Don't create bloom filters on the oldest chunk unless configured.

The recent bulk load change meant that we sometimes created a bloom
filter on the oldest chunk when running compact.

Caused performance to drop by 50% in wtperf medium lsm compact job.

2 files changed, 16 insertions, 0 deletions

diff --git a/src/lsm/lsm_tree.c b/src/lsm/lsm_tree.c
index 97360089d48..640af3caf9d 100644
--- a/src/lsm/lsm_tree.c
+++ b/src/lsm/lsm_tree.c
@@ -1222,6 +1222,18 @@ __wt_lsm_compact(WT_SESSION_IMPL *session, const char *name, int *skip)
 		WT_ERR_MSG(session, EINVAL,
 		    "LSM compaction requires active merge threads");
 
+	/*
+	 * We are done if there is a single chunk in the tree and we have
+	 * already created a bloom filter for it or we are configured not to.
+	 */
+	if (lsm_tree->nchunks == 1 &&
+	    (FLD_ISSET(lsm_tree->bloom, WT_LSM_BLOOM_OLDEST) &&
+	    F_ISSET(lsm_tree->chunk[0], WT_LSM_CHUNK_BLOOM) ||
+	    !FLD_ISSET(lsm_tree->bloom, WT_LSM_BLOOM_OLDEST))) {
+		__wt_lsm_tree_release(session, lsm_tree);
+		return (0);
+	}
+
 	WT_ERR(__wt_seconds(session, &begin));
 
 	/*
diff --git a/src/lsm/lsm_work_unit.c b/src/lsm/lsm_work_unit.c
index 33174c2d40d..7a2c0ebb190 100644
--- a/src/lsm/lsm_work_unit.c
+++ b/src/lsm/lsm_work_unit.c
@@ -215,6 +215,10 @@ __wt_lsm_work_bloom(WT_SESSION_IMPL *session, WT_LSM_TREE *lsm_tree)
 		    chunk->count == 0)
 			continue;
 
+		/* Never create a bloom filter on the oldest chunk */
+		if (chunk == lsm_tree->chunk[0] &&
+		    !FLD_ISSET(lsm_tree->bloom, WT_LSM_BLOOM_OLDEST))
+			continue;
 		/*
 		 * See if we win the race to switch on the "busy" flag and
 		 * recheck that the chunk still needs a Bloom filter.