sea-schema 0.1.4

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Introduction

SeaSchema is a library to help you manage database schema. It provides data structures for representing schema definition and query helpers to discover such schema from INFORMATION_SCHEMA.

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

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 by querying INFORMATION_SCHEMA results in:

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",
            columns: [
                "film_id",
            ],
            order: Ascending,
            sub_part: None,
            nullable: false,
            idx_type: BTree,
            comment: "",
            functional: false,
        },
        IndexInfo {
            unique: true,
            name: "PRIMARY",
            columns: [
                "actor_id",
                "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,
        },
    ],
},