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Overview
| Comment: | Fix the ORDER BY optimization with IN constraints when the RHS of the IN constraint is a descending index. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | desc-orderby-fix-1 |
| Files: | files | file ages | folders |
| SHA1: | 62316ebaca933f7e5df2018e8360a2b7 |
| User & Date: | drh 2013-03-12 20:38:51 |
Context
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2013-03-12
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| 22:13 | Fix a test case that had an ambiguous result. check-in: 38c6bddf user: drh tags: desc-orderby-fix-1 | |
| 20:38 | Fix the ORDER BY optimization with IN constraints when the RHS of the IN constraint is a descending index. check-in: 62316eba user: drh tags: desc-orderby-fix-1 | |
| 18:49 | Revise the patch to make it easier to understand. check-in: 3ce7eb02 user: drh tags: desc-orderby-fix-1 | |
Changes
Changes to src/expr.c.
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** all members of the RHS set, skipping duplicates. ** ** A cursor is opened on the b-tree object that the RHS of the IN operator ** and pX->iTable is set to the index of that cursor. ** ** The returned value of this function indicates the b-tree type, as follows: ** ** IN_INDEX_ROWID - The cursor was opened on a database table. ** IN_INDEX_INDEX - The cursor was opened on a database index. ** IN_INDEX_EPH - The cursor was opened on a specially created and ** populated epheremal table. ** ** An existing b-tree might be used if the RHS expression pX is a simple ** subquery such as: ** ** SELECT <column> FROM <table> ** ** If the RHS of the IN operator is a list or a more complex subquery, then ................................................................................ pKey = (char *)sqlite3IndexKeyinfo(pParse, pIdx); iAddr = sqlite3CodeOnce(pParse); sqlite3VdbeAddOp4(v, OP_OpenRead, iTab, pIdx->tnum, iDb, pKey,P4_KEYINFO_HANDOFF); VdbeComment((v, "%s", pIdx->zName)); eType = IN_INDEX_INDEX; sqlite3VdbeJumpHere(v, iAddr); if( prNotFound && !pTab->aCol[iCol].notNull ){ *prNotFound = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Null, 0, *prNotFound); } } |
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** all members of the RHS set, skipping duplicates. ** ** A cursor is opened on the b-tree object that the RHS of the IN operator ** and pX->iTable is set to the index of that cursor. ** ** The returned value of this function indicates the b-tree type, as follows: ** ** IN_INDEX_ROWID - The cursor was opened on a database table. ** IN_INDEX_INDEX_ASC - The cursor was opened on an ascending index. ** IN_INDEX_INDEX_DESC - The cursor was opened on a descending index. ** IN_INDEX_EPH - The cursor was opened on a specially created and ** populated epheremal table. ** ** An existing b-tree might be used if the RHS expression pX is a simple ** subquery such as: ** ** SELECT <column> FROM <table> ** ** If the RHS of the IN operator is a list or a more complex subquery, then ................................................................................ pKey = (char *)sqlite3IndexKeyinfo(pParse, pIdx); iAddr = sqlite3CodeOnce(pParse); sqlite3VdbeAddOp4(v, OP_OpenRead, iTab, pIdx->tnum, iDb, pKey,P4_KEYINFO_HANDOFF); VdbeComment((v, "%s", pIdx->zName)); assert( IN_INDEX_INDEX_DESC == IN_INDEX_INDEX_ASC+1 ); eType = IN_INDEX_INDEX_ASC + pIdx->aSortOrder[0]; sqlite3VdbeJumpHere(v, iAddr); if( prNotFound && !pTab->aCol[iCol].notNull ){ *prNotFound = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Null, 0, *prNotFound); } } |
Changes to src/sqliteInt.h.
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#else
#define sqlite3BeginBenignMalloc()
#define sqlite3EndBenignMalloc()
#endif
#define IN_INDEX_ROWID 1
#define IN_INDEX_EPH 2
#define IN_INDEX_INDEX 3
int sqlite3FindInIndex(Parse *, Expr *, int*);
#ifdef SQLITE_ENABLE_ATOMIC_WRITE
int sqlite3JournalOpen(sqlite3_vfs *, const char *, sqlite3_file *, int, int);
int sqlite3JournalSize(sqlite3_vfs *);
int sqlite3JournalCreate(sqlite3_file *);
int sqlite3JournalExists(sqlite3_file *p);
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#else #define sqlite3BeginBenignMalloc() #define sqlite3EndBenignMalloc() #endif #define IN_INDEX_ROWID 1 #define IN_INDEX_EPH 2 #define IN_INDEX_INDEX_ASC 3 #define IN_INDEX_INDEX_DESC 4 int sqlite3FindInIndex(Parse *, Expr *, int*); #ifdef SQLITE_ENABLE_ATOMIC_WRITE int sqlite3JournalOpen(sqlite3_vfs *, const char *, sqlite3_file *, int, int); int sqlite3JournalSize(sqlite3_vfs *); int sqlite3JournalCreate(sqlite3_file *); int sqlite3JournalExists(sqlite3_file *p); |
Changes to src/where.c.
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int iTab;
struct InLoop *pIn;
u8 bRev = (pLevel->plan.wsFlags & WHERE_REVERSE)!=0;
if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0
&& pLevel->plan.u.pIdx->aSortOrder[iEq]
){
bRev = 1 - bRev;
}
assert( pX->op==TK_IN );
iReg = iTarget;
eType = sqlite3FindInIndex(pParse, pX, 0);
iTab = pX->iTable;
sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iTab, 0);
assert( pLevel->plan.wsFlags & WHERE_IN_ABLE );
if( pLevel->u.in.nIn==0 ){
pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
}
pLevel->u.in.nIn++;
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int iTab;
struct InLoop *pIn;
u8 bRev = (pLevel->plan.wsFlags & WHERE_REVERSE)!=0;
if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0
&& pLevel->plan.u.pIdx->aSortOrder[iEq]
){
bRev = !bRev;
}
assert( pX->op==TK_IN );
iReg = iTarget;
eType = sqlite3FindInIndex(pParse, pX, 0);
if( eType==IN_INDEX_INDEX_DESC ) bRev = !bRev;
iTab = pX->iTable;
sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iTab, 0);
assert( pLevel->plan.wsFlags & WHERE_IN_ABLE );
if( pLevel->u.in.nIn==0 ){
pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
}
pLevel->u.in.nIn++;
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