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Overview
Comment:Simplify the accumulator reset for aggregate query processing so that it uses a single multi-register OP_Null rather than a separate OP_Null for each register.
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SHA1:2c7fd9b043f5f3d9d8e22dbefa84a9770ca951d0
User & Date: drh 2013-12-20 13:11:45
Context
2013-12-20
14:48
Allow any arbitrary expression as the filename in an ATTACH statement, including functions and subqueries. check-in: df70a1f3 user: drh tags: trunk
13:11
Simplify the accumulator reset for aggregate query processing so that it uses a single multi-register OP_Null rather than a separate OP_Null for each register. check-in: 2c7fd9b0 user: drh tags: trunk
2013-12-19
17:04
Do not inject OOM faults into SQLITE_FCNTL_COMMIT_PHASE_TWO file-control invocations. It causes problems for test scripts. check-in: 8eb28d23 user: dan tags: trunk
Changes
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Changes to src/select.c.

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** routine generates code that stores NULLs in all of those memory
** cells.
*/
static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){
  Vdbe *v = pParse->pVdbe;
  int i;
  struct AggInfo_func *pFunc;
  if( pAggInfo->nFunc+pAggInfo->nColumn==0 ){
    return;







  }
  for(i=0; i<pAggInfo->nColumn; i++){
    sqlite3VdbeAddOp2(v, OP_Null, 0, pAggInfo->aCol[i].iMem);


  }


  for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){
    sqlite3VdbeAddOp2(v, OP_Null, 0, pFunc->iMem);
    if( pFunc->iDistinct>=0 ){
      Expr *pE = pFunc->pExpr;
      assert( !ExprHasProperty(pE, EP_xIsSelect) );
      if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){
        sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one "
           "argument");
        pFunc->iDistinct = -1;
................................................................................
    ** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the
    ** SELECT statement.
    */
    memset(&sNC, 0, sizeof(sNC));
    sNC.pParse = pParse;
    sNC.pSrcList = pTabList;
    sNC.pAggInfo = &sAggInfo;

    sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr+1 : 0;
    sAggInfo.pGroupBy = pGroupBy;
    sqlite3ExprAnalyzeAggList(&sNC, pEList);
    sqlite3ExprAnalyzeAggList(&sNC, pOrderBy);
    if( pHaving ){
      sqlite3ExprAnalyzeAggregates(&sNC, pHaving);
    }
................................................................................
    sAggInfo.nAccumulator = sAggInfo.nColumn;
    for(i=0; i<sAggInfo.nFunc; i++){
      assert( !ExprHasProperty(sAggInfo.aFunc[i].pExpr, EP_xIsSelect) );
      sNC.ncFlags |= NC_InAggFunc;
      sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->x.pList);
      sNC.ncFlags &= ~NC_InAggFunc;
    }

    if( db->mallocFailed ) goto select_end;

    /* Processing for aggregates with GROUP BY is very different and
    ** much more complex than aggregates without a GROUP BY.
    */
    if( pGroupBy ){
      KeyInfo *pKeyInfo;  /* Keying information for the group by clause */







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** routine generates code that stores NULLs in all of those memory
** cells.
*/
static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){
  Vdbe *v = pParse->pVdbe;
  int i;
  struct AggInfo_func *pFunc;
  int nReg = pAggInfo->nFunc + pAggInfo->nColumn;
  if( nReg==0 ) return;
#ifdef SQLITE_DEBUG
  /* Verify that all AggInfo registers are within the range specified by
  ** AggInfo.mnReg..AggInfo.mxReg */
  assert( nReg==pAggInfo->mxReg-pAggInfo->mnReg+1 );
  for(i=0; i<pAggInfo->nColumn; i++){
    assert( pAggInfo->aCol[i].iMem>=pAggInfo->mnReg
         && pAggInfo->aCol[i].iMem<=pAggInfo->mxReg );
  }
  for(i=0; i<pAggInfo->nFunc; i++){

    assert( pAggInfo->aFunc[i].iMem>=pAggInfo->mnReg
         && pAggInfo->aFunc[i].iMem<=pAggInfo->mxReg );
  }
#endif
  sqlite3VdbeAddOp3(v, OP_Null, 0, pAggInfo->mnReg, pAggInfo->mxReg);
  for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){

    if( pFunc->iDistinct>=0 ){
      Expr *pE = pFunc->pExpr;
      assert( !ExprHasProperty(pE, EP_xIsSelect) );
      if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){
        sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one "
           "argument");
        pFunc->iDistinct = -1;
................................................................................
    ** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the
    ** SELECT statement.
    */
    memset(&sNC, 0, sizeof(sNC));
    sNC.pParse = pParse;
    sNC.pSrcList = pTabList;
    sNC.pAggInfo = &sAggInfo;
    sAggInfo.mnReg = pParse->nMem+1;
    sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr+1 : 0;
    sAggInfo.pGroupBy = pGroupBy;
    sqlite3ExprAnalyzeAggList(&sNC, pEList);
    sqlite3ExprAnalyzeAggList(&sNC, pOrderBy);
    if( pHaving ){
      sqlite3ExprAnalyzeAggregates(&sNC, pHaving);
    }
................................................................................
    sAggInfo.nAccumulator = sAggInfo.nColumn;
    for(i=0; i<sAggInfo.nFunc; i++){
      assert( !ExprHasProperty(sAggInfo.aFunc[i].pExpr, EP_xIsSelect) );
      sNC.ncFlags |= NC_InAggFunc;
      sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->x.pList);
      sNC.ncFlags &= ~NC_InAggFunc;
    }
    sAggInfo.mxReg = pParse->nMem;
    if( db->mallocFailed ) goto select_end;

    /* Processing for aggregates with GROUP BY is very different and
    ** much more complex than aggregates without a GROUP BY.
    */
    if( pGroupBy ){
      KeyInfo *pKeyInfo;  /* Keying information for the group by clause */

Changes to src/sqliteInt.h.

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  u8 directMode;          /* Direct rendering mode means take data directly
                          ** from source tables rather than from accumulators */
  u8 useSortingIdx;       /* In direct mode, reference the sorting index rather
                          ** than the source table */
  int sortingIdx;         /* Cursor number of the sorting index */
  int sortingIdxPTab;     /* Cursor number of pseudo-table */
  int nSortingColumn;     /* Number of columns in the sorting index */

  ExprList *pGroupBy;     /* The group by clause */
  struct AggInfo_col {    /* For each column used in source tables */
    Table *pTab;             /* Source table */
    int iTable;              /* Cursor number of the source table */
    int iColumn;             /* Column number within the source table */
    int iSorterColumn;       /* Column number in the sorting index */
    int iMem;                /* Memory location that acts as accumulator */







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  u8 directMode;          /* Direct rendering mode means take data directly
                          ** from source tables rather than from accumulators */
  u8 useSortingIdx;       /* In direct mode, reference the sorting index rather
                          ** than the source table */
  int sortingIdx;         /* Cursor number of the sorting index */
  int sortingIdxPTab;     /* Cursor number of pseudo-table */
  int nSortingColumn;     /* Number of columns in the sorting index */
  int mnReg, mxReg;       /* Range of registers allocated for aCol and aFunc */
  ExprList *pGroupBy;     /* The group by clause */
  struct AggInfo_col {    /* For each column used in source tables */
    Table *pTab;             /* Source table */
    int iTable;              /* Cursor number of the source table */
    int iColumn;             /* Column number within the source table */
    int iSorterColumn;       /* Column number in the sorting index */
    int iMem;                /* Memory location that acts as accumulator */