+def import_wikipedia_articles(dsn, data_path, ignore_errors=False):
+ """ Replaces the wikipedia importance tables with new data.
+ The import is run in a single transaction so that the new data
+ is replace seemlessly.
+
+ Returns 0 if all was well and 1 if the importance file could not
+ be found. Throws an exception if there was an error reading the file.
+ """
+ datafile = data_path / 'wikimedia-importance.sql.gz'
+
+ if not datafile.exists():
+ return 1
+
+ pre_code = """BEGIN;
+ DROP TABLE IF EXISTS "wikipedia_article";
+ DROP TABLE IF EXISTS "wikipedia_redirect"
+ """
+ post_code = "COMMIT"
+ execute_file(dsn, datafile, ignore_errors=ignore_errors,
+ pre_code=pre_code, post_code=post_code)
+
+ return 0
+
+
+def recompute_importance(conn):
+ """ Recompute wikipedia links and importance for all entries in placex.
+ This is a long-running operations that must not be executed in
+ parallel with updates.
+ """
+ with conn.cursor() as cur:
+ cur.execute('ALTER TABLE placex DISABLE TRIGGER ALL')
+ cur.execute("""
+ UPDATE placex SET (wikipedia, importance) =
+ (SELECT wikipedia, importance
+ FROM compute_importance(extratags, country_code, osm_type, osm_id))
+ """)
+ cur.execute("""
+ UPDATE placex s SET wikipedia = d.wikipedia, importance = d.importance
+ FROM placex d
+ WHERE s.place_id = d.linked_place_id and d.wikipedia is not null
+ and (s.wikipedia is null or s.importance < d.importance);
+ """)
+
+ cur.execute('ALTER TABLE placex ENABLE TRIGGER ALL')
+ conn.commit()
+
+