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Make the LIMIT clause work even if the destination of the SELECT is

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something other than a callback.  (Ticket #66) (CVS 619)

FossilOrigin-Name: 699cf362083043615eb88635a228bfa46a315c9c
This commit is contained in:
drh
2002-06-14 22:38:41 +00:00
parent c27a1ce4bd
commit df199a25bd
8 changed files with 134 additions and 82 deletions
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71
src/select.c
View File

@ -12,7 +12,7 @@
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.92 2002/06/06 23:42:28 drh Exp $
** $Id: select.c,v 1.93 2002/06/14 22:38:42 drh Exp $
*/
#include "sqliteInt.h"
@ -294,6 +294,7 @@ static void sqliteAggregateInfoReset(Parse *pParse){
*/
static int selectInnerLoop(
Parse *pParse, /* The parser context */
Select *p, /* The complete select statement being coded */
ExprList *pEList, /* List of values being extracted */
int srcTab, /* Pull data from this table */
int nColumn, /* Number of columns in the source table */
@ -308,6 +309,18 @@ static int selectInnerLoop(
int i;
if( v==0 ) return 0;
/* If there was a LIMIT clause on the SELECT statement, then do the check
** to see if this row should be output.
*/
if( pOrderBy==0 ){
if( p->nOffset>0 ){
sqliteVdbeAddOp(v, OP_LimitCk, 1, iContinue);
}
if( p->nLimit>0 ){
sqliteVdbeAddOp(v, OP_LimitCk, 0, iBreak);
}
}
/* Pull the requested columns.
*/
if( pEList ){
@ -419,7 +432,8 @@ static int selectInnerLoop(
/* If none of the above, send the data to the callback function.
*/
{
sqliteVdbeAddOp(v, OP_Callback, nColumn, iBreak);
assert( eDest==SRT_Callback );
sqliteVdbeAddOp(v, OP_Callback, nColumn, 0);
}
return 0;
}
@ -430,12 +444,18 @@ static int selectInnerLoop(
** we need to run the sorter and output the results. The following
** routine generates the code needed to do that.
*/
static void generateSortTail(Vdbe *v, int nColumn){
static void generateSortTail(Select *p, Vdbe *v, int nColumn){
int end = sqliteVdbeMakeLabel(v);
int addr;
sqliteVdbeAddOp(v, OP_Sort, 0, 0);
addr = sqliteVdbeAddOp(v, OP_SortNext, 0, end);
sqliteVdbeAddOp(v, OP_SortCallback, nColumn, end);
if( p->nOffset>0 ){
sqliteVdbeAddOp(v, OP_LimitCk, 1, addr);
}
if( p->nLimit>0 ){
sqliteVdbeAddOp(v, OP_LimitCk, 0, end);
}
sqliteVdbeAddOp(v, OP_SortCallback, nColumn, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, addr);
sqliteVdbeResolveLabel(v, end);
sqliteVdbeAddOp(v, OP_SortReset, 0, 0);
@ -975,7 +995,7 @@ static int multiSelect(Parse *pParse, Select *p, int eDest, int iParm){
iCont = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_Rewind, unionTab, iBreak);
iStart = sqliteVdbeCurrentAddr(v);
rc = selectInnerLoop(pParse, 0, unionTab, p->pEList->nExpr,
rc = selectInnerLoop(pParse, p, 0, unionTab, p->pEList->nExpr,
p->pOrderBy, -1, eDest, iParm,
iCont, iBreak);
if( rc ) return 1;
@ -984,7 +1004,7 @@ static int multiSelect(Parse *pParse, Select *p, int eDest, int iParm){
sqliteVdbeResolveLabel(v, iBreak);
sqliteVdbeAddOp(v, OP_Close, unionTab, 0);
if( p->pOrderBy ){
generateSortTail(v, p->pEList->nExpr);
generateSortTail(p, v, p->pEList->nExpr);
}
}
break;
@ -1031,7 +1051,7 @@ static int multiSelect(Parse *pParse, Select *p, int eDest, int iParm){
sqliteVdbeAddOp(v, OP_Rewind, tab1, iBreak);
iStart = sqliteVdbeAddOp(v, OP_FullKey, tab1, 0);
sqliteVdbeAddOp(v, OP_NotFound, tab2, iCont);
rc = selectInnerLoop(pParse, 0, tab1, p->pEList->nExpr,
rc = selectInnerLoop(pParse, p, 0, tab1, p->pEList->nExpr,
p->pOrderBy, -1, eDest, iParm,
iCont, iBreak);
if( rc ) return 1;
@ -1041,7 +1061,7 @@ static int multiSelect(Parse *pParse, Select *p, int eDest, int iParm){
sqliteVdbeAddOp(v, OP_Close, tab2, 0);
sqliteVdbeAddOp(v, OP_Close, tab1, 0);
if( p->pOrderBy ){
generateSortTail(v, p->pEList->nExpr);
generateSortTail(p, v, p->pEList->nExpr);
}
break;
}
@ -1176,6 +1196,14 @@ substExprList(ExprList *pList, int iTable, ExprList *pEList, int iSub){
**
** (7) The subquery has a FROM clause.
**
** (8) The subquery does not use LIMIT or the outer query is not a join.
**
** (9) The subquery does not use LIMIT or the outer query does not use
** aggregates.
**
** (10) The subquery does not use aggregates or the outer query does not
** use LIMIT.
**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query
** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
@ -1207,9 +1235,10 @@ int flattenSubquery(Select *p, int iFrom, int isAgg, int subqueryIsAgg){
pSubSrc = pSub->pSrc;
assert( pSubSrc );
if( pSubSrc->nSrc!=1 ) return 0;
if( pSub->isDistinct && pSrc->nSrc>1 ) return 0;
if( pSub->isDistinct && isAgg ) return 0;
if( p->isDistinct && subqueryIsAgg ) return 0;
if( (pSub->isDistinct || pSub->nLimit>=0) && (pSrc->nSrc>1 || isAgg) ){
return 0;
}
if( (p->isDistinct || p->nLimit) && subqueryIsAgg ) return 0;
/* If we reach this point, it means flattening is permitted for the
** i-th entry of the FROM clause in the outer query.
@ -1267,6 +1296,14 @@ int flattenSubquery(Select *p, int iFrom, int isAgg, int subqueryIsAgg){
}
}
p->isDistinct = p->isDistinct || pSub->isDistinct;
if( pSub->nLimit>=0 ){
if( p->nLimit<0 ){
p->nLimit = pSub->nLimit;
}else if( p->nLimit+p->nOffset > pSub->nLimit+pSub->nOffset ){
p->nLimit = pSub->nLimit + pSub->nOffset - p->nOffset;
}
}
p->nOffset += pSub->nOffset;
if( pSrc->a[iFrom].pTab && pSrc->a[iFrom].pTab->isTransient ){
sqliteDeleteTable(0, pSrc->a[iFrom].pTab);
}
@ -1386,7 +1423,7 @@ static int simpleMinMaxQuery(Parse *pParse, Select *p, int eDest, int iParm){
eList.a = &eListItem;
eList.a[0].pExpr = pExpr;
cont = sqliteVdbeMakeLabel(v);
selectInnerLoop(pParse, &eList, base, 1, 0, -1, eDest, iParm, cont, cont);
selectInnerLoop(pParse, p, &eList, base, 1, 0, -1, eDest, iParm, cont, cont);
sqliteVdbeResolveLabel(v, cont);
sqliteVdbeAddOp(v, OP_Close, base, 0);
return 1;
@ -1720,8 +1757,8 @@ int sqliteSelect(
** aggregates
*/
if( !isAgg ){
if( selectInnerLoop(pParse, pEList, 0, 0, pOrderBy, distinct, eDest, iParm,
pWInfo->iContinue, pWInfo->iBreak) ){
if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest,
iParm, pWInfo->iContinue, pWInfo->iBreak) ){
goto select_end;
}
}
@ -1779,8 +1816,8 @@ int sqliteSelect(
if( pHaving ){
sqliteExprIfFalse(pParse, pHaving, startagg, 1);
}
if( selectInnerLoop(pParse, pEList, 0, 0, pOrderBy, distinct, eDest, iParm,
startagg, endagg) ){
if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest,
iParm, startagg, endagg) ){
goto select_end;
}
sqliteVdbeAddOp(v, OP_Goto, 0, startagg);
@ -1793,7 +1830,7 @@ int sqliteSelect(
** and send them to the callback one by one.
*/
if( pOrderBy ){
generateSortTail(v, pEList->nExpr);
generateSortTail(p, v, pEList->nExpr);
}

89
src/vdbe.c
View File

@ -30,7 +30,7 @@
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.155 2002/06/11 02:25:42 danielk1977 Exp $
** $Id: vdbe.c,v 1.156 2002/06/14 22:38:43 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@ -1080,6 +1080,7 @@ static char *zOpName[] = { 0,
"Gt", "Ge", "IsNull", "NotNull",
"Negative", "And", "Or", "Not",
"Concat", "Noop", "Function", "Limit",
"LimitCk",
};
/*
@ -1585,18 +1586,11 @@ case OP_ColumnName: {
break;
}
/* Opcode: Callback P1 P2 *
/* Opcode: Callback P1 * *
**
** Pop P1 values off the stack and form them into an array. Then
** invoke the callback function using the newly formed array as the
** 3rd parameter.
**
** If the offset counter (set by the OP_Limit opcode) is positive,
** then decrement the counter and do not invoke the callback.
**
** If the callback is invoked, then after the callback returns
** decrement the limit counter. When the limit counter reaches
** zero, jump to address P2.
*/
case OP_Callback: {
int i = p->tos - pOp->p1 + 1;
@ -1612,22 +1606,12 @@ case OP_Callback: {
}
zStack[p->tos+1] = 0;
if( xCallback!=0 ){
if( p->iOffset>0 ){
p->iOffset--;
}else{
if( sqliteSafetyOff(db) ) goto abort_due_to_misuse;
if( xCallback(pArg, pOp->p1, &zStack[i], p->azColName)!=0 ){
rc = SQLITE_ABORT;
}
if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
p->nCallback++;
if( p->iLimit>0 ){
p->iLimit--;
if( p->iLimit==0 ){
pc = pOp->p2 - 1;
}
}
if( sqliteSafetyOff(db) ) goto abort_due_to_misuse;
if( xCallback(pArg, pOp->p1, &zStack[i], p->azColName)!=0 ){
rc = SQLITE_ABORT;
}
if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
p->nCallback++;
}
PopStack(p, pOp->p1);
if( sqlite_malloc_failed ) goto no_mem;
@ -3917,6 +3901,35 @@ case OP_Limit: {
break;
}
/* Opcode: LimitCk P1 P2 *
**
** If P1 is 1, then check to see if the offset counter (set by the
** P2 argument of OP_Limit) is positive. If the offset counter is
** positive then decrement the counter and jump immediately to P2.
** Otherwise fall straight through.
**
** If P1 is 0, then check the value of the limit counter (set by the
** P1 argument of OP_Limit). If the limit counter is negative or
** zero then jump immedately to P2. Otherwise decrement the limit
** counter and fall through.
*/
case OP_LimitCk: {
if( pOp->p1 ){
if( p->iOffset ){
p->iOffset--;
pc = pOp->p2 - 1;
}
}else{
if( p->iLimit>0 ){
p->iLimit--;
}else{
pc = pOp->p2 - 1;
}
}
break;
}
/* Opcode: ListWrite * * *
**
** Write the integer on the top of the stack
@ -4207,40 +4220,22 @@ case OP_SortNext: {
break;
}
/* Opcode: SortCallback P1 P2 *
/* Opcode: SortCallback P1 * *
**
** The top of the stack contains a callback record built using
** the SortMakeRec operation with the same P1 value as this
** instruction. Pop this record from the stack and invoke the
** callback on it.
**
** If the offset counter (set by the OP_Limit opcode) is positive,
** then decrement the counter and do not invoke the callback.
**
** If the callback is invoked, then after the callback returns
** decrement the limit counter. When the limit counter reaches
** zero, jump to address P2.
*/
case OP_SortCallback: {
int i = p->tos;
VERIFY( if( i<0 ) goto not_enough_stack; )
if( xCallback!=0 ){
if( p->iOffset>0 ){
p->iOffset--;
}else{
if( sqliteSafetyOff(db) ) goto abort_due_to_misuse;
if( xCallback(pArg, pOp->p1, (char**)zStack[i], p->azColName)!=0 ){
rc = SQLITE_ABORT;
}
if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
p->nCallback++;
if( p->iLimit>0 ){
p->iLimit--;
if( p->iLimit==0 ){
pc = pOp->p2 - 1;
}
}
if( sqliteSafetyOff(db) ) goto abort_due_to_misuse;
if( xCallback(pArg, pOp->p1, (char**)zStack[i], p->azColName)!=0 ){
rc = SQLITE_ABORT;
}
if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
p->nCallback++;
}
POPSTACK;

5
src/vdbe.h
View File

@ -15,7 +15,7 @@
** or VDBE. The VDBE implements an abstract machine that runs a
** simple program to access and modify the underlying database.
**
** $Id: vdbe.h,v 1.54 2002/06/08 23:25:09 drh Exp $
** $Id: vdbe.h,v 1.55 2002/06/14 22:38:43 drh Exp $
*/
#ifndef _SQLITE_VDBE_H_
#define _SQLITE_VDBE_H_
@ -204,9 +204,10 @@ typedef struct VdbeOp VdbeOp;
#define OP_Function 119
#define OP_Limit 120
#define OP_LimitCk 121
#define OP_MAX 120
#define OP_MAX 121
/*
** Prototypes for the VDBE interface. See comments on the implementation

3
src/where.c
View File

@ -13,7 +13,7 @@
** the WHERE clause of SQL statements. Also found here are subroutines
** to generate VDBE code to evaluate expressions.
**
** $Id: where.c,v 1.51 2002/06/14 20:58:45 drh Exp $
** $Id: where.c,v 1.52 2002/06/14 22:38:43 drh Exp $
*/
#include "sqliteInt.h"
@ -258,6 +258,7 @@ WhereInfo *sqliteWhereBegin(
*/
if( pWhere && sqliteExprIsConstant(pWhere) ){
sqliteExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1);
pWhere = 0;
}
/* Split the WHERE clause into as many as 32 separate subexpressions