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Further improvements to USING() processing for RIGHT and FULL JOINs. All

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currently known issues are now resolved.  Performace is improved.

FossilOrigin-Name: 9fd3f22e2228dfba127f6ffe549109f3a4e910fa124adcc9c5483931bd6d5cd7
This commit is contained in:
drh
2022-04-17 18:46:17 +00:00
parent 6fda176ba6
commit fe14699765
4 changed files with 68 additions and 127 deletions
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159
src/select.c
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@@ -320,11 +320,9 @@ int sqlite3ColumnIndex(Table *pTab, const char *zCol){
}
/*
** Search the first N tables in pSrc, looking for a
** table that has a column named zCol.
**
** Search left-to-right if bRightmost is false. Search right-to-left
** if bRightmost is true.
** Search the tables iStart..iEnd (inclusive) in pSrc, looking for a
** table that has a column named zCol. The search is left-to-right.
** The first match found is returned.
**
** When found, set *piTab and *piCol to the table index and column index
** of the matching column and return TRUE.
@@ -333,21 +331,21 @@ int sqlite3ColumnIndex(Table *pTab, const char *zCol){
*/
static int tableAndColumnIndex(
SrcList *pSrc, /* Array of tables to search */
int N, /* Number of tables in pSrc->a[] to search */
int iStart, /* First member of pSrc->a[] to check */
int iEnd, /* Last member of pSrc->a[] to check */
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 bRightmost /* Return the right-most match */
int bIgnoreHidden /* Ignore hidden columns */
){
int i; /* For looping over tables in pSrc */
int iCol; /* Index of column matching zCol */
int rc = 0;
assert( N<=pSrc->nSrc );
assert( iEnd<pSrc->nSrc );
assert( iStart>=0 );
assert( (piTab==0)==(piCol==0) ); /* Both or neither are NULL */
for(i=0; i<N; i++){
for(i=iStart; i<=iEnd; i++){
iCol = sqlite3ColumnIndex(pSrc->a[i].pTab, zCol);
if( iCol>=0
&& (bIgnoreHidden==0 || IsHiddenColumn(&pSrc->a[i].pTab->aCol[iCol])==0)
@@ -356,58 +354,10 @@ static int tableAndColumnIndex(
*piTab = i;
*piCol = iCol;
}
rc = 1;
if( !bRightmost ) break;
return 1;
}
}
return rc;
}
/*
** 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 */
u32 joinType, /* EP_FromJoin or EP_InnerJoin */
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);
assert( pE2!=0 || pEq==0 ); /* Due to db->mallocFailed test
** in sqlite3DbMallocRawNN() called from
** sqlite3PExpr(). */
if( pEq ){
ExprSetProperty(pEq, joinType);
assert( !ExprHasProperty(pEq, EP_TokenOnly|EP_Reduced) );
ExprSetVVAProperty(pEq, EP_NoReduce);
pEq->w.iJoin = pE2->iTable;
}
*ppWhere = sqlite3ExprAnd(pParse, *ppWhere, pEq);
return 0;
}
/*
@@ -532,7 +482,7 @@ static int sqlite3ProcessJoin(Parse *pParse, Select *p){
if( IsHiddenColumn(&pRightTab->aCol[j]) ) continue;
zName = pRightTab->aCol[j].zCnName;
if( tableAndColumnIndex(pSrc, i+1, zName, 0, 0, 1, 0) ){
if( tableAndColumnIndex(pSrc, 0, i, zName, 0, 0, 1) ){
Token x;
x.z = zName;
x.n = sqlite3Strlen30(zName);
@@ -555,64 +505,71 @@ static int sqlite3ProcessJoin(Parse *pParse, Select *p){
*/
if( pRight->fg.isUsing ){
IdList *pList = pRight->u3.pUsing;
int bRight = (pLeft->fg.jointype & JT_RIGHT)!=0;
sqlite3 *db = pParse->db;
assert( pList!=0 );
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 */
int iNxLeft, iNxLeftCol;
Expr *pE1; /* Reference to the column on the LEFT of the join */
Expr *pE2; /* Reference to the column on the RIGHT of the join */
Expr *pEq; /* Equality constraint. pE1 == pE2 */
zName = pList->a[j].zName;
iRightCol = sqlite3ColumnIndex(pRightTab, zName);
if( iRightCol<0
|| !tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol,
pRight->fg.isSynthUsing, bRight)
|| tableAndColumnIndex(pSrc, 0, i, zName, &iLeft, &iLeftCol,
pRight->fg.isSynthUsing)==0
){
sqlite3ErrorMsg(pParse, "cannot join using column %s - column "
"not present in both tables", zName);
return 1;
}
if( (pLeft->fg.jointype & (JT_RIGHT|JT_LEFT))!=(JT_LEFT|JT_RIGHT)
|| 0==tableAndColumnIndex(pSrc, iLeft, zName, &iNxLeft, &iNxLeftCol,
pRight->fg.isSynthUsing, 1)
){
addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, iRightCol,
joinType, &p->pWhere);
}else{
/* Because the left-hand side of this join is another RIGHT or FULL
** JOIN with two or more tables hold zName, we need to construct
** a coalesce() function for left side of the ON constraint.
pE1 = sqlite3CreateColumnExpr(db, pSrc, iLeft, iLeftCol);
if( (pSrc->a[0].fg.jointype & JT_LTORJ)!=0 ){
/* This branch runs if the query contains one or more RIGHT or FULL
** JOINs. If only a single table on the left side of this join
** contains the zName column, then this routine is branch is
** a no-op. But if there are two or more tables on the left side
** of the join, construct a coalesce() function that gathers all
** such tables. Raise an error if more than one of those references
** to zName is not also within a prior USING clause.
**
** We really ought to raise an error if there are two or more
** non-USING references to zName on the left of an INNER or LEFT
** JOIN. But older versions of SQLite do not do that, so we avoid
** adding a new error so as to not break legacy applications.
*/
ExprList *pList;
Expr *pE;
Expr *pE2;
Expr *pEq;
sqlite3 *db = pParse->db;
ExprList *pFuncArgs = 0; /* Arguments to the coalesce() */
static const Token tkCoalesce = { "coalesce", 8 };
pE = sqlite3CreateColumnExpr(db, pSrc, iLeft, iLeftCol);
pList = sqlite3ExprListAppend(pParse, 0, pE);
pE = sqlite3CreateColumnExpr(db, pSrc, iNxLeft, iNxLeftCol);
pList = sqlite3ExprListAppend(pParse, pList, pE);
while( tableAndColumnIndex(pSrc, iNxLeft, zName,
&iNxLeft, &iNxLeftCol,
pRight->fg.isSynthUsing, 1)!=0 ){
pE = sqlite3CreateColumnExpr(db, pSrc, iNxLeft, iNxLeftCol);
pList = sqlite3ExprListAppend(pParse, pList, pE);
while( tableAndColumnIndex(pSrc, iLeft+1, i, zName, &iLeft, &iLeftCol,
pRight->fg.isSynthUsing)!=0 ){
if( pSrc->a[iLeft].fg.isUsing==0
|| sqlite3IdListIndex(pSrc->a[iLeft].u3.pUsing, zName)<0
){
sqlite3ErrorMsg(pParse, "ambiguous reference to %s in USING()",
zName);
break;
}
pFuncArgs = sqlite3ExprListAppend(pParse, pFuncArgs, pE1);
pE1 = sqlite3CreateColumnExpr(db, pSrc, iLeft, iLeftCol);
}
pE = sqlite3ExprFunction(pParse, pList, &tkCoalesce, 0);
pE2 = sqlite3CreateColumnExpr(db, pSrc, i+1, iRightCol);
pEq = sqlite3PExpr(pParse, TK_EQ, pE, pE2);
assert( pE2!=0 || pEq==0 );
if( pEq ){
ExprSetProperty(pEq, joinType);
assert( !ExprHasProperty(pEq, EP_TokenOnly|EP_Reduced) );
ExprSetVVAProperty(pEq, EP_NoReduce);
pEq->w.iJoin = pE2->iTable;
if( pFuncArgs ){
pFuncArgs = sqlite3ExprListAppend(pParse, pFuncArgs, pE1);
pE1 = sqlite3ExprFunction(pParse, pFuncArgs, &tkCoalesce, 0);
}
p->pWhere = sqlite3ExprAnd(pParse, p->pWhere, pEq);
}
pE2 = sqlite3CreateColumnExpr(db, pSrc, i+1, iRightCol);
pEq = sqlite3PExpr(pParse, TK_EQ, pE1, pE2);
assert( pE2!=0 || pEq==0 );
if( pEq ){
ExprSetProperty(pEq, joinType);
assert( !ExprHasProperty(pEq, EP_TokenOnly|EP_Reduced) );
ExprSetVVAProperty(pEq, EP_NoReduce);
pEq->w.iJoin = pE2->iTable;
}
p->pWhere = sqlite3ExprAnd(pParse, p->pWhere, pEq);
}
}