EctoTablestore.Migration.add
add
, go back to EctoTablestore.Migration module for more information.
Adds a primary key when creating a table.
This function only accepts types as :string
| :binary
| :integer
| :hashids
| :id
.
About :auto_increment
option:
set
:auto_increment
astrue
and its field is primary key of non-partitioned key, there will use Tablestore's auto-increment column to process it.set
:auto_increment
astrue
and its field is partition key, there will useex_aliyun_ots
's built-in Sequence function, the actual principle behind it is to use the atomic update operation though another separate table when generate serial integer, by default there will add an:id
partition key as:integer
type, the initial value of the sequence is 0, and the increment step is 1.
Tablestore can only have up to 4 primary keys, meanwhile the first defined primary key is the partition key, Please know that the order of the primary key definition will be directly mapped to the created table.
About :hashids
type to define the partition key:
- set
partition_key
astrue
is required. - set
auto_increment
astrue
is required.
Examples
The auto generated serial integer for partition key:
create table("posts") do
add :title, :string
end
# The above is equivalent to
create table("posts", partition_key: false) do
add :id, :integer, partition_key: true, auto_increment: true
add :title, :string
end
The explicitly defined field with partition_key
:
create table("posts") do
add :title, :string
end
# The above is equivalent to
create table("posts") do
add :id, :integer, partition_key: true, auto_increment: true
add :title, :string
end
The :auto_increment
integer for primary key of non-partitioned key:
create table("posts") do
add :tag, :integer, auto_increment: true
end
# The above is equivalent to
create table("posts", partition_key: false) do
add :id, :integer, partition_key: true, auto_increment: true
add :version, :integer, auto_increment: true
end
The :hashids
type for the partition key with the built-in sequence feature:
create table("posts") do
add :id, :hashids, auto_increment: true, partition_key: true
end
The :id
type for the partition key with the built-in sequence feature:
create table("posts") do
add :id, :id
end
# The above is equivalent to
create table("posts", partition_key: false) do
add :id, :integer, partition_key: true, auto_increment: true
end
Options
:partition_key
- whentrue
, marks this field as the partition key, only the first explicitly defined field is available for this option.:auto_increment
- whentrue
and this field is non-partitioned key, Tablestore automatically generates the primary key value, which is unique in the partition key, and which increases progressively, whentrue
and this field is a partition key, useex_aliyun_ots
's Sequence to build a serial number for this field, theauto_increment: true
option only allows binding of one primary key.