svn commit: r1843416 - /jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java

[tommaso]

Author: tommaso
Date: Wed Oct 10 09:34:48 2018
New Revision: 1843416

URL: http://svn.apache.org/viewvc?rev=1843416&view=rev
Log:
OAK-7795 - Log a debug message when two or more indices have same or very close 
cost amounts

Modified:
    
jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java

Modified: 
jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java
URL: 
http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java?rev=1843416&r1=1843415&r2=1843416&view=diff
==============================================================================
--- 
jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java
 (original)
+++ 
jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java
 Wed Oct 10 09:34:48 2018
@@ -974,6 +974,10 @@ public class QueryImpl implements Query
         double bestCost = Double.POSITIVE_INFINITY;
         IndexPlan bestPlan = null;
 
+        // track similar costs
+        QueryIndex almostBestIndex = null;
+        double almostBestCost = Double.POSITIVE_INFINITY;
+
         // Sort the indexes according to their minimum cost to be able to skip 
the remaining indexes if the cost of the
         // current index is below the minimum cost of the next index.
         List<? extends QueryIndex> queryIndexes = MINIMAL_COST_ORDERING
@@ -1042,12 +1046,25 @@ public class QueryImpl implements Query
             if (cost < 0) {
                 LOG.error("cost below 0 for " + indexName + " is " + cost);
             }
+
             if (cost < bestCost) {
+                almostBestCost = bestCost;
+                almostBestIndex = bestIndex;
+
                 bestCost = cost;
                 bestIndex = index;
                 bestPlan = indexPlan;
+            } else if (cost - bestCost <= 0.1) {
+                almostBestCost = cost;
+                almostBestIndex = index;
             }
         }
+
+        if (LOG.isDebugEnabled() && Math.abs(bestCost - almostBestCost) <= 
0.1) {
+            LOG.debug("selected index {} and {} have similar costs {} and {} 
for query {} - check query explanation / index definitions",
+                    bestIndex, almostBestIndex, bestCost, almostBestCost, 
filter.toString());
+        }
+
         potentiallySlowTraversalQuery = bestIndex == null;
         if (traversalEnabled) {
             TraversingIndex traversal = new TraversingIndex();