Store the collating sequence name for each column of a table as an

extension to the column name, for an additional savings in the heap space
needed to hold the schema.

FossilOrigin-Name: 832ac4c1ee384be0de72a4bdd55ed87e0f8294e7df5eefcf6b4942db3d85a69e

9 files changed, 66 insertions, 18 deletions

diff --git a/src/alter.c b/src/alter.c
index 5780d2df0..c059a62ec 100644
--- a/src/alter.c
+++ b/src/alter.c
@@ -532,7 +532,6 @@ void sqlite3AlterBeginAddColumn(Parse *pParse, SrcList *pSrc){
     Column *pCol = &pNew->aCol[i];
     pCol->zCnName = sqlite3DbStrDup(db, pCol->zCnName);
     pCol->hName = sqlite3StrIHash(pCol->zCnName);
-    pCol->zCnColl = 0;
   }
   assert( !IsVirtual(pNew) );
   pNew->u.tab.pDfltList = sqlite3ExprListDup(db, pTab->u.tab.pDfltList, 0);
diff --git a/src/build.c b/src/build.c
index 942dc85f8..6343da4f5 100644
--- a/src/build.c
+++ b/src/build.c
@@ -711,6 +711,45 @@ Expr *sqlite3ColumnExpr(Table *pTab, Column *pCol){
 }
 
 /*
+** Set the collating sequence name for a column.
+*/
+void sqlite3ColumnSetColl(
+  sqlite3 *db,
+  Column *pCol,
+  const char *zColl
+){
+  int nColl;
+  int n;
+  char *zNew;
+  assert( zColl!=0 );
+  n = sqlite3Strlen30(pCol->zCnName) + 1;
+  if( pCol->colFlags & COLFLAG_HASTYPE ){
+    n += sqlite3Strlen30(pCol->zCnName+n) + 1;
+  }
+  nColl = sqlite3Strlen30(zColl) + 1;
+  zNew = sqlite3DbRealloc(db, pCol->zCnName, nColl+n);
+  if( zNew ){
+    pCol->zCnName = zNew;
+    memcpy(pCol->zCnName + n, zColl, nColl);
+    pCol->colFlags |= COLFLAG_HASCOLL;
+  }
+}
+
+/*
+** Return the collating squence name for a column
+*/
+const char *sqlite3ColumnColl(Column *pCol){
+  const char *z;
+  if( (pCol->colFlags & COLFLAG_HASCOLL)==0 ) return 0;
+  z = pCol->zCnName;
+  while( *z ){ z++; }
+  if( pCol->colFlags & COLFLAG_HASTYPE ){
+    do{ z++; }while( *z );
+  }
+  return z+1;
+}
+
+/*
 ** Delete memory allocated for the column names of a table or view (the
 ** Table.aCol[] array).
 */
@@ -722,7 +761,6 @@ void sqlite3DeleteColumnNames(sqlite3 *db, Table *pTable){
     for(i=0; i<pTable->nCol; i++, pCol++){
       assert( pCol->zCnName==0 || pCol->hName==sqlite3StrIHash(pCol->zCnName) );
       sqlite3DbFree(db, pCol->zCnName);
-      sqlite3DbFree(db, pCol->zCnColl);
     }
     sqlite3DbFree(db, pTable->aCol);
     if( !IsVirtual(pTable) ){
@@ -1891,8 +1929,7 @@ void sqlite3AddCollateType(Parse *pParse, Token *pToken){
 
   if( sqlite3LocateCollSeq(pParse, zColl) ){
     Index *pIdx;
-    sqlite3DbFree(db, p->aCol[i].zCnColl);
-    p->aCol[i].zCnColl = zColl;
+    sqlite3ColumnSetColl(db, &p->aCol[i], zColl);
   
     /* If the column is declared as "<name> PRIMARY KEY COLLATE <type>",
     ** then an index may have been created on this column before the
@@ -1901,12 +1938,11 @@ void sqlite3AddCollateType(Parse *pParse, Token *pToken){
     for(pIdx=p->pIndex; pIdx; pIdx=pIdx->pNext){
       assert( pIdx->nKeyCol==1 );
       if( pIdx->aiColumn[0]==i ){
-        pIdx->azColl[0] = p->aCol[i].zCnColl;
+        pIdx->azColl[0] = sqlite3ColumnColl(&p->aCol[i]);
       }
     }
-  }else{
-    sqlite3DbFree(db, zColl);
   }
+  sqlite3DbFree(db, zColl);
 }
 
 /* Change the most recently parsed column to be a GENERATED ALWAYS AS
@@ -4066,7 +4102,7 @@ void sqlite3CreateIndex(
       zExtra += nColl;
       nExtra -= nColl;
     }else if( j>=0 ){
-      zColl = pTab->aCol[j].zCnColl;
+      zColl = sqlite3ColumnColl(&pTab->aCol[j]);
     }
     if( !zColl ) zColl = sqlite3StrBINARY;
     if( !db->init.busy && !sqlite3LocateCollSeq(pParse, zColl) ){
diff --git a/src/expr.c b/src/expr.c
index 0f900c0c6..34f14e368 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -173,7 +173,7 @@ CollSeq *sqlite3ExprCollSeq(Parse *pParse, const Expr *pExpr){
       ** a TK_COLUMN but was previously evaluated and cached in a register */
       int j = p->iColumn;
       if( j>=0 ){
-        const char *zColl = p->y.pTab->aCol[j].zCnColl;
+        const char *zColl = sqlite3ColumnColl(&p->y.pTab->aCol[j]);
         pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);
       }
       break;
diff --git a/src/fkey.c b/src/fkey.c
index 5105b5cc7..5888e558f 100644
--- a/src/fkey.c
+++ b/src/fkey.c
@@ -259,7 +259,7 @@ int sqlite3FkLocateIndex(
           /* If the index uses a collation sequence that is different from
           ** the default collation sequence for the column, this index is
           ** unusable. Bail out early in this case.  */
-          zDfltColl = pParent->aCol[iCol].zCnColl;
+          zDfltColl = sqlite3ColumnColl(&pParent->aCol[iCol]);
           if( !zDfltColl ) zDfltColl = sqlite3StrBINARY;
           if( sqlite3StrICmp(pIdx->azColl[i], zDfltColl) ) break;
 
@@ -487,7 +487,7 @@ static Expr *exprTableRegister(
       pCol = &pTab->aCol[iCol];
       pExpr->iTable = regBase + sqlite3TableColumnToStorage(pTab,iCol) + 1;
       pExpr->affExpr = pCol->affinity;
-      zColl = pCol->zCnColl;
+      zColl = sqlite3ColumnColl(pCol);
       if( zColl==0 ) zColl = db->pDfltColl->zName;
       pExpr = sqlite3ExprAddCollateString(pParse, pExpr, zColl);
     }else{
diff --git a/src/insert.c b/src/insert.c
index 06952586b..0692198b1 100644
--- a/src/insert.c
+++ b/src/insert.c
@@ -2843,7 +2843,8 @@ static int xferOptimization(
     if( pDestCol->affinity!=pSrcCol->affinity ){
       return 0;    /* Affinity must be the same on all columns */
     }
-    if( sqlite3_stricmp(pDestCol->zCnColl, pSrcCol->zCnColl)!=0 ){
+    if( sqlite3_stricmp(sqlite3ColumnColl(pDestCol), 
+                        sqlite3ColumnColl(pSrcCol))!=0 ){
       return 0;    /* Collating sequence must be the same on all columns */
     }
     if( pDestCol->notNull && !pSrcCol->notNull ){
diff --git a/src/main.c b/src/main.c
index 3c1191c36..a37301a64 100644
--- a/src/main.c
+++ b/src/main.c
@@ -3769,7 +3769,7 @@ int sqlite3_table_column_metadata(
   */ 
   if( pCol ){
     zDataType = sqlite3ColumnType(pCol,0);
-    zCollSeq = pCol->zCnColl;
+    zCollSeq = sqlite3ColumnColl(pCol);
     notnull = pCol->notNull!=0;
     primarykey  = (pCol->colFlags & COLFLAG_PRIMKEY)!=0;
     autoinc = pTab->iPKey==iCol && (pTab->tabFlags & TF_Autoincrement)!=0;
diff --git a/src/select.c b/src/select.c
index 064ea758d..375050bdc 100644
--- a/src/select.c
+++ b/src/select.c
@@ -2193,8 +2193,9 @@ void sqlite3SelectAddColumnTypeAndCollation(
     }
     if( pCol->affinity<=SQLITE_AFF_NONE ) pCol->affinity = aff;
     pColl = sqlite3ExprCollSeq(pParse, p);
-    if( pColl && pCol->zCnColl==0 ){
-      pCol->zCnColl = sqlite3DbStrDup(db, pColl->zName);
+    if( pColl && (pCol->colFlags & COLFLAG_HASCOLL)==0 ){
+      assert( pTab->pIndex==0 );
+      sqlite3ColumnSetColl(db, pCol, pColl->zName);
     }
   }
   pTab->szTabRow = 1; /* Any non-zero value works */
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 083ba5a33..9f4d21175 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -2028,10 +2028,17 @@ struct Module {
 **                            or equal to the table column index.  It is
 **                            equal if and only if there are no VIRTUAL
 **                            columns to the left.
+**
+** Notes on zCnName:
+** The zCnName field stores the name of the column, the datatype of the
+** column, and the collating sequence for the column, in that order, all in
+** a single allocation.  Each string is 0x00 terminated.  The datatype
+** is only included if the COLFLAG_HASTYPE bit of colFlags is set and the
+** collating sequence name is only included if the COLFLAG_HASCOLL bit is
+** set.
 */
 struct Column {
   char *zCnName;   /* Name of this column */
-  char *zCnColl;   /* Collating sequence.  If NULL, use the default */
   u8 notNull : 4;  /* An OE_ code for handling a NOT NULL constraint */
   u8 eType : 4;    /* One of the standard types */
   char affinity;   /* One of the SQLITE_AFF_... values */
@@ -2072,6 +2079,7 @@ struct Column {
 #define COLFLAG_STORED    0x0040   /* GENERATED ALWAYS AS ... STORED */
 #define COLFLAG_NOTAVAIL  0x0080   /* STORED column not yet calculated */
 #define COLFLAG_BUSY      0x0100   /* Blocks recursion on GENERATED columns */
+#define COLFLAG_HASCOLL   0x0200   /* Has collating sequence name in zCnName */
 #define COLFLAG_GENERATED 0x0060   /* Combo: _STORED, _VIRTUAL */
 #define COLFLAG_NOINSERT  0x0062   /* Combo: _HIDDEN, _STORED, _VIRTUAL */
 
@@ -4398,6 +4406,8 @@ void sqlite3CollapseDatabaseArray(sqlite3*);
 void sqlite3CommitInternalChanges(sqlite3*);
 void sqlite3ColumnSetExpr(Parse*,Table*,Column*,Expr*);
 Expr *sqlite3ColumnExpr(Table*,Column*);
+void sqlite3ColumnSetColl(sqlite3*,Column*,const char*zColl);
+const char *sqlite3ColumnColl(Column*);
 void sqlite3DeleteColumnNames(sqlite3*,Table*);
 void sqlite3GenerateColumnNames(Parse *pParse, Select *pSelect);
 int sqlite3ColumnsFromExprList(Parse*,ExprList*,i16*,Column**);
diff --git a/src/wherecode.c b/src/wherecode.c
index f3589bb0a..28b417c9a 100644
--- a/src/wherecode.c
+++ b/src/wherecode.c
@@ -1241,8 +1241,9 @@ static void whereIndexExprTrans(
 #ifndef SQLITE_OMIT_GENERATED_COLUMNS
     }else if( iRef>=0
        && (pTab->aCol[iRef].colFlags & COLFLAG_VIRTUAL)!=0
-       && (pTab->aCol[iRef].zCnColl==0
-           || sqlite3StrICmp(pTab->aCol[iRef].zCnColl, sqlite3StrBINARY)==0)
+       && ((pTab->aCol[iRef].colFlags & COLFLAG_HASCOLL)==0
+           || sqlite3StrICmp(sqlite3ColumnColl(&pTab->aCol[iRef]),
+                                               sqlite3StrBINARY)==0)
     ){
       /* Check to see if there are direct references to generated columns
       ** that are contained in the index.  Pulling the generated column