X-Git-Url: https://git.openstreetmap.org./nominatim.git/blobdiff_plain/7ecfcf7eaa02231c2d5dbbd8a15720b3266ad344..ab9202b1c2de078822756d447e450610f0815692:/docs/admin/Migration.md

diff --git a/docs/admin/Migration.md b/docs/admin/Migration.md
index 0400ed43..b731c37c 100644
--- a/docs/admin/Migration.md
+++ b/docs/admin/Migration.md
@@ -8,6 +8,30 @@ SQL statements should be executed from the PostgreSQL commandline. Execute
 
 ## 3.5.0 -> master
 
+### Change order during indexing
+
+When reindexing places during updates, there is now a different order used
+which needs a different database index. Create it with the following SQL command:
+
+```sql
+CREATE INDEX idx_placex_pendingsector_rank_address
+  ON placex USING BTREE (rank_address, geometry_sector) where indexed_status > 0;
+```
+
+You can then drop the old index with:
+
+```sql
+DROP INDEX idx_placex_pendingsector
+```
+
+### Unused index
+
+This index has been unused ever since the query using it was changed two years ago. Saves about 12GB on a planet installation.
+
+```sql
+DROP INDEX idx_placex_geometry_reverse_lookupPoint
+```
+
 ### Switching to dotenv
 
 As part of the work changing the configuration format, the configuration for