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select.c
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6802 lines (6425 loc) · 244 KB
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/*
** 2001 September 15
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
*/
#include "sqliteInt.h"
/*
** Trace output macros
*/
#if SELECTTRACE_ENABLED
/***/ int sqlite3SelectTrace = 0;
# define SELECTTRACE(K,P,S,X) \
if(sqlite3SelectTrace&(K)) \
sqlite3DebugPrintf("%u/%d/%p: ",(S)->selId,(P)->addrExplain,(S)),\
sqlite3DebugPrintf X
#else
# define SELECTTRACE(K,P,S,X)
#endif
/*
** An instance of the following object is used to record information about
** how to process the DISTINCT keyword, to simplify passing that information
** into the selectInnerLoop() routine.
*/
typedef struct DistinctCtx DistinctCtx;
struct DistinctCtx {
u8 isTnct; /* True if the DISTINCT keyword is present */
u8 eTnctType; /* One of the WHERE_DISTINCT_* operators */
int tabTnct; /* Ephemeral table used for DISTINCT processing */
int addrTnct; /* Address of OP_OpenEphemeral opcode for tabTnct */
};
/*
** An instance of the following object is used to record information about
** the ORDER BY (or GROUP BY) clause of query is being coded.
**
** The aDefer[] array is used by the sorter-references optimization. For
** example, assuming there is no index that can be used for the ORDER BY,
** for the query:
**
** SELECT a, bigblob FROM t1 ORDER BY a LIMIT 10;
**
** it may be more efficient to add just the "a" values to the sorter, and
** retrieve the associated "bigblob" values directly from table t1 as the
** 10 smallest "a" values are extracted from the sorter.
**
** When the sorter-reference optimization is used, there is one entry in the
** aDefer[] array for each database table that may be read as values are
** extracted from the sorter.
*/
typedef struct SortCtx SortCtx;
struct SortCtx {
ExprList *pOrderBy; /* The ORDER BY (or GROUP BY clause) */
int nOBSat; /* Number of ORDER BY terms satisfied by indices */
int iECursor; /* Cursor number for the sorter */
int regReturn; /* Register holding block-output return address */
int labelBkOut; /* Start label for the block-output subroutine */
int addrSortIndex; /* Address of the OP_SorterOpen or OP_OpenEphemeral */
int labelDone; /* Jump here when done, ex: LIMIT reached */
int labelOBLopt; /* Jump here when sorter is full */
u8 sortFlags; /* Zero or more SORTFLAG_* bits */
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
u8 nDefer; /* Number of valid entries in aDefer[] */
struct DeferredCsr {
Table *pTab; /* Table definition */
int iCsr; /* Cursor number for table */
int nKey; /* Number of PK columns for table pTab (>=1) */
} aDefer[4];
#endif
struct RowLoadInfo *pDeferredRowLoad; /* Deferred row loading info or NULL */
};
#define SORTFLAG_UseSorter 0x01 /* Use SorterOpen instead of OpenEphemeral */
/*
** Delete all the content of a Select structure. Deallocate the structure
** itself depending on the value of bFree
**
** If bFree==1, call sqlite3DbFree() on the p object.
** If bFree==0, Leave the first Select object unfreed
*/
static void clearSelect(sqlite3 *db, Select *p, int bFree){
while( p ){
Select *pPrior = p->pPrior;
sqlite3ExprListDelete(db, p->pEList);
sqlite3SrcListDelete(db, p->pSrc);
sqlite3ExprDelete(db, p->pWhere);
sqlite3ExprListDelete(db, p->pGroupBy);
sqlite3ExprDelete(db, p->pHaving);
sqlite3ExprListDelete(db, p->pOrderBy);
sqlite3ExprDelete(db, p->pLimit);
#ifndef SQLITE_OMIT_WINDOWFUNC
if( OK_IF_ALWAYS_TRUE(p->pWinDefn) ){
sqlite3WindowListDelete(db, p->pWinDefn);
}
#endif
if( OK_IF_ALWAYS_TRUE(p->pWith) ) sqlite3WithDelete(db, p->pWith);
if( bFree ) sqlite3DbFreeNN(db, p);
p = pPrior;
bFree = 1;
}
}
/*
** Initialize a SelectDest structure.
*/
void sqlite3SelectDestInit(SelectDest *pDest, int eDest, int iParm){
pDest->eDest = (u8)eDest;
pDest->iSDParm = iParm;
pDest->zAffSdst = 0;
pDest->iSdst = 0;
pDest->nSdst = 0;
}
/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
Select *sqlite3SelectNew(
Parse *pParse, /* Parsing context */
ExprList *pEList, /* which columns to include in the result */
SrcList *pSrc, /* the FROM clause -- which tables to scan */
Expr *pWhere, /* the WHERE clause */
ExprList *pGroupBy, /* the GROUP BY clause */
Expr *pHaving, /* the HAVING clause */
ExprList *pOrderBy, /* the ORDER BY clause */
u32 selFlags, /* Flag parameters, such as SF_Distinct */
Expr *pLimit /* LIMIT value. NULL means not used */
){
Select *pNew, *pAllocated;
Select standin;
pAllocated = pNew = sqlite3DbMallocRawNN(pParse->db, sizeof(*pNew) );
if( pNew==0 ){
assert( pParse->db->mallocFailed );
pNew = &standin;
}
if( pEList==0 ){
pEList = sqlite3ExprListAppend(pParse, 0,
sqlite3Expr(pParse->db,TK_ASTERISK,0));
}
pNew->pEList = pEList;
pNew->op = TK_SELECT;
pNew->selFlags = selFlags;
pNew->iLimit = 0;
pNew->iOffset = 0;
pNew->selId = ++pParse->nSelect;
pNew->addrOpenEphm[0] = -1;
pNew->addrOpenEphm[1] = -1;
pNew->nSelectRow = 0;
if( pSrc==0 ) pSrc = sqlite3DbMallocZero(pParse->db, sizeof(*pSrc));
pNew->pSrc = pSrc;
pNew->pWhere = pWhere;
pNew->pGroupBy = pGroupBy;
pNew->pHaving = pHaving;
pNew->pOrderBy = pOrderBy;
pNew->pPrior = 0;
pNew->pNext = 0;
pNew->pLimit = pLimit;
pNew->pWith = 0;
#ifndef SQLITE_OMIT_WINDOWFUNC
pNew->pWin = 0;
pNew->pWinDefn = 0;
#endif
if( pParse->db->mallocFailed ) {
clearSelect(pParse->db, pNew, pNew!=&standin);
pAllocated = 0;
}else{
assert( pNew->pSrc!=0 || pParse->nErr>0 );
}
return pAllocated;
}
/*
** Delete the given Select structure and all of its substructures.
*/
void sqlite3SelectDelete(sqlite3 *db, Select *p){
if( OK_IF_ALWAYS_TRUE(p) ) clearSelect(db, p, 1);
}
/*
** Delete all the substructure for p, but keep p allocated. Redefine
** p to be a single SELECT where every column of the result set has a
** value of NULL.
*/
void sqlite3SelectReset(Parse *pParse, Select *p){
if( ALWAYS(p) ){
clearSelect(pParse->db, p, 0);
memset(&p->iLimit, 0, sizeof(Select) - offsetof(Select,iLimit));
p->pEList = sqlite3ExprListAppend(pParse, 0,
sqlite3ExprAlloc(pParse->db,TK_NULL,0,0));
p->pSrc = sqlite3DbMallocZero(pParse->db, sizeof(SrcList));
}
}
/*
** Return a pointer to the right-most SELECT statement in a compound.
*/
static Select *findRightmost(Select *p){
while( p->pNext ) p = p->pNext;
return p;
}
/*
** Given 1 to 3 identifiers preceding the JOIN keyword, determine the
** type of join. Return an integer constant that expresses that type
** in terms of the following bit values:
**
** JT_INNER
** JT_CROSS
** JT_OUTER
** JT_NATURAL
** JT_LEFT
** JT_RIGHT
**
** A full outer join is the combination of JT_LEFT and JT_RIGHT.
**
** If an illegal or unsupported join type is seen, then still return
** a join type, but put an error in the pParse structure.
*/
int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){
int jointype = 0;
Token *apAll[3];
Token *p;
/* 0123456789 123456789 123456789 123 */
static const char zKeyText[] = "naturaleftouterightfullinnercross";
static const struct {
u8 i; /* Beginning of keyword text in zKeyText[] */
u8 nChar; /* Length of the keyword in characters */
u8 code; /* Join type mask */
} aKeyword[] = {
/* natural */ { 0, 7, JT_NATURAL },
/* left */ { 6, 4, JT_LEFT|JT_OUTER },
/* outer */ { 10, 5, JT_OUTER },
/* right */ { 14, 5, JT_RIGHT|JT_OUTER },
/* full */ { 19, 4, JT_LEFT|JT_RIGHT|JT_OUTER },
/* inner */ { 23, 5, JT_INNER },
/* cross */ { 28, 5, JT_INNER|JT_CROSS },
};
int i, j;
apAll[0] = pA;
apAll[1] = pB;
apAll[2] = pC;
for(i=0; i<3 && apAll[i]; i++){
p = apAll[i];
for(j=0; j<ArraySize(aKeyword); j++){
if( p->n==aKeyword[j].nChar
&& sqlite3StrNICmp((char*)p->z, &zKeyText[aKeyword[j].i], p->n)==0 ){
jointype |= aKeyword[j].code;
break;
}
}
testcase( j==0 || j==1 || j==2 || j==3 || j==4 || j==5 || j==6 );
if( j>=ArraySize(aKeyword) ){
jointype |= JT_ERROR;
break;
}
}
if(
(jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) ||
(jointype & JT_ERROR)!=0
){
const char *zSp = " ";
assert( pB!=0 );
if( pC==0 ){ zSp++; }
sqlite3ErrorMsg(pParse, "unknown or unsupported join type: "
"%T %T%s%T", pA, pB, zSp, pC);
jointype = JT_INNER;
}else if( (jointype & JT_OUTER)!=0
&& (jointype & (JT_LEFT|JT_RIGHT))!=JT_LEFT ){
sqlite3ErrorMsg(pParse,
"RIGHT and FULL OUTER JOINs are not currently supported");
jointype = JT_INNER;
}
return jointype;
}
/*
** Return the index of a column in a table. Return -1 if the column
** is not contained in the table.
*/
static int columnIndex(Table *pTab, const char *zCol){
int i;
for(i=0; i<pTab->nCol; i++){
if( sqlite3StrICmp(pTab->aCol[i].zName, zCol)==0 ) return i;
}
return -1;
}
/*
** Search the first N tables in pSrc, from left to right, looking for a
** table that has a column named zCol.
**
** When found, set *piTab and *piCol to the table index and column index
** of the matching column and return TRUE.
**
** If not found, return FALSE.
*/
static int tableAndColumnIndex(
SrcList *pSrc, /* Array of tables to search */
int N, /* Number of tables in pSrc->a[] to search */
const char *zCol, /* Name of the column we are looking for */
int *piTab, /* Write index of pSrc->a[] here */
int *piCol, /* Write index of pSrc->a[*piTab].pTab->aCol[] here */
int bIgnoreHidden /* True to ignore hidden columns */
){
int i; /* For looping over tables in pSrc */
int iCol; /* Index of column matching zCol */
assert( (piTab==0)==(piCol==0) ); /* Both or neither are NULL */
for(i=0; i<N; i++){
iCol = columnIndex(pSrc->a[i].pTab, zCol);
if( iCol>=0
&& (bIgnoreHidden==0 || IsHiddenColumn(&pSrc->a[i].pTab->aCol[iCol])==0)
){
if( piTab ){
*piTab = i;
*piCol = iCol;
}
return 1;
}
}
return 0;
}
/*
** This function is used to add terms implied by JOIN syntax to the
** WHERE clause expression of a SELECT statement. The new term, which
** is ANDed with the existing WHERE clause, is of the form:
**
** (tab1.col1 = tab2.col2)
**
** where tab1 is the iSrc'th table in SrcList pSrc and tab2 is the
** (iSrc+1)'th. Column col1 is column iColLeft of tab1, and col2 is
** column iColRight of tab2.
*/
static void addWhereTerm(
Parse *pParse, /* Parsing context */
SrcList *pSrc, /* List of tables in FROM clause */
int iLeft, /* Index of first table to join in pSrc */
int iColLeft, /* Index of column in first table */
int iRight, /* Index of second table in pSrc */
int iColRight, /* Index of column in second table */
int isOuterJoin, /* True if this is an OUTER join */
Expr **ppWhere /* IN/OUT: The WHERE clause to add to */
){
sqlite3 *db = pParse->db;
Expr *pE1;
Expr *pE2;
Expr *pEq;
assert( iLeft<iRight );
assert( pSrc->nSrc>iRight );
assert( pSrc->a[iLeft].pTab );
assert( pSrc->a[iRight].pTab );
pE1 = sqlite3CreateColumnExpr(db, pSrc, iLeft, iColLeft);
pE2 = sqlite3CreateColumnExpr(db, pSrc, iRight, iColRight);
pEq = sqlite3PExpr(pParse, TK_EQ, pE1, pE2);
if( pEq && isOuterJoin ){
ExprSetProperty(pEq, EP_FromJoin);
assert( !ExprHasProperty(pEq, EP_TokenOnly|EP_Reduced) );
ExprSetVVAProperty(pEq, EP_NoReduce);
pEq->iRightJoinTable = (i16)pE2->iTable;
}
*ppWhere = sqlite3ExprAnd(pParse, *ppWhere, pEq);
}
/*
** Set the EP_FromJoin property on all terms of the given expression.
** And set the Expr.iRightJoinTable to iTable for every term in the
** expression.
**
** The EP_FromJoin property is used on terms of an expression to tell
** the LEFT OUTER JOIN processing logic that this term is part of the
** join restriction specified in the ON or USING clause and not a part
** of the more general WHERE clause. These terms are moved over to the
** WHERE clause during join processing but we need to remember that they
** originated in the ON or USING clause.
**
** The Expr.iRightJoinTable tells the WHERE clause processing that the
** expression depends on table iRightJoinTable even if that table is not
** explicitly mentioned in the expression. That information is needed
** for cases like this:
**
** SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5
**
** The where clause needs to defer the handling of the t1.x=5
** term until after the t2 loop of the join. In that way, a
** NULL t2 row will be inserted whenever t1.x!=5. If we do not
** defer the handling of t1.x=5, it will be processed immediately
** after the t1 loop and rows with t1.x!=5 will never appear in
** the output, which is incorrect.
*/
void sqlite3SetJoinExpr(Expr *p, int iTable){
while( p ){
ExprSetProperty(p, EP_FromJoin);
assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
ExprSetVVAProperty(p, EP_NoReduce);
p->iRightJoinTable = (i16)iTable;
if( p->op==TK_FUNCTION && p->x.pList ){
int i;
for(i=0; i<p->x.pList->nExpr; i++){
sqlite3SetJoinExpr(p->x.pList->a[i].pExpr, iTable);
}
}
sqlite3SetJoinExpr(p->pLeft, iTable);
p = p->pRight;
}
}
/* Undo the work of sqlite3SetJoinExpr(). In the expression p, convert every
** term that is marked with EP_FromJoin and iRightJoinTable==iTable into
** an ordinary term that omits the EP_FromJoin mark.
**
** This happens when a LEFT JOIN is simplified into an ordinary JOIN.
*/
static void unsetJoinExpr(Expr *p, int iTable){
while( p ){
if( ExprHasProperty(p, EP_FromJoin)
&& (iTable<0 || p->iRightJoinTable==iTable) ){
ExprClearProperty(p, EP_FromJoin);
}
if( p->op==TK_FUNCTION && p->x.pList ){
int i;
for(i=0; i<p->x.pList->nExpr; i++){
unsetJoinExpr(p->x.pList->a[i].pExpr, iTable);
}
}
unsetJoinExpr(p->pLeft, iTable);
p = p->pRight;
}
}
/*
** This routine processes the join information for a SELECT statement.
** ON and USING clauses are converted into extra terms of the WHERE clause.
** NATURAL joins also create extra WHERE clause terms.
**
** The terms of a FROM clause are contained in the Select.pSrc structure.
** The left most table is the first entry in Select.pSrc. The right-most
** table is the last entry. The join operator is held in the entry to
** the left. Thus entry 0 contains the join operator for the join between
** entries 0 and 1. Any ON or USING clauses associated with the join are
** also attached to the left entry.
**
** This routine returns the number of errors encountered.
*/
static int sqliteProcessJoin(Parse *pParse, Select *p){
SrcList *pSrc; /* All tables in the FROM clause */
int i, j; /* Loop counters */
struct SrcList_item *pLeft; /* Left table being joined */
struct SrcList_item *pRight; /* Right table being joined */
pSrc = p->pSrc;
pLeft = &pSrc->a[0];
pRight = &pLeft[1];
for(i=0; i<pSrc->nSrc-1; i++, pRight++, pLeft++){
Table *pRightTab = pRight->pTab;
int isOuter;
if( NEVER(pLeft->pTab==0 || pRightTab==0) ) continue;
isOuter = (pRight->fg.jointype & JT_OUTER)!=0;
/* When the NATURAL keyword is present, add WHERE clause terms for
** every column that the two tables have in common.
*/
if( pRight->fg.jointype & JT_NATURAL ){
if( pRight->pOn || pRight->pUsing ){
sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
"an ON or USING clause", 0);
return 1;
}
for(j=0; j<pRightTab->nCol; j++){
char *zName; /* Name of column in the right table */
int iLeft; /* Matching left table */
int iLeftCol; /* Matching column in the left table */
if( IsHiddenColumn(&pRightTab->aCol[j]) ) continue;
zName = pRightTab->aCol[j].zName;
if( tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol, 1) ){
addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, j,
isOuter, &p->pWhere);
}
}
}
/* Disallow both ON and USING clauses in the same join
*/
if( pRight->pOn && pRight->pUsing ){
sqlite3ErrorMsg(pParse, "cannot have both ON and USING "
"clauses in the same join");
return 1;
}
/* Add the ON clause to the end of the WHERE clause, connected by
** an AND operator.
*/
if( pRight->pOn ){
if( isOuter ) sqlite3SetJoinExpr(pRight->pOn, pRight->iCursor);
p->pWhere = sqlite3ExprAnd(pParse, p->pWhere, pRight->pOn);
pRight->pOn = 0;
}
/* Create extra terms on the WHERE clause for each column named
** in the USING clause. Example: If the two tables to be joined are
** A and B and the USING clause names X, Y, and Z, then add this
** to the WHERE clause: A.X=B.X AND A.Y=B.Y AND A.Z=B.Z
** Report an error if any column mentioned in the USING clause is
** not contained in both tables to be joined.
*/
if( pRight->pUsing ){
IdList *pList = pRight->pUsing;
for(j=0; j<pList->nId; j++){
char *zName; /* Name of the term in the USING clause */
int iLeft; /* Table on the left with matching column name */
int iLeftCol; /* Column number of matching column on the left */
int iRightCol; /* Column number of matching column on the right */
zName = pList->a[j].zName;
iRightCol = columnIndex(pRightTab, zName);
if( iRightCol<0
|| !tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol, 0)
){
sqlite3ErrorMsg(pParse, "cannot join using column %s - column "
"not present in both tables", zName);
return 1;
}
addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, iRightCol,
isOuter, &p->pWhere);
}
}
}
return 0;
}
/*
** An instance of this object holds information (beyond pParse and pSelect)
** needed to load the next result row that is to be added to the sorter.
*/
typedef struct RowLoadInfo RowLoadInfo;
struct RowLoadInfo {
int regResult; /* Store results in array of registers here */
u8 ecelFlags; /* Flag argument to ExprCodeExprList() */
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
ExprList *pExtra; /* Extra columns needed by sorter refs */
int regExtraResult; /* Where to load the extra columns */
#endif
};
/*
** This routine does the work of loading query data into an array of
** registers so that it can be added to the sorter.
*/
static void innerLoopLoadRow(
Parse *pParse, /* Statement under construction */
Select *pSelect, /* The query being coded */
RowLoadInfo *pInfo /* Info needed to complete the row load */
){
sqlite3ExprCodeExprList(pParse, pSelect->pEList, pInfo->regResult,
0, pInfo->ecelFlags);
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
if( pInfo->pExtra ){
sqlite3ExprCodeExprList(pParse, pInfo->pExtra, pInfo->regExtraResult, 0, 0);
sqlite3ExprListDelete(pParse->db, pInfo->pExtra);
}
#endif
}
/*
** Code the OP_MakeRecord instruction that generates the entry to be
** added into the sorter.
**
** Return the register in which the result is stored.
*/
static int makeSorterRecord(
Parse *pParse,
SortCtx *pSort,
Select *pSelect,
int regBase,
int nBase
){
int nOBSat = pSort->nOBSat;
Vdbe *v = pParse->pVdbe;
int regOut = ++pParse->nMem;
if( pSort->pDeferredRowLoad ){
innerLoopLoadRow(pParse, pSelect, pSort->pDeferredRowLoad);
}
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat, regOut);
return regOut;
}
/*
** Generate code that will push the record in registers regData
** through regData+nData-1 onto the sorter.
*/
static void pushOntoSorter(
Parse *pParse, /* Parser context */
SortCtx *pSort, /* Information about the ORDER BY clause */
Select *pSelect, /* The whole SELECT statement */
int regData, /* First register holding data to be sorted */
int regOrigData, /* First register holding data before packing */
int nData, /* Number of elements in the regData data array */
int nPrefixReg /* No. of reg prior to regData available for use */
){
Vdbe *v = pParse->pVdbe; /* Stmt under construction */
int bSeq = ((pSort->sortFlags & SORTFLAG_UseSorter)==0);
int nExpr = pSort->pOrderBy->nExpr; /* No. of ORDER BY terms */
int nBase = nExpr + bSeq + nData; /* Fields in sorter record */
int regBase; /* Regs for sorter record */
int regRecord = 0; /* Assembled sorter record */
int nOBSat = pSort->nOBSat; /* ORDER BY terms to skip */
int op; /* Opcode to add sorter record to sorter */
int iLimit; /* LIMIT counter */
int iSkip = 0; /* End of the sorter insert loop */
assert( bSeq==0 || bSeq==1 );
/* Three cases:
** (1) The data to be sorted has already been packed into a Record
** by a prior OP_MakeRecord. In this case nData==1 and regData
** will be completely unrelated to regOrigData.
** (2) All output columns are included in the sort record. In that
** case regData==regOrigData.
** (3) Some output columns are omitted from the sort record due to
** the SQLITE_ENABLE_SORTER_REFERENCE optimization, or due to the
** SQLITE_ECEL_OMITREF optimization, or due to the
** SortCtx.pDeferredRowLoad optimiation. In any of these cases
** regOrigData is 0 to prevent this routine from trying to copy
** values that might not yet exist.
*/
assert( nData==1 || regData==regOrigData || regOrigData==0 );
if( nPrefixReg ){
assert( nPrefixReg==nExpr+bSeq );
regBase = regData - nPrefixReg;
}else{
regBase = pParse->nMem + 1;
pParse->nMem += nBase;
}
assert( pSelect->iOffset==0 || pSelect->iLimit!=0 );
iLimit = pSelect->iOffset ? pSelect->iOffset+1 : pSelect->iLimit;
pSort->labelDone = sqlite3VdbeMakeLabel(pParse);
sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, regOrigData,
SQLITE_ECEL_DUP | (regOrigData? SQLITE_ECEL_REF : 0));
if( bSeq ){
sqlite3VdbeAddOp2(v, OP_Sequence, pSort->iECursor, regBase+nExpr);
}
if( nPrefixReg==0 && nData>0 ){
sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+bSeq, nData);
}
if( nOBSat>0 ){
int regPrevKey; /* The first nOBSat columns of the previous row */
int addrFirst; /* Address of the OP_IfNot opcode */
int addrJmp; /* Address of the OP_Jump opcode */
VdbeOp *pOp; /* Opcode that opens the sorter */
int nKey; /* Number of sorting key columns, including OP_Sequence */
KeyInfo *pKI; /* Original KeyInfo on the sorter table */
regRecord = makeSorterRecord(pParse, pSort, pSelect, regBase, nBase);
regPrevKey = pParse->nMem+1;
pParse->nMem += pSort->nOBSat;
nKey = nExpr - pSort->nOBSat + bSeq;
if( bSeq ){
addrFirst = sqlite3VdbeAddOp1(v, OP_IfNot, regBase+nExpr);
}else{
addrFirst = sqlite3VdbeAddOp1(v, OP_SequenceTest, pSort->iECursor);
}
VdbeCoverage(v);
sqlite3VdbeAddOp3(v, OP_Compare, regPrevKey, regBase, pSort->nOBSat);
pOp = sqlite3VdbeGetOp(v, pSort->addrSortIndex);
if( pParse->db->mallocFailed ) return;
pOp->p2 = nKey + nData;
pKI = pOp->p4.pKeyInfo;
memset(pKI->aSortFlags, 0, pKI->nKeyField); /* Makes OP_Jump testable */
sqlite3VdbeChangeP4(v, -1, (char*)pKI, P4_KEYINFO);
testcase( pKI->nAllField > pKI->nKeyField+2 );
pOp->p4.pKeyInfo = sqlite3KeyInfoFromExprList(pParse,pSort->pOrderBy,nOBSat,
pKI->nAllField-pKI->nKeyField-1);
pOp = 0; /* Ensure pOp not used after sqltie3VdbeAddOp3() */
addrJmp = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp3(v, OP_Jump, addrJmp+1, 0, addrJmp+1); VdbeCoverage(v);
pSort->labelBkOut = sqlite3VdbeMakeLabel(pParse);
pSort->regReturn = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut);
sqlite3VdbeAddOp1(v, OP_ResetSorter, pSort->iECursor);
if( iLimit ){
sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, pSort->labelDone);
VdbeCoverage(v);
}
sqlite3VdbeJumpHere(v, addrFirst);
sqlite3ExprCodeMove(pParse, regBase, regPrevKey, pSort->nOBSat);
sqlite3VdbeJumpHere(v, addrJmp);
}
if( iLimit ){
/* At this point the values for the new sorter entry are stored
** in an array of registers. They need to be composed into a record
** and inserted into the sorter if either (a) there are currently
** less than LIMIT+OFFSET items or (b) the new record is smaller than
** the largest record currently in the sorter. If (b) is true and there
** are already LIMIT+OFFSET items in the sorter, delete the largest
** entry before inserting the new one. This way there are never more
** than LIMIT+OFFSET items in the sorter.
**
** If the new record does not need to be inserted into the sorter,
** jump to the next iteration of the loop. If the pSort->labelOBLopt
** value is not zero, then it is a label of where to jump. Otherwise,
** just bypass the row insert logic. See the header comment on the
** sqlite3WhereOrderByLimitOptLabel() function for additional info.
*/
int iCsr = pSort->iECursor;
sqlite3VdbeAddOp2(v, OP_IfNotZero, iLimit, sqlite3VdbeCurrentAddr(v)+4);
VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_Last, iCsr, 0);
iSkip = sqlite3VdbeAddOp4Int(v, OP_IdxLE,
iCsr, 0, regBase+nOBSat, nExpr-nOBSat);
VdbeCoverage(v);
sqlite3VdbeAddOp1(v, OP_Delete, iCsr);
}
if( regRecord==0 ){
regRecord = makeSorterRecord(pParse, pSort, pSelect, regBase, nBase);
}
if( pSort->sortFlags & SORTFLAG_UseSorter ){
op = OP_SorterInsert;
}else{
op = OP_IdxInsert;
}
sqlite3VdbeAddOp4Int(v, op, pSort->iECursor, regRecord,
regBase+nOBSat, nBase-nOBSat);
if( iSkip ){
sqlite3VdbeChangeP2(v, iSkip,
pSort->labelOBLopt ? pSort->labelOBLopt : sqlite3VdbeCurrentAddr(v));
}
}
/*
** Add code to implement the OFFSET
*/
static void codeOffset(
Vdbe *v, /* Generate code into this VM */
int iOffset, /* Register holding the offset counter */
int iContinue /* Jump here to skip the current record */
){
if( iOffset>0 ){
sqlite3VdbeAddOp3(v, OP_IfPos, iOffset, iContinue, 1); VdbeCoverage(v);
VdbeComment((v, "OFFSET"));
}
}
/*
** Add code that will check to make sure the N registers starting at iMem
** form a distinct entry. iTab is a sorting index that holds previously
** seen combinations of the N values. A new entry is made in iTab
** if the current N values are new.
**
** A jump to addrRepeat is made and the N+1 values are popped from the
** stack if the top N elements are not distinct.
*/
static void codeDistinct(
Parse *pParse, /* Parsing and code generating context */
int iTab, /* A sorting index used to test for distinctness */
int addrRepeat, /* Jump to here if not distinct */
int N, /* Number of elements */
int iMem /* First element */
){
Vdbe *v;
int r1;
v = pParse->pVdbe;
r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp4Int(v, OP_Found, iTab, addrRepeat, iMem, N); VdbeCoverage(v);
sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, N, r1);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iTab, r1, iMem, N);
sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
sqlite3ReleaseTempReg(pParse, r1);
}
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
/*
** This function is called as part of inner-loop generation for a SELECT
** statement with an ORDER BY that is not optimized by an index. It
** determines the expressions, if any, that the sorter-reference
** optimization should be used for. The sorter-reference optimization
** is used for SELECT queries like:
**
** SELECT a, bigblob FROM t1 ORDER BY a LIMIT 10
**
** If the optimization is used for expression "bigblob", then instead of
** storing values read from that column in the sorter records, the PK of
** the row from table t1 is stored instead. Then, as records are extracted from
** the sorter to return to the user, the required value of bigblob is
** retrieved directly from table t1. If the values are very large, this
** can be more efficient than storing them directly in the sorter records.
**
** The ExprList_item.bSorterRef flag is set for each expression in pEList
** for which the sorter-reference optimization should be enabled.
** Additionally, the pSort->aDefer[] array is populated with entries
** for all cursors required to evaluate all selected expressions. Finally.
** output variable (*ppExtra) is set to an expression list containing
** expressions for all extra PK values that should be stored in the
** sorter records.
*/
static void selectExprDefer(
Parse *pParse, /* Leave any error here */
SortCtx *pSort, /* Sorter context */
ExprList *pEList, /* Expressions destined for sorter */
ExprList **ppExtra /* Expressions to append to sorter record */
){
int i;
int nDefer = 0;
ExprList *pExtra = 0;
for(i=0; i<pEList->nExpr; i++){
struct ExprList_item *pItem = &pEList->a[i];
if( pItem->u.x.iOrderByCol==0 ){
Expr *pExpr = pItem->pExpr;
Table *pTab = pExpr->y.pTab;
if( pExpr->op==TK_COLUMN && pExpr->iColumn>=0 && pTab && !IsVirtual(pTab)
&& (pTab->aCol[pExpr->iColumn].colFlags & COLFLAG_SORTERREF)
){
int j;
for(j=0; j<nDefer; j++){
if( pSort->aDefer[j].iCsr==pExpr->iTable ) break;
}
if( j==nDefer ){
if( nDefer==ArraySize(pSort->aDefer) ){
continue;
}else{
int nKey = 1;
int k;
Index *pPk = 0;
if( !HasRowid(pTab) ){
pPk = sqlite3PrimaryKeyIndex(pTab);
nKey = pPk->nKeyCol;
}
for(k=0; k<nKey; k++){
Expr *pNew = sqlite3PExpr(pParse, TK_COLUMN, 0, 0);
if( pNew ){
pNew->iTable = pExpr->iTable;
pNew->y.pTab = pExpr->y.pTab;
pNew->iColumn = pPk ? pPk->aiColumn[k] : -1;
pExtra = sqlite3ExprListAppend(pParse, pExtra, pNew);
}
}
pSort->aDefer[nDefer].pTab = pExpr->y.pTab;
pSort->aDefer[nDefer].iCsr = pExpr->iTable;
pSort->aDefer[nDefer].nKey = nKey;
nDefer++;
}
}
pItem->bSorterRef = 1;
}
}
}
pSort->nDefer = (u8)nDefer;
*ppExtra = pExtra;
}
#endif
/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**
** If srcTab is negative, then the p->pEList expressions
** are evaluated in order to get the data for this row. If srcTab is
** zero or more, then data is pulled from srcTab and p->pEList is used only
** to get the number of columns and the collation sequence for each column.
*/
static void selectInnerLoop(
Parse *pParse, /* The parser context */
Select *p, /* The complete select statement being coded */
int srcTab, /* Pull data from this table if non-negative */
SortCtx *pSort, /* If not NULL, info on how to process ORDER BY */
DistinctCtx *pDistinct, /* If not NULL, info on how to process DISTINCT */
SelectDest *pDest, /* How to dispose of the results */
int iContinue, /* Jump here to continue with next row */
int iBreak /* Jump here to break out of the inner loop */
){
Vdbe *v = pParse->pVdbe;
int i;
int hasDistinct; /* True if the DISTINCT keyword is present */
int eDest = pDest->eDest; /* How to dispose of results */
int iParm = pDest->iSDParm; /* First argument to disposal method */
int nResultCol; /* Number of result columns */
int nPrefixReg = 0; /* Number of extra registers before regResult */
RowLoadInfo sRowLoadInfo; /* Info for deferred row loading */
/* Usually, regResult is the first cell in an array of memory cells
** containing the current result row. In this case regOrig is set to the
** same value. However, if the results are being sent to the sorter, the
** values for any expressions that are also part of the sort-key are omitted
** from this array. In this case regOrig is set to zero. */
int regResult; /* Start of memory holding current results */
int regOrig; /* Start of memory holding full result (or 0) */
assert( v );
assert( p->pEList!=0 );
hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP;
if( pSort && pSort->pOrderBy==0 ) pSort = 0;
if( pSort==0 && !hasDistinct ){
assert( iContinue!=0 );
codeOffset(v, p->iOffset, iContinue);
}
/* Pull the requested columns.
*/
nResultCol = p->pEList->nExpr;
if( pDest->iSdst==0 ){
if( pSort ){
nPrefixReg = pSort->pOrderBy->nExpr;
if( !(pSort->sortFlags & SORTFLAG_UseSorter) ) nPrefixReg++;
pParse->nMem += nPrefixReg;
}
pDest->iSdst = pParse->nMem+1;
pParse->nMem += nResultCol;
}else if( pDest->iSdst+nResultCol > pParse->nMem ){
/* This is an error condition that can result, for example, when a SELECT
** on the right-hand side of an INSERT contains more result columns than
** there are columns in the table on the left. The error will be caught
** and reported later. But we need to make sure enough memory is allocated
** to avoid other spurious errors in the meantime. */
pParse->nMem += nResultCol;
}
pDest->nSdst = nResultCol;
regOrig = regResult = pDest->iSdst;
if( srcTab>=0 ){
for(i=0; i<nResultCol; i++){
sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
VdbeComment((v, "%s", p->pEList->a[i].zEName));
}
}else if( eDest!=SRT_Exists ){
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
ExprList *pExtra = 0;
#endif
/* If the destination is an EXISTS(...) expression, the actual
** values returned by the SELECT are not required.
*/
u8 ecelFlags; /* "ecel" is an abbreviation of "ExprCodeExprList" */
ExprList *pEList;
if( eDest==SRT_Mem || eDest==SRT_Output || eDest==SRT_Coroutine ){
ecelFlags = SQLITE_ECEL_DUP;
}else{
ecelFlags = 0;
}
if( pSort && hasDistinct==0 && eDest!=SRT_EphemTab && eDest!=SRT_Table ){
/* For each expression in p->pEList that is a copy of an expression in
** the ORDER BY clause (pSort->pOrderBy), set the associated
** iOrderByCol value to one more than the index of the ORDER BY
** expression within the sort-key that pushOntoSorter() will generate.
** This allows the p->pEList field to be omitted from the sorted record,
** saving space and CPU cycles. */
ecelFlags |= (SQLITE_ECEL_OMITREF|SQLITE_ECEL_REF);
for(i=pSort->nOBSat; i<pSort->pOrderBy->nExpr; i++){
int j;
if( (j = pSort->pOrderBy->a[i].u.x.iOrderByCol)>0 ){
p->pEList->a[j-1].u.x.iOrderByCol = i+1-pSort->nOBSat;
}
}
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
selectExprDefer(pParse, pSort, p->pEList, &pExtra);
if( pExtra && pParse->db->mallocFailed==0 ){
/* If there are any extra PK columns to add to the sorter records,
** allocate extra memory cells and adjust the OpenEphemeral
** instruction to account for the larger records. This is only
** required if there are one or more WITHOUT ROWID tables with
** composite primary keys in the SortCtx.aDefer[] array. */
VdbeOp *pOp = sqlite3VdbeGetOp(v, pSort->addrSortIndex);
pOp->p2 += (pExtra->nExpr - pSort->nDefer);
pOp->p4.pKeyInfo->nAllField += (pExtra->nExpr - pSort->nDefer);
pParse->nMem += pExtra->nExpr;
}
#endif
/* Adjust nResultCol to account for columns that are omitted
** from the sorter by the optimizations in this branch */
pEList = p->pEList;
for(i=0; i<pEList->nExpr; i++){
if( pEList->a[i].u.x.iOrderByCol>0
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
|| pEList->a[i].bSorterRef
#endif
){
nResultCol--;
regOrig = 0;
}
}