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diff --git a/reftable/reftable-merged.h b/reftable/reftable-merged.h
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+/*
+ * Copyright 2020 Google LLC
+ *
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file or at
+ * https://developers.google.com/open-source/licenses/bsd
+ */
+
+#ifndef REFTABLE_MERGED_H
+#define REFTABLE_MERGED_H
+
+#include "reftable-iterator.h"
+
+/*
+ * Merged tables
+ *
+ * A ref database kept in a sequence of table files. The merged_table presents a
+ * unified view to reading (seeking, iterating) a sequence of immutable tables.
+ *
+ * The merged tables are on purpose kept disconnected from their actual storage
+ * (eg. files on disk), because it is useful to merge tables aren't files. For
+ * example, the per-workspace and global ref namespace can be implemented as a
+ * merged table of two stacks of file-backed reftables.
+ */
+
+/* A merged table is implements seeking/iterating over a stack of tables. */
+struct reftable_merged_table;
+
+struct reftable_table;
+
+/*
+ * reftable_merged_table_new creates a new merged table. The tables must be
+ * kept alive as long as the merged table is still in use.
+ */
+int reftable_merged_table_new(struct reftable_merged_table **dest,
+			      struct reftable_table **tables, size_t n,
+			      enum reftable_hash hash_id);
+
+/* Initialize a merged table iterator for reading refs. */
+int reftable_merged_table_init_ref_iterator(struct reftable_merged_table *mt,
+					    struct reftable_iterator *it);
+
+/* Initialize a merged table iterator for reading logs. */
+int reftable_merged_table_init_log_iterator(struct reftable_merged_table *mt,
+					    struct reftable_iterator *it);
+
+/* returns the max update_index covered by this merged table. */
+uint64_t
+reftable_merged_table_max_update_index(struct reftable_merged_table *mt);
+
+/* returns the min update_index covered by this merged table. */
+uint64_t
+reftable_merged_table_min_update_index(struct reftable_merged_table *mt);
+
+/* releases memory for the merged_table */
+void reftable_merged_table_free(struct reftable_merged_table *m);
+
+/* return the hash ID of the merged table. */
+enum reftable_hash reftable_merged_table_hash_id(struct reftable_merged_table *m);
+
+#endif