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runleonarun authored Dec 24, 2024
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92 changes: 92 additions & 0 deletions website/docs/docs/build/dimensions.md
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ All dimensions require a `name`, `type`, and can optionally include an `expr` pa
| `description` | A clear description of the dimension. | Optional | String |
| `expr` | Defines the underlying column or SQL query for a dimension. If no `expr` is specified, MetricFlow will use the column with the same name as the group. You can use the column name itself to input a SQL expression. | Optional | String |
| `label` | Defines the display value in downstream tools. Accepts plain text, spaces, and quotes (such as `orders_total` or `"orders_total"`). | Optional | String |
| [`meta`](/reference/resource-configs/meta) | Set metadata for a resource and organize resources. Accepts plain text, spaces, and quotes. | Optional | Dictionary |

Refer to the following for the complete specification for dimensions:

Expand All @@ -37,6 +38,8 @@ dimensions:
Refer to the following example to see how dimensions are used in a semantic model:
<VersionBlock firstVersion="1.9">
```yaml
semantic_models:
- name: transactions
Expand All @@ -59,13 +62,50 @@ semantic_models:
type_params:
time_granularity: day
label: "Date of transaction" # Recommend adding a label to provide more context to users consuming the data
config:
meta:
data_owner: "Finance team"
expr: ts
- name: is_bulk
type: categorical
expr: case when quantity > 10 then true else false end
- name: type
type: categorical
```
</VersionBlock>
<VersionBlock lastVersion="1.8">
```yaml
semantic_models:
- name: transactions
description: A record for every transaction that takes place. Carts are considered multiple transactions for each SKU.
model: {{ ref('fact_transactions') }}
defaults:
agg_time_dimension: order_date
# --- entities ---
entities:
- name: transaction
type: primary
...
# --- measures ---
measures:
...
# --- dimensions ---
dimensions:
- name: order_date
type: time
type_params:
time_granularity: day
label: "Date of transaction" # Recommend adding a label to provide more context to users consuming the data
expr: ts
- name: is_bulk
type: categorical
expr: case when quantity > 10 then true else false end
- name: type
type: categorical
```
</VersionBlock>
Dimensions are bound to the primary entity of the semantic model they are defined in. For example the dimension `type` is defined in a model that has `transaction` as a primary entity. `type` is scoped to the `transaction` entity, and to reference this dimension you would use the fully qualified dimension name i.e `transaction__type`.

Expand Down Expand Up @@ -101,12 +141,28 @@ This section further explains the dimension definitions, along with examples. Di

Categorical dimensions are used to group metrics by different attributes, features, or characteristics such as product type. They can refer to existing columns in your dbt model or be calculated using a SQL expression with the `expr` parameter. An example of a categorical dimension is `is_bulk_transaction`, which is a group created by applying a case statement to the underlying column `quantity`. This allows users to group or filter the data based on bulk transactions.

<VersionBlock firstVersion="1.9">

```yaml
dimensions:
- name: is_bulk_transaction
type: categorical
expr: case when quantity > 10 then true else false end
config:
meta:
usage: "Filter to identify bulk transactions, like where quantity > 10."
```
</VersionBlock>

<VersionBlock lastVersion="1.8">

```yaml
dimensions:
- name: is_bulk_transaction
type: categorical
expr: case when quantity > 10 then true else false end
```
</VersionBlock>

## Time

Expand All @@ -130,12 +186,17 @@ You can set `is_partition` for time to define specific time spans. Additionally,

Use `is_partition: True` to show that a dimension exists over a specific time window. For example, a date-partitioned dimensional table. When you query metrics from different tables, the dbt Semantic Layer uses this parameter to ensure that the correct dimensional values are joined to measures.

<VersionBlock firstVersion="1.9">

```yaml
dimensions:
- name: created_at
type: time
label: "Date of creation"
expr: ts_created # ts_created is the underlying column name from the table
config:
meta:
notes: "Only valid for orders from 2022 onward"
is_partition: True
type_params:
time_granularity: day
Expand All @@ -156,6 +217,37 @@ measures:
expr: 1
agg: sum
```
</VersionBlock>

<VersionBlock lastVersion="1.8">

```yaml
dimensions:
- name: created_at
type: time
label: "Date of creation"
expr: ts_created # ts_created is the underlying column name from the table
is_partition: True
type_params:
time_granularity: day
- name: deleted_at
type: time
label: "Date of deletion"
expr: ts_deleted # ts_deleted is the underlying column name from the table
is_partition: True
type_params:
time_granularity: day
measures:
- name: users_deleted
expr: 1
agg: sum
agg_time_dimension: deleted_at
- name: users_created
expr: 1
agg: sum
```
</VersionBlock>

</TabItem>

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69 changes: 63 additions & 6 deletions website/docs/docs/build/entities.md
Original file line number Diff line number Diff line change
Expand Up @@ -95,17 +95,67 @@ Natural keys are columns or combinations of columns in a table that uniquely ide

The following is the complete spec for entities:

<VersionBlock firstVersion="1.9">

```yaml
semantic_models:
- name: semantic_model_name
..rest of the semantic model config
entities:
- name: entity_name ## Required
type: Primary, natural, foreign, or unique ## Required
description: A description of the field or role the entity takes in this table ## Optional
expr: The field that denotes that entity (transaction_id). ## Optional
Defaults to name if unspecified.
[config](/reference/resource-properties/config): Specify configurations for entity. ## Optional
[meta](/reference/resource-configs/meta): {<dictionary>} Set metadata for a resource and organize resources. Accepts plain text, spaces, and quotes. ## Optional
```
</VersionBlock>
<VersionBlock lastVersion="1.8">
```yaml
semantic_models:
- name: semantic_model_name
..rest of the semantic model config
entities:
- name: entity_name ## Required
type: Primary, or natural, or foreign, or unique ## Required
description: A description of the field or role the entity takes in this table ## Optional
expr: The field that denotes that entity (transaction_id). ## Optional
Defaults to name if unspecified.
```
</VersionBlock>
Here's an example of how to define entities in a semantic model:
<VersionBlock firstVersion="1.9">
```yaml
entities:
- name: transaction ## Required
type: Primary or natural or foreign or unique ## Required
- name: transaction
type: primary
expr: id_transaction
- name: order
type: foreign
expr: id_order
- name: user
type: foreign
expr: substring(id_order from 2)
entities:
- name: transaction
type:
description: A description of the field or role the entity takes in this table ## Optional
expr: The field that denotes that entity (transaction_id). ## Optional
expr: The field that denotes that entity (transaction_id).
Defaults to name if unspecified.
[config](/reference/resource-properties/config):
[meta](/reference/resource-configs/meta):
data_owner: "Finance team"
```
</VersionBlock>
<VersionBlock lastVersion="1.8">
Here's an example of how to define entities in a semantic model:
```yaml
entities:
- name: transaction
Expand All @@ -117,11 +167,18 @@ entities:
- name: user
type: foreign
expr: substring(id_order from 2)
entities:
- name: transaction
type:
description: A description of the field or role the entity takes in this table ## Optional
expr: The field that denotes that entity (transaction_id).
Defaults to name if unspecified.
```
</VersionBlock>
## Combine columns with a key
If a table doesn't have any key (like a primary key), use _surrogate combination_ to form a key that will help you identify a record by combining two columns. This applies to any [entity type](/docs/build/entities#entity-types). For example, you can combine `date_key` and `brand_code` from the `raw_brand_target_weekly` table to form a _surrogate key_. The following example creates a surrogate key by joining `date_key` and `brand_code` using a pipe (`|`) as a separator.
If a table doesn't have any key (like a primary key), use _surrogate combination_ to form a key that will help you identify a record by combining two columns. This applies to any [entity type](/docs/build/entities#entity-types). For example, you can combine `date_key` and `brand_code` from the `raw_brand_target_weekly` table to form a _surrogate key_. The following example creates a surrogate key by joining `date_key` and `brand_code` using a pipe (`|`) as a separator.

```yaml
Expand Down
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