Proposed optimization to the IS NULL and NOT NULL operators that avoids

loading the entire content of larges strings and BLOBs.  Response to
[forum:/info/3c08d4715dc05b00|forum post 3c08d4715dc05b00].

FossilOrigin-Name: 45f171565442f9fd6574fb93ae7abe83c168b20be68af42531bc55571450d3ab

1 files changed, 16 insertions, 0 deletions

diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index 8785e3b56..275ba6f77 100644
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -1156,6 +1156,22 @@ void sqlite3VdbeChangeP5(Vdbe *p, u16 p5){
 }
 
 /*
+** If the previous opcode is an OP_Column that delivers results
+** into register iDest, then add the OPFLAG_TYPEOF flag to that
+** opcode.
+*/
+void sqlite3VdbeTypeofColumn(Vdbe *p, int iDest){
+  if( p->nOp>0 ){
+    VdbeOp *pOp = &p->aOp[p->nOp-1];
+    if( pOp->opcode==OP_Column && pOp->p3==iDest ){
+      pOp->p5 |= OPFLAG_TYPEOFARG;
+    }
+  }else{
+    assert( p->db->mallocFailed );
+  }
+}
+
+/*
 ** Change the P2 operand of instruction addr so that it points to
 ** the address of the next instruction to be coded.
 */