Fixed reading of dict-encoded, plain pages (fallback). (#367)

src/io/parquet/read/binary/basic.rs

@@ -231,15 +231,15 @@ fn extend_from_page<O: Offset>(
             values,
             validity,
         ),
-        (Encoding::Plain, None, true) => read_plain_optional::<O>(
+        (Encoding::Plain, _, true) => read_plain_optional::<O>(
             validity_buffer,
             values_buffer,
             page.num_values(),
             offsets,
             values,
             validity,
         ),
-        (Encoding::Plain, None, false) => {
+        (Encoding::Plain, _, false) => {
             read_plain_required::<O>(page.buffer(), page.num_values(), offsets, values)
         }
         _ => {

src/io/parquet/read/fixed_size_binary.rs

@@ -210,15 +210,17 @@ pub(crate) fn extend_from_page(
             values,
             validity,
         ),
-        (Encoding::Plain, None, true) => read_optional(
+        (Encoding::Plain, _, true) => read_optional(
             validity_buffer,
             values_buffer,
             page.num_values() as u32,
             size,
             values,
             validity,
         ),
-        (Encoding::Plain, None, false) => {
+        // it can happen that there is a dictionary but the encoding is plain because
+        // it falled back.
+        (Encoding::Plain, _, false) => {
             read_required(page.buffer(), page.num_values() as u32, size, values)
         }
         _ => {

src/io/parquet/read/primitive/basic.rs

@@ -168,15 +168,17 @@ where
                 op,
             )
         }
-        (Encoding::Plain, None, true) => read_nullable(
+        // it can happen that there is a dictionary but the encoding is plain because
+        // it falled back.
+        (Encoding::Plain, _, true) => read_nullable(
             validity_buffer,
             values_buffer,
             additional,
             values,
             validity,
             op,
         ),
-        (Encoding::Plain, None, false) => read_required(page.buffer(), additional, values, op),
+        (Encoding::Plain, _, false) => read_required(page.buffer(), additional, values, op),
         _ => {
             return Err(other_utils::not_implemented(
                 &page.encoding(),