教程:在本地创建、运行和测试 dbt 模型

本教程将引导你了解如何在本地创建、运行和测试 dbt 模型。

开始之前的准备工作

要遵循本教程,必须先将 Azure Databricks 工作区连接到 dbt Core。 有关详细信息,请参阅连接到 dbt Core

步骤 1:创建并运行模型

在本步骤中,需要使用喜欢的文本编辑器创建模型,这些模型是 语句,会根据同一数据库中的现有数据在数据库中创建一个新视图(默认行为)或一个新表。 此过程基于示例数据集中的示例 diamonds 表创建模型。

使用以下代码创建此表。

DROP TABLE IF EXISTS diamonds;

CREATE TABLE diamonds USING CSV OPTIONS (path "/databricks-datasets/Rdatasets/data-001/csv/ggplot2/diamonds.csv", header "true")
  1. 在项目的 models 目录中,创建包含以下 SQL 语句的名为 diamonds_four_cs.sql 的文件。 此语句仅从 diamonds 表中选择每颗钻石的克拉数、切工、颜色和透明度详细信息。 config 块指示 dbt 根据此语句在数据库中创建表。

    {{ config(
      materialized='table',
      file_format='delta'
    ) }}
    
    select carat, cut, color, clarity
    from diamonds
    

    提示

    有关其他 config 选项(例如使用 Delta 文件格式和 merge 增量策略),请参阅 dbt 文档中的 Databricks 配置

  2. 在项目的 models 目录中,创建第二个包含以下 SQL 语句的名为 diamonds_list_colors.sql 的文件。 此语句从 colors 表中的 diamonds_four_cs 列中选择唯一值,按字母顺序依次对结果进行排序。 由于没有 config 块,此模型将指示 dbt 根据此语句在数据库中创建视图。

    select distinct color
    from {{ ref('diamonds_four_cs') }}
    sort by color asc
    
  3. 在项目的 models 目录中,创建第三个包含以下 SQL 语句的名为 diamonds_prices.sql 的文件。 此语句按颜色计算钻石的平均价格,并按平均价格从高到低对结果进行排序。 此模型指示 dbt 根据此语句在数据库中创建视图。

    select color, avg(price) as price
    from diamonds
    group by color
    order by price desc
    
  4. 激活虚拟环境后,使用上述三个文件的路径运行 dbt run 命令。 在 default 数据库中(如 profiles.yml 文件中指定),dbt 会创建一个名为 diamonds_four_cs 的表和两个名为 diamonds_list_colorsdiamonds_prices 的视图。 dbt 从相关的 .sql 文件名获取这些视图和表名称。

    dbt run --model models/diamonds_four_cs.sql models/diamonds_list_colors.sql models/diamonds_prices.sql
    
    ...
    ... | 1 of 3 START table model default.diamonds_four_cs.................... [RUN]
    ... | 1 of 3 OK created table model default.diamonds_four_cs............... [OK ...]
    ... | 2 of 3 START view model default.diamonds_list_colors................. [RUN]
    ... | 2 of 3 OK created view model default.diamonds_list_colors............ [OK ...]
    ... | 3 of 3 START view model default.diamonds_prices...................... [RUN]
    ... | 3 of 3 OK created view model default.diamonds_prices................. [OK ...]
    ... |
    ... | Finished running 1 table model, 2 view models ...
    
    Completed successfully
    
    Done. PASS=3 WARN=0 ERROR=0 SKIP=0 TOTAL=3
    
  5. 运行以下 SQL 代码,列出有关新视图的信息,并选择表和视图中所有行。

    如果要连接到群集,可以从连接到群集的笔记本中运行此 SQL 代码,同时指定 SQL 作为笔记本的默认语言。 如果要连接到 SQL 仓库,可以从查询运行此 SQL 代码。

    SHOW views IN default;
    
    +-----------+----------------------+-------------+
    | namespace | viewName             | isTemporary |
    +===========+======================+=============+
    | default   | diamonds_list_colors | false       |
    +-----------+----------------------+-------------+
    | default   | diamonds_prices      | false       |
    +-----------+----------------------+-------------+
    
    SELECT * FROM diamonds_four_cs;
    
    +-------+---------+-------+---------+
    | carat | cut     | color | clarity |
    +=======+=========+=======+=========+
    | 0.23  | Ideal   | E     | SI2     |
    +-------+---------+-------+---------+
    | 0.21  | Premium | E     | SI1     |
    +-------+---------+-------+---------+
    ...
    
    SELECT * FROM diamonds_list_colors;
    
    +-------+
    | color |
    +=======+
    | D     |
    +-------+
    | E     |
    +-------+
    ...
    
    SELECT * FROM diamonds_prices;
    
    +-------+---------+
    | color | price   |
    +=======+=========+
    | J     | 5323.82 |
    +-------+---------+
    | I     | 5091.87 |
    +-------+---------+
    ...
    

步骤 2:创建并运行更复杂的模型

在此步骤中,你将为一组相关数据表创建更复杂的模型。 这些数据表包含有关虚拟的体育联赛的信息,其中三支队伍需要在一个赛季中完成六场比赛。 此过程将创建数据表、创建模型并运行模型。

  1. 运行以下 SQL 代码以创建必要的数据表。

    如果要连接到群集,可以从连接到群集的笔记本中运行此 SQL 代码,同时指定 SQL 作为笔记本的默认语言。 如果要连接到 SQL 仓库,可以从查询运行此 SQL 代码。

    本步骤中的表和视图以 zzz_ 开头,有助于在本示例中识别它们。 对于自己的表和视图,无需遵循此模式。

    DROP TABLE IF EXISTS zzz_game_opponents;
    DROP TABLE IF EXISTS zzz_game_scores;
    DROP TABLE IF EXISTS zzz_games;
    DROP TABLE IF EXISTS zzz_teams;
    
    CREATE TABLE zzz_game_opponents (
    game_id INT,
    home_team_id INT,
    visitor_team_id INT
    ) USING DELTA;
    
    INSERT INTO zzz_game_opponents VALUES (1, 1, 2);
    INSERT INTO zzz_game_opponents VALUES (2, 1, 3);
    INSERT INTO zzz_game_opponents VALUES (3, 2, 1);
    INSERT INTO zzz_game_opponents VALUES (4, 2, 3);
    INSERT INTO zzz_game_opponents VALUES (5, 3, 1);
    INSERT INTO zzz_game_opponents VALUES (6, 3, 2);
    
    -- Result:
    -- +---------+--------------+-----------------+
    -- | game_id | home_team_id | visitor_team_id |
    -- +=========+==============+=================+
    -- | 1       | 1            | 2               |
    -- +---------+--------------+-----------------+
    -- | 2       | 1            | 3               |
    -- +---------+--------------+-----------------+
    -- | 3       | 2            | 1               |
    -- +---------+--------------+-----------------+
    -- | 4       | 2            | 3               |
    -- +---------+--------------+-----------------+
    -- | 5       | 3            | 1               |
    -- +---------+--------------+-----------------+
    -- | 6       | 3            | 2               |
    -- +---------+--------------+-----------------+
    
    CREATE TABLE zzz_game_scores (
    game_id INT,
    home_team_score INT,
    visitor_team_score INT
    ) USING DELTA;
    
    INSERT INTO zzz_game_scores VALUES (1, 4, 2);
    INSERT INTO zzz_game_scores VALUES (2, 0, 1);
    INSERT INTO zzz_game_scores VALUES (3, 1, 2);
    INSERT INTO zzz_game_scores VALUES (4, 3, 2);
    INSERT INTO zzz_game_scores VALUES (5, 3, 0);
    INSERT INTO zzz_game_scores VALUES (6, 3, 1);
    
    -- Result:
    -- +---------+-----------------+--------------------+
    -- | game_id | home_team_score | visitor_team_score |
    -- +=========+=================+====================+
    -- | 1       | 4               | 2                  |
    -- +---------+-----------------+--------------------+
    -- | 2       | 0               | 1                  |
    -- +---------+-----------------+--------------------+
    -- | 3       | 1               | 2                  |
    -- +---------+-----------------+--------------------+
    -- | 4       | 3               | 2                  |
    -- +---------+-----------------+--------------------+
    -- | 5       | 3               | 0                  |
    -- +---------+-----------------+--------------------+
    -- | 6       | 3               | 1                  |
    -- +---------+-----------------+--------------------+
    
    CREATE TABLE zzz_games (
    game_id INT,
    game_date DATE
    ) USING DELTA;
    
    INSERT INTO zzz_games VALUES (1, '2020-12-12');
    INSERT INTO zzz_games VALUES (2, '2021-01-09');
    INSERT INTO zzz_games VALUES (3, '2020-12-19');
    INSERT INTO zzz_games VALUES (4, '2021-01-16');
    INSERT INTO zzz_games VALUES (5, '2021-01-23');
    INSERT INTO zzz_games VALUES (6, '2021-02-06');
    
    -- Result:
    -- +---------+------------+
    -- | game_id | game_date  |
    -- +=========+============+
    -- | 1       | 2020-12-12 |
    -- +---------+------------+
    -- | 2       | 2021-01-09 |
    -- +---------+------------+
    -- | 3       | 2020-12-19 |
    -- +---------+------------+
    -- | 4       | 2021-01-16 |
    -- +---------+------------+
    -- | 5       | 2021-01-23 |
    -- +---------+------------+
    -- | 6       | 2021-02-06 |
    -- +---------+------------+
    
    CREATE TABLE zzz_teams (
    team_id INT,
    team_city VARCHAR(15)
    ) USING DELTA;
    
    INSERT INTO zzz_teams VALUES (1, "San Francisco");
    INSERT INTO zzz_teams VALUES (2, "Seattle");
    INSERT INTO zzz_teams VALUES (3, "Amsterdam");
    
    -- Result:
    -- +---------+---------------+
    -- | team_id | team_city     |
    -- +=========+===============+
    -- | 1       | San Francisco |
    -- +---------+---------------+
    -- | 2       | Seattle       |
    -- +---------+---------------+
    -- | 3       | Amsterdam     |
    -- +---------+---------------+
    
  2. 在项目的 models 目录中,创建包含以下 SQL 语句的名为 zzz_game_details.sql 的文件。 此语句会创建一个表,该表提供每场比赛的详细信息,例如队伍名称和分数。 config 块指示 dbt 根据此语句在数据库中创建表。

    -- Create a table that provides full details for each game, including
    -- the game ID, the home and visiting teams' city names and scores,
    -- the game winner's city name, and the game date.
    
    {{ config(
      materialized='table',
      file_format='delta'
    ) }}
    
    -- Step 4 of 4: Replace the visitor team IDs with their city names.
    select
      game_id,
      home,
      t.team_city as visitor,
      home_score,
      visitor_score,
      -- Step 3 of 4: Display the city name for each game's winner.
      case
        when
          home_score > visitor_score
            then
              home
        when
          visitor_score > home_score
            then
              t.team_city
      end as winner,
      game_date as date
    from (
      -- Step 2 of 4: Replace the home team IDs with their actual city names.
      select
        game_id,
        t.team_city as home,
        home_score,
        visitor_team_id,
        visitor_score,
        game_date
      from (
        -- Step 1 of 4: Combine data from various tables (for example, game and team IDs, scores, dates).
        select
          g.game_id,
          go.home_team_id,
          gs.home_team_score as home_score,
          go.visitor_team_id,
          gs.visitor_team_score as visitor_score,
          g.game_date
        from
          zzz_games as g,
          zzz_game_opponents as go,
          zzz_game_scores as gs
        where
          g.game_id = go.game_id and
          g.game_id = gs.game_id
      ) as all_ids,
        zzz_teams as t
      where
        all_ids.home_team_id = t.team_id
    ) as visitor_ids,
      zzz_teams as t
    where
      visitor_ids.visitor_team_id = t.team_id
    order by game_date desc
    
  3. 在项目的 models 目录中,创建包含以下 SQL 语句的名为 zzz_win_loss_records.sql 的文件。 此语句会创建一个视图,视图中会列出该赛季队伍的胜负记录。

    -- Create a view that summarizes the season's win and loss records by team.
    
    -- Step 2 of 2: Calculate the number of wins and losses for each team.
    select
      winner as team,
      count(winner) as wins,
      -- Each team played in 4 games.
      (4 - count(winner)) as losses
    from (
      -- Step 1 of 2: Determine the winner and loser for each game.
      select
        game_id,
        winner,
        case
          when
            home = winner
              then
                visitor
          else
            home
        end as loser
      from {{ ref('zzz_game_details') }}
    )
    group by winner
    order by wins desc
    
  4. 激活虚拟环境后,使用上述两个文件的路径运行 dbt run 命令。 在 default 数据库中(如 profiles.yml 文件中指定),dbt 会创建一个名为 zzz_game_details 的表和一个名为 zzz_win_loss_records 的视图。 dbt 从相关的 .sql 文件名获取这些视图和表名称。

    dbt run --model models/zzz_game_details.sql models/zzz_win_loss_records.sql
    
    ...
    ... | 1 of 2 START table model default.zzz_game_details.................... [RUN]
    ... | 1 of 2 OK created table model default.zzz_game_details............... [OK ...]
    ... | 2 of 2 START view model default.zzz_win_loss_records................. [RUN]
    ... | 2 of 2 OK created view model default.zzz_win_loss_records............ [OK ...]
    ... |
    ... | Finished running 1 table model, 1 view model ...
    
    Completed successfully
    
    Done. PASS=2 WARN=0 ERROR=0 SKIP=0 TOTAL=2
    
  5. 运行以下 SQL 代码,列出有关新视图的信息,并选择表和视图中所有行。

    如果要连接到群集,可以从连接到群集的笔记本中运行此 SQL 代码,同时指定 SQL 作为笔记本的默认语言。 如果要连接到 SQL 仓库,可以从查询运行此 SQL 代码。

    SHOW VIEWS FROM default LIKE 'zzz_win_loss_records';
    
    +-----------+----------------------+-------------+
    | namespace | viewName             | isTemporary |
    +===========+======================+=============+
    | default   | zzz_win_loss_records | false       |
    +-----------+----------------------+-------------+
    
    SELECT * FROM zzz_game_details;
    
    +---------+---------------+---------------+------------+---------------+---------------+------------+
    | game_id | home          | visitor       | home_score | visitor_score | winner        | date       |
    +=========+===============+===============+============+===============+===============+============+
    | 1       | San Francisco | Seattle       | 4          | 2             | San Francisco | 2020-12-12 |
    +---------+---------------+---------------+------------+---------------+---------------+------------+
    | 2       | San Francisco | Amsterdam     | 0          | 1             | Amsterdam     | 2021-01-09 |
    +---------+---------------+---------------+------------+---------------+---------------+------------+
    | 3       | Seattle       | San Francisco | 1          | 2             | San Francisco | 2020-12-19 |
    +---------+---------------+---------------+------------+---------------+---------------+------------+
    | 4       | Seattle       | Amsterdam     | 3          | 2             | Seattle       | 2021-01-16 |
    +---------+---------------+---------------+------------+---------------+---------------+------------+
    | 5       | Amsterdam     | San Francisco | 3          | 0             | Amsterdam     | 2021-01-23 |
    +---------+---------------+---------------+------------+---------------+---------------+------------+
    | 6       | Amsterdam     | Seattle       | 3          | 1             | Amsterdam     | 2021-02-06 |
    +---------+---------------+---------------+------------+---------------+---------------+------------+
    
    SELECT * FROM zzz_win_loss_records;
    
    +---------------+------+--------+
    | team          | wins | losses |
    +===============+======+========+
    | Amsterdam     | 3    | 1      |
    +---------------+------+--------+
    | San Francisco | 2    | 2      |
    +---------------+------+--------+
    | Seattle       | 1    | 3      |
    +---------------+------+--------+
    

步骤 3:创建并运行测试

在此步骤中,你将创建测试,这些测试是有关模型的断言。 运行这些测试时,dbt 会告诉你项目中的每个测试是通过还是失败。

有两种类型的测试。 架构测试,在 YAML 中应用,返回未通过断言的记录数。 如果此数字为零,则所有记录都通过,因此测试也通过。 数据测试是必须返回零条记录才算通过的特定查询。

  1. 在项目的 models 目录中,创建包含以下内容的名为 schema.yml 的文件。 此文件包含架构测试,用于确定指定的列是否具有唯一值、不为 null、仅具有指定值或具有组合。

    version: 2
    
    models:
      - name: zzz_game_details
        columns:
          - name: game_id
            tests:
              - unique
              - not_null
          - name: home
            tests:
              - not_null
              - accepted_values:
                  values: ['Amsterdam', 'San Francisco', 'Seattle']
          - name: visitor
            tests:
              - not_null
              - accepted_values:
                  values: ['Amsterdam', 'San Francisco', 'Seattle']
          - name: home_score
            tests:
              - not_null
          - name: visitor_score
            tests:
              - not_null
          - name: winner
            tests:
              - not_null
              - accepted_values:
                  values: ['Amsterdam', 'San Francisco', 'Seattle']
          - name: date
            tests:
              - not_null
      - name: zzz_win_loss_records
        columns:
          - name: team
            tests:
              - unique
              - not_null
              - relationships:
                  to: ref('zzz_game_details')
                  field: home
          - name: wins
            tests:
              - not_null
          - name: losses
            tests:
              - not_null
    
  2. 在项目的 tests 目录中,创建包含以下 SQL 语句的名为 zzz_game_details_check_dates.sql 的文件。 此文件包含一个数据测试,用于确定常规赛季外是否进行了任何比赛。

    -- This season's games happened between 2020-12-12 and 2021-02-06.
    -- For this test to pass, this query must return no results.
    
    select date
    from {{ ref('zzz_game_details') }}
    where date < '2020-12-12'
    or date > '2021-02-06'
    
  3. 在项目的 tests 目录中,创建包含以下 SQL 语句的名为 zzz_game_details_check_scores.sql 的文件。 此文件包含一个数据测试,用于确定是否有任何分数为负或任何比赛为平局。

    -- This sport allows no negative scores or tie games.
    -- For this test to pass, this query must return no results.
    
    select home_score, visitor_score
    from {{ ref('zzz_game_details') }}
    where home_score < 0
    or visitor_score < 0
    or home_score = visitor_score
    
  4. 在项目的 tests 目录中,创建包含以下 SQL 语句的名为 zzz_win_loss_records_check_records.sql 的文件。 此文件包含一个数据测试,用于确定任何队伍是否有负数的胜场或败场记录、是否有超过进行比赛数的胜负记录,或者进行的比赛数是否多于允许的比赛数。

    -- Each team participated in 4 games this season.
    -- For this test to pass, this query must return no results.
    
    select wins, losses
    from {{ ref('zzz_win_loss_records') }}
    where wins < 0 or wins > 4
    or losses < 0 or losses > 4
    or (wins + losses) > 4
    
  5. 激活虚拟环境后,运行 dbt test 命令。

    dbt test --models zzz_game_details zzz_win_loss_records
    
    ...
    ... | 1 of 19 START test accepted_values_zzz_game_details_home__Amsterdam__San_Francisco__Seattle [RUN]
    ... | 1 of 19 PASS accepted_values_zzz_game_details_home__Amsterdam__San_Francisco__Seattle [PASS ...]
    ...
    ... |
    ... | Finished running 19 tests ...
    
    Completed successfully
    
    Done. PASS=19 WARN=0 ERROR=0 SKIP=0 TOTAL=19
    

步骤 4:清理

可以通过运行以下 SQL 代码来删除为此示例创建的表和视图。

如果要连接到群集,可以从连接到群集的笔记本中运行此 SQL 代码,同时指定 SQL 作为笔记本的默认语言。 如果要连接到 SQL 仓库,可以从查询运行此 SQL 代码。

DROP TABLE zzz_game_opponents;
DROP TABLE zzz_game_scores;
DROP TABLE zzz_games;
DROP TABLE zzz_teams;
DROP TABLE zzz_game_details;
DROP VIEW zzz_win_loss_records;

DROP TABLE diamonds;
DROP TABLE diamonds_four_cs;
DROP VIEW diamonds_list_colors;
DROP VIEW diamonds_prices;

故障排除

有关将 dbt Core 与 Azure Databricks 配合使用时的常见问题以及如何解决这些问题的信息,请参阅 dbt 实验室网站上的获取帮助

其他资源

在 dbt 实验室网站上浏览以下资源: