add new geoalchemy requirement

[nominatim.git] / docs / customize / Settings.md

diff --git a/docs/customize/Settings.md b/docs/customize/Settings.md
index d080dc77b2f77ce5b18c705507ac40664f50a3d6..bb552744ddc3aec13ab3637e4d927e073221f81b 100644 (file)
--- a/docs/customize/Settings.md
+++ b/docs/customize/Settings.md
@@ -148,6 +148,29 @@ Setting this option to 'yes' means that Nominatim skips reindexing of contained
 objects when the area becomes too large.
 
 
+#### NOMINATIM_UPDATE_FORWARD_DEPENDENCIES
+
+| Summary            |                                                     |
+| --------------     | --------------------------------------------------- |
+| **Description:**   | Forward geometry changes to dependet objects |
+| **Format:**        | bool |
+| **Default:**       | no |
+| **Comment:**       | EXPERT ONLY. Must not be enabled after import. |
+
+The geometry of OSM ways and relations may change when a node that is part
+of the object is moved around. These changes are not propagated per default.
+The geometry of ways/relations is only updated the next time that the object
+itself is touched. When enabling this option, then dependent objects will
+be marked for update when one of its member objects changes.
+
+Enabling this option may slow down updates significantly.
+
+!!! warning
+    If you want to enable this option, it must be set already on import.
+    Do not enable this option on an existing database that was imported with
+    NOMINATIM_UPDATE_FORWARD_DEPENDENCIES=no.
+    Updates will become unusably slow.
+
 #### NOMINATIM_LANGUAGES
 
 | Summary            |                                                     |
@@ -643,7 +666,7 @@ The entries in the log file have the following format:
     <request time> <execution time in s> <number of results> <type> "<query string>"
 
 Request time is the time when the request was started. The execution time is
-given in ms and corresponds to the time the query took executing in PHP.
+given in seconds and corresponds to the time the query took executing in PHP.
 type contains the name of the endpoint used.
 
 Can be used as the same time as NOMINATIM_LOG_DB.