Document field names changes

[rtsisyk]

1. space:format() syntax was extended.

In addition to current syntax of space fileds format definition:

• space:format({{name='field_id', type='integer'}, ...})

Add more ways to define it:

• space:format({{'field_name', 'integer'}, ...})
• space:format({{'field_name', type='integer'}, ...})
• space:format({{'field_name'}, ...})
• space:format({'field_name', ...})

tarantool/tarantool#2814

2. index_parts syntax was extended

Add new method of defining indexes:

• parts = { {field = field_name1, type = field_type}, {field = field_name2, type = field_type}, ...}
• parts = { {field_name1, field_type}, {field_name2, field_type}, ...}
• parts = { {field_name1}, {field_name2}, ...}
• parts = {field_name1, field_name2}
• parts = {field_id, field_id}

Now you can use both field numbers and field names from space:format() to define indexes.

tarantool/tarantool#2802
tarantool/tarantool#2815

3. Field names from space:format() now can be used as aliases for tuple field indexes:

subscriber = box.schema.space.create('subscriber')
subscriber:format({
    {'contract_id', 'integer'},
    {'subscriber_id', 'integer'},
    {'phone', 'string'},
    {'subscriber_status_id', 'integer'},
})
subscriber:create_index('primary', {parts={'contract_id', 'subscriber_id'}})
subscriber:create_index('phone', {parts={'phone'}, unique = false })

tarantool> subscriber:replace({1, 1, '79160000000', 42})
---
- [1, 1, '79160000000', 42]
...

tarantool> t = subscriber:get({1, 1})
---
...

tarantool> t.subscriber_id
---
- 1
...

tarantool> t.phone
---
- '79160000000'
...

tarantool/tarantool#1014