Review comment, and handle case of online_delete not having

happened before.

src/ripple/app/misc/SHAMapStore.h

@@ -70,7 +70,34 @@ class SHAMapStore
     virtual int fdRequired() const = 0;
 
     /** If online deletion is enabled, return the minimum ledger
-     * to keep. */
+     * to keep online, which is the lower bound for attempting to acquire
+     * historical ledgers over the peer to peer network.
+     *
+     * This value is governed by the following circumstances:
+     *
+     * Upon process startup:
+     *
+     * With advisory_delete enabled and online_delete having been executed
+     * previously:
+     * Upon process startup, this value is set to one past the value
+     * that is allowed to be deleted. In other words, anything greater
+     * than what can be deleted should be acquired from the network and
+     * then retained. If nothing has yet been deleted, then do not
+     * rely upon the value of what is allowed to be deleted because it
+     * could cause fetching of more history than configured by
+     * ledger_history.
+     *
+     * Without advisory_delete or if online_delete has never executed:
+     * Upon process startup, this value is set to the earliest ledger
+     * that has been persisted in SQLite.
+     *
+     * Each time online_delete executes:
+     *
+     * Just prior to clearing SQL databases of historical ledgers, move
+     * the value forward to one past the greatest ledger being deleted.
+     * This minimizes fetching of ledgers that are in the process of being
+     * deleted.
+     */
     virtual std::optional<LedgerIndex> const minimumOnline() const = 0;
 };
 

src/ripple/app/misc/SHAMapStoreImp.cpp

@@ -330,7 +330,7 @@ SHAMapStoreImp::run()
     transactionDb_ = &app_.getTxnDB();
     ledgerDb_ = &app_.getLedgerDB();
 
-    if (advisoryDelete_)
+    if (advisoryDelete_ && state_db_.getState().lastRotated)
     {
         canDelete_ = state_db_.getCanDelete();
         // On startup, don't acquire ledgers from the network that