crates/integrations/datafusion/src/table/metadata_table.rs

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// to you under the Apache License, Version 2.0 (the
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//
//   http://www.apache.org/licenses/LICENSE-2.0
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use std::sync::Arc;

use async_trait::async_trait;
use datafusion::arrow::array::RecordBatch;
use datafusion::arrow::datatypes::SchemaRef as ArrowSchemaRef;
use datafusion::catalog::Session;
use datafusion::datasource::{TableProvider, TableType};
use datafusion::error::Result as DFResult;
use datafusion::logical_expr::Expr;
use datafusion::physical_plan::ExecutionPlan;
use futures::TryStreamExt;
use futures::stream::BoxStream;
use iceberg::arrow::schema_to_arrow_schema;
use iceberg::inspect::MetadataTableType;
use iceberg::table::Table;

use crate::physical_plan::metadata_scan::IcebergMetadataScan;
use crate::to_datafusion_error;

/// Represents a [`TableProvider`] for the Iceberg [`iceberg::Catalog`],
/// managing access to a [`iceberg::inspect::MetadataTable`].
#[derive(Debug, Clone)]
pub struct IcebergMetadataTableProvider {
    pub(crate) table: Table,
    pub(crate) r#type: MetadataTableType,
}

#[async_trait]
impl TableProvider for IcebergMetadataTableProvider {
    fn schema(&self) -> ArrowSchemaRef {
        let metadata_table = self.table.inspect();
        let schema = match self.r#type {
            MetadataTableType::Snapshots => metadata_table.snapshots().schema(),
            MetadataTableType::Manifests => metadata_table.manifests().schema(),
            MetadataTableType::History => metadata_table.history().schema(),
        };
        schema_to_arrow_schema(&schema).unwrap().into()
    }

    fn table_type(&self) -> TableType {
        TableType::Base
    }

    async fn scan(
        &self,
        _state: &dyn Session,
        _projection: Option<&Vec<usize>>,
        _filters: &[Expr],
        _limit: Option<usize>,
    ) -> DFResult<Arc<dyn ExecutionPlan>> {
        Ok(Arc::new(IcebergMetadataScan::new(self.clone())))
    }
}

impl IcebergMetadataTableProvider {
    pub async fn scan(self) -> DFResult<BoxStream<'static, DFResult<RecordBatch>>> {
        let metadata_table = self.table.inspect();
        let stream = match self.r#type {
            MetadataTableType::Snapshots => metadata_table.snapshots().scan().await,
            MetadataTableType::Manifests => metadata_table.manifests().scan().await,
            MetadataTableType::History => metadata_table.history().scan().await,
        }
        .map_err(to_datafusion_error)?;
        let stream = stream.map_err(to_datafusion_error);
        Ok(Box::pin(stream))
    }
}