ActorDB Schemer

ActorDB Schemer provides versioned Actor schema upgrades through a record based model that is converted to SQL queries and executes them on request. ActorDB Schemer requires requires schema change privileges in order to work.

Goal:

ActorDB Schemer can be integrated directly into Erlang/Elixir application that connect to ActorDB via ActorDB Client (Thrift Connector) that is available at https://github.com/biokoda/actordb_client.

In conjunction with ActorDB Schemer an application can perform automatic schema updates for Actors from a predefined database model.

EXPERIMENTAL

Usage:

1. Include with rebar into your project.

2. Create your schema through a module that matches the behaviour of actordb_schemer_proto.

Example A - Schema version 0:

-module(test_schema).
-include_lib("actordb_schemer.hrl").
-behaviour(actordb_schemer_proto).
-export([schema_ver/0, schema_def/0]).

schema_ver() ->
  0.

schema_def() ->
  [
    #adb_actor{ name = <<"user">>, tables = [
      #adb_table{ name = <<"some_table">>, opts = [without_rowid, {primary_key,[<<"data1">>]}], fields = [
        #adb_field{ name = <<"data1">>, type = <<"TEXT">> },
        #adb_field{ name = <<"data2">>, type = <<"TEXT">> },
        #adb_field{ name = <<"data3">>, type = <<"BOOLEAN">> }
      ]}
  ]
].

Example A - Schema version 1:

-module(test_schema).
-include_lib("actordb_schemer.hrl").
-behaviour(actordb_schemer_proto).
-export([schema_ver/0, schema_def/0]).

schema_ver() ->
  1.  % we updated schema_ver() to 1, this way all actors, tables and columns with this version are included when building the change table

schema_def() ->
  [
    #adb_actor{ name = <<"user">>, tables = [
      #adb_table{ name = <<"some_table">>, opts = [without_rowid, {primary_key,[<<"data1">>]}], fields = [
        #adb_field{ name = <<"data1">>, type = <<"TEXT">> },
        #adb_field{ name = <<"data2">>, type = <<"TEXT">> },
        #adb_field{ name = <<"data3">>, type = <<"BOOLEAN">> },
        #adb_field{ name = <<"new_column">>, type = <<"INTEGER">>, ver = 1 }    % we added this field in schema_ver 1
      ]}
  ]
].

Schema changes will appear only for all actors, tables and fields that have version (ver field) lower or equal to the schema_ver() value.

3. Setup the schemer with the module that matches the required behaviour

actordb_schemer:setup(test_schema).

3. Check required actions that need to be done in order to bring actors to the latest schema

actordb_schemer:check(actordb_client:config()).

4. Execute actions on the actor

actordb_schemer:upgrade(actordb_client:config()).

NOTE : actordb_client connection needs to have permissions to change schema, else commands for update will fail.

EXPERIMENTAL