MySQL & MariaDB Support

Relevant source files

The following files were used as context for generating this wiki page:

• src/mysql/mod.rs
• src/mysql/def/system.rs
• src/mysql/parser/system.rs
• README.md
• CHANGELOG.md
• tests/live/mysql/src/main.rs
• src/mysql/def/mod.rs

SeaSchema provides a robust framework for managing database schemas specifically tailored for MySQL and MariaDB. It maps database structures to Rust type definitions, allowing developers to perform schema discovery, parsing, and SQL generation (writing) with high precision. The library treats MySQL and MariaDB as closely related but distinct systems, providing specific logic to handle their versioning and feature differences, such as MariaDB's SYSTEM VERSIONED tables.

Sources: README.md:9-12, CHANGELOG.md:129-130, src/mysql/def/system.rs:18-26

Architecture and Module Structure

The MySQL support is organized into specialized modules that handle different stages of the schema management lifecycle. These modules are conditionally compiled based on feature flags such as def, discovery, parser, query, writer, and probe.

Key Components

Component	Description
def	Contains structures for TableDef, ColumnInfo, IndexInfo, and ForeignKeyInfo.
query	Executes specific SQL against INFORMATION_SCHEMA to retrieve raw metadata.
parser	Converts raw query results into structured Rust types defined in def.
discovery	Orchestrates the process of connecting to a database and building a complete Schema.
writer	Translates TableDef and other structures into sea-query statements or raw SQL.

Sources: README.md:23-28, src/mysql/def/mod.rs:3-13

System Identification and Versioning

SeaSchema distinguishes between MySQL and MariaDB by parsing the system version string. This is critical for handling vendor-specific features like MariaDB's unique table versioning or specific index types.

SystemInfo Structure

The SystemInfo struct stores the parsed version and identifies the vendor. The version is stored as a u32 using a calculated formula: major * 10000 + minor * 100 + sub_version.

pub struct SystemInfo {
    pub version: u32,
    pub system: String, // e.g., "MariaDB" or "0ubuntu0.*"
    pub suffix: Vec<String>,
}

Sources: src/mysql/def/system.rs:5-13

Parsing Logic

The parser splits the version string (e.g., 10.2.31-MariaDB) to extract the numeric version and the system identifier.

Schema Discovery and Definition

Schema discovery involves mapping physical database tables to the TableDef structure. This includes capturing metadata such as storage engines (e.g., InnoDB), character sets (e.g., utf8mb4), and specific column attributes.

Table Definition Metadata

The library captures extensive details about MySQL tables:

• Columns: Type (e.g., SmallInt, Timestamp), nullability, default values, and extra attributes (e.g., auto_increment, on_update_current_timestamp).
• Indexes: Type (BTree, Vector), uniqueness, and functional status.
• Foreign Keys: Referenced tables/columns and referential actions (Cascade, Restrict).

Sources: README.md:37-149, CHANGELOG.md:30-31, tests/live/mysql/src/main.rs:136-152

Data Type Mapping

SeaSchema handles a wide array of MySQL-specific types and attributes:

• Numeric Attributes: Unsigned flags and zerofill.
• Time Attributes: Fractional seconds for timestamps and CURRENT_TIMESTAMP defaults.
• PlanetScale Support: Includes IndexType::Vector support when the planetscale feature is enabled.

Sources: README.md:58-63, CHANGELOG.md:29-30, tests/live/mysql/src/main.rs:293-300

Live Testing and SQL Generation

The tests/live/mysql/src/main.rs file demonstrates how the library performs end-to-end schema synchronization. It creates tables using sea-query, discovers them back into TableDef objects, and then verifies that the writer can regenerate the original SQL.

Conclusion

MySQL and MariaDB support in SeaSchema is built to provide high-fidelity mapping between Rust code and database schemas. By leveraging specialized modules for parsing system versions and information schema metadata, it enables automated migration and discovery workflows that are aware of the subtle differences between MySQL versions and MariaDB forks.