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Copy pathdelete.c
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1028 lines (968 loc) · 38.7 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
** in order to generate code for DELETE FROM statements.
*/
#include "sqliteInt.h"
/*
** While a SrcList can in general represent multiple tables and subqueries
** (as in the FROM clause of a SELECT statement) in this case it contains
** the name of a single table, as one might find in an INSERT, DELETE,
** or UPDATE statement. Look up that table in the symbol table and
** return a pointer. Set an error message and return NULL if the table
** name is not found or if any other error occurs.
**
** The following fields are initialized appropriate in pSrc:
**
** pSrc->a[0].pTab Pointer to the Table object
** pSrc->a[0].pIndex Pointer to the INDEXED BY index, if there is one
**
*/
Table *sqlite3SrcListLookup(Parse *pParse, SrcList *pSrc){
SrcItem *pItem = pSrc->a;
Table *pTab;
assert( pItem && pSrc->nSrc>=1 );
pTab = sqlite3LocateTableItem(pParse, 0, pItem);
if( pItem->pTab ) sqlite3DeleteTable(pParse->db, pItem->pTab);
pItem->pTab = pTab;
pItem->fg.notCte = 1;
if( pTab ){
pTab->nTabRef++;
if( pItem->fg.isIndexedBy && sqlite3IndexedByLookup(pParse, pItem) ){
pTab = 0;
}
}
return pTab;
}
/* Generate byte-code that will report the number of rows modified
** by a DELETE, INSERT, or UPDATE statement.
*/
void sqlite3CodeChangeCount(Vdbe *v, int regCounter, const char *zColName){
sqlite3VdbeAddOp0(v, OP_FkCheck);
sqlite3VdbeAddOp2(v, OP_ResultRow, regCounter, 1);
sqlite3VdbeSetNumCols(v, 1);
sqlite3VdbeSetColName(v, 0, COLNAME_NAME, zColName, SQLITE_STATIC);
}
/* Return true if table pTab is read-only.
**
** A table is read-only if any of the following are true:
**
** 1) It is a virtual table and no implementation of the xUpdate method
** has been provided
**
** 2) A trigger is currently being coded and the table is a virtual table
** that is SQLITE_VTAB_DIRECTONLY or if PRAGMA trusted_schema=OFF and
** the table is not SQLITE_VTAB_INNOCUOUS.
**
** 3) It is a system table (i.e. sqlite_schema), this call is not
** part of a nested parse and writable_schema pragma has not
** been specified
**
** 4) The table is a shadow table, the database connection is in
** defensive mode, and the current sqlite3_prepare()
** is for a top-level SQL statement.
*/
static int vtabIsReadOnly(Parse *pParse, Table *pTab){
if( sqlite3GetVTable(pParse->db, pTab)->pMod->pModule->xUpdate==0 ){
return 1;
}
/* Within triggers:
** * Do not allow DELETE, INSERT, or UPDATE of SQLITE_VTAB_DIRECTONLY
** virtual tables
** * Only allow DELETE, INSERT, or UPDATE of non-SQLITE_VTAB_INNOCUOUS
** virtual tables if PRAGMA trusted_schema=ON.
*/
if( pParse->pToplevel!=0
&& pTab->u.vtab.p->eVtabRisk >
((pParse->db->flags & SQLITE_TrustedSchema)!=0)
){
sqlite3ErrorMsg(pParse, "unsafe use of virtual table \"%s\"",
pTab->zName);
}
return 0;
}
static int tabIsReadOnly(Parse *pParse, Table *pTab){
sqlite3 *db;
if( IsVirtual(pTab) ){
return vtabIsReadOnly(pParse, pTab);
}
if( (pTab->tabFlags & (TF_Readonly|TF_Shadow))==0 ) return 0;
db = pParse->db;
if( (pTab->tabFlags & TF_Readonly)!=0 ){
return sqlite3WritableSchema(db)==0 && pParse->nested==0;
}
assert( pTab->tabFlags & TF_Shadow );
return sqlite3ReadOnlyShadowTables(db);
}
/*
** Check to make sure the given table is writable.
**
** If pTab is not writable -> generate an error message and return 1.
** If pTab is writable but other errors have occurred -> return 1.
** If pTab is writable and no prior errors -> return 0;
*/
int sqlite3IsReadOnly(Parse *pParse, Table *pTab, Trigger *pTrigger){
if( tabIsReadOnly(pParse, pTab) ){
sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName);
return 1;
}
#ifndef SQLITE_OMIT_VIEW
if( IsView(pTab)
&& (pTrigger==0 || (pTrigger->bReturning && pTrigger->pNext==0))
){
sqlite3ErrorMsg(pParse,"cannot modify %s because it is a view",pTab->zName);
return 1;
}
#endif
return 0;
}
#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
/*
** Evaluate a view and store its result in an ephemeral table. The
** pWhere argument is an optional WHERE clause that restricts the
** set of rows in the view that are to be added to the ephemeral table.
*/
void sqlite3MaterializeView(
Parse *pParse, /* Parsing context */
Table *pView, /* View definition */
Expr *pWhere, /* Optional WHERE clause to be added */
ExprList *pOrderBy, /* Optional ORDER BY clause */
Expr *pLimit, /* Optional LIMIT clause */
int iCur /* Cursor number for ephemeral table */
){
SelectDest dest;
Select *pSel;
SrcList *pFrom;
sqlite3 *db = pParse->db;
int iDb = sqlite3SchemaToIndex(db, pView->pSchema);
pWhere = sqlite3ExprDup(db, pWhere, 0);
pFrom = sqlite3SrcListAppend(pParse, 0, 0, 0);
if( pFrom ){
assert( pFrom->nSrc==1 );
pFrom->a[0].zName = sqlite3DbStrDup(db, pView->zName);
pFrom->a[0].zDatabase = sqlite3DbStrDup(db, db->aDb[iDb].zDbSName);
assert( pFrom->a[0].fg.isUsing==0 );
assert( pFrom->a[0].u3.pOn==0 );
}
pSel = sqlite3SelectNew(pParse, 0, pFrom, pWhere, 0, 0, pOrderBy,
SF_IncludeHidden, pLimit);
sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur);
sqlite3Select(pParse, pSel, &dest);
sqlite3SelectDelete(db, pSel);
}
#endif /* !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) */
#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
/*
** Generate an expression tree to implement the WHERE, ORDER BY,
** and LIMIT/OFFSET portion of DELETE and UPDATE statements.
**
** DELETE FROM table_wxyz WHERE a<5 ORDER BY a LIMIT 1;
** \__________________________/
** pLimitWhere (pInClause)
*/
Expr *sqlite3LimitWhere(
Parse *pParse, /* The parser context */
SrcList *pSrc, /* the FROM clause -- which tables to scan */
Expr *pWhere, /* The WHERE clause. May be null */
ExprList *pOrderBy, /* The ORDER BY clause. May be null */
Expr *pLimit, /* The LIMIT clause. May be null */
char *zStmtType /* Either DELETE or UPDATE. For err msgs. */
){
sqlite3 *db = pParse->db;
Expr *pLhs = NULL; /* LHS of IN(SELECT...) operator */
Expr *pInClause = NULL; /* WHERE rowid IN ( select ) */
ExprList *pEList = NULL; /* Expression list containing only pSelectRowid*/
SrcList *pSelectSrc = NULL; /* SELECT rowid FROM x ... (dup of pSrc) */
Select *pSelect = NULL; /* Complete SELECT tree */
Table *pTab;
/* Check that there isn't an ORDER BY without a LIMIT clause.
*/
if( pOrderBy && pLimit==0 ) {
sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on %s", zStmtType);
sqlite3ExprDelete(pParse->db, pWhere);
sqlite3ExprListDelete(pParse->db, pOrderBy);
return 0;
}
/* We only need to generate a select expression if there
** is a limit/offset term to enforce.
*/
if( pLimit == 0 ) {
return pWhere;
}
/* Generate a select expression tree to enforce the limit/offset
** term for the DELETE or UPDATE statement. For example:
** DELETE FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
** becomes:
** DELETE FROM table_a WHERE rowid IN (
** SELECT rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
** );
*/
pTab = pSrc->a[0].pTab;
if( HasRowid(pTab) ){
pLhs = sqlite3PExpr(pParse, TK_ROW, 0, 0);
pEList = sqlite3ExprListAppend(
pParse, 0, sqlite3PExpr(pParse, TK_ROW, 0, 0)
);
}else{
Index *pPk = sqlite3PrimaryKeyIndex(pTab);
assert( pPk!=0 );
assert( pPk->nKeyCol>=1 );
if( pPk->nKeyCol==1 ){
const char *zName;
assert( pPk->aiColumn[0]>=0 && pPk->aiColumn[0]<pTab->nCol );
zName = pTab->aCol[pPk->aiColumn[0]].zCnName;
pLhs = sqlite3Expr(db, TK_ID, zName);
pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db, TK_ID, zName));
}else{
int i;
for(i=0; i<pPk->nKeyCol; i++){
Expr *p;
assert( pPk->aiColumn[i]>=0 && pPk->aiColumn[i]<pTab->nCol );
p = sqlite3Expr(db, TK_ID, pTab->aCol[pPk->aiColumn[i]].zCnName);
pEList = sqlite3ExprListAppend(pParse, pEList, p);
}
pLhs = sqlite3PExpr(pParse, TK_VECTOR, 0, 0);
if( pLhs ){
pLhs->x.pList = sqlite3ExprListDup(db, pEList, 0);
}
}
}
/* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
** and the SELECT subtree. */
pSrc->a[0].pTab = 0;
pSelectSrc = sqlite3SrcListDup(db, pSrc, 0);
pSrc->a[0].pTab = pTab;
if( pSrc->a[0].fg.isIndexedBy ){
assert( pSrc->a[0].fg.isCte==0 );
pSrc->a[0].u2.pIBIndex = 0;
pSrc->a[0].fg.isIndexedBy = 0;
sqlite3DbFree(db, pSrc->a[0].u1.zIndexedBy);
}else if( pSrc->a[0].fg.isCte ){
pSrc->a[0].u2.pCteUse->nUse++;
}
/* generate the SELECT expression tree. */
pSelect = sqlite3SelectNew(pParse, pEList, pSelectSrc, pWhere, 0 ,0,
pOrderBy,0,pLimit
);
/* now generate the new WHERE rowid IN clause for the DELETE/UPDATE */
pInClause = sqlite3PExpr(pParse, TK_IN, pLhs, 0);
sqlite3PExprAddSelect(pParse, pInClause, pSelect);
return pInClause;
}
#endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) */
/* && !defined(SQLITE_OMIT_SUBQUERY) */
/*
** Generate code for a DELETE FROM statement.
**
** DELETE FROM table_wxyz WHERE a<5 AND b NOT NULL;
** \________/ \________________/
** pTabList pWhere
*/
void sqlite3DeleteFrom(
Parse *pParse, /* The parser context */
SrcList *pTabList, /* The table from which we should delete things */
Expr *pWhere, /* The WHERE clause. May be null */
ExprList *pOrderBy, /* ORDER BY clause. May be null */
Expr *pLimit /* LIMIT clause. May be null */
){
Vdbe *v; /* The virtual database engine */
Table *pTab; /* The table from which records will be deleted */
int i; /* Loop counter */
WhereInfo *pWInfo; /* Information about the WHERE clause */
Index *pIdx; /* For looping over indices of the table */
int iTabCur; /* Cursor number for the table */
int iDataCur = 0; /* VDBE cursor for the canonical data source */
int iIdxCur = 0; /* Cursor number of the first index */
int nIdx; /* Number of indices */
sqlite3 *db; /* Main database structure */
AuthContext sContext; /* Authorization context */
NameContext sNC; /* Name context to resolve expressions in */
int iDb; /* Database number */
int memCnt = 0; /* Memory cell used for change counting */
int rcauth; /* Value returned by authorization callback */
int eOnePass; /* ONEPASS_OFF or _SINGLE or _MULTI */
int aiCurOnePass[2]; /* The write cursors opened by WHERE_ONEPASS */
u8 *aToOpen = 0; /* Open cursor iTabCur+j if aToOpen[j] is true */
Index *pPk; /* The PRIMARY KEY index on the table */
int iPk = 0; /* First of nPk registers holding PRIMARY KEY value */
i16 nPk = 1; /* Number of columns in the PRIMARY KEY */
int iKey; /* Memory cell holding key of row to be deleted */
i16 nKey; /* Number of memory cells in the row key */
int iEphCur = 0; /* Ephemeral table holding all primary key values */
int iRowSet = 0; /* Register for rowset of rows to delete */
int addrBypass = 0; /* Address of jump over the delete logic */
int addrLoop = 0; /* Top of the delete loop */
int addrEphOpen = 0; /* Instruction to open the Ephemeral table */
int bComplex; /* True if there are triggers or FKs or
** subqueries in the WHERE clause */
#ifndef SQLITE_OMIT_TRIGGER
int isView; /* True if attempting to delete from a view */
Trigger *pTrigger; /* List of table triggers, if required */
#endif
memset(&sContext, 0, sizeof(sContext));
db = pParse->db;
assert( db->pParse==pParse );
if( pParse->nErr ){
goto delete_from_cleanup;
}
assert( db->mallocFailed==0 );
assert( pTabList->nSrc==1 );
/* Locate the table which we want to delete. This table has to be
** put in an SrcList structure because some of the subroutines we
** will be calling are designed to work with multiple tables and expect
** an SrcList* parameter instead of just a Table* parameter.
*/
pTab = sqlite3SrcListLookup(pParse, pTabList);
if( pTab==0 ) goto delete_from_cleanup;
/* Figure out if we have any triggers and if the table being
** deleted from is a view
*/
#ifndef SQLITE_OMIT_TRIGGER
pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
isView = IsView(pTab);
#else
# define pTrigger 0
# define isView 0
#endif
bComplex = pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0);
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x10000 ){
sqlite3TreeViewLine(0, "In sqlite3Delete() at %s:%d", __FILE__, __LINE__);
sqlite3TreeViewDelete(pParse->pWith, pTabList, pWhere,
pOrderBy, pLimit, pTrigger);
}
#endif
#ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
if( !isView ){
pWhere = sqlite3LimitWhere(
pParse, pTabList, pWhere, pOrderBy, pLimit, "DELETE"
);
pOrderBy = 0;
pLimit = 0;
}
#endif
/* If pTab is really a view, make sure it has been initialized.
*/
if( sqlite3ViewGetColumnNames(pParse, pTab) ){
goto delete_from_cleanup;
}
if( sqlite3IsReadOnly(pParse, pTab, pTrigger) ){
goto delete_from_cleanup;
}
iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
assert( iDb<db->nDb );
rcauth = sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0,
db->aDb[iDb].zDbSName);
assert( rcauth==SQLITE_OK || rcauth==SQLITE_DENY || rcauth==SQLITE_IGNORE );
if( rcauth==SQLITE_DENY ){
goto delete_from_cleanup;
}
assert(!isView || pTrigger);
/* Assign cursor numbers to the table and all its indices.
*/
assert( pTabList->nSrc==1 );
iTabCur = pTabList->a[0].iCursor = pParse->nTab++;
for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){
pParse->nTab++;
}
/* Start the view context
*/
if( isView ){
sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
}
/* Begin generating code.
*/
v = sqlite3GetVdbe(pParse);
if( v==0 ){
goto delete_from_cleanup;
}
if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
sqlite3BeginWriteOperation(pParse, bComplex, iDb);
/* If we are trying to delete from a view, realize that view into
** an ephemeral table.
*/
#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
if( isView ){
sqlite3MaterializeView(pParse, pTab,
pWhere, pOrderBy, pLimit, iTabCur
);
iDataCur = iIdxCur = iTabCur;
pOrderBy = 0;
pLimit = 0;
}
#endif
/* Resolve the column names in the WHERE clause.
*/
memset(&sNC, 0, sizeof(sNC));
sNC.pParse = pParse;
sNC.pSrcList = pTabList;
if( sqlite3ResolveExprNames(&sNC, pWhere) ){
goto delete_from_cleanup;
}
/* Initialize the counter of the number of rows deleted, if
** we are counting rows.
*/
if( (db->flags & SQLITE_CountRows)!=0
&& !pParse->nested
&& !pParse->pTriggerTab
&& !pParse->bReturning
){
memCnt = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Integer, 0, memCnt);
}
#ifndef SQLITE_OMIT_TRUNCATE_OPTIMIZATION
/* Special case: A DELETE without a WHERE clause deletes everything.
** It is easier just to erase the whole table. Prior to version 3.6.5,
** this optimization caused the row change count (the value returned by
** API function sqlite3_count_changes) to be set incorrectly.
**
** The "rcauth==SQLITE_OK" terms is the
** IMPLEMENTATION-OF: R-17228-37124 If the action code is SQLITE_DELETE and
** the callback returns SQLITE_IGNORE then the DELETE operation proceeds but
** the truncate optimization is disabled and all rows are deleted
** individually.
*/
if( rcauth==SQLITE_OK
&& pWhere==0
&& !bComplex
&& !IsVirtual(pTab)
#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
&& db->xPreUpdateCallback==0
#endif
){
assert( !isView );
sqlite3TableLock(pParse, iDb, pTab->tnum, 1, pTab->zName);
if( HasRowid(pTab) ){
sqlite3VdbeAddOp4(v, OP_Clear, pTab->tnum, iDb, memCnt ? memCnt : -1,
pTab->zName, P4_STATIC);
}
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
assert( pIdx->pSchema==pTab->pSchema );
if( IsPrimaryKeyIndex(pIdx) && !HasRowid(pTab) ){
sqlite3VdbeAddOp3(v, OP_Clear, pIdx->tnum, iDb, memCnt ? memCnt : -1);
}else{
sqlite3VdbeAddOp2(v, OP_Clear, pIdx->tnum, iDb);
}
}
}else
#endif /* SQLITE_OMIT_TRUNCATE_OPTIMIZATION */
{
u16 wcf = WHERE_ONEPASS_DESIRED|WHERE_DUPLICATES_OK;
if( sNC.ncFlags & NC_Subquery ) bComplex = 1;
wcf |= (bComplex ? 0 : WHERE_ONEPASS_MULTIROW);
if( HasRowid(pTab) ){
/* For a rowid table, initialize the RowSet to an empty set */
pPk = 0;
assert( nPk==1 );
iRowSet = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet);
}else{
/* For a WITHOUT ROWID table, create an ephemeral table used to
** hold all primary keys for rows to be deleted. */
pPk = sqlite3PrimaryKeyIndex(pTab);
assert( pPk!=0 );
nPk = pPk->nKeyCol;
iPk = pParse->nMem+1;
pParse->nMem += nPk;
iEphCur = pParse->nTab++;
addrEphOpen = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iEphCur, nPk);
sqlite3VdbeSetP4KeyInfo(pParse, pPk);
}
/* Construct a query to find the rowid or primary key for every row
** to be deleted, based on the WHERE clause. Set variable eOnePass
** to indicate the strategy used to implement this delete:
**
** ONEPASS_OFF: Two-pass approach - use a FIFO for rowids/PK values.
** ONEPASS_SINGLE: One-pass approach - at most one row deleted.
** ONEPASS_MULTI: One-pass approach - any number of rows may be deleted.
*/
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0,0,wcf,iTabCur+1);
if( pWInfo==0 ) goto delete_from_cleanup;
eOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
assert( IsVirtual(pTab)==0 || eOnePass!=ONEPASS_MULTI );
assert( IsVirtual(pTab) || bComplex || eOnePass!=ONEPASS_OFF
|| OptimizationDisabled(db, SQLITE_OnePass) );
if( eOnePass!=ONEPASS_SINGLE ) sqlite3MultiWrite(pParse);
if( sqlite3WhereUsesDeferredSeek(pWInfo) ){
sqlite3VdbeAddOp1(v, OP_FinishSeek, iTabCur);
}
/* Keep track of the number of rows to be deleted */
if( memCnt ){
sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1);
}
/* Extract the rowid or primary key for the current row */
if( pPk ){
for(i=0; i<nPk; i++){
assert( pPk->aiColumn[i]>=0 );
sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur,
pPk->aiColumn[i], iPk+i);
}
iKey = iPk;
}else{
iKey = ++pParse->nMem;
sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur, -1, iKey);
}
if( eOnePass!=ONEPASS_OFF ){
/* For ONEPASS, no need to store the rowid/primary-key. There is only
** one, so just keep it in its register(s) and fall through to the
** delete code. */
nKey = nPk; /* OP_Found will use an unpacked key */
aToOpen = sqlite3DbMallocRawNN(db, nIdx+2);
if( aToOpen==0 ){
sqlite3WhereEnd(pWInfo);
goto delete_from_cleanup;
}
memset(aToOpen, 1, nIdx+1);
aToOpen[nIdx+1] = 0;
if( aiCurOnePass[0]>=0 ) aToOpen[aiCurOnePass[0]-iTabCur] = 0;
if( aiCurOnePass[1]>=0 ) aToOpen[aiCurOnePass[1]-iTabCur] = 0;
if( addrEphOpen ) sqlite3VdbeChangeToNoop(v, addrEphOpen);
addrBypass = sqlite3VdbeMakeLabel(pParse);
}else{
if( pPk ){
/* Add the PK key for this row to the temporary table */
iKey = ++pParse->nMem;
nKey = 0; /* Zero tells OP_Found to use a composite key */
sqlite3VdbeAddOp4(v, OP_MakeRecord, iPk, nPk, iKey,
sqlite3IndexAffinityStr(pParse->db, pPk), nPk);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iEphCur, iKey, iPk, nPk);
}else{
/* Add the rowid of the row to be deleted to the RowSet */
nKey = 1; /* OP_DeferredSeek always uses a single rowid */
sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, iKey);
}
sqlite3WhereEnd(pWInfo);
}
/* Unless this is a view, open cursors for the table we are
** deleting from and all its indices. If this is a view, then the
** only effect this statement has is to fire the INSTEAD OF
** triggers.
*/
if( !isView ){
int iAddrOnce = 0;
if( eOnePass==ONEPASS_MULTI ){
iAddrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
}
testcase( IsVirtual(pTab) );
sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, OPFLAG_FORDELETE,
iTabCur, aToOpen, &iDataCur, &iIdxCur);
assert( pPk || IsVirtual(pTab) || iDataCur==iTabCur );
assert( pPk || IsVirtual(pTab) || iIdxCur==iDataCur+1 );
if( eOnePass==ONEPASS_MULTI ){
sqlite3VdbeJumpHereOrPopInst(v, iAddrOnce);
}
}
/* Set up a loop over the rowids/primary-keys that were found in the
** where-clause loop above.
*/
if( eOnePass!=ONEPASS_OFF ){
assert( nKey==nPk ); /* OP_Found will use an unpacked key */
if( !IsVirtual(pTab) && aToOpen[iDataCur-iTabCur] ){
assert( pPk!=0 || IsView(pTab) );
sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, addrBypass, iKey, nKey);
VdbeCoverage(v);
}
}else if( pPk ){
addrLoop = sqlite3VdbeAddOp1(v, OP_Rewind, iEphCur); VdbeCoverage(v);
if( IsVirtual(pTab) ){
sqlite3VdbeAddOp3(v, OP_Column, iEphCur, 0, iKey);
}else{
sqlite3VdbeAddOp2(v, OP_RowData, iEphCur, iKey);
}
assert( nKey==0 ); /* OP_Found will use a composite key */
}else{
addrLoop = sqlite3VdbeAddOp3(v, OP_RowSetRead, iRowSet, 0, iKey);
VdbeCoverage(v);
assert( nKey==1 );
}
/* Delete the row */
#ifndef SQLITE_OMIT_VIRTUALTABLE
if( IsVirtual(pTab) ){
const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
sqlite3VtabMakeWritable(pParse, pTab);
assert( eOnePass==ONEPASS_OFF || eOnePass==ONEPASS_SINGLE );
sqlite3MayAbort(pParse);
if( eOnePass==ONEPASS_SINGLE ){
sqlite3VdbeAddOp1(v, OP_Close, iTabCur);
if( sqlite3IsToplevel(pParse) ){
pParse->isMultiWrite = 0;
}
}
sqlite3VdbeAddOp4(v, OP_VUpdate, 0, 1, iKey, pVTab, P4_VTAB);
sqlite3VdbeChangeP5(v, OE_Abort);
}else
#endif
{
int count = (pParse->nested==0); /* True to count changes */
sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
iKey, nKey, count, OE_Default, eOnePass, aiCurOnePass[1]);
}
/* End of the loop over all rowids/primary-keys. */
if( eOnePass!=ONEPASS_OFF ){
sqlite3VdbeResolveLabel(v, addrBypass);
sqlite3WhereEnd(pWInfo);
}else if( pPk ){
sqlite3VdbeAddOp2(v, OP_Next, iEphCur, addrLoop+1); VdbeCoverage(v);
sqlite3VdbeJumpHere(v, addrLoop);
}else{
sqlite3VdbeGoto(v, addrLoop);
sqlite3VdbeJumpHere(v, addrLoop);
}
} /* End non-truncate path */
/* Update the sqlite_sequence table by storing the content of the
** maximum rowid counter values recorded while inserting into
** autoincrement tables.
*/
if( pParse->nested==0 && pParse->pTriggerTab==0 ){
sqlite3AutoincrementEnd(pParse);
}
/* Return the number of rows that were deleted. If this routine is
** generating code because of a call to sqlite3NestedParse(), do not
** invoke the callback function.
*/
if( memCnt ){
sqlite3CodeChangeCount(v, memCnt, "rows deleted");
}
delete_from_cleanup:
sqlite3AuthContextPop(&sContext);
sqlite3SrcListDelete(db, pTabList);
sqlite3ExprDelete(db, pWhere);
#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT)
sqlite3ExprListDelete(db, pOrderBy);
sqlite3ExprDelete(db, pLimit);
#endif
if( aToOpen ) sqlite3DbNNFreeNN(db, aToOpen);
return;
}
/* Make sure "isView" and other macros defined above are undefined. Otherwise
** they may interfere with compilation of other functions in this file
** (or in another file, if this file becomes part of the amalgamation). */
#ifdef isView
#undef isView
#endif
#ifdef pTrigger
#undef pTrigger
#endif
/*
** This routine generates VDBE code that causes a single row of a
** single table to be deleted. Both the original table entry and
** all indices are removed.
**
** Preconditions:
**
** 1. iDataCur is an open cursor on the btree that is the canonical data
** store for the table. (This will be either the table itself,
** in the case of a rowid table, or the PRIMARY KEY index in the case
** of a WITHOUT ROWID table.)
**
** 2. Read/write cursors for all indices of pTab must be open as
** cursor number iIdxCur+i for the i-th index.
**
** 3. The primary key for the row to be deleted must be stored in a
** sequence of nPk memory cells starting at iPk. If nPk==0 that means
** that a search record formed from OP_MakeRecord is contained in the
** single memory location iPk.
**
** eMode:
** Parameter eMode may be passed either ONEPASS_OFF (0), ONEPASS_SINGLE, or
** ONEPASS_MULTI. If eMode is not ONEPASS_OFF, then the cursor
** iDataCur already points to the row to delete. If eMode is ONEPASS_OFF
** then this function must seek iDataCur to the entry identified by iPk
** and nPk before reading from it.
**
** If eMode is ONEPASS_MULTI, then this call is being made as part
** of a ONEPASS delete that affects multiple rows. In this case, if
** iIdxNoSeek is a valid cursor number (>=0) and is not the same as
** iDataCur, then its position should be preserved following the delete
** operation. Or, if iIdxNoSeek is not a valid cursor number, the
** position of iDataCur should be preserved instead.
**
** iIdxNoSeek:
** If iIdxNoSeek is a valid cursor number (>=0) not equal to iDataCur,
** then it identifies an index cursor (from within array of cursors
** starting at iIdxCur) that already points to the index entry to be deleted.
** Except, this optimization is disabled if there are BEFORE triggers since
** the trigger body might have moved the cursor.
*/
void sqlite3GenerateRowDelete(
Parse *pParse, /* Parsing context */
Table *pTab, /* Table containing the row to be deleted */
Trigger *pTrigger, /* List of triggers to (potentially) fire */
int iDataCur, /* Cursor from which column data is extracted */
int iIdxCur, /* First index cursor */
int iPk, /* First memory cell containing the PRIMARY KEY */
i16 nPk, /* Number of PRIMARY KEY memory cells */
u8 count, /* If non-zero, increment the row change counter */
u8 onconf, /* Default ON CONFLICT policy for triggers */
u8 eMode, /* ONEPASS_OFF, _SINGLE, or _MULTI. See above */
int iIdxNoSeek /* Cursor number of cursor that does not need seeking */
){
Vdbe *v = pParse->pVdbe; /* Vdbe */
int iOld = 0; /* First register in OLD.* array */
int iLabel; /* Label resolved to end of generated code */
u8 opSeek; /* Seek opcode */
/* Vdbe is guaranteed to have been allocated by this stage. */
assert( v );
VdbeModuleComment((v, "BEGIN: GenRowDel(%d,%d,%d,%d)",
iDataCur, iIdxCur, iPk, (int)nPk));
/* Seek cursor iCur to the row to delete. If this row no longer exists
** (this can happen if a trigger program has already deleted it), do
** not attempt to delete it or fire any DELETE triggers. */
iLabel = sqlite3VdbeMakeLabel(pParse);
opSeek = HasRowid(pTab) ? OP_NotExists : OP_NotFound;
if( eMode==ONEPASS_OFF ){
sqlite3VdbeAddOp4Int(v, opSeek, iDataCur, iLabel, iPk, nPk);
VdbeCoverageIf(v, opSeek==OP_NotExists);
VdbeCoverageIf(v, opSeek==OP_NotFound);
}
/* If there are any triggers to fire, allocate a range of registers to
** use for the old.* references in the triggers. */
if( sqlite3FkRequired(pParse, pTab, 0, 0) || pTrigger ){
u32 mask; /* Mask of OLD.* columns in use */
int iCol; /* Iterator used while populating OLD.* */
int addrStart; /* Start of BEFORE trigger programs */
/* TODO: Could use temporary registers here. Also could attempt to
** avoid copying the contents of the rowid register. */
mask = sqlite3TriggerColmask(
pParse, pTrigger, 0, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onconf
);
mask |= sqlite3FkOldmask(pParse, pTab);
iOld = pParse->nMem+1;
pParse->nMem += (1 + pTab->nCol);
/* Populate the OLD.* pseudo-table register array. These values will be
** used by any BEFORE and AFTER triggers that exist. */
sqlite3VdbeAddOp2(v, OP_Copy, iPk, iOld);
for(iCol=0; iCol<pTab->nCol; iCol++){
testcase( mask!=0xffffffff && iCol==31 );
testcase( mask!=0xffffffff && iCol==32 );
if( mask==0xffffffff || (iCol<=31 && (mask & MASKBIT32(iCol))!=0) ){
int kk = sqlite3TableColumnToStorage(pTab, iCol);
sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, iCol, iOld+kk+1);
}
}
/* Invoke BEFORE DELETE trigger programs. */
addrStart = sqlite3VdbeCurrentAddr(v);
sqlite3CodeRowTrigger(pParse, pTrigger,
TK_DELETE, 0, TRIGGER_BEFORE, pTab, iOld, onconf, iLabel
);
/* If any BEFORE triggers were coded, then seek the cursor to the
** row to be deleted again. It may be that the BEFORE triggers moved
** the cursor or already deleted the row that the cursor was
** pointing to.
**
** Also disable the iIdxNoSeek optimization since the BEFORE trigger
** may have moved that cursor.
*/
if( addrStart<sqlite3VdbeCurrentAddr(v) ){
sqlite3VdbeAddOp4Int(v, opSeek, iDataCur, iLabel, iPk, nPk);
VdbeCoverageIf(v, opSeek==OP_NotExists);
VdbeCoverageIf(v, opSeek==OP_NotFound);
testcase( iIdxNoSeek>=0 );
iIdxNoSeek = -1;
}
/* Do FK processing. This call checks that any FK constraints that
** refer to this table (i.e. constraints attached to other tables)
** are not violated by deleting this row. */
sqlite3FkCheck(pParse, pTab, iOld, 0, 0, 0);
}
/* Delete the index and table entries. Skip this step if pTab is really
** a view (in which case the only effect of the DELETE statement is to
** fire the INSTEAD OF triggers).
**
** If variable 'count' is non-zero, then this OP_Delete instruction should
** invoke the update-hook. The pre-update-hook, on the other hand should
** be invoked unless table pTab is a system table. The difference is that
** the update-hook is not invoked for rows removed by REPLACE, but the
** pre-update-hook is.
*/
if( !IsView(pTab) ){
u8 p5 = 0;
sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur,0,iIdxNoSeek);
sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, (count?OPFLAG_NCHANGE:0));
if( pParse->nested==0 || 0==sqlite3_stricmp(pTab->zName, "sqlite_stat1") ){
sqlite3VdbeAppendP4(v, (char*)pTab, P4_TABLE);
}
if( eMode!=ONEPASS_OFF ){
sqlite3VdbeChangeP5(v, OPFLAG_AUXDELETE);
}
if( iIdxNoSeek>=0 && iIdxNoSeek!=iDataCur ){
sqlite3VdbeAddOp1(v, OP_Delete, iIdxNoSeek);
}
if( eMode==ONEPASS_MULTI ) p5 |= OPFLAG_SAVEPOSITION;
sqlite3VdbeChangeP5(v, p5);
}
/* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
** handle rows (possibly in other tables) that refer via a foreign key
** to the row just deleted. */
sqlite3FkActions(pParse, pTab, 0, iOld, 0, 0);
/* Invoke AFTER DELETE trigger programs. */
if( pTrigger ){
sqlite3CodeRowTrigger(pParse, pTrigger,
TK_DELETE, 0, TRIGGER_AFTER, pTab, iOld, onconf, iLabel
);
}
/* Jump here if the row had already been deleted before any BEFORE
** trigger programs were invoked. Or if a trigger program throws a
** RAISE(IGNORE) exception. */
sqlite3VdbeResolveLabel(v, iLabel);
VdbeModuleComment((v, "END: GenRowDel()"));
}
/*
** This routine generates VDBE code that causes the deletion of all
** index entries associated with a single row of a single table, pTab
**
** Preconditions:
**
** 1. A read/write cursor "iDataCur" must be open on the canonical storage
** btree for the table pTab. (This will be either the table itself
** for rowid tables or to the primary key index for WITHOUT ROWID
** tables.)
**
** 2. Read/write cursors for all indices of pTab must be open as
** cursor number iIdxCur+i for the i-th index. (The pTab->pIndex
** index is the 0-th index.)
**
** 3. The "iDataCur" cursor must be already be positioned on the row
** that is to be deleted.
*/
void sqlite3GenerateRowIndexDelete(
Parse *pParse, /* Parsing and code generating context */
Table *pTab, /* Table containing the row to be deleted */
int iDataCur, /* Cursor of table holding data. */
int iIdxCur, /* First index cursor */
int *aRegIdx, /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
int iIdxNoSeek /* Do not delete from this cursor */
){
int i; /* Index loop counter */
int r1 = -1; /* Register holding an index key */
int iPartIdxLabel; /* Jump destination for skipping partial index entries */
Index *pIdx; /* Current index */
Index *pPrior = 0; /* Prior index */
Vdbe *v; /* The prepared statement under construction */
Index *pPk; /* PRIMARY KEY index, or NULL for rowid tables */
v = pParse->pVdbe;
pPk = HasRowid(pTab) ? 0 : sqlite3PrimaryKeyIndex(pTab);
for(i=0, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
assert( iIdxCur+i!=iDataCur || pPk==pIdx );
if( aRegIdx!=0 && aRegIdx[i]==0 ) continue;
if( pIdx==pPk ) continue;
if( iIdxCur+i==iIdxNoSeek ) continue;
VdbeModuleComment((v, "GenRowIdxDel for %s", pIdx->zName));
r1 = sqlite3GenerateIndexKey(pParse, pIdx, iDataCur, 0, 1,
&iPartIdxLabel, pPrior, r1);
sqlite3VdbeAddOp3(v, OP_IdxDelete, iIdxCur+i, r1,
pIdx->uniqNotNull ? pIdx->nKeyCol : pIdx->nColumn);
sqlite3VdbeChangeP5(v, 1); /* Cause IdxDelete to error if no entry found */
sqlite3ResolvePartIdxLabel(pParse, iPartIdxLabel);
pPrior = pIdx;
}
}
/*
** Generate code that will assemble an index key and stores it in register
** regOut. The key with be for index pIdx which is an index on pTab.
** iCur is the index of a cursor open on the pTab table and pointing to
** the entry that needs indexing. If pTab is a WITHOUT ROWID table, then
** iCur must be the cursor of the PRIMARY KEY index.
**
** Return a register number which is the first in a block of
** registers that holds the elements of the index key. The
** block of registers has already been deallocated by the time
** this routine returns.
**
** If *piPartIdxLabel is not NULL, fill it in with a label and jump
** to that label if pIdx is a partial index that should be skipped.
** The label should be resolved using sqlite3ResolvePartIdxLabel().
** A partial index should be skipped if its WHERE clause evaluates
** to false or null. If pIdx is not a partial index, *piPartIdxLabel
** will be set to zero which is an empty label that is ignored by
** sqlite3ResolvePartIdxLabel().
**
** The pPrior and regPrior parameters are used to implement a cache to
** avoid unnecessary register loads. If pPrior is not NULL, then it is
** a pointer to a different index for which an index key has just been
** computed into register regPrior. If the current pIdx index is generating
** its key into the same sequence of registers and if pPrior and pIdx share
** a column in common, then the register corresponding to that column already
** holds the correct value and the loading of that register is skipped.
** This optimization is helpful when doing a DELETE or an INTEGRITY_CHECK
** on a table with multiple indices, and especially with the ROWID or
** PRIMARY KEY columns of the index.
*/
int sqlite3GenerateIndexKey(
Parse *pParse, /* Parsing context */
Index *pIdx, /* The index for which to generate a key */
int iDataCur, /* Cursor number from which to take column data */
int regOut, /* Put the new key into this register if not 0 */
int prefixOnly, /* Compute only a unique prefix of the key */
int *piPartIdxLabel, /* OUT: Jump to this label to skip partial index */
Index *pPrior, /* Previously generated index key */
int regPrior /* Register holding previous generated key */
){
Vdbe *v = pParse->pVdbe;
int j;
int regBase;
int nCol;
if( piPartIdxLabel ){
if( pIdx->pPartIdxWhere ){
*piPartIdxLabel = sqlite3VdbeMakeLabel(pParse);
pParse->iSelfTab = iDataCur + 1;
sqlite3ExprIfFalseDup(pParse, pIdx->pPartIdxWhere, *piPartIdxLabel,
SQLITE_JUMPIFNULL);
pParse->iSelfTab = 0;
pPrior = 0; /* Ticket a9efb42811fa41ee 2019-11-02;
** pPartIdxWhere may have corrupted regPrior registers */
}else{
*piPartIdxLabel = 0;
}
}
nCol = (prefixOnly && pIdx->uniqNotNull) ? pIdx->nKeyCol : pIdx->nColumn;
regBase = sqlite3GetTempRange(pParse, nCol);
if( pPrior && (regBase!=regPrior || pPrior->pPartIdxWhere) ) pPrior = 0;
for(j=0; j<nCol; j++){
if( pPrior
&& pPrior->aiColumn[j]==pIdx->aiColumn[j]
&& pPrior->aiColumn[j]!=XN_EXPR
){
/* This column was already computed by the previous index */
continue;
}