Eliminate the need for the Column.zDflt (using Column.pDflt instead) to reduce

the amount of memory needed to hold the schema.

FossilOrigin-Name: d8c94a46dfa94930732c2de2aa79675c5087d36e

8 files changed, 30 insertions, 15 deletions

diff --git a/src/alter.c b/src/alter.c
index f10a85022..9edd7fff3 100644
--- a/src/alter.c
+++ b/src/alter.c
@@ -628,7 +628,8 @@ void sqlite3AlterFinishAddColumn(Parse *pParse, Token *pColDef){
   ** literal NULL, then set pDflt to 0. This simplifies checking
   ** for an SQL NULL default below.
   */
-  if( pDflt && pDflt->op==TK_NULL ){
+  assert( pDflt==0 || pDflt->op==TK_SPAN );
+  if( pDflt && pDflt->pLeft->op==TK_NULL ){
     pDflt = 0;
   }
 
@@ -787,7 +788,6 @@ void sqlite3AlterBeginAddColumn(Parse *pParse, SrcList *pSrc){
     pCol->zColl = 0;
     pCol->zType = 0;
     pCol->pDflt = 0;
-    pCol->zDflt = 0;
   }
   pNew->pSchema = db->aDb[iDb].pSchema;
   pNew->addColOffset = pTab->addColOffset;
diff --git a/src/build.c b/src/build.c
index b14d45f6d..bcf71442d 100644
--- a/src/build.c
+++ b/src/build.c
@@ -571,7 +571,6 @@ void sqlite3DeleteColumnNames(sqlite3 *db, Table *pTable){
     for(i=0; i<pTable->nCol; i++, pCol++){
       sqlite3DbFree(db, pCol->zName);
       sqlite3ExprDelete(db, pCol->pDflt);
-      sqlite3DbFree(db, pCol->zDflt);
       sqlite3DbFree(db, pCol->zType);
       sqlite3DbFree(db, pCol->zColl);
     }
@@ -1231,11 +1230,16 @@ void sqlite3AddDefaultValue(Parse *pParse, ExprSpan *pSpan){
       ** tokens that point to volatile memory. The 'span' of the expression
       ** is required by pragma table_info.
       */
+      Expr x;
       sqlite3ExprDelete(db, pCol->pDflt);
-      pCol->pDflt = sqlite3ExprDup(db, pSpan->pExpr, EXPRDUP_REDUCE);
-      sqlite3DbFree(db, pCol->zDflt);
-      pCol->zDflt = sqlite3DbStrNDup(db, (char*)pSpan->zStart,
-                                     (int)(pSpan->zEnd - pSpan->zStart));
+      memset(&x, 0, sizeof(x));
+      x.op = TK_SPAN;
+      x.u.zToken = sqlite3DbStrNDup(db, (char*)pSpan->zStart,
+                                    (int)(pSpan->zEnd - pSpan->zStart));
+      x.pLeft = pSpan->pExpr;
+      x.flags = EP_Skip;
+      pCol->pDflt = sqlite3ExprDup(db, &x, EXPRDUP_REDUCE);
+      sqlite3DbFree(db, x.u.zToken);
     }
   }
   sqlite3ExprDelete(db, pSpan->pExpr);
diff --git a/src/expr.c b/src/expr.c
index 3070de96f..8a6973219 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -3070,6 +3070,7 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
       sqlite3ReleaseTempReg(pParse, r4);
       break;
     }
+    case TK_SPAN:
     case TK_COLLATE: 
     case TK_UPLUS: {
       inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
diff --git a/src/insert.c b/src/insert.c
index 7ff884b8c..03fdf09ac 100644
--- a/src/insert.c
+++ b/src/insert.c
@@ -1999,11 +1999,15 @@ static int xferOptimization(
       return 0;    /* tab2 must be NOT NULL if tab1 is */
     }
     /* Default values for second and subsequent columns need to match. */
-    if( i>0
-     && ((pDestCol->zDflt==0)!=(pSrcCol->zDflt==0) 
-         || (pDestCol->zDflt && strcmp(pDestCol->zDflt, pSrcCol->zDflt)!=0))
-    ){
-      return 0;    /* Default values must be the same for all columns */
+    if( i>0 ){
+      assert( pDestCol->pDflt==0 || pDestCol->pDflt->op==TK_SPAN );
+      assert( pSrcCol->pDflt==0 || pSrcCol->pDflt->op==TK_SPAN );
+      if( (pDestCol->pDflt==0)!=(pSrcCol->pDflt==0) 
+       || (pDestCol->pDflt && strcmp(pDestCol->pDflt->u.zToken,
+                                       pSrcCol->pDflt->u.zToken)!=0)
+      ){
+        return 0;    /* Default values must be the same for all columns */
+      }
     }
   }
   for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
diff --git a/src/pragma.c b/src/pragma.c
index 8b8f1f7bf..0460f663f 100644
--- a/src/pragma.c
+++ b/src/pragma.c
@@ -1076,12 +1076,13 @@ void sqlite3Pragma(
         }else{
           for(k=1; k<=pTab->nCol && pPk->aiColumn[k-1]!=i; k++){}
         }
+        assert( pCol->pDflt==0 || pCol->pDflt->op==TK_SPAN );
         sqlite3VdbeMultiLoad(v, 1, "issisi",
                i-nHidden,
                pCol->zName,
                pCol->zType ? pCol->zType : "",
                pCol->notNull ? 1 : 0,
-               pCol->zDflt,
+               pCol->pDflt ? pCol->pDflt->u.zToken : 0,
                k);
         sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 6);
       }
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 759d7ca5e..7d1757e4d 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1545,7 +1545,6 @@ struct Module {
 struct Column {
   char *zName;     /* Name of this column */
   Expr *pDflt;     /* Default value of this column */
-  char *zDflt;     /* Original text of the default value */
   char *zType;     /* Data type for this column */
   char *zColl;     /* Collating sequence.  If NULL, use the default */
   u8 notNull;      /* An OE_ code for handling a NOT NULL constraint */
diff --git a/src/treeview.c b/src/treeview.c
index ff3b4be5a..907159c06 100644
--- a/src/treeview.c
+++ b/src/treeview.c
@@ -339,6 +339,12 @@ void sqlite3TreeViewExpr(TreeView *pView, const Expr *pExpr, u8 moreToFollow){
     case TK_ISNULL:  zUniOp = "ISNULL"; break;
     case TK_NOTNULL: zUniOp = "NOTNULL"; break;
 
+    case TK_SPAN: {
+      sqlite3TreeViewLine(pView, "SPAN %Q", pExpr->u.zToken);
+      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
+      break;
+    }
+
     case TK_COLLATE: {
       sqlite3TreeViewLine(pView, "COLLATE %Q", pExpr->u.zToken);
       sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
diff --git a/src/vdbemem.c b/src/vdbemem.c
index 87d233b98..b5139fe32 100644
--- a/src/vdbemem.c
+++ b/src/vdbemem.c
@@ -1285,7 +1285,7 @@ static int valueFromExpr(
     *ppVal = 0;
     return SQLITE_OK;
   }
-  while( (op = pExpr->op)==TK_UPLUS ) pExpr = pExpr->pLeft;
+  while( (op = pExpr->op)==TK_UPLUS || op==TK_SPAN ) pExpr = pExpr->pLeft;
   if( NEVER(op==TK_REGISTER) ) op = pExpr->op2;
 
   /* Compressed expressions only appear when parsing the DEFAULT clause