diff --git a/vortex-duckdb/src/exporter/mod.rs b/vortex-duckdb/src/exporter/mod.rs
index 539a6d994a2..0714f6e8f4f 100644
--- a/vortex-duckdb/src/exporter/mod.rs
+++ b/vortex-duckdb/src/exporter/mod.rs
@@ -32,9 +32,12 @@ use vortex::array::ExecutionCtx;
 use vortex::array::arrays::Chunked;
 use vortex::array::arrays::Constant;
 use vortex::array::arrays::Dict;
+use vortex::array::arrays::Filter;
 use vortex::array::arrays::List;
+use vortex::array::arrays::Slice;
 use vortex::array::arrays::StructArray;
 use vortex::array::arrays::struct_::StructArrayExt;
+use vortex::array::matcher::Matcher;
 use vortex::buffer::BitChunks;
 use vortex::encodings::fastlanes::RLE;
 use vortex::encodings::runend::RunEnd;
@@ -220,6 +223,23 @@ fn cached_values_dict(
     Ok(dict)
 }
 
+/// Matches arrays that are not lazy filters or slices. A scan leaves these over its columns, and
+/// executing them lets the encodings below them, run-end for example, be exported as they are
+/// instead of decoded.
+struct NotSliceOrFilter;
+
+impl Matcher for NotSliceOrFilter {
+    type Match<'a> = &'a ArrayRef;
+
+    fn matches(array: &ArrayRef) -> bool {
+        !array.is::<Filter>() && !array.is::<Slice>()
+    }
+
+    fn try_match(array: &ArrayRef) -> Option<Self::Match<'_>> {
+        Self::matches(array).then_some(array)
+    }
+}
+
 /// Create a DuckDB exporter for the given Vortex array.
 fn new_array_exporter_with_flatten(
     array: ArrayRef,
@@ -227,6 +247,8 @@ fn new_array_exporter_with_flatten(
     ctx: &mut ExecutionCtx,
     flatten: bool,
 ) -> VortexResult<Box<dyn ColumnExporter>> {
+    let array = array.execute_until::<NotSliceOrFilter>(ctx)?;
+
     let array = match array.try_downcast::<Constant>() {
         Ok(array) => return constant::new_exporter_with_flatten(array, cache, ctx, flatten),
         Err(array) => array,
diff --git a/vortex-duckdb/src/exporter/primitive.rs b/vortex-duckdb/src/exporter/primitive.rs
index 515ed3bbe24..d023b4616f1 100644
--- a/vortex-duckdb/src/exporter/primitive.rs
+++ b/vortex-duckdb/src/exporter/primitive.rs
@@ -62,6 +62,9 @@ impl<T: NativePType> ColumnExporter for PrimitiveExporter<T> {
 
 #[cfg(test)]
 mod tests {
+    use vortex::array::validity::Validity;
+    use vortex::buffer::BitBuffer;
+    use vortex::buffer::buffer;
     use vortex_array::VortexSessionExecute;
 
     use super::*;
@@ -113,6 +116,31 @@ mod tests {
         );
     }
 
+    /// A validity bitmap that starts inside its first byte cannot be shared with DuckDB, so its
+    /// bits are copied from the bitmap's own offset.
+    #[test]
+    fn test_primitive_exporter_with_offset_validity() -> VortexResult<()> {
+        let validity = [true, true, true, false, true, false, false, true]
+            .into_iter()
+            .collect::<BitBuffer>()
+            .slice(3..);
+        let arr = PrimitiveArray::new(buffer![3i32, 4, 5, 6, 7], Validity::from(validity));
+
+        let mut chunk = DataChunk::new([LogicalType::new(cpp::duckdb_type::DUCKDB_TYPE_INTEGER)]);
+        let mut ctx = SESSION.create_execution_ctx();
+
+        new_exporter(arr, &mut ctx)?.export(0, 5, chunk.get_vector_mut(0), &mut ctx)?;
+        chunk.set_len(5);
+
+        assert_eq!(
+            String::try_from(&*chunk)?,
+            r#"Chunk - [1 Columns]
+- FLAT INTEGER: 5 = [ NULL, 4, NULL, NULL, 7]
+"#
+        );
+        Ok(())
+    }
+
     /// Export a large nullable primitive array over many chunks to exercise the
     /// zero-copy value and validity paths.
     #[test]
diff --git a/vortex-duckdb/src/exporter/rle.rs b/vortex-duckdb/src/exporter/rle.rs
index 483c79f289c..fe3fbf64a59 100644
--- a/vortex-duckdb/src/exporter/rle.rs
+++ b/vortex-duckdb/src/exporter/rle.rs
@@ -254,7 +254,7 @@ mod tests {
         assert_eq!(
             chunk_str,
             r#"Chunk - [1 Columns]
-- FLAT INTEGER: 10 = [ 20, 20, 20, 20, 20, 20, 20, 20, 20, 20]
+- DICTIONARY INTEGER: 10 = [ 20, 20, 20, 20, 20, 20, 20, 20, 20, 20]
 "#
         );
         Ok(())
diff --git a/vortex-duckdb/src/exporter/vector.rs b/vortex-duckdb/src/exporter/vector.rs
index 1e457efed51..5cf4c7adad3 100644
--- a/vortex-duckdb/src/exporter/vector.rs
+++ b/vortex-duckdb/src/exporter/vector.rs
@@ -60,11 +60,11 @@ impl VectorRef {
             unsafe { self.set_validity_data(u64_offset, len, validity_data) };
         } else {
             debug_assert!(zero_copy.is_none() || !offset.is_multiple_of(64));
-            let source = values.bit_buffer().inner().as_slice();
+            let bit_buffer = values.bit_buffer();
             copy_from_slice(
                 unsafe { self.ensure_validity_slice(len) },
-                source,
-                offset,
+                bit_buffer.inner().as_slice(),
+                bit_buffer.offset() + offset,
                 len,
             );
         }
diff --git a/vortex-layout/src/layouts/flat/reader.rs b/vortex-layout/src/layouts/flat/reader.rs
index 38a9bf0218d..2469aaa3dff 100644
--- a/vortex-layout/src/layouts/flat/reader.rs
+++ b/vortex-layout/src/layouts/flat/reader.rs
@@ -145,6 +145,7 @@ impl LayoutReader for FlatReader {
             //  to evaluating the expression.
             let mut array = array.clone().await?;
             let mask = mask.await?;
+            let mut ctx = session.create_execution_ctx();
 
             // Slice the array based on the row mask.
             if row_range.start > 0 || row_range.end < array.len() {
@@ -158,14 +159,12 @@ impl LayoutReader for FlatReader {
                 // after this.
                 let array = array.apply_bound(&expr)?;
                 let array = array.filter(mask.clone())?;
-                let mut ctx = session.create_execution_ctx();
                 let array_mask = array.fill_null(false)?.execute::<Mask>(&mut ctx)?;
 
                 mask.intersect_by_rank(&array_mask)
             } else {
                 // Run over the full array, with a simpler bitand at the end.
                 let array = array.apply_bound(&expr)?;
-                let mut ctx = session.create_execution_ctx();
                 let array_mask = array.fill_null(false)?.execute::<Mask>(&mut ctx)?;
 
                 mask.bitand(&array_mask)