1 files changed, 51 insertions, 0 deletions
diff --git a/platform/default/include/mbgl/storage/merge_sideloaded.sql b/platform/default/include/mbgl/storage/merge_sideloaded.sql
new file mode 100644
index 0000000000..55345a6f15
--- /dev/null
+++ b/platform/default/include/mbgl/storage/merge_sideloaded.sql
@@ -0,0 +1,51 @@
+INSERT INTO regions
+   SELECT DISTINCT NULL, sr.definition, sr.description -- Merge duplicate regions
+    FROM side.regions sr 
+    LEFT JOIN regions r ON sr.definition = r.definition AND sr.description IS r.description
+      WHERE r.definition IS NULL;
+
+CREATE TEMPORARY TABLE region_mapping AS
+    SELECT sr.id AS side_region_id,
+      r.id AS main_region_id
+    FROM side.regions sr
+    JOIN regions r ON sr.definition = r.definition  AND sr.description IS r.description;
+
+--Insert /Update tiles
+REPLACE INTO tiles
+    SELECT t.id, -- use the old ID in case we run a REPLACE. If it doesn't exist yet, it'll be NULL which will auto-assign a new ID.
+        st.url_template, st.pixel_ratio, st.z, st.x, st.y,
+        st.expires, st.modified, st.etag, st.data, st.compressed, st.accessed, st.must_revalidate
+    FROM (SELECT DISTINCT sti.* FROM side.region_tiles srt JOIN side.tiles sti ON srt.tile_id = sti.id)   -- ensure that we're only considering region tiles, and not ambient tiles.
+    AS st
+    LEFT JOIN tiles t ON st.url_template = t.url_template AND st.pixel_ratio = t.pixel_ratio AND st.z = t.z AND st.x = t.x AND st.y = t.y
+        WHERE t.id IS NULL -- only consider tiles that don't exist yet in the original database.
+        OR st.modified > t.modified; -- ...or tiles that are newer in the side loaded DB.
+
+-- Update region_tiles usage
+INSERT OR IGNORE INTO region_tiles
+    SELECT rm.main_region_id, sti.id
+    FROM side.region_tiles srt
+    JOIN region_mapping rm ON srt.region_id = rm.side_region_id
+    JOIN (SELECT t.id, st.id AS side_tile_id FROM side.tiles st
+            JOIN tiles t ON st.url_template = t.url_template AND st.pixel_ratio = t.pixel_ratio AND st.z = t.z AND st.x = t.x AND st.y = t.y
+    ) AS sti ON srt.tile_id = sti.side_tile_id;
+
+-- copy over resources
+REPLACE INTO resources
+    SELECT r.id, 
+        sr.url, sr.kind, sr.expires, sr.modified, sr.etag,
+        sr.data, sr.compressed, sr.accessed, sr.must_revalidate
+    FROM side.region_resources srr JOIN side.resources sr ON srr.resource_id = sr.id   --only consider region resources, and not ambient resources.
+    LEFT JOIN resources r ON sr.url = r.url
+        WHERE r.id IS NULL -- only consider resources that don't exist yet in the main database
+        OR sr.modified > r.modified; -- ...or resources that are newer in the side loaded DB.
+
+-- Update region_resources usage
+INSERT OR IGNORE INTO region_resources
+  SELECT rm.main_region_id, sri.id
+  FROM side.region_resources srr
+  JOIN region_mapping rm ON srr.region_id = rm.side_region_id
+  JOIN (SELECT r.id, sr.id AS side_resource_id FROM side.resources sr
+          JOIN resources r ON sr.url = r.url) AS sri  ON srr.resource_id = sri.side_resource_id;
+ 
+DROP TABLE region_mapping;
+\ No newline at end of file