fix _id lookup with no index SERVER-608

mongodb · Feb 6, 2010 · 2dc3d5b · 2dc3d5b
1 parent 188436f
commit 2dc3d5b
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Showing 3 changed files with 29 additions and 19 deletions.
diff --git a/db/dbhelpers.cpp b/db/dbhelpers.cpp
@@ -104,13 +104,13 @@ namespace mongo {
         return true;
     }
 
-    bool Helpers::findById(const char *ns, BSONObj query, BSONObj& result ){
+    int Helpers::findById(const char *ns, BSONObj query, BSONObj& result ){
         NamespaceDetails *d = nsdetails(ns);
         if ( ! d )
-            return false;
+            return -1;
         int idxNo = d->findIdIndex();
         if ( idxNo < 0 )
-            return false;
+            return -1;
         IndexDetails& i = d->idx( idxNo );
 
         BSONObj key = i.getKeyFromQuery( query );

diff --git a/db/dbhelpers.h b/db/dbhelpers.h
@@ -49,7 +49,12 @@ namespace mongo {
         */
         static bool findOne(const char *ns, BSONObj query, BSONObj& result, bool requireIndex = false);
 
-        static bool findById(const char *ns, BSONObj query, BSONObj& result );
+        /**
+           -1 no index
+           0 not found
+           1 found
+         */
+        static int findById(const char *ns, BSONObj query, BSONObj& result );
 
         /* Get/put the first object from a collection.  Generally only useful if the collection
            only ever has a single object -- which is a "singleton collection".

diff --git a/db/query.cpp b/db/query.cpp
@@ -771,26 +771,31 @@ namespace mongo {
                 uassert("bad query object", false);
             }
 
+            int idxHackWorked = false;
             if ( strcmp( query.firstElement().fieldName() , "_id" ) == 0 && query.nFields() == 1 && query.firstElement().isSimpleType() ){
                 nscanned = 1;
 
                 BSONObj resObject;
-                bool found = Helpers::findById( ns , query , resObject );
-                if ( found ){
-                    n = 1;
-                    fillQueryResultFromObj( bb , filter.get() , resObject );
-                }
-                qr.reset( (QueryResult *) bb.buf() );
-                bb.decouple();
-                qr->resultFlags() = 0;
-                qr->len = bb.len();
-                ss << " reslen:" << bb.len();
-                qr->setOperation(opReply);
-                qr->cursorId = cursorid;
-                qr->startingFrom = 0;
-                qr->nReturned = n;            
+                int found = Helpers::findById( ns , query , resObject );
+                if ( found >= 0 ){
+                    idxHackWorked = true;
+                    if ( found ){
+                        n = 1;
+                        fillQueryResultFromObj( bb , filter.get() , resObject );
+                    }
+                    qr.reset( (QueryResult *) bb.buf() );
+                    bb.decouple();
+                    qr->resultFlags() = 0;
+                    qr->len = bb.len();
+                    ss << " reslen:" << bb.len();
+                    qr->setOperation(opReply);
+                    qr->cursorId = cursorid;
+                    qr->startingFrom = 0;
+                    qr->nReturned = n;       
+                }     
             }
-            else { // non-simple _id lookup
+
+            if ( ! idxHackWorked ){
                 BSONObj oldPlan;
                 if ( explain && hint.eoo() && min.isEmpty() && max.isEmpty() ) {
                     QueryPlanSet qps( ns, query, order );