Stored Procedures & Functions

Call stored procedures and user-defined functions across all supported databases with type-safe parameter handling.

Overview

Prax provides a unified API for calling stored procedures and functions across PostgreSQL, MySQL, MSSQL, and SQLite. Support includes IN/OUT/INOUT parameters, table-valued functions, and custom aggregates.

Feature	PostgreSQL	MySQL	SQLite	MSSQL	MongoDB
Stored Procedures	✅	✅	❌	✅	❌
User-Defined Functions	✅	✅	✅ Rust	✅	✅ $function
Table-Valued Functions	✅	❌	❌	✅	❌
Aggregate Functions	✅	✅	✅ Rust	✅	✅ $accumulator

Calling Procedures

Use ProcedureCall to invoke stored procedures with type-safe parameters.

OUT and INOUT Parameters

Handle output parameters with ParameterMode.

User-Defined Functions

Call scalar and table-valued functions with the same fluent API.

SQLite Rust UDFs

Since SQLite doesn't support stored procedures, register Rust functions directly with the connection.

Note: SQLite UDFs are registered per-connection. Use the connection pool's after_connect hook to register functions on all connections.

MongoDB $function & $accumulator

Define custom JavaScript functions for MongoDB aggregation pipelines.

Procedure Migrations

Version control your stored procedures with Prax migrations. The differ detects changes automatically.

Generated SQL by Database

Prax generates the correct syntax for each database:

Best Practices

Use Transactions

Wrap procedure calls in transactions when they modify data. Some procedures handle their own transactions—check the procedure definition.

Handle Multiple Result Sets

Some procedures return multiple result sets. Use result.next_result_set() to iterate through them.

Version Control Procedures

Keep procedure definitions in migrations. Use ProcedureDiffer to detect changes and generate appropriate ALTER/DROP/CREATE statements.

Avoid N+1 with Procedures

Don't call procedures in a loop. Batch operations when possible, or design procedures to accept arrays/table-valued parameters.