Substantially optimize reference-row-fetching

[rapid-gossip-sync-server] / src / lookup.rs

diff --git a/src/lookup.rs b/src/lookup.rs
index 8018e5ca19d62a5b564b9f40a777f2aad18100b3..5969b2a10bdbb0727f39c7a7a297c18a810fc02b 100644 (file)
--- a/src/lookup.rs
+++ b/src/lookup.rs
@@ -209,14 +209,17 @@ pub(super) async fn fetch_channel_updates(delta_set: &mut DeltaSet, client: &Cli
        // there was an update in either direction that happened after the last sync (to avoid
        // collecting too many reference updates)
        let reference_rows = client.query("
-               SELECT DISTINCT ON (short_channel_id, direction) id, direction, blob_signed
-               FROM channel_updates
-               WHERE seen < $1 AND short_channel_id IN (
+               SELECT id, direction, blob_signed FROM channel_updates
+               WHERE id IN (
+                       SELECT DISTINCT ON (short_channel_id, direction) id
+                       FROM channel_updates
+                       WHERE seen < $1
+                       ORDER BY short_channel_id ASC, direction ASC, seen DESC
+               ) AND short_channel_id IN (
                        SELECT DISTINCT ON (short_channel_id) short_channel_id
                        FROM channel_updates
                        WHERE seen >= $1
                )
-               ORDER BY short_channel_id ASC, direction ASC, seen DESC
                ", &[&last_sync_timestamp_object]).await.unwrap();
 
        println!("Fetched reference rows ({}): {:?}", reference_rows.len(), start.elapsed());