wallet/db.c: Speed up deletion of single peers.

ChangeLog-Fixed: Database: Speed up deletion of peer especially when there is a long history with that peer.

Author: ZmnSCPxj

wallet/db.c

@@ -669,6 +669,11 @@ static struct migration dbmigrations[] = {
     /* A reference into our own offers table, if it was made from one */
     {SQL("ALTER TABLE payments ADD COLUMN local_offer_id BLOB DEFAULT NULL REFERENCES offers(offer_id);"), NULL},
     {SQL("ALTER TABLE channels ADD funding_tx_remote_sigs_received INTEGER DEFAULT 0;"), NULL},
+
+    /* Speeds up deletion of one peer from the database, measurements suggest
+     * it cuts down the time by 80%.  */
+    {SQL("CREATE INDEX forwarded_payments_out_htlc_id"
+	 " ON forwarded_payments (out_htlc_id);"), NULL},
 };
 
 /* Leak tracking. */