total requests count since instance start or stats restart. time is the total time of requests execution. latency_average is time / count. latency_quantile_recent is the 0.99 quantile of request execution time for a recent period (see metrics summary API). It is computed only if metrics driver is used and quantiles are enabled. latency_quantile_recent value may be -nan if there wasn't any observations for several ages, see tarantool/metrics#303. latency is a latency_quantile_recent if metrics driver is used and quantiles are enabled, otherwise it's latency_average.

In metrics registry statistics are stored as tnt_crud_stats metrics with operation, status and name labels.

metrics:collect()
---
- - label_pairs:
      status: ok
      operation: insert
      name: customers
    value: 221411
    metric_name: tnt_crud_stats_count
  - label_pairs:
      status: ok
      operation: insert
      name: customers
    value: 10.49834896344692
    metric_name: tnt_crud_stats_sum
  - label_pairs:
      status: ok
      operation: insert
      name: customers
      quantile: 0.99
    value: 0.00023606420935973
    metric_name: tnt_crud_stats
...

If you see -Inf value in quantile metrics, try to decrease the tolerated error:

crud.cfg{stats_quantile_tolerated_error = 1e-4}

See tarantool/metrics#189 for details about the issue. You can also configure quantile age_bucket_count (default: 2) and max_age_time (in seconds, default: 60):

crud.cfg{
    stats_quantile_age_bucket_count = 3,
    stats_quantile_max_age_time = 30,
}

See metrics summary API for details. These parameters can be used to smooth time window move or reduce the amount on -nan gaps for low request frequency applications.

select section additionally contains details collectors.

crud.stats('my_space').select.details
---
- map_reduces: 4
  tuples_fetched: 10500
  tuples_lookup: 238000
...

map_reduces is the count of planned map reduces (including those not executed successfully). tuples_fetched is the count of tuples fetched from storages during execution, tuples_lookup is the count of tuples looked up on storages while collecting responses for calls (including scrolls for multibatch requests). Details data is updated as part of the request process, so you may get new details before select/pairs call is finished and observed with count, latency and time collectors. In metrics registry they are stored as tnt_crud_map_reduces, tnt_crud_tuples_fetched and tnt_crud_tuples_lookup metrics with { operation = 'select', name = space_name } labels.

Since pairs request behavior differs from any other crud request, its statistics collection also has specific behavior. Statistics (select section) are updated after pairs cycle is finished: you either have iterated through all records or an error was thrown. If your pairs cycle was interrupted with break, statistics will be collected when pairs objects are cleaned up with Lua garbage collector.

Statistics are preserved between package reloads. Statistics are preserved between Tarantool Cartridge role reloads if you use CRUD Cartridge roles. Beware that metrics 0.12.0 and below do not support preserving stats between role reload (see tarantool/metrics#334), thus this feature will be unsupported for metrics driver.

Read view

A read view is an in-memory snapshot of data on instance that isn’t affected by future data modifications. Read views allow you to retrieve data using the read_view_object:select() and read_view_object:pairs() operations.

Read views can be used to make complex analytical queries. This reduces the load on the main database and improves RPS for a single Tarantool instance.

Read views have the following limitations:

Creating a read view

To create a read view, call the crud.readview() function.

local rv = crud.readview(opts)

where:

Example:

local rv = crud.readview({name = 'foo', timeout = 3})

Closing a read view

When a read view is no longer needed, close it using the read_view_object:close() method because a read view may consume a substantial amount of memory.

local rv = crud.readview()
rv:close(opts)

where:

A read view is also closed implicitly when the read view object is collected by the Lua garbage collector.

Example:

local rv = crud.readview()
rv:close({timeout = 3})

Read view select

read_view_object:select() supports multi-conditional selects, treating a cluster as a single space, same as crud.select.

local rv = crud.readview()
local result, err = rv:select(space_name, conditions, opts)
rv:close()

Opts are the same as select opts, except balance, prefer_replica and mode are not supported.

Returns metadata and array of rows, error.

Example:

local rv = crud.readview()
rv:select('customers', nil, {batch_size=1, fullscan=true})
---
- metadata: [{'name': 'id', 'type': 'unsigned'}, {'name': 'bucket_id', 'type': 'unsigned'},
    {'name': 'name', 'type': 'string'}, {'name': 'age', 'type': 'number'}]
  rows:
  - [1, 477, 'Elizabeth', 12]
  - [2, 401, 'Mary', 46]
  - [3, 2804, 'David', 33]
  - [4, 1161, 'William', 81]
  - [5, 1172, 'Jack', 35]
  - [6, 1064, 'William', 25]
  - [7, 693, 'Elizabeth', 18]
- null
...
crud.insert('customers', {8, box.NULL, 'Elizabeth', 23})
---
- rows:
  - [8, 185, 'Elizabeth', 23]
  metadata: [{'name': 'id', 'type': 'unsigned'}, {'name': 'bucket_id', 'type': 'unsigned'},
    {'name': 'name', 'type': 'string'}, {'name': 'age', 'type': 'number'}]
- null
...
rv:select('customers', nil, {batch_size=1, fullscan=true})
---
- metadata: [{'name': 'id', 'type': 'unsigned'}, {'name': 'bucket_id', 'type': 'unsigned'},
    {'name': 'name', 'type': 'string'}, {'name': 'age', 'type': 'number'}]
  rows:
  - [1, 477, 'Elizabeth', 12]
  - [2, 401, 'Mary', 46]
  - [3, 2804, 'David', 33]
  - [4, 1161, 'William', 81]
  - [5, 1172, 'Jack', 35]
  - [6, 1064, 'William', 25]
  - [7, 693, 'Elizabeth', 18]
- null
...
rv:close()
Read view select conditions

Select conditions for read_view_object:select() are the same as select conditions for crud.select.

Example:

rv = crud.readview()
rv:select('customers', {{'<=', 'age', 35}}, {first = 10})
---
- metadata:
  - {'name': 'id', 'type': 'unsigned'}
  - {'name': 'bucket_id', 'type': 'unsigned'}
  - {'name': 'name', 'type': 'string'}
  - {'name': 'age', 'type': 'number'}
  rows:
  - [5, 1172, 'Jack', 35]
  - [3, 2804, 'David', 33]
  - [6, 1064, 'William', 25]
  - [7, 693, 'Elizabeth', 18]
  - [1, 477, 'Elizabeth', 12]
...
rv.close()

Read view pairs

You can iterate across a distributed space using the read_view_object:pairs() method. Its arguments are the same as crud.readview.select arguments except fullscan (it does not exist because crud.pairs does not generate a critical log entry on potentially long requests) and negative first values aren't allowed. User could pass use_tomap flag (false by default) to iterate over flat tuples or objects.

Example:

rv = crud.readview()
local tuples = {}
for _, tuple in rv:pairs('customers', {{'<=', 'age', 35}}, {use_tomap = false}) do
    -- {5, 1172, 'Jack', 35}
    table.insert(tuples, tuple)
end

local objects = {}
for _, object in rv:pairs('customers', {{'<=', 'age', 35}}, {use_tomap = true}) do
    -- {id = 5, name = 'Jack', bucket_id = 1172, age = 35}
    table.insert(objects, object)
end
rv:close()

Schema

crud routers provide API to introspect spaces schema.

local schema, err = crud.update(space_name, opts)

where:

Returns space schema (or spaces schema map), error.

Beware that schema info is not exactly the same as underlying storage spaces schema. The reason is that crud generates bucket_id, if it isn't provided, so this field is actually nullable for a crud user. We also do not expose bucket_id index info since it's a vshard utility and do not related to application logic.

Example:

crud.schema('customers')
---
- format:
    - name: id
      type: unsigned
    - name: bucket_id
      type: unsigned
      is_nullable: true
    - name: name
      type: string
    - name: age
      type: number
  indexes:
    0:
      unique: true
      parts:
      - fieldno: 1
        type: unsigned
        exclude_null: false
        is_nullable: false
      id: 0
      type: TREE
      name: primary_index
    2:
      unique: false
      parts:
      - fieldno: 4
        type: number
        exclude_null: false
        is_nullable: false
      id: 2
      type: TREE
      name: age
...
crud.schema()
---
- customers:
    format: ...
    indexes: ...
  shops:
    format: ...
    indexes: ...

Tarantool 3 roles

roles.crud-storage is a Tarantool 3 role that initializes functions that are used on the storage side to perform CRUD operations. Role must be enabled on sharding storages.

cartridge.roles.crud-router is a role that exposes public crud functions to the global scope so that you can call them via net.box or with connectors. Role must be enabled on sharding routers.

Roles support Tarantool 3.0.2, Tarantool 3.1.0 and newer. Older versions are not supported due to tarantool/tarantool#9643 and tarantool/tarantool#9649 issues.

Usage

  1. Add crud to dependencies in the project rockspec.

    Note: it's better to use tagged version than scm-1. Check the latest available release tag and use it.

    -- <project-name>-scm-1.rockspec
dependencies = {
   ...
   'crud == <the-latest-tag>-1',
    ...
}

  2. Add crud roles to your application configuration. Application must be a sharded one. It is required that roles.crud-storage is enabled on each sharding storage.

    groups:
  routers:
    sharding:
      roles:
        - router
    roles:
      - roles.crud-router
    replicasets:
      router:

  storages:
    sharding:
      roles:
        - storage
    roles:
      - roles.crud-storage
    replicasets:
      s-1:
      s-2:
    Full configuration example ```yaml credentials: users: replicator: password: replicating roles: - replication storage: password: storing-buckets roles: - sharding guest: roles: - super sharding: bucket_count: 30000 replication: failover: manual iproto: advertise: peer: login: replicator sharding: login: storage groups: routers: sharding: roles: - router roles: - roles.crud-router app: module: myrouter replicasets: router: leader: router instances: router: iproto: listen: - uri: localhost:3301 storages: sharding: roles: - storage roles: - roles.crud-storage app: module: mystorage replicasets: s-1: leader: s1-master instances: s1-master: iproto: listen: - uri: localhost:3302 s1-replica: iproto: listen: - uri: localhost:3303 s-2: leader: s2-master instances: s2-replica: iproto: listen: - uri: localhost:3304 s2-master: iproto: listen: - uri: localhost:3305 ```

  3. Bootstrap vshard routers (for example, through app.module section in Tarantool 3 routers configuration).

    -- myrouter.lua

local clock = require('clock')
local fiber = require('fiber')
local log = require('log')

local vshard = require('vshard')

local TIMEOUT = 60
local DELAY = 0.1

local start = clock.monotonic()
while clock.monotonic() - start < TIMEOUT do
    local ok, err = vshard.router.bootstrap({
        if_not_bootstrapped = true,
    })

    if ok then
        break
    end

    log.info(('Router bootstrap error: %s'):format(err))
    fiber.sleep(DELAY)
end

  4. Set up your schema on storages (for example, through app.module section in Tarantool 3 storages configuration).

    -- mystorage.lua

-- Schema setup is idempotent.
box.watch('box.status', function()
    if box.info.ro then
        return
    end

    local customers_space = box.schema.space.create('customers', {
        format = {
            {name = 'id', type = 'unsigned'},
            {name = 'bucket_id', type = 'unsigned'},
            {name = 'name', type = 'string'},
            {name = 'age', type = 'number'},
        },
        if_not_exists = true,
    })

    customers_space:create_index('id', {
        parts = { {field ='id', is_nullable = false} },
        if_not_exists = true,
    })

    customers_space:create_index('bucket_id', {
        parts = { {field ='bucket_id', is_nullable = false} },
        if_not_exists = true,
    })

    customers_space:create_index('age', {
        parts = { {field ='age'} },
        unique = false,
        if_not_exists = true,
    })
end)

  5. Start the application cluster. You can check whether asynchronous bootstrap had finished through crud.storage_info() calls on router.

  6. Configure the statistics with roles configuration (see crud.cfg options in statistics section):

    roles:
  - roles.crud-router
roles_cfg:
  roles.crud-router:
    stats: true
    stats_driver: metrics
    stats_quantiles: true
    stats_quantile_tolerated_error: 0.001
    stats_quantile_age_buckets_count: 5
    stats_quantile_max_age_time: 180

Now your cluster contains storages that are configured to be used for CRUD-operations. You can simply call CRUD functions on the router to insert, select, and update data across the cluster.

Cartridge roles

cartridge.roles.crud-storage is a Tarantool Cartridge role that depends on the vshard-storage role, but also initializes functions that are used on the storage side to perform CRUD operations.

cartridge.roles.crud-router is a role that depends on the vshard-router role, but also exposes public crud functions in the global scope, so that you can call them via net.box.

Usage

  1. Add crud to dependencies in the project rockspec.

    Note: it's better to use tagged version than scm-1. Check the latest available release tag and use it.

    -- <project-name>-scm-1.rockspec
dependencies = {
    ...
    'crud == <the-latest-tag>-1',
    ...
}

  2. Create the role that stores your data and depends on crud-storage.

    -- app.roles.customers-storage.lua
local cartridge = require('cartridge')

return {
        role_name = 'customers-storage',
        init = function()
            local customers_space = box.schema.space.create('customers', {
                format = {
                    {name = 'id', type = 'unsigned'},
                    {name = 'bucket_id', type = 'unsigned'},
                    {name = 'name', type = 'string'},
                    {name = 'age', type = 'number'},
                },
                if_not_exists = true,
            })
            customers_space:create_index('id', {
                parts = { {field ='id', is_nullable = false} },
                if_not_exists = true,
            })
            customers_space:create_index('bucket_id', {
                parts = { {field ='bucket_id', is_nullable = false} },
                if_not_exists = true,
            })
            customers_space:create_index('age', {
                parts = { {field ='age'} },
                unique = false,
                if_not_exists = true,
            })
        end,
        dependencies = {'cartridge.roles.crud-storage'},
    }
    -- app.roles.customers-router.lua
local cartridge = require('cartridge')
return {
        role_name = 'customers-router',
        dependencies = {'cartridge.roles.crud-router'},
    }

  3. Start the application and create customers-storage and customers-router replica sets.

  4. Don't forget to bootstrap vshard.

  5. Configure the statistics with clusterwide configuration (see crud.cfg options in statistics section):

    crud:
  stats: true
  stats_driver: metrics
  stats_quantiles: true
  stats_quantile_tolerated_error: 0.001
  stats_quantile_age_buckets_count: 5
  stats_quantile_max_age_time: 180

Now your cluster contains storages that are configured to be used for CRUD-operations. You can simply call CRUD functions on the router to insert, select, and update data across the cluster.

License

BSD-2-Clause. See the LICENSE file.