Struct CsvForeignWrapper 

pub struct CsvForeignWrapper;

The CSV wrapper registers under the kind "csv": CREATE SERVER srv FOREIGN DATA WRAPPER csv OPTIONS (base_path '/data/csv').

Trait Implementations

impl ForeignDataWrapper for CsvForeignWrapper

fn kind(&self) -> &'static str

Unique identifier for the wrapper kind (e.g. “csv”, “postgres”). Matches the FOREIGN DATA WRAPPER <name> clause in DDL.

fn build_server_state( &self, options: &FdwOptions, ) -> Result<Option<Arc<dyn WrapperState>>, FdwError>

Validate + materialise a server’s options. Called once on CREATE SERVER and cached on ForeignServer. Wrappers that don’t need per-server state return Ok(None).

fn scan( &self, server_state: Option<&Arc<dyn WrapperState>>, table_options: &FdwOptions, ) -> Result<Vec<UnifiedRecord>, FdwError>

Stream rows from the foreign table. table_options merges the server’s options with the table’s options (table takes priority on conflicts). filter is opaque to the wrapper unless it advertises pushdown via supports_pushdown.

fn estimated_row_count( &self, server_state: Option<&Arc<dyn WrapperState>>, table_options: &FdwOptions, ) -> Option<usize>

Estimated row count — drives planner cost. None means the wrapper has no cheap way to estimate and the planner falls back to its default assumption.

fn supports_pushdown(&self) -> bool

Whether the wrapper can evaluate a SQL WHERE predicate natively. When true, the planner will hand the AST to scan_with_filter; when false, the runtime applies the filter after the scan.