Take more care not to use a stale value for the oldest reader transaction ID.

2 files changed, 8 insertions, 6 deletions

diff --git a/src/include/txn.h b/src/include/txn.h
index ba0a397699f..e87df4bae5d 100644
--- a/src/include/txn.h
+++ b/src/include/txn.h
@@ -80,8 +80,8 @@ struct __wt_txn {
 	 */
 	wt_txnid_t oldest_snap_min;
 
-	/* Saved global state, to avoid scans. */
-	wt_txnid_t last_id;
+	/* Saved global state, to avoid repeating scans. */
+	wt_txnid_t last_id, last_oldest_id;
 	uint32_t last_gen, last_oldest_gen;
 
 	/*
diff --git a/src/txn/txn.c b/src/txn/txn.c
index ae88a19a478..6e2ba2d5e33 100644
--- a/src/txn/txn.c
+++ b/src/txn/txn.c
@@ -76,13 +76,15 @@ __wt_txn_get_oldest(WT_SESSION_IMPL *session)
 	txn = &session->txn;
 	txn_global = &conn->txn_global;
 
+	oldest_snap_min =
+	    (txn->id != WT_TXN_NONE) ? txn->id : txn_global->current;
+
 	/* If nothing has changed since last time, we're done. */
-	if (txn->last_oldest_gen == txn_global->gen)
+	if (txn->last_oldest_gen == txn_global->gen &&
+	    txn->last_oldest_id == oldest_snap_min)
 		return;
 	txn->last_oldest_gen = txn_global->gen;
-
-	oldest_snap_min =
-	    (txn->id != WT_TXN_NONE) ? txn->id : txn_global->current;
+	txn->last_oldest_id = oldest_snap_min;
 
 	WT_ORDERED_READ(session_cnt, conn->session_cnt);
 	for (i = 0, s = txn_global->states;