datafusion

structure of datafusion

0.config
datafusion的所有config都写在一个macro!里,这个marco会生成对应的变量

macro_rules! config_namespace {
    (
     $(#[doc = $struct_d:tt])*
     $vis:vis struct $struct_name:ident {
        $(
        $(#[doc = $d:tt])*
        $field_vis:vis $field_name:ident : $field_type:ty, default = $default:expr
        )*$(,)*
    }
    ) => {

        $(#[doc = $struct_d])*
        #[derive(Debug, Clone)]
        #[non_exhaustive]
        $vis struct $struct_name{
            $(
            $(#[doc = $d])*
            $field_vis $field_name : $field_type,
            )*
        }

        impl ConfigField for $struct_name {
            fn set(&mut self, key: &str, value: &str) -> Result<()> {
                let (key, rem) = key.split_once('.').unwrap_or((key, ""));
                match key {
                    $(
                       stringify!($field_name) => self.$field_name.set(rem, value),
                    )*
                    _ => _internal_err!(
                        "Config value \"{}\" not found on {}", key, stringify!($struct_name)
                    )
                }
            }

            fn visit<V: Visit>(&self, v: &mut V, key_prefix: &str, _description: &'static str) {
                $(
                let key = format!(concat!("{}.", stringify!($field_name)), key_prefix);
                let desc = concat!($($d),*).trim();
                self.$field_name.visit(v, key.as_str(), desc);
                )*
            }
        }

        impl Default for $struct_name {
            fn default() -> Self {
                Self {
                    $($field_name: $default),*
                }
            }
        }
    }
}

1.SessionContext
使用SessionConfig来初始化,一步一步地来初始化catalog_list、SessionState(之后会继续分析，目前未知)

pub struct SessionContext {
    /// UUID for the session
    session_id: String,
    /// Session start time
    session_start_time: DateTime<Utc>,
    /// Shared session state for the session
    state: Arc<RwLock<SessionState>>,
}

类似mysql 的con* 负责一个sesson的链接和对应的用户变量

options涵盖了所有的对应config（physical plan/ logical plan etc）
extensions 是个Hashmap : 目前不知道对应什么

pub struct SessionConfig {
    /// Configuration options
    options: ConfigOptions,
    /// Opaque extensions.
    extensions: AnyMap,
}

没太多好分析的，注视里基本上都有了，看一看，这玩意儿就喝THD一样，要的时候往里面塞往里面拿就好
SessionStates

pub struct SessionState {
    /// A unique UUID that identifies the session
    session_id: String,
    /// Responsible for analyzing and rewrite a logical plan before optimization
    analyzer: Analyzer,
    /// Responsible for optimizing a logical plan
    optimizer: Optimizer,
    /// Responsible for optimizing a physical execution plan
    physical_optimizers: PhysicalOptimizer,
    /// Responsible for planning `LogicalPlan`s, and `ExecutionPlan`
    query_planner: Arc<dyn QueryPlanner + Send + Sync>,
    /// Collection of catalogs containing schemas and ultimately TableProviders
    catalog_list: Arc<dyn CatalogList>,
    /// Table Functions
    table_functions: HashMap<String, Arc<TableFunction>>,
    /// Scalar functions that are registered with the context
    scalar_functions: HashMap<String, Arc<ScalarUDF>>,
    /// Aggregate functions registered in the context
    aggregate_functions: HashMap<String, Arc<AggregateUDF>>,
    /// Window functions registered in the context
    window_functions: HashMap<String, Arc<WindowUDF>>,
    /// Deserializer registry for extensions.
    serializer_registry: Arc<dyn SerializerRegistry>,
    /// Session configuration
    config: SessionConfig,
    /// Execution properties
    execution_props: ExecutionProps,
    /// TableProviderFactories for different file formats.
    ///
    /// Maps strings like "JSON" to an instance of  [`TableProviderFactory`]
    ///
    /// This is used to create [`TableProvider`] instances for the
    /// `CREATE EXTERNAL TABLE ... STORED AS <FORMAT>` for custom file
    /// formats other than those built into DataFusion
    table_factories: HashMap<String, Arc<dyn TableProviderFactory>>,
    /// Runtime environment
    runtime_env: Arc<RuntimeEnv>,
}

OPTIMIZER

有四种不同的Analyze类型

InlineTableScan
CountWildcardRule
OperatorToFunction
TypeCoercion
MyAnalyzerRule

LOGICAL OPTIMIZER

这么总结下去太慢了，得找点对应的活才行

TABLE SCAN