Have where.c ignore any plan from a virtual table that tries to use LIMIT/OFFSET without also using all WHERE constraints.

FossilOrigin-Name: 7d30596496c6a7a37b925f13d8d94d5de224ec31bb86594fa4cc07b10082e776

1 files changed, 26 insertions, 4 deletions

diff --git a/src/where.c b/src/where.c
index 39210ddb2..820e92249 100644
--- a/src/where.c
+++ b/src/where.c
@@ -4058,6 +4058,21 @@ static int isLimitTerm(WhereTerm *pTerm){
 }
 
 /*
+** Return true if the first nCons constraints in the pUsage array are
+** marked as in-use (have argvIndex>0). False otherwise.
+*/
+static int allConstraintsUsed(
+  struct sqlite3_index_constraint_usage *aUsage, 
+  int nCons
+){
+  int ii;
+  for(ii=0; ii<nCons; ii++){
+    if( aUsage[ii].argvIndex<=0 ) return 0;
+  }
+  return 1;
+}
+
+/*
 ** Argument pIdxInfo is already populated with all constraints that may
 ** be used by the virtual table identified by pBuilder->pNew->iTab. This
 ** function marks a subset of those constraints usable, invokes the
@@ -4197,13 +4212,20 @@ static int whereLoopAddVirtualOne(
         *pbIn = 1; assert( (mExclude & WO_IN)==0 );
       }
 
+      /* Unless pbRetryLimit is non-NULL, there should be no LIMIT/OFFSET
+      ** terms. And if there are any, they should follow all other terms. */
       assert( pbRetryLimit || !isLimitTerm(pTerm) );
-      if( isLimitTerm(pTerm) && *pbIn ){
+      assert( !isLimitTerm(pTerm) || i>=nConstraint-2 );
+      assert( !isLimitTerm(pTerm) || i==nConstraint-1 || isLimitTerm(pTerm+1) );
+
+      if( isLimitTerm(pTerm) && (*pbIn || !allConstraintsUsed(pUsage, i)) ){
         /* If there is an IN(...) term handled as an == (separate call to
         ** xFilter for each value on the RHS of the IN) and a LIMIT or
-        ** OFFSET term handled as well, the plan is unusable. Set output
-        ** variable *pbRetryLimit to true to tell the caller to retry with
-        ** LIMIT and OFFSET disabled. */
+        ** OFFSET term handled as well, the plan is unusable. Similarly,
+        ** if there is a LIMIT/OFFSET and there are other unused terms,
+        ** the plan cannot be used. In these cases set variable *pbRetryLimit
+        ** to true to tell the caller to retry with LIMIT and OFFSET 
+        ** disabled. */
         if( pIdxInfo->needToFreeIdxStr ){
           sqlite3_free(pIdxInfo->idxStr);
           pIdxInfo->idxStr = 0;