Add an experimental location(X) SQL function that attempt to return the

location of the payload within the database for the record that contains
column X.  location(X) returns NULL if X is not an ordinary table column or
if SQLite cannot figure out the location because it is using a covering index.

FossilOrigin-Name: 51be9558164301c5dd4df23ab8b3e67de0b522f8d36f79f3d84d45d3dc2a83a4

1 files changed, 12 insertions, 3 deletions

diff --git a/src/expr.c b/src/expr.c
index 524e53934..b7c64d3c1 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -3871,9 +3871,18 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
         if( !pColl ) pColl = db->pDfltColl; 
         sqlite3VdbeAddOp4(v, OP_CollSeq, 0, 0, 0, (char *)pColl, P4_COLLSEQ);
       }
-      sqlite3VdbeAddOp4(v, pParse->iSelfTab ? OP_PureFunc0 : OP_Function0,
-                        constMask, r1, target, (char*)pDef, P4_FUNCDEF);
-      sqlite3VdbeChangeP5(v, (u8)nFarg);
+      if( pDef->funcFlags & SQLITE_FUNC_LOCATION ){
+        Expr *pArg = pFarg->a[0].pExpr;
+        if( pArg->op==TK_COLUMN ){
+          sqlite3VdbeAddOp2(v, OP_Location, pArg->iTable, target);
+        }else{
+          sqlite3VdbeAddOp2(v, OP_Null, 0, target);
+        }
+      }else{
+        sqlite3VdbeAddOp4(v, pParse->iSelfTab ? OP_PureFunc0 : OP_Function0,
+                          constMask, r1, target, (char*)pDef, P4_FUNCDEF);
+        sqlite3VdbeChangeP5(v, (u8)nFarg);
+      }
       if( nFarg && constMask==0 ){
         sqlite3ReleaseTempRange(pParse, r1, nFarg);
       }