diff --git a/include/ircd/m/vm.h b/include/ircd/m/vm.h
index 4e1a9b8bd..646e1f0b7 100644
--- a/include/ircd/m/vm.h
+++ b/include/ircd/m/vm.h
@@ -176,6 +176,7 @@ enum ircd::m::vm::phase
 	FETCH_PREV,            ///< Previous events fetch phase.
 	FETCH_STATE,           ///< State events fetch phase.
 	PRECOMMIT,             ///< Precommit sequence.
+	PREINDEX,              ///< Prefetch indexing & transaction dependencies.
 	AUTH_RELA,             ///< Relative authentication phase.
 	COMMIT,                ///< Commit sequence.
 	AUTH_PRES,             ///< Authentication phase.
diff --git a/matrix/homeserver_bootstrap.cc b/matrix/homeserver_bootstrap.cc
index c7b697c85..9506dabc1 100644
--- a/matrix/homeserver_bootstrap.cc
+++ b/matrix/homeserver_bootstrap.cc
@@ -247,6 +247,7 @@ try
 
 	// Primary interest is to perform the INDEX and WRITE phase which create
 	// a database transaction and commit it respectively.
+	vmopts.phase.set(vm::phase::PREINDEX, true);
 	vmopts.phase.set(vm::phase::INDEX, true);
 	vmopts.phase.set(vm::phase::WRITE, true);
 
diff --git a/matrix/vm.cc b/matrix/vm.cc
index 57e0d3a90..db6ce8ae6 100644
--- a/matrix/vm.cc
+++ b/matrix/vm.cc
@@ -178,6 +178,7 @@ ircd::m::vm::reflect(const enum phase &code)
 		case phase::FETCH_PREV:   return "FETCH_PREV";
 		case phase::FETCH_STATE:  return "FETCH_STATE";
 		case phase::PRECOMMIT:    return "PRECOMMIT";
+		case phase::PREINDEX:     return "PREINDEX";
 		case phase::AUTH_RELA:    return "AUTH_RELA";
 		case phase::COMMIT:       return "COMMIT";
 		case phase::AUTH_PRES:    return "AUTH_PRES";
diff --git a/matrix/vm_execute.cc b/matrix/vm_execute.cc
index 6de3330af..abf368c7b 100644
--- a/matrix/vm_execute.cc
+++ b/matrix/vm_execute.cc
@@ -869,6 +869,22 @@ ircd::m::vm::execute_pdu(eval &eval,
 		&& eval.parent->event_->event_id
 	};
 
+	// Allocate transaction; prefetch dependencies.
+	if(likely(opts.phase[phase::PREINDEX]))
+	{
+		const scope_restore eval_phase
+		{
+			eval.phase, phase::PREINDEX
+		};
+
+		dbs::write_opts wopts(opts.wopts);
+		wopts.event_idx = eval.sequence;
+		const size_t prefetched
+		{
+			dbs::prefetch(event, wopts)
+		};
+	}
+
 	const scope_restore eval_phase_precommit
 	{
 		eval.phase, phase::PRECOMMIT
@@ -1151,6 +1167,7 @@ ircd::m::vm::write_append(eval &eval,
 		}
 	}
 
+	assert(eval.txn);
 	const size_t wrote
 	{
 		dbs::write(*eval.txn, event, wopts)