Agent skill

understanding-db-schema

Deep expertise in Logseq's Datascript database schema. Auto-invokes when users ask about Logseq DB schema, Datascript attributes, built-in classes, property types, entity relationships, schema validation, or the node/block/page data model. Provides authoritative knowledge of the DB graph architecture.

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npx add-skill https://github.com/aiskillstore/marketplace/tree/main/skills/c0ntr0lledcha0s/understanding-db-schema

SKILL.md

Understanding Logseq DB Schema

When to Use This Skill

This skill auto-invokes when:

  • User asks about Logseq's database schema or Datascript
  • Questions about built-in classes (Tag, Page, Task, Property, etc.)
  • Property type system questions (:default, :number, :date, :checkbox, etc.)
  • Entity relationship questions (block/tags, block/refs, block/parent)
  • Schema validation or Malli schemas
  • Node model or unified page/block concept
  • User mentions :db/ident, :logseq.class/*, or :logseq.property/*

Reference Material: See {baseDir}/references/built-in-classes.md for complete class hierarchy.

You have expert knowledge of Logseq's database schema architecture.

Datascript Foundation

Logseq DB graphs are built on Datascript, a Clojure/ClojureScript in-memory database that supports:

  • Entity-Attribute-Value (EAV) data model
  • Datalog queries
  • Schema-driven attribute definitions

Attribute Types

clojure
;; Value types
:db.type/ref      ; References to other entities
:db.type/string   ; Text values
:db.type/long     ; Integer numbers
:db.type/double   ; Floating point numbers
:db.type/boolean  ; True/false
:db.type/instant  ; Timestamps
:db.type/keyword  ; Clojure keywords
:db.type/uuid     ; UUIDs

;; Cardinality
:db.cardinality/one   ; Single value
:db.cardinality/many  ; Multiple values (set)

Core Reference Attributes

clojure
:block/tags    ; Classes/tags assigned to the entity
:block/refs    ; Outgoing references to other entities
:block/alias   ; Alternative names for a page
:block/parent  ; Parent block in hierarchy
:block/page    ; Page containing this block

Built-in Classes Hierarchy

:logseq.class/Root
├── :logseq.class/Page
├── :logseq.class/Tag (classes themselves)
├── :logseq.class/Property
├── :logseq.class/Task
│   └── Status, Priority, Deadline, Scheduled
├── :logseq.class/Query
├── :logseq.class/Asset
├── :logseq.class/Code-block
└── :logseq.class/Template

All non-Root classes extend :logseq.class/Root via :logseq.property.class/extends.

Property Type System

Type Validator Closed Values Use Case
:default text-entity? ✅ Text blocks with titles
:number number-entity? ✅ Numeric values
:date date? ❌ Journal page entities
:datetime datetime? ❌ Time-based scheduling
:checkbox boolean? ❌ Toggle properties
:url url-entity? ✅ URL strings or macros
:node node-entity? ❌ Block/page references
:class class-entity? ❌ Class entities

Property Configuration Keys

clojure
{:db/ident :user.property/my-property
 :logseq.property/type :default           ; Property type
 :logseq.property/cardinality :one        ; :one or :many
 :logseq.property/hide? false             ; Hide by default
 :logseq.property.ui/position :properties ; UI placement
 :logseq.property/closed-values [...]     ; Restricted choices
 :logseq.property/schema-classes [...]    ; Associated classes
 :block/title "My Property"}              ; Display name

Property Namespaces

Namespace Purpose Example
logseq.property Core system properties :logseq.property/type
logseq.property.class Class-related :logseq.property.class/extends
logseq.property.table Table views :logseq.property.table/columns
user.property User-defined :user.property/author
plugin.property Plugin-defined :plugin.property/custom

Schema Versioning

clojure
;; Version format
{:major 65 :minor 12}

;; Stored in
:logseq.kv/schema-version  ; Graph's current version
db-schema/version          ; Expected version

Migrations handle schema upgrades between versions (65.0 → 65.12+).

Malli Validation Flow

  1. Entity transformation: Properties → [property-map value] tuples
  2. Schema dispatch: Validation dispatches on :logseq.property/type
  3. Value validation: Individual values checked against type schemas
  4. Cardinality handling: Automatic :many vs :one handling
  5. Transaction validation: validate-tx-report ensures integrity

Node Model

Unified Node Concept

In DB version, nodes represent both pages and blocks:

Node
├── Page (unique by tag combination)
│   ├── Journal pages (#Journal)
│   ├── Regular pages (#Page)
│   └── Class pages (#Tag)
└── Block (within pages)
    ├── Content blocks
    ├── Property blocks
    └── Convertible to page via #Page tag

Page Uniqueness

Pages are unique by their tag combination:

  • "Apple #Company" ≠ "Apple #Fruit"
  • Both can coexist as separate entities

Common Patterns

Creating a Custom Class

clojure
;; Define a class with properties
{:db/ident :user.class/Book
 :block/tags [:logseq.class/Tag]
 :block/title "Book"
 :logseq.property.class/extends :logseq.class/Root
 :logseq.property/schema-classes
   [:user.property/author
    :user.property/isbn
    :user.property/rating]}

Creating a Typed Property

clojure
;; Number property with choices
{:db/ident :user.property/rating
 :block/title "Rating"
 :logseq.property/type :number
 :logseq.property/cardinality :one
 :logseq.property/closed-values [1 2 3 4 5]}

Resources

When users need more information, reference:

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