Merge remote-tracking branch 'upstream/master'

[nominatim.git] / docs / admin / Migration.md

diff --git a/docs/admin/Migration.md b/docs/admin/Migration.md
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--- a/docs/admin/Migration.md
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@@ -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