document incremental stuck fix bug

doc/stuck.md

@@ -0,0 +1,34 @@
+
+# Stuck incremental rendering
+
+In case the incremental rendering is stuck (a bug between 1.0.1 and 2.0.0)
+NOTE: this is for the mapserver database, NOT the map database!
+
+## Sqlite
+
+Execute this command in the sqlite database (`sqlite3 ./mapserver.sqlite`)
+
+```
+update settings
+set value = strftime('%s', 'now')
+where key = 'last_mtime';
+```
+
+This will reset the current rendering time to now
+
+## Postgres
+
+For postgresql:
+
+Enter the shell (for example):
+```
+psql -U postgres
+```
+
+And reset the current mtime
+```
+update settings
+set value = floor(EXTRACT(EPOCH from now()) * 1000)
+where key = 'last_mtime';
+```
+