CSharpDB.Execution 1.1.0

CSharpDB.Execution

Query planner, operator tree, and expression evaluator for the CSharpDB embedded database engine.

Overview

CSharpDB.Execution transforms parsed SQL (AST from CSharpDB.Sql) into executable query plans. It implements the classic iterator model with physical operators for scans, joins, aggregation, sorting, filtering, and projection. Expression evaluation is handled by both an interpreter (for one-off use) and a compiler (for hot-path evaluation with column binding at compile time).

Key Components

Query Planner

• Translates AST statements into physical operator trees
• Dispatches to type-specific handlers for all DDL and DML statements
• System catalog virtual tables: system_tables, system_columns, system_indexes, system_views, system_triggers
• Compiled expression cache (up to 4096 entries) for repeated queries
• Trigger body caching with schema-sensitive invalidation
• Sync point-lookup fast path for SELECT ... WHERE pk = value

Operator Tree (Iterator Model)

• IOperator interface: OpenAsync, MoveNextAsync, Current, OutputSchema
• TableScanOperator with pre-decode filtering, projection pushdown, and row count estimation
• Join operators, filter, sort, aggregate, limit/offset, projection, and more
• Internal optimization interfaces: IPreDecodeFilterSupport, IProjectionPushdownTarget, IMaterializedRowsProvider

Expression Evaluation

• ExpressionEvaluator - Static interpreter for simple/infrequent evaluations
• ExpressionCompiler - Compiles expression ASTs into Func<DbValue[], DbValue> delegates with column indices bound at compile time, eliminating per-row schema lookups

Query Result

• Wraps operator output (SELECT) or rows-affected counts (DML/DDL)
• Sync fast-path for point lookups via FromSyncLookup
• ToListAsync for materializing full result sets

Usage

using CSharpDB.Execution;
using CSharpDB.Sql;

// Parse SQL
var statements = Parser.Parse("SELECT name, age FROM users WHERE age > 21");

// Plan and execute (typically called through CSharpDB.Engine)
var planner = new QueryPlanner(storageContext);
var result = await planner.ExecuteAsync(statements[0]);

// Iterate results
while (await result.MoveNextAsync())
{
    DbValue[] row = result.Current;
    Console.WriteLine($"{row[0].AsText}, {row[1].AsInteger}");
}

Installation

dotnet add package CSharpDB.Execution

Dependencies

• CSharpDB.Core - shared type system
• CSharpDB.Sql - SQL parser and AST
• CSharpDB.Storage - B+tree storage engine

Related Packages

License

MIT - see LICENSE for details.