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Define the term as 'schema dimension' (shortened to 'dimension') #239

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Define the term as 'schema dimension' (shortened to 'dimension') #239

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3 changes: 2 additions & 1 deletion src/explanation/entity-integrity.md
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Expand Up @@ -213,7 +213,8 @@ in a single statement.

## Schema dimensions

A **dimension** is an independent axis of variation in the data. The rule:
A **schema dimension** — often shortened to *dimension* — is an independent axis of
variation in the data. The rule:

> **Any table that introduces a new primary-key attribute introduces a new
> dimension.**
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17 changes: 2 additions & 15 deletions src/how-to/read-diagrams.ipynb
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Expand Up @@ -389,20 +389,7 @@
"cell_type": "markdown",
"id": "cell-dim-md",
"metadata": {},
"source": [
"## Dimensions and Underlined Names\n",
"\n",
"A **dimension** is a new entity type introduced by a table that defines new primary key attributes. Each underlined table introduces exactly **one** dimension—even if it has multiple new PK attributes, together they identify one new entity type.\n",
"\n",
"| Visual | Meaning |\n",
"|--------|--------|\n",
"| **Underlined** | Introduces a new dimension (new entity type) |\n",
"| Not underlined | Exists in the space defined by dimensions from referenced tables |\n",
"\n",
"**Key rules:**\n",
"- Computed tables **never** introduce dimensions (always non-underlined)\n",
"- Part tables **can** introduce dimensions (may be underlined)"
]
"source": "## Dimensions and Underlined Names\n\nA **schema dimension** (often shortened to *dimension*) is a new entity type introduced by a table that defines new primary key attributes. Each underlined table introduces exactly **one** dimension—even if it has multiple new PK attributes, together they identify one new entity type.\n\n| Visual | Meaning |\n|--------|--------|\n| **Underlined** | Introduces a new dimension (new entity type) |\n| Not underlined | Exists in the space defined by dimensions from referenced tables |\n\n**Key rules:**\n- Computed tables **never** introduce dimensions (always non-underlined)\n- Part tables **can** introduce dimensions (may be underlined)"
},
{
"cell_type": "code",
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},
"nbformat": 4,
"nbformat_minor": 5
}
}
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