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Refactor the code that figures out which SELECT in a cascade of nested queries

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a particular aggregate function belongs to.  This fixes the problem
reported by [forum:/forumpost/c7cc2aa3546e39c1|forum post c7cc2aa3546e39c1].
New test cases in dbsqlfuzz and th3.

FossilOrigin-Name: 74aec5dd1df95b5635f4da1f13753f113ea1d61de3dc3a1523ba51089c1900e4
This commit is contained in:
drh
2021-11-08 23:24:00 +00:00
parent a32536b498
commit 90cf38be63
5 changed files with 105 additions and 67 deletions
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141
src/expr.c
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@@ -5879,81 +5879,109 @@ int sqlite3ExprCoveredByIndex(
}
/*
** An instance of the following structure is used by the tree walker
** to count references to table columns in the arguments of an
** aggregate function, in order to implement the
** sqlite3FunctionThisSrc() routine.
/* Structure used to pass information throught the Walker in order to
** implement sqlite3ReferencesSrcList().
*/
struct SrcCount {
SrcList *pSrc; /* One particular FROM clause in a nested query */
int iSrcInner; /* Smallest cursor number in this context */
int nThis; /* Number of references to columns in pSrcList */
int nOther; /* Number of references to columns in other FROM clauses */
struct RefSrcList {
sqlite3 *db; /* Database connection used for sqlite3DbRealloc() */
SrcList *pRef; /* Looking for references to these tables */
int nExclude; /* Number of tables to exclude from the search */
int *aiExclude; /* Cursor IDs for tables to exclude from the search */
};
/*
** xSelect callback for sqlite3FunctionUsesThisSrc(). If this is the first
** SELECT with a FROM clause encountered during this iteration, set
** SrcCount.iSrcInner to the cursor number of the leftmost object in
** the FROM cause.
** Walker SELECT callbacks for sqlite3ReferencesSrcList().
**
** When entering a new subquery on the pExpr argument, add all FROM clause
** entries for that subquery to the exclude list.
**
** When leaving the subquery, remove those entries from the exclude list.
*/
static int selectSrcCount(Walker *pWalker, Select *pSel){
struct SrcCount *p = pWalker->u.pSrcCount;
if( p->iSrcInner==0x7FFFFFFF && ALWAYS(pSel->pSrc) && pSel->pSrc->nSrc ){
pWalker->u.pSrcCount->iSrcInner = pSel->pSrc->a[0].iCursor;
static int selectRefEnter(Walker *pWalker, Select *pSelect){
struct RefSrcList *p = pWalker->u.pRefSrcList;
SrcList *pSrc = pSelect->pSrc;
int i, j, *piNew;
if( pSrc->nSrc==0 ) return WRC_Continue;
j = p->nExclude;
p->nExclude += pSrc->nSrc;
piNew = sqlite3DbRealloc(p->db, p->aiExclude, p->nExclude*sizeof(int));
if( piNew==0 ){
p->nExclude = 0;
return WRC_Abort;
}else{
p->aiExclude = piNew;
}
for(i=0; i<pSrc->nSrc; i++, j++){
p->aiExclude[j] = pSrc->a[i].iCursor;
}
return WRC_Continue;
}
static void selectRefLeave(Walker *pWalker, Select *pSelect){
struct RefSrcList *p = pWalker->u.pRefSrcList;
SrcList *pSrc = pSelect->pSrc;
if( p->nExclude ){
assert( p->nExclude>=pSrc->nSrc );
p->nExclude -= pSrc->nSrc;
}
}
/*
** Count the number of references to columns.
/* This is the Walker EXPR callback for sqlite3ReferencesSrcList().
**
** Set the 0x01 bit of pWalker->eCode if there is a reference to any
** of the tables shown in RefSrcList.pRef.
**
** Set the 0x02 bit of pWalker->eCode if there is a reference to a
** table is in neither RefSrcList.pRef nor RefSrcList.aiExclude.
*/
static int exprSrcCount(Walker *pWalker, Expr *pExpr){
/* There was once a NEVER() on the second term on the grounds that
** sqlite3FunctionUsesThisSrc() was always called before
** sqlite3ExprAnalyzeAggregates() and so the TK_COLUMNs have not yet
** been converted into TK_AGG_COLUMN. But this is no longer true due
** to window functions - sqlite3WindowRewrite() may now indirectly call
** FunctionUsesThisSrc() when creating a new sub-select. */
if( pExpr->op==TK_COLUMN || pExpr->op==TK_AGG_COLUMN ){
static int exprRefToSrcList(Walker *pWalker, Expr *pExpr){
if( pExpr->op==TK_COLUMN
|| pExpr->op==TK_AGG_COLUMN
){
int i;
struct SrcCount *p = pWalker->u.pSrcCount;
SrcList *pSrc = p->pSrc;
struct RefSrcList *p = pWalker->u.pRefSrcList;
SrcList *pSrc = p->pRef;
int nSrc = pSrc ? pSrc->nSrc : 0;
for(i=0; i<nSrc; i++){
if( pExpr->iTable==pSrc->a[i].iCursor ) break;
if( pExpr->iTable==pSrc->a[i].iCursor ){
pWalker->eCode |= 1;
return WRC_Continue;
}
}
if( i<nSrc ){
p->nThis++;
}else if( pExpr->iTable<p->iSrcInner ){
/* In a well-formed parse tree (no name resolution errors),
** TK_COLUMN nodes with smaller Expr.iTable values are in an
** outer context. Those are the only ones to count as "other" */
p->nOther++;
for(i=0; i<p->nExclude && p->aiExclude[i]!=pExpr->iTable; i++){}
if( i>=p->nExclude ){
pWalker->eCode |= 2;
}
}
return WRC_Continue;
}
/*
** Determine if any of the arguments to the pExpr Function reference
** pSrcList. Return true if they do. Also return true if the function
** has no arguments or has only constant arguments. Return false if pExpr
** references columns but not columns of tables found in pSrcList.
** Check to see if pExpr references any tables in pSrcList.
** Possible return values:
**
** 1 pExpr does references a table in pSrcList.
**
** 0 pExpr references some table that is not defined in either
** pSrcList or in subqueries of pExpr itself.
**
** -1 pExpr only references no tables at all, or it only
** references tables defined in subqueries of pExpr itself.
**
** As currently used, pExpr is always an aggregate function call. That
** fact is exploited for efficiency.
*/
int sqlite3FunctionUsesThisSrc(Expr *pExpr, SrcList *pSrcList){
int sqlite3ReferencesSrcList(Parse *pParse, Expr *pExpr, SrcList *pSrcList){
Walker w;
struct SrcCount cnt;
assert( pExpr->op==TK_AGG_FUNCTION );
struct RefSrcList x;
memset(&w, 0, sizeof(w));
w.xExprCallback = exprSrcCount;
w.xSelectCallback = selectSrcCount;
w.u.pSrcCount = &cnt;
cnt.pSrc = pSrcList;
cnt.iSrcInner = (pSrcList&&pSrcList->nSrc)?pSrcList->a[0].iCursor:0x7FFFFFFF;
cnt.nThis = 0;
cnt.nOther = 0;
memset(&x, 0, sizeof(x));
w.xExprCallback = exprRefToSrcList;
w.xSelectCallback = selectRefEnter;
w.xSelectCallback2 = selectRefLeave;
w.u.pRefSrcList = &x;
x.db = pParse->db;
x.pRef = pSrcList;
assert( pExpr->op==TK_AGG_FUNCTION );
assert( ExprUseXList(pExpr) );
sqlite3WalkExprList(&w, pExpr->x.pList);
#ifndef SQLITE_OMIT_WINDOWFUNC
@@ -5961,7 +5989,14 @@ int sqlite3FunctionUsesThisSrc(Expr *pExpr, SrcList *pSrcList){
sqlite3WalkExpr(&w, pExpr->y.pWin->pFilter);
}
#endif
return cnt.nThis>0 || cnt.nOther==0;
sqlite3DbFree(pParse->db, x.aiExclude);
if( w.eCode & 0x01 ){
return 1;
}else if( w.eCode ){
return 0;
}else{
return -1;
}
}
/*