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Diffstat (limited to '')
| -rw-r--r-- | src/delete.c | 1016 |
1 files changed, 1016 insertions, 0 deletions
diff --git a/src/delete.c b/src/delete.c new file mode 100644 index 0000000..704a3c7 --- /dev/null +++ b/src/delete.c @@ -0,0 +1,1016 @@ +/* +** 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); + sqlite3DeleteTable(pParse->db, pItem->pTab); + pItem->pTab = pTab; + 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, int viewOk){ + if( tabIsReadOnly(pParse, pTab) ){ + sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName); + return 1; + } +#ifndef SQLITE_OMIT_VIEW + if( !viewOk && IsView(pTab) ){ + 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 contaning 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); + if( pPk->nKeyCol==1 ){ + const char *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 = 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/UDPATE */ + 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?1:0)) ){ + 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_VarSelect ) bComplex = 1; + wcf |= (bComplex ? 0 : WHERE_ONEPASS_MULTIROW); + if( HasRowid(pTab) ){ + /* For a rowid table, initialize the RowSet to an empty set */ + pPk = 0; + 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 ); + 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. */ + 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; + } + sqlite3ExprCodeLoadIndexColumn(pParse, pIdx, iDataCur, j, regBase+j); + if( pIdx->aiColumn[j]>=0 ){ + /* If the column affinity is REAL but the number is an integer, then it + ** might be stored in the table as an integer (using a compact + ** representation) then converted to REAL by an OP_RealAffinity opcode. + ** But we are getting ready to store this value back into an index, where + ** it should be converted by to INTEGER again. So omit the + ** OP_RealAffinity opcode if it is present */ + sqlite3VdbeDeletePriorOpcode(v, OP_RealAffinity); + } + } + if( regOut ){ + sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regOut); + } + sqlite3ReleaseTempRange(pParse, regBase, nCol); + return regBase; +} + +/* +** If a prior call to sqlite3GenerateIndexKey() generated a jump-over label +** because it was a partial index, then this routine should be called to +** resolve that label. +*/ +void sqlite3ResolvePartIdxLabel(Parse *pParse, int iLabel){ + if( iLabel ){ + sqlite3VdbeResolveLabel(pParse->pVdbe, iLabel); + } +} |