diff --git a/src/backend/storage/aio/read_stream.c b/src/backend/storage/aio/read_stream.c
index 7f0e07d958..b8ea1180e2 100644
--- a/src/backend/storage/aio/read_stream.c
+++ b/src/backend/storage/aio/read_stream.c
@@ -797,6 +797,20 @@ read_stream_next_buffer(ReadStream *stream, void **per_buffer_data)
 	return buffer;
 }
 
+/*
+ * Transitional support for code that would like to perform or skip reads
+ * itself, without using the stream.  Returns, and consumes, the next block
+ * number that would be read by the stream's look-ahead algorithm, or
+ * InvalidBlockNumber if the end of the stream is reached.  Also reports the
+ * strategy that would be used to read it.
+ */
+BlockNumber
+read_stream_next_block(ReadStream *stream, BufferAccessStrategy *strategy)
+{
+	*strategy = stream->ios[0].op.strategy;
+	return read_stream_get_block(stream, NULL);
+}
+
 /*
  * Reset a read stream by releasing any queued up buffers, allowing the stream
  * to be used again for different blocks.  This can be used to clear an
diff --git a/src/include/storage/read_stream.h b/src/include/storage/read_stream.h
index 2f94ee744b..2f98b600f7 100644
--- a/src/include/storage/read_stream.h
+++ b/src/include/storage/read_stream.h
@@ -68,6 +68,8 @@ extern ReadStream *read_stream_begin_relation(int flags,
 											  void *callback_private_data,
 											  size_t per_buffer_data_size);
 extern Buffer read_stream_next_buffer(ReadStream *stream, void **per_buffer_data);
+extern BlockNumber read_stream_next_block(ReadStream *stream,
+										  BufferAccessStrategy *strategy);
 extern ReadStream *read_stream_begin_smgr_relation(int flags,
 												   BufferAccessStrategy strategy,
 												   SMgrRelation smgr,