From 602728895e7c35ed1f434acb8af6acfaa66033f3 Mon Sep 17 00:00:00 2001
From: Sarah Hoffmann <lonvia@denofr.de>
Date: Thu, 29 Apr 2021 21:57:43 +0200
Subject: [PATCH] indexer: fetch ids in batches

---
 nominatim/indexer/indexer.py | 46 ++++++++++++++++++++++++++++++------
 1 file changed, 39 insertions(+), 7 deletions(-)

diff --git a/nominatim/indexer/indexer.py b/nominatim/indexer/indexer.py
index d0c6ea0c..41535af8 100644
--- a/nominatim/indexer/indexer.py
+++ b/nominatim/indexer/indexer.py
@@ -183,6 +183,9 @@ class Indexer:
                 total_tuples = cur.scalar(runner.sql_count_objects())
                 LOG.debug("Total number of rows: %i", total_tuples)
 
+                hstore_oid = cur.scalar("SELECT 'hstore'::regtype::oid")
+                hstore_array_oid = cur.scalar("SELECT 'hstore[]'::regtype::oid")
+
             conn.commit()
 
             progress = ProgressLogger(runner.name(), total_tuples)
@@ -191,20 +194,49 @@ class Indexer:
                 with conn.cursor(name='places') as cur:
                     cur.execute(runner.sql_get_objects())
 
+                    fetcher = DBConnection(self.dsn)
+                    psycopg2.extras.register_hstore(fetcher.conn,
+                                                    oid=hstore_oid,
+                                                    array_oid=hstore_array_oid)
+
                     with WorkerPool(self.dsn, self.num_threads) as pool:
-                        while True:
-                            places = cur.fetchmany(batch)
+                        places = self._fetch_next_batch(cur, fetcher, runner)
+                        while places is not None:
                             if not places:
-                                break
+                                fetcher.wait()
+                                places = fetcher.cursor.fetchall()
+
+                            # asynchronously get the next batch
+                            next_places = self._fetch_next_batch(cur, fetcher, runner)
 
-                            LOG.debug("Processing places: %s", str(places))
-                            worker = pool.next_free_worker()
+                            # And insert the curent batch
+                            for idx in range(0, len(places), batch):
+                                worker = pool.next_free_worker()
+                                part = places[idx:idx+batch]
+                                LOG.debug("Processing places: %s", str(part))
+                                runner.index_places(worker, part)
+                                progress.add(len(part))
 
-                            runner.index_places(worker, places)
-                            progress.add(len(places))
+                            places = next_places
 
                         pool.finish_all()
 
+                    fetcher.wait()
+                    fetcher.close()
+
                 conn.commit()
 
         progress.done()
+
+
+    def _fetch_next_batch(self, cur, fetcher, runner):
+        ids = cur.fetchmany(1000)
+
+        if not ids:
+            return None
+
+        if not hasattr(runner, 'get_place_details'):
+            return ids
+
+        runner.get_place_details(fetcher, ids)
+        return []
-- 
2.39.5