#database #sql #mysql #postgres #sqlite

sea-schema-derive

Derive macro for sea-schema’s Name trait

1 unstable release

0.1.0 Apr 8, 2021

#26 in #mysql


Used in 2 crates (via sea-schema)

MIT/Apache

6KB
121 lines

SeaSchema

🌿 SQL schema definition and discovery

crate docs build status

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About

SeaSchema is a library to help you manage database schema. It provides data structures for representing schema definitions and tools to discover and manipulate them.

For now, MySQL support is done and Postgres support is in progress. At the end, we'd want to support schema conversion between MySQL and Postgres.

Architecture

You can use SeaSchema for many purposes, so the crate is divided into 5 features:

  • def: type definitions
  • query: query builder for querying information_schema
  • parser: for parsing information_schema (parsing sqldump is WIP)
  • writer: for writing Schema as TableStatement and SQL
  • discovery: query, parse and construct a Schema

JSON de/serialize on type definitions can be enabled with with-serde.

Example

Take the MySQL Sakila Sample Database as example, given the following table:

CREATE TABLE film_actor (
  actor_id SMALLINT UNSIGNED NOT NULL,
  film_id SMALLINT UNSIGNED NOT NULL,
  last_update TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY  (actor_id,film_id),
  KEY idx_fk_film_id (`film_id`),
  CONSTRAINT fk_film_actor_actor FOREIGN KEY (actor_id) REFERENCES actor (actor_id) ON DELETE RESTRICT ON UPDATE CASCADE,
  CONSTRAINT fk_film_actor_film FOREIGN KEY (film_id) REFERENCES film (film_id) ON DELETE RESTRICT ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

The discovered schema result:

TableDef {
    info: TableInfo {
        name: "film_actor",
        engine: InnoDb,
        auto_increment: None,
        char_set: Utf8Mb4,
        collation: Utf8Mb40900AiCi,
        comment: "",
    },
    columns: [
        ColumnInfo {
            name: "actor_id",
            col_type: SmallInt(
                NumericAttr {
                    maximum: None,
                    decimal: None,
                    unsigned: Some(
                        true,
                    ),
                    zero_fill: None,
                },
            ),
            null: false,
            key: Primary,
            default: None,
            extra: ColumnExtra {
                auto_increment: false,
                on_update_current_timestamp: false,
                generated: false,
                default_generated: false,
            },
            expression: None,
            comment: "",
        },
        ColumnInfo {
            name: "film_id",
            col_type: SmallInt(
                NumericAttr {
                    maximum: None,
                    decimal: None,
                    unsigned: Some(
                        true,
                    ),
                    zero_fill: None,
                },
            ),
            null: false,
            key: Primary,
            default: None,
            extra: ColumnExtra {
                auto_increment: false,
                on_update_current_timestamp: false,
                generated: false,
                default_generated: false,
            },
            expression: None,
            comment: "",
        },
        ColumnInfo {
            name: "last_update",
            col_type: Timestamp(
                TimeAttr {
                    fractional: None,
                },
            ),
            null: false,
            key: NotKey,
            default: Some(
                ColumnDefault {
                    expr: "CURRENT_TIMESTAMP",
                },
            ),
            extra: ColumnExtra {
                auto_increment: false,
                on_update_current_timestamp: true,
                generated: false,
                default_generated: true,
            },
            expression: None,
            comment: "",
        },
    ],
    indexes: [
        IndexInfo {
            unique: false,
            name: "idx_fk_film_id",
            parts: [
                IndexPart {
                    column: "film_id",
                    order: Ascending,
                    sub_part: None,
                },
            ],
            nullable: false,
            idx_type: BTree,
            comment: "",
            functional: false,
        },
        IndexInfo {
            unique: true,
            name: "PRIMARY",
            parts: [
                IndexPart {
                    column: "actor_id",
                    order: Ascending,
                    sub_part: None,
                },
                IndexPart {
                    column: "film_id",
                    order: Ascending,
                    sub_part: None,
                },
            ],
            nullable: false,
            idx_type: BTree,
            comment: "",
            functional: false,
        },
    ],
    foreign_keys: [
        ForeignKeyInfo {
            name: "fk_film_actor_actor",
            columns: [
                "actor_id",
            ],
            referenced_table: "actor",
            referenced_columns: [
                "actor_id",
            ],
            on_update: Cascade,
            on_delete: Restrict,
        },
        ForeignKeyInfo {
            name: "fk_film_actor_film",
            columns: [
                "film_id",
            ],
            referenced_table: "film",
            referenced_columns: [
                "film_id",
            ],
            on_update: Cascade,
            on_delete: Restrict,
        },
    ],
}

Dependencies

~0.7–1.2MB
~24K SLoC