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Overview
Comment:Eliminate the need for the Column.zDflt (using Column.pDflt instead) to reduce the amount of memory needed to hold the schema.
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SHA1: d8c94a46dfa94930732c2de2aa79675c5087d36e
User & Date: drh 2016-02-27 21:16:04
Context
2016-02-29
13:44
Very minor improvement to the performance and reduction in size to the parser by capturing the name and datatype of table columns in a single grammar rule reduction. (check-in: 4b55c520 user: drh tags: trunk)
2016-02-27
23:25
Update the parser so that it pulls out the column name and type all in one go, rather than using separate reductions. (check-in: ad3ffe2e user: drh tags: schema-storage)
21:16
Eliminate the need for the Column.zDflt (using Column.pDflt instead) to reduce the amount of memory needed to hold the schema. (check-in: d8c94a46 user: drh tags: trunk)
19:19
Tighter description of I/O stats in the shell. Show I/O stats on speedtest1.c. (check-in: f681d800 user: drh tags: trunk)
Changes
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Changes to src/alter.c. 

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  }
#endif

  /* If the default value for the new column was specified with a 
  ** literal NULL, then set pDflt to 0. This simplifies checking
  ** for an SQL NULL default below.
  */

  if( pDflt && pDflt->op==TK_NULL ){
    pDflt = 0;
  }

  /* Check that the new column is not specified as PRIMARY KEY or UNIQUE.
  ** If there is a NOT NULL constraint, then the default value for the
  ** column must not be NULL.
  */
................................................................................
  memcpy(pNew->aCol, pTab->aCol, sizeof(Column)*pNew->nCol);
  for(i=0; i<pNew->nCol; i++){
    Column *pCol = &pNew->aCol[i];
    pCol->zName = sqlite3DbStrDup(db, pCol->zName);
    pCol->zColl = 0;
    pCol->zType = 0;
    pCol->pDflt = 0;
    pCol->zDflt = 0;
  }
  pNew->pSchema = db->aDb[iDb].pSchema;
  pNew->addColOffset = pTab->addColOffset;
  pNew->nRef = 1;

  /* Begin a transaction and increment the schema cookie.  */
  sqlite3BeginWriteOperation(pParse, 0, iDb);








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  }
#endif

  /* If the default value for the new column was specified with a 
  ** literal NULL, then set pDflt to 0. This simplifies checking
  ** for an SQL NULL default below.
  */
  assert( pDflt==0 || pDflt->op==TK_SPAN );
  if( pDflt && pDflt->pLeft->op==TK_NULL ){
    pDflt = 0;
  }

  /* Check that the new column is not specified as PRIMARY KEY or UNIQUE.
  ** If there is a NOT NULL constraint, then the default value for the
  ** column must not be NULL.
  */
................................................................................
  memcpy(pNew->aCol, pTab->aCol, sizeof(Column)*pNew->nCol);
  for(i=0; i<pNew->nCol; i++){
    Column *pCol = &pNew->aCol[i];
    pCol->zName = sqlite3DbStrDup(db, pCol->zName);
    pCol->zColl = 0;
    pCol->zType = 0;
    pCol->pDflt = 0;

  }
  pNew->pSchema = db->aDb[iDb].pSchema;
  pNew->addColOffset = pTab->addColOffset;
  pNew->nRef = 1;

  /* Begin a transaction and increment the schema cookie.  */
  sqlite3BeginWriteOperation(pParse, 0, iDb);

Changes to src/build.c. 

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  int i;
  Column *pCol;
  assert( pTable!=0 );
  if( (pCol = pTable->aCol)!=0 ){
    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);
    }
    sqlite3DbFree(db, pTable->aCol);
  }
}

................................................................................
      sqlite3ErrorMsg(pParse, "default value of column [%s] is not constant",
          pCol->zName);
    }else{
      /* A copy of pExpr is used instead of the original, as pExpr contains
      ** tokens that point to volatile memory. The 'span' of the expression
      ** is required by pragma table_info.
      */

      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));




    }
  }
  sqlite3ExprDelete(db, pSpan->pExpr);
}

/*
** Backwards Compatibility Hack:








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  int i;
  Column *pCol;
  assert( pTable!=0 );
  if( (pCol = pTable->aCol)!=0 ){
    for(i=0; i<pTable->nCol; i++, pCol++){
      sqlite3DbFree(db, pCol->zName);
      sqlite3ExprDelete(db, pCol->pDflt);

      sqlite3DbFree(db, pCol->zType);
      sqlite3DbFree(db, pCol->zColl);
    }
    sqlite3DbFree(db, pTable->aCol);
  }
}

................................................................................
      sqlite3ErrorMsg(pParse, "default value of column [%s] is not constant",
          pCol->zName);
    }else{
      /* A copy of pExpr is used instead of the original, as pExpr contains
      ** tokens that point to volatile memory. The 'span' of the expression
      ** is required by pragma table_info.
      */
      Expr x;
      sqlite3ExprDelete(db, pCol->pDflt);

      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);
}

/*
** Backwards Compatibility Hack:

Changes to src/expr.c. 

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      codeCompare(pParse, pLeft, pRight, OP_Le, r1, r2, r4, SQLITE_STOREP2);
      VdbeCoverage(v);
      sqlite3VdbeAddOp3(v, OP_And, r3, r4, target);
      sqlite3ReleaseTempReg(pParse, r3);
      sqlite3ReleaseTempReg(pParse, r4);
      break;
    }

    case TK_COLLATE: 
    case TK_UPLUS: {
      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
      break;
    }

    case TK_TRIGGER: {








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      codeCompare(pParse, pLeft, pRight, OP_Le, r1, r2, r4, SQLITE_STOREP2);
      VdbeCoverage(v);
      sqlite3VdbeAddOp3(v, OP_And, r3, r4, target);
      sqlite3ReleaseTempReg(pParse, r3);
      sqlite3ReleaseTempReg(pParse, r4);
      break;
    }
    case TK_SPAN:
    case TK_COLLATE: 
    case TK_UPLUS: {
      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
      break;
    }

    case TK_TRIGGER: {

Changes to src/insert.c. 

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    if( sqlite3_stricmp(pDestCol->zColl, pSrcCol->zColl)!=0 ){
      return 0;    /* Collating sequence must be the same on all columns */
    }
    if( pDestCol->notNull && !pSrcCol->notNull ){
      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 */

    }
  }
  for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
    if( IsUniqueIndex(pDestIdx) ){
      destHasUniqueIdx = 1;
    }
    for(pSrcIdx=pSrc->pIndex; pSrcIdx; pSrcIdx=pSrcIdx->pNext){








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    if( sqlite3_stricmp(pDestCol->zColl, pSrcCol->zColl)!=0 ){
      return 0;    /* Collating sequence must be the same on all columns */
    }
    if( pDestCol->notNull && !pSrcCol->notNull ){
      return 0;    /* tab2 must be NOT NULL if tab1 is */
    }
    /* Default values for second and subsequent columns need to match. */
    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){
    if( IsUniqueIndex(pDestIdx) ){
      destHasUniqueIdx = 1;
    }
    for(pSrcIdx=pSrc->pIndex; pSrcIdx; pSrcIdx=pSrcIdx->pNext){

Changes to src/pragma.c. 

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        if( (pCol->colFlags & COLFLAG_PRIMKEY)==0 ){
          k = 0;
        }else if( pPk==0 ){
          k = 1;
        }else{
          for(k=1; k<=pTab->nCol && pPk->aiColumn[k-1]!=i; k++){}
        }

        sqlite3VdbeMultiLoad(v, 1, "issisi",
               i-nHidden,
               pCol->zName,
               pCol->zType ? pCol->zType : "",
               pCol->notNull ? 1 : 0,
               pCol->zDflt,
               k);
        sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 6);
      }
    }
  }
  break;









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        if( (pCol->colFlags & COLFLAG_PRIMKEY)==0 ){
          k = 0;
        }else if( pPk==0 ){
          k = 1;
        }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->pDflt ? pCol->pDflt->u.zToken : 0,
               k);
        sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 6);
      }
    }
  }
  break;

Changes to src/sqliteInt.h. 

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/*
** information about each column of an SQL table is held in an instance
** of this structure.
*/
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 */
  char affinity;   /* One of the SQLITE_AFF_... values */
  u8 szEst;        /* Estimated size of value in this column. sizeof(INT)==1 */
  u8 colFlags;     /* Boolean properties.  See COLFLAG_ defines below */
};








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/*
** information about each column of an SQL table is held in an instance
** of this structure.
*/
struct Column {
  char *zName;     /* Name of this column */
  Expr *pDflt;     /* Default value of this column */

  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 */
  char affinity;   /* One of the SQLITE_AFF_... values */
  u8 szEst;        /* Estimated size of value in this column. sizeof(INT)==1 */
  u8 colFlags;     /* Boolean properties.  See COLFLAG_ defines below */
};

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    case TK_UMINUS:  zUniOp = "UMINUS"; break;
    case TK_UPLUS:   zUniOp = "UPLUS";  break;
    case TK_BITNOT:  zUniOp = "BITNOT"; break;
    case TK_NOT:     zUniOp = "NOT";    break;
    case TK_ISNULL:  zUniOp = "ISNULL"; break;
    case TK_NOTNULL: zUniOp = "NOTNULL"; break;







    case TK_COLLATE: {
      sqlite3TreeViewLine(pView, "COLLATE %Q", pExpr->u.zToken);
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
      break;
    }









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    case TK_UMINUS:  zUniOp = "UMINUS"; break;
    case TK_UPLUS:   zUniOp = "UPLUS";  break;
    case TK_BITNOT:  zUniOp = "BITNOT"; break;
    case TK_NOT:     zUniOp = "NOT";    break;
    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);
      break;
    }

Changes to src/vdbemem.c. 

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  const char *zNeg = "";
  int rc = SQLITE_OK;

  if( !pExpr ){
    *ppVal = 0;
    return SQLITE_OK;
  }
  while( (op = pExpr->op)==TK_UPLUS ) pExpr = pExpr->pLeft;
  if( NEVER(op==TK_REGISTER) ) op = pExpr->op2;

  /* Compressed expressions only appear when parsing the DEFAULT clause
  ** on a table column definition, and hence only when pCtx==0.  This
  ** check ensures that an EP_TokenOnly expression is never passed down
  ** into valueFromFunction(). */
  assert( (pExpr->flags & EP_TokenOnly)==0 || pCtx==0 );








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  const char *zNeg = "";
  int rc = SQLITE_OK;

  if( !pExpr ){
    *ppVal = 0;
    return SQLITE_OK;
  }
  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
  ** on a table column definition, and hence only when pCtx==0.  This
  ** check ensures that an EP_TokenOnly expression is never passed down
  ** into valueFromFunction(). */
  assert( (pExpr->flags & EP_TokenOnly)==0 || pCtx==0 );

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  COLUMN
  AGG_FUNCTION
  AGG_COLUMN
  UMINUS
  UPLUS
  REGISTER
  ASTERISK

  SPACE
  ILLEGAL
}
if {[lrange $extras end-1 end]!="SPACE ILLEGAL"} {
  error "SPACE and ILLEGAL must be the last two token codes and they\
         must be in that order"
}








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  COLUMN
  AGG_FUNCTION
  AGG_COLUMN
  UMINUS
  UPLUS
  REGISTER
  ASTERISK
  SPAN
  SPACE
  ILLEGAL
}
if {[lrange $extras end-1 end]!="SPACE ILLEGAL"} {
  error "SPACE and ILLEGAL must be the last two token codes and they\
         must be in that order"
}

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