Improved the comment on the block of code the provides the performance

optimization originally added by check-in [925840cfdb].  The original
check-in omitted condition 4, which was the cause of bug [30027b613b].

FossilOrigin-Name: c6506b82aa6583ccde5f673c79526d5f3920b67a

1 files changed, 14 insertions, 8 deletions

diff --git a/src/insert.c b/src/insert.c
index 2cc0457a9..bd6efe68b 100644
--- a/src/insert.c
+++ b/src/insert.c
@@ -1549,16 +1549,22 @@ void sqlite3GenerateConstraintChecks(
       onError = OE_Abort;
     }
 
-    if( ix==0 && pPk==pIdx && onError==OE_Replace && pPk->pNext==0 ){
-      if( 0==(db->flags&SQLITE_RecTriggers)
-       || 0==sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0)
-      ){
-        sqlite3VdbeResolveLabel(v, addrUniqueOk);
-        continue;
-      }
+    /* Collision detection may be omitted if all of the following are true:
+    **   (1) The conflict resolution algorithm is REPLACE
+    **   (2) The table is a WITHOUT ROWID table
+    **   (3) There are no secondary indexes on the table
+    **   (4) No delete triggers need to be fired if there is a conflict
+    */ 
+    if( (ix==0 && pIdx->pNext==0)                   /* Condition 3 */
+     && pPk==pIdx                                   /* Condition 2 */
+     && onError==OE_Replace                         /* Condition 1 */
+     && ( 0==(db->flags&SQLITE_RecTriggers) ||      /* Condition 4 */
+          0==sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0))
+    ){
+      sqlite3VdbeResolveLabel(v, addrUniqueOk);
+      continue;
     }
 
-    
     /* Check to see if the new index entry will be unique */
     sqlite3VdbeAddOp4Int(v, OP_NoConflict, iThisCur, addrUniqueOk,
                          regIdx, pIdx->nKeyCol); VdbeCoverage(v);