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      1 /*
      2 ** 2001 September 15
      3 **
      4 ** The author disclaims copyright to this source code.  In place of
      5 ** a legal notice, here is a blessing:
      6 **
      7 **    May you do good and not evil.
      8 **    May you find forgiveness for yourself and forgive others.
      9 **    May you share freely, never taking more than you give.
     10 **
     11 *************************************************************************
     12 ** This file contains C code routines that are called by the parser
     13 ** to handle INSERT statements in SQLite.
     14 */
     15 #include "sqliteInt.h"
     16 
     17 /*
     18 ** Generate code that will open a table for reading.
     19 */
     20 void sqlite3OpenTable(
     21   Parse *p,       /* Generate code into this VDBE */
     22   int iCur,       /* The cursor number of the table */
     23   int iDb,        /* The database index in sqlite3.aDb[] */
     24   Table *pTab,    /* The table to be opened */
     25   int opcode      /* OP_OpenRead or OP_OpenWrite */
     26 ){
     27   Vdbe *v;
     28   if( IsVirtual(pTab) ) return;
     29   v = sqlite3GetVdbe(p);
     30   assert( opcode==OP_OpenWrite || opcode==OP_OpenRead );
     31   sqlite3TableLock(p, iDb, pTab->tnum, (opcode==OP_OpenWrite)?1:0, pTab->zName);
     32   sqlite3VdbeAddOp3(v, opcode, iCur, pTab->tnum, iDb);
     33   sqlite3VdbeChangeP4(v, -1, SQLITE_INT_TO_PTR(pTab->nCol), P4_INT32);
     34   VdbeComment((v, "%s", pTab->zName));
     35 }
     36 
     37 /*
     38 ** Return a pointer to the column affinity string associated with index
     39 ** pIdx. A column affinity string has one character for each column in
     40 ** the table, according to the affinity of the column:
     41 **
     42 **  Character      Column affinity
     43 **  ------------------------------
     44 **  'a'            TEXT
     45 **  'b'            NONE
     46 **  'c'            NUMERIC
     47 **  'd'            INTEGER
     48 **  'e'            REAL
     49 **
     50 ** An extra 'b' is appended to the end of the string to cover the
     51 ** rowid that appears as the last column in every index.
     52 **
     53 ** Memory for the buffer containing the column index affinity string
     54 ** is managed along with the rest of the Index structure. It will be
     55 ** released when sqlite3DeleteIndex() is called.
     56 */
     57 const char *sqlite3IndexAffinityStr(Vdbe *v, Index *pIdx){
     58   if( !pIdx->zColAff ){
     59     /* The first time a column affinity string for a particular index is
     60     ** required, it is allocated and populated here. It is then stored as
     61     ** a member of the Index structure for subsequent use.
     62     **
     63     ** The column affinity string will eventually be deleted by
     64     ** sqliteDeleteIndex() when the Index structure itself is cleaned
     65     ** up.
     66     */
     67     int n;
     68     Table *pTab = pIdx->pTable;
     69     sqlite3 *db = sqlite3VdbeDb(v);
     70     pIdx->zColAff = (char *)sqlite3DbMallocRaw(0, pIdx->nColumn+2);
     71     if( !pIdx->zColAff ){
     72       db->mallocFailed = 1;
     73       return 0;
     74     }
     75     for(n=0; n<pIdx->nColumn; n++){
     76       pIdx->zColAff[n] = pTab->aCol[pIdx->aiColumn[n]].affinity;
     77     }
     78     pIdx->zColAff[n++] = SQLITE_AFF_NONE;
     79     pIdx->zColAff[n] = 0;
     80   }
     81 
     82   return pIdx->zColAff;
     83 }
     84 
     85 /*
     86 ** Set P4 of the most recently inserted opcode to a column affinity
     87 ** string for table pTab. A column affinity string has one character
     88 ** for each column indexed by the index, according to the affinity of the
     89 ** column:
     90 **
     91 **  Character      Column affinity
     92 **  ------------------------------
     93 **  'a'            TEXT
     94 **  'b'            NONE
     95 **  'c'            NUMERIC
     96 **  'd'            INTEGER
     97 **  'e'            REAL
     98 */
     99 void sqlite3TableAffinityStr(Vdbe *v, Table *pTab){
    100   /* The first time a column affinity string for a particular table
    101   ** is required, it is allocated and populated here. It is then
    102   ** stored as a member of the Table structure for subsequent use.
    103   **
    104   ** The column affinity string will eventually be deleted by
    105   ** sqlite3DeleteTable() when the Table structure itself is cleaned up.
    106   */
    107   if( !pTab->zColAff ){
    108     char *zColAff;
    109     int i;
    110     sqlite3 *db = sqlite3VdbeDb(v);
    111 
    112     zColAff = (char *)sqlite3DbMallocRaw(0, pTab->nCol+1);
    113     if( !zColAff ){
    114       db->mallocFailed = 1;
    115       return;
    116     }
    117 
    118     for(i=0; i<pTab->nCol; i++){
    119       zColAff[i] = pTab->aCol[i].affinity;
    120     }
    121     zColAff[pTab->nCol] = '\0';
    122 
    123     pTab->zColAff = zColAff;
    124   }
    125 
    126   sqlite3VdbeChangeP4(v, -1, pTab->zColAff, P4_TRANSIENT);
    127 }
    128 
    129 /*
    130 ** Return non-zero if the table pTab in database iDb or any of its indices
    131 ** have been opened at any point in the VDBE program beginning at location
    132 ** iStartAddr throught the end of the program.  This is used to see if
    133 ** a statement of the form  "INSERT INTO <iDb, pTab> SELECT ..." can
    134 ** run without using temporary table for the results of the SELECT.
    135 */
    136 static int readsTable(Parse *p, int iStartAddr, int iDb, Table *pTab){
    137   Vdbe *v = sqlite3GetVdbe(p);
    138   int i;
    139   int iEnd = sqlite3VdbeCurrentAddr(v);
    140 #ifndef SQLITE_OMIT_VIRTUALTABLE
    141   VTable *pVTab = IsVirtual(pTab) ? sqlite3GetVTable(p->db, pTab) : 0;
    142 #endif
    143 
    144   for(i=iStartAddr; i<iEnd; i++){
    145     VdbeOp *pOp = sqlite3VdbeGetOp(v, i);
    146     assert( pOp!=0 );
    147     if( pOp->opcode==OP_OpenRead && pOp->p3==iDb ){
    148       Index *pIndex;
    149       int tnum = pOp->p2;
    150       if( tnum==pTab->tnum ){
    151         return 1;
    152       }
    153       for(pIndex=pTab->pIndex; pIndex; pIndex=pIndex->pNext){
    154         if( tnum==pIndex->tnum ){
    155           return 1;
    156         }
    157       }
    158     }
    159 #ifndef SQLITE_OMIT_VIRTUALTABLE
    160     if( pOp->opcode==OP_VOpen && pOp->p4.pVtab==pVTab ){
    161       assert( pOp->p4.pVtab!=0 );
    162       assert( pOp->p4type==P4_VTAB );
    163       return 1;
    164     }
    165 #endif
    166   }
    167   return 0;
    168 }
    169 
    170 #ifndef SQLITE_OMIT_AUTOINCREMENT
    171 /*
    172 ** Locate or create an AutoincInfo structure associated with table pTab
    173 ** which is in database iDb.  Return the register number for the register
    174 ** that holds the maximum rowid.
    175 **
    176 ** There is at most one AutoincInfo structure per table even if the
    177 ** same table is autoincremented multiple times due to inserts within
    178 ** triggers.  A new AutoincInfo structure is created if this is the
    179 ** first use of table pTab.  On 2nd and subsequent uses, the original
    180 ** AutoincInfo structure is used.
    181 **
    182 ** Three memory locations are allocated:
    183 **
    184 **   (1)  Register to hold the name of the pTab table.
    185 **   (2)  Register to hold the maximum ROWID of pTab.
    186 **   (3)  Register to hold the rowid in sqlite_sequence of pTab
    187 **
    188 ** The 2nd register is the one that is returned.  That is all the
    189 ** insert routine needs to know about.
    190 */
    191 static int autoIncBegin(
    192   Parse *pParse,      /* Parsing context */
    193   int iDb,            /* Index of the database holding pTab */
    194   Table *pTab         /* The table we are writing to */
    195 ){
    196   int memId = 0;      /* Register holding maximum rowid */
    197   if( pTab->tabFlags & TF_Autoincrement ){
    198     Parse *pToplevel = sqlite3ParseToplevel(pParse);
    199     AutoincInfo *pInfo;
    200 
    201     pInfo = pToplevel->pAinc;
    202     while( pInfo && pInfo->pTab!=pTab ){ pInfo = pInfo->pNext; }
    203     if( pInfo==0 ){
    204       pInfo = sqlite3DbMallocRaw(pParse->db, sizeof(*pInfo));
    205       if( pInfo==0 ) return 0;
    206       pInfo->pNext = pToplevel->pAinc;
    207       pToplevel->pAinc = pInfo;
    208       pInfo->pTab = pTab;
    209       pInfo->iDb = iDb;
    210       pToplevel->nMem++;                  /* Register to hold name of table */
    211       pInfo->regCtr = ++pToplevel->nMem;  /* Max rowid register */
    212       pToplevel->nMem++;                  /* Rowid in sqlite_sequence */
    213     }
    214     memId = pInfo->regCtr;
    215   }
    216   return memId;
    217 }
    218 
    219 /*
    220 ** This routine generates code that will initialize all of the
    221 ** register used by the autoincrement tracker.
    222 */
    223 void sqlite3AutoincrementBegin(Parse *pParse){
    224   AutoincInfo *p;            /* Information about an AUTOINCREMENT */
    225   sqlite3 *db = pParse->db;  /* The database connection */
    226   Db *pDb;                   /* Database only autoinc table */
    227   int memId;                 /* Register holding max rowid */
    228   int addr;                  /* A VDBE address */
    229   Vdbe *v = pParse->pVdbe;   /* VDBE under construction */
    230 
    231   /* This routine is never called during trigger-generation.  It is
    232   ** only called from the top-level */
    233   assert( pParse->pTriggerTab==0 );
    234   assert( pParse==sqlite3ParseToplevel(pParse) );
    235 
    236   assert( v );   /* We failed long ago if this is not so */
    237   for(p = pParse->pAinc; p; p = p->pNext){
    238     pDb = &db->aDb[p->iDb];
    239     memId = p->regCtr;
    240     assert( sqlite3SchemaMutexHeld(db, 0, pDb->pSchema) );
    241     sqlite3OpenTable(pParse, 0, p->iDb, pDb->pSchema->pSeqTab, OP_OpenRead);
    242     addr = sqlite3VdbeCurrentAddr(v);
    243     sqlite3VdbeAddOp4(v, OP_String8, 0, memId-1, 0, p->pTab->zName, 0);
    244     sqlite3VdbeAddOp2(v, OP_Rewind, 0, addr+9);
    245     sqlite3VdbeAddOp3(v, OP_Column, 0, 0, memId);
    246     sqlite3VdbeAddOp3(v, OP_Ne, memId-1, addr+7, memId);
    247     sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
    248     sqlite3VdbeAddOp2(v, OP_Rowid, 0, memId+1);
    249     sqlite3VdbeAddOp3(v, OP_Column, 0, 1, memId);
    250     sqlite3VdbeAddOp2(v, OP_Goto, 0, addr+9);
    251     sqlite3VdbeAddOp2(v, OP_Next, 0, addr+2);
    252     sqlite3VdbeAddOp2(v, OP_Integer, 0, memId);
    253     sqlite3VdbeAddOp0(v, OP_Close);
    254   }
    255 }
    256 
    257 /*
    258 ** Update the maximum rowid for an autoincrement calculation.
    259 **
    260 ** This routine should be called when the top of the stack holds a
    261 ** new rowid that is about to be inserted.  If that new rowid is
    262 ** larger than the maximum rowid in the memId memory cell, then the
    263 ** memory cell is updated.  The stack is unchanged.
    264 */
    265 static void autoIncStep(Parse *pParse, int memId, int regRowid){
    266   if( memId>0 ){
    267     sqlite3VdbeAddOp2(pParse->pVdbe, OP_MemMax, memId, regRowid);
    268   }
    269 }
    270 
    271 /*
    272 ** This routine generates the code needed to write autoincrement
    273 ** maximum rowid values back into the sqlite_sequence register.
    274 ** Every statement that might do an INSERT into an autoincrement
    275 ** table (either directly or through triggers) needs to call this
    276 ** routine just before the "exit" code.
    277 */
    278 void sqlite3AutoincrementEnd(Parse *pParse){
    279   AutoincInfo *p;
    280   Vdbe *v = pParse->pVdbe;
    281   sqlite3 *db = pParse->db;
    282 
    283   assert( v );
    284   for(p = pParse->pAinc; p; p = p->pNext){
    285     Db *pDb = &db->aDb[p->iDb];
    286     int j1, j2, j3, j4, j5;
    287     int iRec;
    288     int memId = p->regCtr;
    289 
    290     iRec = sqlite3GetTempReg(pParse);
    291     assert( sqlite3SchemaMutexHeld(db, 0, pDb->pSchema) );
    292     sqlite3OpenTable(pParse, 0, p->iDb, pDb->pSchema->pSeqTab, OP_OpenWrite);
    293     j1 = sqlite3VdbeAddOp1(v, OP_NotNull, memId+1);
    294     j2 = sqlite3VdbeAddOp0(v, OP_Rewind);
    295     j3 = sqlite3VdbeAddOp3(v, OP_Column, 0, 0, iRec);
    296     j4 = sqlite3VdbeAddOp3(v, OP_Eq, memId-1, 0, iRec);
    297     sqlite3VdbeAddOp2(v, OP_Next, 0, j3);
    298     sqlite3VdbeJumpHere(v, j2);
    299     sqlite3VdbeAddOp2(v, OP_NewRowid, 0, memId+1);
    300     j5 = sqlite3VdbeAddOp0(v, OP_Goto);
    301     sqlite3VdbeJumpHere(v, j4);
    302     sqlite3VdbeAddOp2(v, OP_Rowid, 0, memId+1);
    303     sqlite3VdbeJumpHere(v, j1);
    304     sqlite3VdbeJumpHere(v, j5);
    305     sqlite3VdbeAddOp3(v, OP_MakeRecord, memId-1, 2, iRec);
    306     sqlite3VdbeAddOp3(v, OP_Insert, 0, iRec, memId+1);
    307     sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
    308     sqlite3VdbeAddOp0(v, OP_Close);
    309     sqlite3ReleaseTempReg(pParse, iRec);
    310   }
    311 }
    312 #else
    313 /*
    314 ** If SQLITE_OMIT_AUTOINCREMENT is defined, then the three routines
    315 ** above are all no-ops
    316 */
    317 # define autoIncBegin(A,B,C) (0)
    318 # define autoIncStep(A,B,C)
    319 #endif /* SQLITE_OMIT_AUTOINCREMENT */
    320 
    321 
    322 /* Forward declaration */
    323 static int xferOptimization(
    324   Parse *pParse,        /* Parser context */
    325   Table *pDest,         /* The table we are inserting into */
    326   Select *pSelect,      /* A SELECT statement to use as the data source */
    327   int onError,          /* How to handle constraint errors */
    328   int iDbDest           /* The database of pDest */
    329 );
    330 
    331 /*
    332 ** This routine is call to handle SQL of the following forms:
    333 **
    334 **    insert into TABLE (IDLIST) values(EXPRLIST)
    335 **    insert into TABLE (IDLIST) select
    336 **
    337 ** The IDLIST following the table name is always optional.  If omitted,
    338 ** then a list of all columns for the table is substituted.  The IDLIST
    339 ** appears in the pColumn parameter.  pColumn is NULL if IDLIST is omitted.
    340 **
    341 ** The pList parameter holds EXPRLIST in the first form of the INSERT
    342 ** statement above, and pSelect is NULL.  For the second form, pList is
    343 ** NULL and pSelect is a pointer to the select statement used to generate
    344 ** data for the insert.
    345 **
    346 ** The code generated follows one of four templates.  For a simple
    347 ** select with data coming from a VALUES clause, the code executes
    348 ** once straight down through.  Pseudo-code follows (we call this
    349 ** the "1st template"):
    350 **
    351 **         open write cursor to <table> and its indices
    352 **         puts VALUES clause expressions onto the stack
    353 **         write the resulting record into <table>
    354 **         cleanup
    355 **
    356 ** The three remaining templates assume the statement is of the form
    357 **
    358 **   INSERT INTO <table> SELECT ...
    359 **
    360 ** If the SELECT clause is of the restricted form "SELECT * FROM <table2>" -
    361 ** in other words if the SELECT pulls all columns from a single table
    362 ** and there is no WHERE or LIMIT or GROUP BY or ORDER BY clauses, and
    363 ** if <table2> and <table1> are distinct tables but have identical
    364 ** schemas, including all the same indices, then a special optimization
    365 ** is invoked that copies raw records from <table2> over to <table1>.
    366 ** See the xferOptimization() function for the implementation of this
    367 ** template.  This is the 2nd template.
    368 **
    369 **         open a write cursor to <table>
    370 **         open read cursor on <table2>
    371 **         transfer all records in <table2> over to <table>
    372 **         close cursors
    373 **         foreach index on <table>
    374 **           open a write cursor on the <table> index
    375 **           open a read cursor on the corresponding <table2> index
    376 **           transfer all records from the read to the write cursors
    377 **           close cursors
    378 **         end foreach
    379 **
    380 ** The 3rd template is for when the second template does not apply
    381 ** and the SELECT clause does not read from <table> at any time.
    382 ** The generated code follows this template:
    383 **
    384 **         EOF <- 0
    385 **         X <- A
    386 **         goto B
    387 **      A: setup for the SELECT
    388 **         loop over the rows in the SELECT
    389 **           load values into registers R..R+n
    390 **           yield X
    391 **         end loop
    392 **         cleanup after the SELECT
    393 **         EOF <- 1
    394 **         yield X
    395 **         goto A
    396 **      B: open write cursor to <table> and its indices
    397 **      C: yield X
    398 **         if EOF goto D
    399 **         insert the select result into <table> from R..R+n
    400 **         goto C
    401 **      D: cleanup
    402 **
    403 ** The 4th template is used if the insert statement takes its
    404 ** values from a SELECT but the data is being inserted into a table
    405 ** that is also read as part of the SELECT.  In the third form,
    406 ** we have to use a intermediate table to store the results of
    407 ** the select.  The template is like this:
    408 **
    409 **         EOF <- 0
    410 **         X <- A
    411 **         goto B
    412 **      A: setup for the SELECT
    413 **         loop over the tables in the SELECT
    414 **           load value into register R..R+n
    415 **           yield X
    416 **         end loop
    417 **         cleanup after the SELECT
    418 **         EOF <- 1
    419 **         yield X
    420 **         halt-error
    421 **      B: open temp table
    422 **      L: yield X
    423 **         if EOF goto M
    424 **         insert row from R..R+n into temp table
    425 **         goto L
    426 **      M: open write cursor to <table> and its indices
    427 **         rewind temp table
    428 **      C: loop over rows of intermediate table
    429 **           transfer values form intermediate table into <table>
    430 **         end loop
    431 **      D: cleanup
    432 */
    433 void sqlite3Insert(
    434   Parse *pParse,        /* Parser context */
    435   SrcList *pTabList,    /* Name of table into which we are inserting */
    436   ExprList *pList,      /* List of values to be inserted */
    437   Select *pSelect,      /* A SELECT statement to use as the data source */
    438   IdList *pColumn,      /* Column names corresponding to IDLIST. */
    439   int onError           /* How to handle constraint errors */
    440 ){
    441   sqlite3 *db;          /* The main database structure */
    442   Table *pTab;          /* The table to insert into.  aka TABLE */
    443   char *zTab;           /* Name of the table into which we are inserting */
    444   const char *zDb;      /* Name of the database holding this table */
    445   int i, j, idx;        /* Loop counters */
    446   Vdbe *v;              /* Generate code into this virtual machine */
    447   Index *pIdx;          /* For looping over indices of the table */
    448   int nColumn;          /* Number of columns in the data */
    449   int nHidden = 0;      /* Number of hidden columns if TABLE is virtual */
    450   int baseCur = 0;      /* VDBE Cursor number for pTab */
    451   int keyColumn = -1;   /* Column that is the INTEGER PRIMARY KEY */
    452   int endOfLoop;        /* Label for the end of the insertion loop */
    453   int useTempTable = 0; /* Store SELECT results in intermediate table */
    454   int srcTab = 0;       /* Data comes from this temporary cursor if >=0 */
    455   int addrInsTop = 0;   /* Jump to label "D" */
    456   int addrCont = 0;     /* Top of insert loop. Label "C" in templates 3 and 4 */
    457   int addrSelect = 0;   /* Address of coroutine that implements the SELECT */
    458   SelectDest dest;      /* Destination for SELECT on rhs of INSERT */
    459   int iDb;              /* Index of database holding TABLE */
    460   Db *pDb;              /* The database containing table being inserted into */
    461   int appendFlag = 0;   /* True if the insert is likely to be an append */
    462 
    463   /* Register allocations */
    464   int regFromSelect = 0;/* Base register for data coming from SELECT */
    465   int regAutoinc = 0;   /* Register holding the AUTOINCREMENT counter */
    466   int regRowCount = 0;  /* Memory cell used for the row counter */
    467   int regIns;           /* Block of regs holding rowid+data being inserted */
    468   int regRowid;         /* registers holding insert rowid */
    469   int regData;          /* register holding first column to insert */
    470   int regEof = 0;       /* Register recording end of SELECT data */
    471   int *aRegIdx = 0;     /* One register allocated to each index */
    472 
    473 #ifndef SQLITE_OMIT_TRIGGER
    474   int isView;                 /* True if attempting to insert into a view */
    475   Trigger *pTrigger;          /* List of triggers on pTab, if required */
    476   int tmask;                  /* Mask of trigger times */
    477 #endif
    478 
    479   db = pParse->db;
    480   memset(&dest, 0, sizeof(dest));
    481   if( pParse->nErr || db->mallocFailed ){
    482     goto insert_cleanup;
    483   }
    484 
    485   /* Locate the table into which we will be inserting new information.
    486   */
    487   assert( pTabList->nSrc==1 );
    488   zTab = pTabList->a[0].zName;
    489   if( NEVER(zTab==0) ) goto insert_cleanup;
    490   pTab = sqlite3SrcListLookup(pParse, pTabList);
    491   if( pTab==0 ){
    492     goto insert_cleanup;
    493   }
    494   iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
    495   assert( iDb<db->nDb );
    496   pDb = &db->aDb[iDb];
    497   zDb = pDb->zName;
    498   if( sqlite3AuthCheck(pParse, SQLITE_INSERT, pTab->zName, 0, zDb) ){
    499     goto insert_cleanup;
    500   }
    501 
    502   /* Figure out if we have any triggers and if the table being
    503   ** inserted into is a view
    504   */
    505 #ifndef SQLITE_OMIT_TRIGGER
    506   pTrigger = sqlite3TriggersExist(pParse, pTab, TK_INSERT, 0, &tmask);
    507   isView = pTab->pSelect!=0;
    508 #else
    509 # define pTrigger 0
    510 # define tmask 0
    511 # define isView 0
    512 #endif
    513 #ifdef SQLITE_OMIT_VIEW
    514 # undef isView
    515 # define isView 0
    516 #endif
    517   assert( (pTrigger && tmask) || (pTrigger==0 && tmask==0) );
    518 
    519   /* If pTab is really a view, make sure it has been initialized.
    520   ** ViewGetColumnNames() is a no-op if pTab is not a view (or virtual
    521   ** module table).
    522   */
    523   if( sqlite3ViewGetColumnNames(pParse, pTab) ){
    524     goto insert_cleanup;
    525   }
    526 
    527   /* Ensure that:
    528   *  (a) the table is not read-only,
    529   *  (b) that if it is a view then ON INSERT triggers exist
    530   */
    531   if( sqlite3IsReadOnly(pParse, pTab, tmask) ){
    532     goto insert_cleanup;
    533   }
    534 
    535   /* Allocate a VDBE
    536   */
    537   v = sqlite3GetVdbe(pParse);
    538   if( v==0 ) goto insert_cleanup;
    539   if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
    540   sqlite3BeginWriteOperation(pParse, pSelect || pTrigger, iDb);
    541 
    542 #ifndef SQLITE_OMIT_XFER_OPT
    543   /* If the statement is of the form
    544   **
    545   **       INSERT INTO <table1> SELECT * FROM <table2>;
    546   **
    547   ** Then special optimizations can be applied that make the transfer
    548   ** very fast and which reduce fragmentation of indices.
    549   **
    550   ** This is the 2nd template.
    551   */
    552   if( pColumn==0 && xferOptimization(pParse, pTab, pSelect, onError, iDb) ){
    553     assert( !pTrigger );
    554     assert( pList==0 );
    555     goto insert_end;
    556   }
    557 #endif /* SQLITE_OMIT_XFER_OPT */
    558 
    559   /* If this is an AUTOINCREMENT table, look up the sequence number in the
    560   ** sqlite_sequence table and store it in memory cell regAutoinc.
    561   */
    562   regAutoinc = autoIncBegin(pParse, iDb, pTab);
    563 
    564   /* Figure out how many columns of data are supplied.  If the data
    565   ** is coming from a SELECT statement, then generate a co-routine that
    566   ** produces a single row of the SELECT on each invocation.  The
    567   ** co-routine is the common header to the 3rd and 4th templates.
    568   */
    569   if( pSelect ){
    570     /* Data is coming from a SELECT.  Generate code to implement that SELECT
    571     ** as a co-routine.  The code is common to both the 3rd and 4th
    572     ** templates:
    573     **
    574     **         EOF <- 0
    575     **         X <- A
    576     **         goto B
    577     **      A: setup for the SELECT
    578     **         loop over the tables in the SELECT
    579     **           load value into register R..R+n
    580     **           yield X
    581     **         end loop
    582     **         cleanup after the SELECT
    583     **         EOF <- 1
    584     **         yield X
    585     **         halt-error
    586     **
    587     ** On each invocation of the co-routine, it puts a single row of the
    588     ** SELECT result into registers dest.iMem...dest.iMem+dest.nMem-1.
    589     ** (These output registers are allocated by sqlite3Select().)  When
    590     ** the SELECT completes, it sets the EOF flag stored in regEof.
    591     */
    592     int rc, j1;
    593 
    594     regEof = ++pParse->nMem;
    595     sqlite3VdbeAddOp2(v, OP_Integer, 0, regEof);      /* EOF <- 0 */
    596     VdbeComment((v, "SELECT eof flag"));
    597     sqlite3SelectDestInit(&dest, SRT_Coroutine, ++pParse->nMem);
    598     addrSelect = sqlite3VdbeCurrentAddr(v)+2;
    599     sqlite3VdbeAddOp2(v, OP_Integer, addrSelect-1, dest.iParm);
    600     j1 = sqlite3VdbeAddOp2(v, OP_Goto, 0, 0);
    601     VdbeComment((v, "Jump over SELECT coroutine"));
    602 
    603     /* Resolve the expressions in the SELECT statement and execute it. */
    604     rc = sqlite3Select(pParse, pSelect, &dest);
    605     assert( pParse->nErr==0 || rc );
    606     if( rc || NEVER(pParse->nErr) || db->mallocFailed ){
    607       goto insert_cleanup;
    608     }
    609     sqlite3VdbeAddOp2(v, OP_Integer, 1, regEof);         /* EOF <- 1 */
    610     sqlite3VdbeAddOp1(v, OP_Yield, dest.iParm);   /* yield X */
    611     sqlite3VdbeAddOp2(v, OP_Halt, SQLITE_INTERNAL, OE_Abort);
    612     VdbeComment((v, "End of SELECT coroutine"));
    613     sqlite3VdbeJumpHere(v, j1);                          /* label B: */
    614 
    615     regFromSelect = dest.iMem;
    616     assert( pSelect->pEList );
    617     nColumn = pSelect->pEList->nExpr;
    618     assert( dest.nMem==nColumn );
    619 
    620     /* Set useTempTable to TRUE if the result of the SELECT statement
    621     ** should be written into a temporary table (template 4).  Set to
    622     ** FALSE if each* row of the SELECT can be written directly into
    623     ** the destination table (template 3).
    624     **
    625     ** A temp table must be used if the table being updated is also one
    626     ** of the tables being read by the SELECT statement.  Also use a
    627     ** temp table in the case of row triggers.
    628     */
    629     if( pTrigger || readsTable(pParse, addrSelect, iDb, pTab) ){
    630       useTempTable = 1;
    631     }
    632 
    633     if( useTempTable ){
    634       /* Invoke the coroutine to extract information from the SELECT
    635       ** and add it to a transient table srcTab.  The code generated
    636       ** here is from the 4th template:
    637       **
    638       **      B: open temp table
    639       **      L: yield X
    640       **         if EOF goto M
    641       **         insert row from R..R+n into temp table
    642       **         goto L
    643       **      M: ...
    644       */
    645       int regRec;          /* Register to hold packed record */
    646       int regTempRowid;    /* Register to hold temp table ROWID */
    647       int addrTop;         /* Label "L" */
    648       int addrIf;          /* Address of jump to M */
    649 
    650       srcTab = pParse->nTab++;
    651       regRec = sqlite3GetTempReg(pParse);
    652       regTempRowid = sqlite3GetTempReg(pParse);
    653       sqlite3VdbeAddOp2(v, OP_OpenEphemeral, srcTab, nColumn);
    654       addrTop = sqlite3VdbeAddOp1(v, OP_Yield, dest.iParm);
    655       addrIf = sqlite3VdbeAddOp1(v, OP_If, regEof);
    656       sqlite3VdbeAddOp3(v, OP_MakeRecord, regFromSelect, nColumn, regRec);
    657       sqlite3VdbeAddOp2(v, OP_NewRowid, srcTab, regTempRowid);
    658       sqlite3VdbeAddOp3(v, OP_Insert, srcTab, regRec, regTempRowid);
    659       sqlite3VdbeAddOp2(v, OP_Goto, 0, addrTop);
    660       sqlite3VdbeJumpHere(v, addrIf);
    661       sqlite3ReleaseTempReg(pParse, regRec);
    662       sqlite3ReleaseTempReg(pParse, regTempRowid);
    663     }
    664   }else{
    665     /* This is the case if the data for the INSERT is coming from a VALUES
    666     ** clause
    667     */
    668     NameContext sNC;
    669     memset(&sNC, 0, sizeof(sNC));
    670     sNC.pParse = pParse;
    671     srcTab = -1;
    672     assert( useTempTable==0 );
    673     nColumn = pList ? pList->nExpr : 0;
    674     for(i=0; i<nColumn; i++){
    675       if( sqlite3ResolveExprNames(&sNC, pList->a[i].pExpr) ){
    676         goto insert_cleanup;
    677       }
    678     }
    679   }
    680 
    681   /* Make sure the number of columns in the source data matches the number
    682   ** of columns to be inserted into the table.
    683   */
    684   if( IsVirtual(pTab) ){
    685     for(i=0; i<pTab->nCol; i++){
    686       nHidden += (IsHiddenColumn(&pTab->aCol[i]) ? 1 : 0);
    687     }
    688   }
    689   if( pColumn==0 && nColumn && nColumn!=(pTab->nCol-nHidden) ){
    690     sqlite3ErrorMsg(pParse,
    691        "table %S has %d columns but %d values were supplied",
    692        pTabList, 0, pTab->nCol-nHidden, nColumn);
    693     goto insert_cleanup;
    694   }
    695   if( pColumn!=0 && nColumn!=pColumn->nId ){
    696     sqlite3ErrorMsg(pParse, "%d values for %d columns", nColumn, pColumn->nId);
    697     goto insert_cleanup;
    698   }
    699 
    700   /* If the INSERT statement included an IDLIST term, then make sure
    701   ** all elements of the IDLIST really are columns of the table and
    702   ** remember the column indices.
    703   **
    704   ** If the table has an INTEGER PRIMARY KEY column and that column
    705   ** is named in the IDLIST, then record in the keyColumn variable
    706   ** the index into IDLIST of the primary key column.  keyColumn is
    707   ** the index of the primary key as it appears in IDLIST, not as
    708   ** is appears in the original table.  (The index of the primary
    709   ** key in the original table is pTab->iPKey.)
    710   */
    711   if( pColumn ){
    712     for(i=0; i<pColumn->nId; i++){
    713       pColumn->a[i].idx = -1;
    714     }
    715     for(i=0; i<pColumn->nId; i++){
    716       for(j=0; j<pTab->nCol; j++){
    717         if( sqlite3StrICmp(pColumn->a[i].zName, pTab->aCol[j].zName)==0 ){
    718           pColumn->a[i].idx = j;
    719           if( j==pTab->iPKey ){
    720             keyColumn = i;
    721           }
    722           break;
    723         }
    724       }
    725       if( j>=pTab->nCol ){
    726         if( sqlite3IsRowid(pColumn->a[i].zName) ){
    727           keyColumn = i;
    728         }else{
    729           sqlite3ErrorMsg(pParse, "table %S has no column named %s",
    730               pTabList, 0, pColumn->a[i].zName);
    731           pParse->checkSchema = 1;
    732           goto insert_cleanup;
    733         }
    734       }
    735     }
    736   }
    737 
    738   /* If there is no IDLIST term but the table has an integer primary
    739   ** key, the set the keyColumn variable to the primary key column index
    740   ** in the original table definition.
    741   */
    742   if( pColumn==0 && nColumn>0 ){
    743     keyColumn = pTab->iPKey;
    744   }
    745 
    746   /* Initialize the count of rows to be inserted
    747   */
    748   if( db->flags & SQLITE_CountRows ){
    749     regRowCount = ++pParse->nMem;
    750     sqlite3VdbeAddOp2(v, OP_Integer, 0, regRowCount);
    751   }
    752 
    753   /* If this is not a view, open the table and and all indices */
    754   if( !isView ){
    755     int nIdx;
    756 
    757     baseCur = pParse->nTab;
    758     nIdx = sqlite3OpenTableAndIndices(pParse, pTab, baseCur, OP_OpenWrite);
    759     aRegIdx = sqlite3DbMallocRaw(db, sizeof(int)*(nIdx+1));
    760     if( aRegIdx==0 ){
    761       goto insert_cleanup;
    762     }
    763     for(i=0; i<nIdx; i++){
    764       aRegIdx[i] = ++pParse->nMem;
    765     }
    766   }
    767 
    768   /* This is the top of the main insertion loop */
    769   if( useTempTable ){
    770     /* This block codes the top of loop only.  The complete loop is the
    771     ** following pseudocode (template 4):
    772     **
    773     **         rewind temp table
    774     **      C: loop over rows of intermediate table
    775     **           transfer values form intermediate table into <table>
    776     **         end loop
    777     **      D: ...
    778     */
    779     addrInsTop = sqlite3VdbeAddOp1(v, OP_Rewind, srcTab);
    780     addrCont = sqlite3VdbeCurrentAddr(v);
    781   }else if( pSelect ){
    782     /* This block codes the top of loop only.  The complete loop is the
    783     ** following pseudocode (template 3):
    784     **
    785     **      C: yield X
    786     **         if EOF goto D
    787     **         insert the select result into <table> from R..R+n
    788     **         goto C
    789     **      D: ...
    790     */
    791     addrCont = sqlite3VdbeAddOp1(v, OP_Yield, dest.iParm);
    792     addrInsTop = sqlite3VdbeAddOp1(v, OP_If, regEof);
    793   }
    794 
    795   /* Allocate registers for holding the rowid of the new row,
    796   ** the content of the new row, and the assemblied row record.
    797   */
    798   regRowid = regIns = pParse->nMem+1;
    799   pParse->nMem += pTab->nCol + 1;
    800   if( IsVirtual(pTab) ){
    801     regRowid++;
    802     pParse->nMem++;
    803   }
    804   regData = regRowid+1;
    805 
    806   /* Run the BEFORE and INSTEAD OF triggers, if there are any
    807   */
    808   endOfLoop = sqlite3VdbeMakeLabel(v);
    809   if( tmask & TRIGGER_BEFORE ){
    810     int regCols = sqlite3GetTempRange(pParse, pTab->nCol+1);
    811 
    812     /* build the NEW.* reference row.  Note that if there is an INTEGER
    813     ** PRIMARY KEY into which a NULL is being inserted, that NULL will be
    814     ** translated into a unique ID for the row.  But on a BEFORE trigger,
    815     ** we do not know what the unique ID will be (because the insert has
    816     ** not happened yet) so we substitute a rowid of -1
    817     */
    818     if( keyColumn<0 ){
    819       sqlite3VdbeAddOp2(v, OP_Integer, -1, regCols);
    820     }else{
    821       int j1;
    822       if( useTempTable ){
    823         sqlite3VdbeAddOp3(v, OP_Column, srcTab, keyColumn, regCols);
    824       }else{
    825         assert( pSelect==0 );  /* Otherwise useTempTable is true */
    826         sqlite3ExprCode(pParse, pList->a[keyColumn].pExpr, regCols);
    827       }
    828       j1 = sqlite3VdbeAddOp1(v, OP_NotNull, regCols);
    829       sqlite3VdbeAddOp2(v, OP_Integer, -1, regCols);
    830       sqlite3VdbeJumpHere(v, j1);
    831       sqlite3VdbeAddOp1(v, OP_MustBeInt, regCols);
    832     }
    833 
    834     /* Cannot have triggers on a virtual table. If it were possible,
    835     ** this block would have to account for hidden column.
    836     */
    837     assert( !IsVirtual(pTab) );
    838 
    839     /* Create the new column data
    840     */
    841     for(i=0; i<pTab->nCol; i++){
    842       if( pColumn==0 ){
    843         j = i;
    844       }else{
    845         for(j=0; j<pColumn->nId; j++){
    846           if( pColumn->a[j].idx==i ) break;
    847         }
    848       }
    849       if( (!useTempTable && !pList) || (pColumn && j>=pColumn->nId) ){
    850         sqlite3ExprCode(pParse, pTab->aCol[i].pDflt, regCols+i+1);
    851       }else if( useTempTable ){
    852         sqlite3VdbeAddOp3(v, OP_Column, srcTab, j, regCols+i+1);
    853       }else{
    854         assert( pSelect==0 ); /* Otherwise useTempTable is true */
    855         sqlite3ExprCodeAndCache(pParse, pList->a[j].pExpr, regCols+i+1);
    856       }
    857     }
    858 
    859     /* If this is an INSERT on a view with an INSTEAD OF INSERT trigger,
    860     ** do not attempt any conversions before assembling the record.
    861     ** If this is a real table, attempt conversions as required by the
    862     ** table column affinities.
    863     */
    864     if( !isView ){
    865       sqlite3VdbeAddOp2(v, OP_Affinity, regCols+1, pTab->nCol);
    866       sqlite3TableAffinityStr(v, pTab);
    867     }
    868 
    869     /* Fire BEFORE or INSTEAD OF triggers */
    870     sqlite3CodeRowTrigger(pParse, pTrigger, TK_INSERT, 0, TRIGGER_BEFORE,
    871         pTab, regCols-pTab->nCol-1, onError, endOfLoop);
    872 
    873     sqlite3ReleaseTempRange(pParse, regCols, pTab->nCol+1);
    874   }
    875 
    876   /* Push the record number for the new entry onto the stack.  The
    877   ** record number is a randomly generate integer created by NewRowid
    878   ** except when the table has an INTEGER PRIMARY KEY column, in which
    879   ** case the record number is the same as that column.
    880   */
    881   if( !isView ){
    882     if( IsVirtual(pTab) ){
    883       /* The row that the VUpdate opcode will delete: none */
    884       sqlite3VdbeAddOp2(v, OP_Null, 0, regIns);
    885     }
    886     if( keyColumn>=0 ){
    887       if( useTempTable ){
    888         sqlite3VdbeAddOp3(v, OP_Column, srcTab, keyColumn, regRowid);
    889       }else if( pSelect ){
    890         sqlite3VdbeAddOp2(v, OP_SCopy, regFromSelect+keyColumn, regRowid);
    891       }else{
    892         VdbeOp *pOp;
    893         sqlite3ExprCode(pParse, pList->a[keyColumn].pExpr, regRowid);
    894         pOp = sqlite3VdbeGetOp(v, -1);
    895         if( ALWAYS(pOp) && pOp->opcode==OP_Null && !IsVirtual(pTab) ){
    896           appendFlag = 1;
    897           pOp->opcode = OP_NewRowid;
    898           pOp->p1 = baseCur;
    899           pOp->p2 = regRowid;
    900           pOp->p3 = regAutoinc;
    901         }
    902       }
    903       /* If the PRIMARY KEY expression is NULL, then use OP_NewRowid
    904       ** to generate a unique primary key value.
    905       */
    906       if( !appendFlag ){
    907         int j1;
    908         if( !IsVirtual(pTab) ){
    909           j1 = sqlite3VdbeAddOp1(v, OP_NotNull, regRowid);
    910           sqlite3VdbeAddOp3(v, OP_NewRowid, baseCur, regRowid, regAutoinc);
    911           sqlite3VdbeJumpHere(v, j1);
    912         }else{
    913           j1 = sqlite3VdbeCurrentAddr(v);
    914           sqlite3VdbeAddOp2(v, OP_IsNull, regRowid, j1+2);
    915         }
    916         sqlite3VdbeAddOp1(v, OP_MustBeInt, regRowid);
    917       }
    918     }else if( IsVirtual(pTab) ){
    919       sqlite3VdbeAddOp2(v, OP_Null, 0, regRowid);
    920     }else{
    921       sqlite3VdbeAddOp3(v, OP_NewRowid, baseCur, regRowid, regAutoinc);
    922       appendFlag = 1;
    923     }
    924     autoIncStep(pParse, regAutoinc, regRowid);
    925 
    926     /* Push onto the stack, data for all columns of the new entry, beginning
    927     ** with the first column.
    928     */
    929     nHidden = 0;
    930     for(i=0; i<pTab->nCol; i++){
    931       int iRegStore = regRowid+1+i;
    932       if( i==pTab->iPKey ){
    933         /* The value of the INTEGER PRIMARY KEY column is always a NULL.
    934         ** Whenever this column is read, the record number will be substituted
    935         ** in its place.  So will fill this column with a NULL to avoid
    936         ** taking up data space with information that will never be used. */
    937         sqlite3VdbeAddOp2(v, OP_Null, 0, iRegStore);
    938         continue;
    939       }
    940       if( pColumn==0 ){
    941         if( IsHiddenColumn(&pTab->aCol[i]) ){
    942           assert( IsVirtual(pTab) );
    943           j = -1;
    944           nHidden++;
    945         }else{
    946           j = i - nHidden;
    947         }
    948       }else{
    949         for(j=0; j<pColumn->nId; j++){
    950           if( pColumn->a[j].idx==i ) break;
    951         }
    952       }
    953       if( j<0 || nColumn==0 || (pColumn && j>=pColumn->nId) ){
    954         sqlite3ExprCode(pParse, pTab->aCol[i].pDflt, iRegStore);
    955       }else if( useTempTable ){
    956         sqlite3VdbeAddOp3(v, OP_Column, srcTab, j, iRegStore);
    957       }else if( pSelect ){
    958         sqlite3VdbeAddOp2(v, OP_SCopy, regFromSelect+j, iRegStore);
    959       }else{
    960         sqlite3ExprCode(pParse, pList->a[j].pExpr, iRegStore);
    961       }
    962     }
    963 
    964     /* Generate code to check constraints and generate index keys and
    965     ** do the insertion.
    966     */
    967 #ifndef SQLITE_OMIT_VIRTUALTABLE
    968     if( IsVirtual(pTab) ){
    969       const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
    970       sqlite3VtabMakeWritable(pParse, pTab);
    971       sqlite3VdbeAddOp4(v, OP_VUpdate, 1, pTab->nCol+2, regIns, pVTab, P4_VTAB);
    972       sqlite3MayAbort(pParse);
    973     }else
    974 #endif
    975     {
    976       int isReplace;    /* Set to true if constraints may cause a replace */
    977       sqlite3GenerateConstraintChecks(pParse, pTab, baseCur, regIns, aRegIdx,
    978           keyColumn>=0, 0, onError, endOfLoop, &isReplace
    979       );
    980       sqlite3FkCheck(pParse, pTab, 0, regIns);
    981       sqlite3CompleteInsertion(
    982           pParse, pTab, baseCur, regIns, aRegIdx, 0, appendFlag, isReplace==0
    983       );
    984     }
    985   }
    986 
    987   /* Update the count of rows that are inserted
    988   */
    989   if( (db->flags & SQLITE_CountRows)!=0 ){
    990     sqlite3VdbeAddOp2(v, OP_AddImm, regRowCount, 1);
    991   }
    992 
    993   if( pTrigger ){
    994     /* Code AFTER triggers */
    995     sqlite3CodeRowTrigger(pParse, pTrigger, TK_INSERT, 0, TRIGGER_AFTER,
    996         pTab, regData-2-pTab->nCol, onError, endOfLoop);
    997   }
    998 
    999   /* The bottom of the main insertion loop, if the data source
   1000   ** is a SELECT statement.
   1001   */
   1002   sqlite3VdbeResolveLabel(v, endOfLoop);
   1003   if( useTempTable ){
   1004     sqlite3VdbeAddOp2(v, OP_Next, srcTab, addrCont);
   1005     sqlite3VdbeJumpHere(v, addrInsTop);
   1006     sqlite3VdbeAddOp1(v, OP_Close, srcTab);
   1007   }else if( pSelect ){
   1008     sqlite3VdbeAddOp2(v, OP_Goto, 0, addrCont);
   1009     sqlite3VdbeJumpHere(v, addrInsTop);
   1010   }
   1011 
   1012   if( !IsVirtual(pTab) && !isView ){
   1013     /* Close all tables opened */
   1014     sqlite3VdbeAddOp1(v, OP_Close, baseCur);
   1015     for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
   1016       sqlite3VdbeAddOp1(v, OP_Close, idx+baseCur);
   1017     }
   1018   }
   1019 
   1020 insert_end:
   1021   /* Update the sqlite_sequence table by storing the content of the
   1022   ** maximum rowid counter values recorded while inserting into
   1023   ** autoincrement tables.
   1024   */
   1025   if( pParse->nested==0 && pParse->pTriggerTab==0 ){
   1026     sqlite3AutoincrementEnd(pParse);
   1027   }
   1028 
   1029   /*
   1030   ** Return the number of rows inserted. If this routine is
   1031   ** generating code because of a call to sqlite3NestedParse(), do not
   1032   ** invoke the callback function.
   1033   */
   1034   if( (db->flags&SQLITE_CountRows) && !pParse->nested && !pParse->pTriggerTab ){
   1035     sqlite3VdbeAddOp2(v, OP_ResultRow, regRowCount, 1);
   1036     sqlite3VdbeSetNumCols(v, 1);
   1037     sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows inserted", SQLITE_STATIC);
   1038   }
   1039 
   1040 insert_cleanup:
   1041   sqlite3SrcListDelete(db, pTabList);
   1042   sqlite3ExprListDelete(db, pList);
   1043   sqlite3SelectDelete(db, pSelect);
   1044   sqlite3IdListDelete(db, pColumn);
   1045   sqlite3DbFree(db, aRegIdx);
   1046 }
   1047 
   1048 /* Make sure "isView" and other macros defined above are undefined. Otherwise
   1049 ** thely may interfere with compilation of other functions in this file
   1050 ** (or in another file, if this file becomes part of the amalgamation).  */
   1051 #ifdef isView
   1052  #undef isView
   1053 #endif
   1054 #ifdef pTrigger
   1055  #undef pTrigger
   1056 #endif
   1057 #ifdef tmask
   1058  #undef tmask
   1059 #endif
   1060 
   1061 
   1062 /*
   1063 ** Generate code to do constraint checks prior to an INSERT or an UPDATE.
   1064 **
   1065 ** The input is a range of consecutive registers as follows:
   1066 **
   1067 **    1.  The rowid of the row after the update.
   1068 **
   1069 **    2.  The data in the first column of the entry after the update.
   1070 **
   1071 **    i.  Data from middle columns...
   1072 **
   1073 **    N.  The data in the last column of the entry after the update.
   1074 **
   1075 ** The regRowid parameter is the index of the register containing (1).
   1076 **
   1077 ** If isUpdate is true and rowidChng is non-zero, then rowidChng contains
   1078 ** the address of a register containing the rowid before the update takes
   1079 ** place. isUpdate is true for UPDATEs and false for INSERTs. If isUpdate
   1080 ** is false, indicating an INSERT statement, then a non-zero rowidChng
   1081 ** indicates that the rowid was explicitly specified as part of the
   1082 ** INSERT statement. If rowidChng is false, it means that  the rowid is
   1083 ** computed automatically in an insert or that the rowid value is not
   1084 ** modified by an update.
   1085 **
   1086 ** The code generated by this routine store new index entries into
   1087 ** registers identified by aRegIdx[].  No index entry is created for
   1088 ** indices where aRegIdx[i]==0.  The order of indices in aRegIdx[] is
   1089 ** the same as the order of indices on the linked list of indices
   1090 ** attached to the table.
   1091 **
   1092 ** This routine also generates code to check constraints.  NOT NULL,
   1093 ** CHECK, and UNIQUE constraints are all checked.  If a constraint fails,
   1094 ** then the appropriate action is performed.  There are five possible
   1095 ** actions: ROLLBACK, ABORT, FAIL, REPLACE, and IGNORE.
   1096 **
   1097 **  Constraint type  Action       What Happens
   1098 **  ---------------  ----------   ----------------------------------------
   1099 **  any              ROLLBACK     The current transaction is rolled back and
   1100 **                                sqlite3_exec() returns immediately with a
   1101 **                                return code of SQLITE_CONSTRAINT.
   1102 **
   1103 **  any              ABORT        Back out changes from the current command
   1104 **                                only (do not do a complete rollback) then
   1105 **                                cause sqlite3_exec() to return immediately
   1106 **                                with SQLITE_CONSTRAINT.
   1107 **
   1108 **  any              FAIL         Sqlite_exec() returns immediately with a
   1109 **                                return code of SQLITE_CONSTRAINT.  The
   1110 **                                transaction is not rolled back and any
   1111 **                                prior changes are retained.
   1112 **
   1113 **  any              IGNORE       The record number and data is popped from
   1114 **                                the stack and there is an immediate jump
   1115 **                                to label ignoreDest.
   1116 **
   1117 **  NOT NULL         REPLACE      The NULL value is replace by the default
   1118 **                                value for that column.  If the default value
   1119 **                                is NULL, the action is the same as ABORT.
   1120 **
   1121 **  UNIQUE           REPLACE      The other row that conflicts with the row
   1122 **                                being inserted is removed.
   1123 **
   1124 **  CHECK            REPLACE      Illegal.  The results in an exception.
   1125 **
   1126 ** Which action to take is determined by the overrideError parameter.
   1127 ** Or if overrideError==OE_Default, then the pParse->onError parameter
   1128 ** is used.  Or if pParse->onError==OE_Default then the onError value
   1129 ** for the constraint is used.
   1130 **
   1131 ** The calling routine must open a read/write cursor for pTab with
   1132 ** cursor number "baseCur".  All indices of pTab must also have open
   1133 ** read/write cursors with cursor number baseCur+i for the i-th cursor.
   1134 ** Except, if there is no possibility of a REPLACE action then
   1135 ** cursors do not need to be open for indices where aRegIdx[i]==0.
   1136 */
   1137 void sqlite3GenerateConstraintChecks(
   1138   Parse *pParse,      /* The parser context */
   1139   Table *pTab,        /* the table into which we are inserting */
   1140   int baseCur,        /* Index of a read/write cursor pointing at pTab */
   1141   int regRowid,       /* Index of the range of input registers */
   1142   int *aRegIdx,       /* Register used by each index.  0 for unused indices */
   1143   int rowidChng,      /* True if the rowid might collide with existing entry */
   1144   int isUpdate,       /* True for UPDATE, False for INSERT */
   1145   int overrideError,  /* Override onError to this if not OE_Default */
   1146   int ignoreDest,     /* Jump to this label on an OE_Ignore resolution */
   1147   int *pbMayReplace   /* OUT: Set to true if constraint may cause a replace */
   1148 ){
   1149   int i;              /* loop counter */
   1150   Vdbe *v;            /* VDBE under constrution */
   1151   int nCol;           /* Number of columns */
   1152   int onError;        /* Conflict resolution strategy */
   1153   int j1;             /* Addresss of jump instruction */
   1154   int j2 = 0, j3;     /* Addresses of jump instructions */
   1155   int regData;        /* Register containing first data column */
   1156   int iCur;           /* Table cursor number */
   1157   Index *pIdx;         /* Pointer to one of the indices */
   1158   int seenReplace = 0; /* True if REPLACE is used to resolve INT PK conflict */
   1159   int regOldRowid = (rowidChng && isUpdate) ? rowidChng : regRowid;
   1160 
   1161   v = sqlite3GetVdbe(pParse);
   1162   assert( v!=0 );
   1163   assert( pTab->pSelect==0 );  /* This table is not a VIEW */
   1164   nCol = pTab->nCol;
   1165   regData = regRowid + 1;
   1166 
   1167   /* Test all NOT NULL constraints.
   1168   */
   1169   for(i=0; i<nCol; i++){
   1170     if( i==pTab->iPKey ){
   1171       continue;
   1172     }
   1173     onError = pTab->aCol[i].notNull;
   1174     if( onError==OE_None ) continue;
   1175     if( overrideError!=OE_Default ){
   1176       onError = overrideError;
   1177     }else if( onError==OE_Default ){
   1178       onError = OE_Abort;
   1179     }
   1180     if( onError==OE_Replace && pTab->aCol[i].pDflt==0 ){
   1181       onError = OE_Abort;
   1182     }
   1183     assert( onError==OE_Rollback || onError==OE_Abort || onError==OE_Fail
   1184         || onError==OE_Ignore || onError==OE_Replace );
   1185     switch( onError ){
   1186       case OE_Abort:
   1187         sqlite3MayAbort(pParse);
   1188       case OE_Rollback:
   1189       case OE_Fail: {
   1190         char *zMsg;
   1191         sqlite3VdbeAddOp3(v, OP_HaltIfNull,
   1192                                   SQLITE_CONSTRAINT, onError, regData+i);
   1193         zMsg = sqlite3MPrintf(pParse->db, "%s.%s may not be NULL",
   1194                               pTab->zName, pTab->aCol[i].zName);
   1195         sqlite3VdbeChangeP4(v, -1, zMsg, P4_DYNAMIC);
   1196         break;
   1197       }
   1198       case OE_Ignore: {
   1199         sqlite3VdbeAddOp2(v, OP_IsNull, regData+i, ignoreDest);
   1200         break;
   1201       }
   1202       default: {
   1203         assert( onError==OE_Replace );
   1204         j1 = sqlite3VdbeAddOp1(v, OP_NotNull, regData+i);
   1205         sqlite3ExprCode(pParse, pTab->aCol[i].pDflt, regData+i);
   1206         sqlite3VdbeJumpHere(v, j1);
   1207         break;
   1208       }
   1209     }
   1210   }
   1211 
   1212   /* Test all CHECK constraints
   1213   */
   1214 #ifndef SQLITE_OMIT_CHECK
   1215   if( pTab->pCheck && (pParse->db->flags & SQLITE_IgnoreChecks)==0 ){
   1216     int allOk = sqlite3VdbeMakeLabel(v);
   1217     pParse->ckBase = regData;
   1218     sqlite3ExprIfTrue(pParse, pTab->pCheck, allOk, SQLITE_JUMPIFNULL);
   1219     onError = overrideError!=OE_Default ? overrideError : OE_Abort;
   1220     if( onError==OE_Ignore ){
   1221       sqlite3VdbeAddOp2(v, OP_Goto, 0, ignoreDest);
   1222     }else{
   1223       if( onError==OE_Replace ) onError = OE_Abort; /* IMP: R-15569-63625 */
   1224       sqlite3HaltConstraint(pParse, onError, 0, 0);
   1225     }
   1226     sqlite3VdbeResolveLabel(v, allOk);
   1227   }
   1228 #endif /* !defined(SQLITE_OMIT_CHECK) */
   1229 
   1230   /* If we have an INTEGER PRIMARY KEY, make sure the primary key
   1231   ** of the new record does not previously exist.  Except, if this
   1232   ** is an UPDATE and the primary key is not changing, that is OK.
   1233   */
   1234   if( rowidChng ){
   1235     onError = pTab->keyConf;
   1236     if( overrideError!=OE_Default ){
   1237       onError = overrideError;
   1238     }else if( onError==OE_Default ){
   1239       onError = OE_Abort;
   1240     }
   1241 
   1242     if( isUpdate ){
   1243       j2 = sqlite3VdbeAddOp3(v, OP_Eq, regRowid, 0, rowidChng);
   1244     }
   1245     j3 = sqlite3VdbeAddOp3(v, OP_NotExists, baseCur, 0, regRowid);
   1246     switch( onError ){
   1247       default: {
   1248         onError = OE_Abort;
   1249         /* Fall thru into the next case */
   1250       }
   1251       case OE_Rollback:
   1252       case OE_Abort:
   1253       case OE_Fail: {
   1254         sqlite3HaltConstraint(
   1255           pParse, onError, "PRIMARY KEY must be unique", P4_STATIC);
   1256         break;
   1257       }
   1258       case OE_Replace: {
   1259         /* If there are DELETE triggers on this table and the
   1260         ** recursive-triggers flag is set, call GenerateRowDelete() to
   1261         ** remove the conflicting row from the the table. This will fire
   1262         ** the triggers and remove both the table and index b-tree entries.
   1263         **
   1264         ** Otherwise, if there are no triggers or the recursive-triggers
   1265         ** flag is not set, but the table has one or more indexes, call
   1266         ** GenerateRowIndexDelete(). This removes the index b-tree entries
   1267         ** only. The table b-tree entry will be replaced by the new entry
   1268         ** when it is inserted.
   1269         **
   1270         ** If either GenerateRowDelete() or GenerateRowIndexDelete() is called,
   1271         ** also invoke MultiWrite() to indicate that this VDBE may require
   1272         ** statement rollback (if the statement is aborted after the delete
   1273         ** takes place). Earlier versions called sqlite3MultiWrite() regardless,
   1274         ** but being more selective here allows statements like:
   1275         **
   1276         **   REPLACE INTO t(rowid) VALUES($newrowid)
   1277         **
   1278         ** to run without a statement journal if there are no indexes on the
   1279         ** table.
   1280         */
   1281         Trigger *pTrigger = 0;
   1282         if( pParse->db->flags&SQLITE_RecTriggers ){
   1283           pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
   1284         }
   1285         if( pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0) ){
   1286           sqlite3MultiWrite(pParse);
   1287           sqlite3GenerateRowDelete(
   1288               pParse, pTab, baseCur, regRowid, 0, pTrigger, OE_Replace
   1289           );
   1290         }else if( pTab->pIndex ){
   1291           sqlite3MultiWrite(pParse);
   1292           sqlite3GenerateRowIndexDelete(pParse, pTab, baseCur, 0);
   1293         }
   1294         seenReplace = 1;
   1295         break;
   1296       }
   1297       case OE_Ignore: {
   1298         assert( seenReplace==0 );
   1299         sqlite3VdbeAddOp2(v, OP_Goto, 0, ignoreDest);
   1300         break;
   1301       }
   1302     }
   1303     sqlite3VdbeJumpHere(v, j3);
   1304     if( isUpdate ){
   1305       sqlite3VdbeJumpHere(v, j2);
   1306     }
   1307   }
   1308 
   1309   /* Test all UNIQUE constraints by creating entries for each UNIQUE
   1310   ** index and making sure that duplicate entries do not already exist.
   1311   ** Add the new records to the indices as we go.
   1312   */
   1313   for(iCur=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, iCur++){
   1314     int regIdx;
   1315     int regR;
   1316 
   1317     if( aRegIdx[iCur]==0 ) continue;  /* Skip unused indices */
   1318 
   1319     /* Create a key for accessing the index entry */
   1320     regIdx = sqlite3GetTempRange(pParse, pIdx->nColumn+1);
   1321     for(i=0; i<pIdx->nColumn; i++){
   1322       int idx = pIdx->aiColumn[i];
   1323       if( idx==pTab->iPKey ){
   1324         sqlite3VdbeAddOp2(v, OP_SCopy, regRowid, regIdx+i);
   1325       }else{
   1326         sqlite3VdbeAddOp2(v, OP_SCopy, regData+idx, regIdx+i);
   1327       }
   1328     }
   1329     sqlite3VdbeAddOp2(v, OP_SCopy, regRowid, regIdx+i);
   1330     sqlite3VdbeAddOp3(v, OP_MakeRecord, regIdx, pIdx->nColumn+1, aRegIdx[iCur]);
   1331     sqlite3VdbeChangeP4(v, -1, sqlite3IndexAffinityStr(v, pIdx), P4_TRANSIENT);
   1332     sqlite3ExprCacheAffinityChange(pParse, regIdx, pIdx->nColumn+1);
   1333 
   1334     /* Find out what action to take in case there is an indexing conflict */
   1335     onError = pIdx->onError;
   1336     if( onError==OE_None ){
   1337       sqlite3ReleaseTempRange(pParse, regIdx, pIdx->nColumn+1);
   1338       continue;  /* pIdx is not a UNIQUE index */
   1339     }
   1340     if( overrideError!=OE_Default ){
   1341       onError = overrideError;
   1342     }else if( onError==OE_Default ){
   1343       onError = OE_Abort;
   1344     }
   1345     if( seenReplace ){
   1346       if( onError==OE_Ignore ) onError = OE_Replace;
   1347       else if( onError==OE_Fail ) onError = OE_Abort;
   1348     }
   1349 
   1350     /* Check to see if the new index entry will be unique */
   1351     regR = sqlite3GetTempReg(pParse);
   1352     sqlite3VdbeAddOp2(v, OP_SCopy, regOldRowid, regR);
   1353     j3 = sqlite3VdbeAddOp4(v, OP_IsUnique, baseCur+iCur+1, 0,
   1354                            regR, SQLITE_INT_TO_PTR(regIdx),
   1355                            P4_INT32);
   1356     sqlite3ReleaseTempRange(pParse, regIdx, pIdx->nColumn+1);
   1357 
   1358     /* Generate code that executes if the new index entry is not unique */
   1359     assert( onError==OE_Rollback || onError==OE_Abort || onError==OE_Fail
   1360         || onError==OE_Ignore || onError==OE_Replace );
   1361     switch( onError ){
   1362       case OE_Rollback:
   1363       case OE_Abort:
   1364       case OE_Fail: {
   1365         int j;
   1366         StrAccum errMsg;
   1367         const char *zSep;
   1368         char *zErr;
   1369 
   1370         sqlite3StrAccumInit(&errMsg, 0, 0, 200);
   1371         errMsg.db = pParse->db;
   1372         zSep = pIdx->nColumn>1 ? "columns " : "column ";
   1373         for(j=0; j<pIdx->nColumn; j++){
   1374           char *zCol = pTab->aCol[pIdx->aiColumn[j]].zName;
   1375           sqlite3StrAccumAppend(&errMsg, zSep, -1);
   1376           zSep = ", ";
   1377           sqlite3StrAccumAppend(&errMsg, zCol, -1);
   1378         }
   1379         sqlite3StrAccumAppend(&errMsg,
   1380             pIdx->nColumn>1 ? " are not unique" : " is not unique", -1);
   1381         zErr = sqlite3StrAccumFinish(&errMsg);
   1382         sqlite3HaltConstraint(pParse, onError, zErr, 0);
   1383         sqlite3DbFree(errMsg.db, zErr);
   1384         break;
   1385       }
   1386       case OE_Ignore: {
   1387         assert( seenReplace==0 );
   1388         sqlite3VdbeAddOp2(v, OP_Goto, 0, ignoreDest);
   1389         break;
   1390       }
   1391       default: {
   1392         Trigger *pTrigger = 0;
   1393         assert( onError==OE_Replace );
   1394         sqlite3MultiWrite(pParse);
   1395         if( pParse->db->flags&SQLITE_RecTriggers ){
   1396           pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
   1397         }
   1398         sqlite3GenerateRowDelete(
   1399             pParse, pTab, baseCur, regR, 0, pTrigger, OE_Replace
   1400         );
   1401         seenReplace = 1;
   1402         break;
   1403       }
   1404     }
   1405     sqlite3VdbeJumpHere(v, j3);
   1406     sqlite3ReleaseTempReg(pParse, regR);
   1407   }
   1408 
   1409   if( pbMayReplace ){
   1410     *pbMayReplace = seenReplace;
   1411   }
   1412 }
   1413 
   1414 /*
   1415 ** This routine generates code to finish the INSERT or UPDATE operation
   1416 ** that was started by a prior call to sqlite3GenerateConstraintChecks.
   1417 ** A consecutive range of registers starting at regRowid contains the
   1418 ** rowid and the content to be inserted.
   1419 **
   1420 ** The arguments to this routine should be the same as the first six
   1421 ** arguments to sqlite3GenerateConstraintChecks.
   1422 */
   1423 void sqlite3CompleteInsertion(
   1424   Parse *pParse,      /* The parser context */
   1425   Table *pTab,        /* the table into which we are inserting */
   1426   int baseCur,        /* Index of a read/write cursor pointing at pTab */
   1427   int regRowid,       /* Range of content */
   1428   int *aRegIdx,       /* Register used by each index.  0 for unused indices */
   1429   int isUpdate,       /* True for UPDATE, False for INSERT */
   1430   int appendBias,     /* True if this is likely to be an append */
   1431   int useSeekResult   /* True to set the USESEEKRESULT flag on OP_[Idx]Insert */
   1432 ){
   1433   int i;
   1434   Vdbe *v;
   1435   int nIdx;
   1436   Index *pIdx;
   1437   u8 pik_flags;
   1438   int regData;
   1439   int regRec;
   1440 
   1441   v = sqlite3GetVdbe(pParse);
   1442   assert( v!=0 );
   1443   assert( pTab->pSelect==0 );  /* This table is not a VIEW */
   1444   for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){}
   1445   for(i=nIdx-1; i>=0; i--){
   1446     if( aRegIdx[i]==0 ) continue;
   1447     sqlite3VdbeAddOp2(v, OP_IdxInsert, baseCur+i+1, aRegIdx[i]);
   1448     if( useSeekResult ){
   1449       sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
   1450     }
   1451   }
   1452   regData = regRowid + 1;
   1453   regRec = sqlite3GetTempReg(pParse);
   1454   sqlite3VdbeAddOp3(v, OP_MakeRecord, regData, pTab->nCol, regRec);
   1455   sqlite3TableAffinityStr(v, pTab);
   1456   sqlite3ExprCacheAffinityChange(pParse, regData, pTab->nCol);
   1457   if( pParse->nested ){
   1458     pik_flags = 0;
   1459   }else{
   1460     pik_flags = OPFLAG_NCHANGE;
   1461     pik_flags |= (isUpdate?OPFLAG_ISUPDATE:OPFLAG_LASTROWID);
   1462   }
   1463   if( appendBias ){
   1464     pik_flags |= OPFLAG_APPEND;
   1465   }
   1466   if( useSeekResult ){
   1467     pik_flags |= OPFLAG_USESEEKRESULT;
   1468   }
   1469   sqlite3VdbeAddOp3(v, OP_Insert, baseCur, regRec, regRowid);
   1470   if( !pParse->nested ){
   1471     sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_TRANSIENT);
   1472   }
   1473   sqlite3VdbeChangeP5(v, pik_flags);
   1474 }
   1475 
   1476 /*
   1477 ** Generate code that will open cursors for a table and for all
   1478 ** indices of that table.  The "baseCur" parameter is the cursor number used
   1479 ** for the table.  Indices are opened on subsequent cursors.
   1480 **
   1481 ** Return the number of indices on the table.
   1482 */
   1483 int sqlite3OpenTableAndIndices(
   1484   Parse *pParse,   /* Parsing context */
   1485   Table *pTab,     /* Table to be opened */
   1486   int baseCur,     /* Cursor number assigned to the table */
   1487   int op           /* OP_OpenRead or OP_OpenWrite */
   1488 ){
   1489   int i;
   1490   int iDb;
   1491   Index *pIdx;
   1492   Vdbe *v;
   1493 
   1494   if( IsVirtual(pTab) ) return 0;
   1495   iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
   1496   v = sqlite3GetVdbe(pParse);
   1497   assert( v!=0 );
   1498   sqlite3OpenTable(pParse, baseCur, iDb, pTab, op);
   1499   for(i=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
   1500     KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
   1501     assert( pIdx->pSchema==pTab->pSchema );
   1502     sqlite3VdbeAddOp4(v, op, i+baseCur, pIdx->tnum, iDb,
   1503                       (char*)pKey, P4_KEYINFO_HANDOFF);
   1504     VdbeComment((v, "%s", pIdx->zName));
   1505   }
   1506   if( pParse->nTab<baseCur+i ){
   1507     pParse->nTab = baseCur+i;
   1508   }
   1509   return i-1;
   1510 }
   1511 
   1512 
   1513 #ifdef SQLITE_TEST
   1514 /*
   1515 ** The following global variable is incremented whenever the
   1516 ** transfer optimization is used.  This is used for testing
   1517 ** purposes only - to make sure the transfer optimization really
   1518 ** is happening when it is suppose to.
   1519 */
   1520 int sqlite3_xferopt_count;
   1521 #endif /* SQLITE_TEST */
   1522 
   1523 
   1524 #ifndef SQLITE_OMIT_XFER_OPT
   1525 /*
   1526 ** Check to collation names to see if they are compatible.
   1527 */
   1528 static int xferCompatibleCollation(const char *z1, const char *z2){
   1529   if( z1==0 ){
   1530     return z2==0;
   1531   }
   1532   if( z2==0 ){
   1533     return 0;
   1534   }
   1535   return sqlite3StrICmp(z1, z2)==0;
   1536 }
   1537 
   1538 
   1539 /*
   1540 ** Check to see if index pSrc is compatible as a source of data
   1541 ** for index pDest in an insert transfer optimization.  The rules
   1542 ** for a compatible index:
   1543 **
   1544 **    *   The index is over the same set of columns
   1545 **    *   The same DESC and ASC markings occurs on all columns
   1546 **    *   The same onError processing (OE_Abort, OE_Ignore, etc)
   1547 **    *   The same collating sequence on each column
   1548 */
   1549 static int xferCompatibleIndex(Index *pDest, Index *pSrc){
   1550   int i;
   1551   assert( pDest && pSrc );
   1552   assert( pDest->pTable!=pSrc->pTable );
   1553   if( pDest->nColumn!=pSrc->nColumn ){
   1554     return 0;   /* Different number of columns */
   1555   }
   1556   if( pDest->onError!=pSrc->onError ){
   1557     return 0;   /* Different conflict resolution strategies */
   1558   }
   1559   for(i=0; i<pSrc->nColumn; i++){
   1560     if( pSrc->aiColumn[i]!=pDest->aiColumn[i] ){
   1561       return 0;   /* Different columns indexed */
   1562     }
   1563     if( pSrc->aSortOrder[i]!=pDest->aSortOrder[i] ){
   1564       return 0;   /* Different sort orders */
   1565     }
   1566     if( !xferCompatibleCollation(pSrc->azColl[i],pDest->azColl[i]) ){
   1567       return 0;   /* Different collating sequences */
   1568     }
   1569   }
   1570 
   1571   /* If no test above fails then the indices must be compatible */
   1572   return 1;
   1573 }
   1574 
   1575 /*
   1576 ** Attempt the transfer optimization on INSERTs of the form
   1577 **
   1578 **     INSERT INTO tab1 SELECT * FROM tab2;
   1579 **
   1580 ** This optimization is only attempted if
   1581 **
   1582 **    (1)  tab1 and tab2 have identical schemas including all the
   1583 **         same indices and constraints
   1584 **
   1585 **    (2)  tab1 and tab2 are different tables
   1586 **
   1587 **    (3)  There must be no triggers on tab1
   1588 **
   1589 **    (4)  The result set of the SELECT statement is "*"
   1590 **
   1591 **    (5)  The SELECT statement has no WHERE, HAVING, ORDER BY, GROUP BY,
   1592 **         or LIMIT clause.
   1593 **
   1594 **    (6)  The SELECT statement is a simple (not a compound) select that
   1595 **         contains only tab2 in its FROM clause
   1596 **
   1597 ** This method for implementing the INSERT transfers raw records from
   1598 ** tab2 over to tab1.  The columns are not decoded.  Raw records from
   1599 ** the indices of tab2 are transfered to tab1 as well.  In so doing,
   1600 ** the resulting tab1 has much less fragmentation.
   1601 **
   1602 ** This routine returns TRUE if the optimization is attempted.  If any
   1603 ** of the conditions above fail so that the optimization should not
   1604 ** be attempted, then this routine returns FALSE.
   1605 */
   1606 static int xferOptimization(
   1607   Parse *pParse,        /* Parser context */
   1608   Table *pDest,         /* The table we are inserting into */
   1609   Select *pSelect,      /* A SELECT statement to use as the data source */
   1610   int onError,          /* How to handle constraint errors */
   1611   int iDbDest           /* The database of pDest */
   1612 ){
   1613   ExprList *pEList;                /* The result set of the SELECT */
   1614   Table *pSrc;                     /* The table in the FROM clause of SELECT */
   1615   Index *pSrcIdx, *pDestIdx;       /* Source and destination indices */
   1616   struct SrcList_item *pItem;      /* An element of pSelect->pSrc */
   1617   int i;                           /* Loop counter */
   1618   int iDbSrc;                      /* The database of pSrc */
   1619   int iSrc, iDest;                 /* Cursors from source and destination */
   1620   int addr1, addr2;                /* Loop addresses */
   1621   int emptyDestTest;               /* Address of test for empty pDest */
   1622   int emptySrcTest;                /* Address of test for empty pSrc */
   1623   Vdbe *v;                         /* The VDBE we are building */
   1624   KeyInfo *pKey;                   /* Key information for an index */
   1625   int regAutoinc;                  /* Memory register used by AUTOINC */
   1626   int destHasUniqueIdx = 0;        /* True if pDest has a UNIQUE index */
   1627   int regData, regRowid;           /* Registers holding data and rowid */
   1628 
   1629   if( pSelect==0 ){
   1630     return 0;   /* Must be of the form  INSERT INTO ... SELECT ... */
   1631   }
   1632   if( sqlite3TriggerList(pParse, pDest) ){
   1633     return 0;   /* tab1 must not have triggers */
   1634   }
   1635 #ifndef SQLITE_OMIT_VIRTUALTABLE
   1636   if( pDest->tabFlags & TF_Virtual ){
   1637     return 0;   /* tab1 must not be a virtual table */
   1638   }
   1639 #endif
   1640   if( onError==OE_Default ){
   1641     onError = OE_Abort;
   1642   }
   1643   if( onError!=OE_Abort && onError!=OE_Rollback ){
   1644     return 0;   /* Cannot do OR REPLACE or OR IGNORE or OR FAIL */
   1645   }
   1646   assert(pSelect->pSrc);   /* allocated even if there is no FROM clause */
   1647   if( pSelect->pSrc->nSrc!=1 ){
   1648     return 0;   /* FROM clause must have exactly one term */
   1649   }
   1650   if( pSelect->pSrc->a[0].pSelect ){
   1651     return 0;   /* FROM clause cannot contain a subquery */
   1652   }
   1653   if( pSelect->pWhere ){
   1654     return 0;   /* SELECT may not have a WHERE clause */
   1655   }
   1656   if( pSelect->pOrderBy ){
   1657     return 0;   /* SELECT may not have an ORDER BY clause */
   1658   }
   1659   /* Do not need to test for a HAVING clause.  If HAVING is present but
   1660   ** there is no ORDER BY, we will get an error. */
   1661   if( pSelect->pGroupBy ){
   1662     return 0;   /* SELECT may not have a GROUP BY clause */
   1663   }
   1664   if( pSelect->pLimit ){
   1665     return 0;   /* SELECT may not have a LIMIT clause */
   1666   }
   1667   assert( pSelect->pOffset==0 );  /* Must be so if pLimit==0 */
   1668   if( pSelect->pPrior ){
   1669     return 0;   /* SELECT may not be a compound query */
   1670   }
   1671   if( pSelect->selFlags & SF_Distinct ){
   1672     return 0;   /* SELECT may not be DISTINCT */
   1673   }
   1674   pEList = pSelect->pEList;
   1675   assert( pEList!=0 );
   1676   if( pEList->nExpr!=1 ){
   1677     return 0;   /* The result set must have exactly one column */
   1678   }
   1679   assert( pEList->a[0].pExpr );
   1680   if( pEList->a[0].pExpr->op!=TK_ALL ){
   1681     return 0;   /* The result set must be the special operator "*" */
   1682   }
   1683 
   1684   /* At this point we have established that the statement is of the
   1685   ** correct syntactic form to participate in this optimization.  Now
   1686   ** we have to check the semantics.
   1687   */
   1688   pItem = pSelect->pSrc->a;
   1689   pSrc = sqlite3LocateTable(pParse, 0, pItem->zName, pItem->zDatabase);
   1690   if( pSrc==0 ){
   1691     return 0;   /* FROM clause does not contain a real table */
   1692   }
   1693   if( pSrc==pDest ){
   1694     return 0;   /* tab1 and tab2 may not be the same table */
   1695   }
   1696 #ifndef SQLITE_OMIT_VIRTUALTABLE
   1697   if( pSrc->tabFlags & TF_Virtual ){
   1698     return 0;   /* tab2 must not be a virtual table */
   1699   }
   1700 #endif
   1701   if( pSrc->pSelect ){
   1702     return 0;   /* tab2 may not be a view */
   1703   }
   1704   if( pDest->nCol!=pSrc->nCol ){
   1705     return 0;   /* Number of columns must be the same in tab1 and tab2 */
   1706   }
   1707   if( pDest->iPKey!=pSrc->iPKey ){
   1708     return 0;   /* Both tables must have the same INTEGER PRIMARY KEY */
   1709   }
   1710   for(i=0; i<pDest->nCol; i++){
   1711     if( pDest->aCol[i].affinity!=pSrc->aCol[i].affinity ){
   1712       return 0;    /* Affinity must be the same on all columns */
   1713     }
   1714     if( !xferCompatibleCollation(pDest->aCol[i].zColl, pSrc->aCol[i].zColl) ){
   1715       return 0;    /* Collating sequence must be the same on all columns */
   1716     }
   1717     if( pDest->aCol[i].notNull && !pSrc->aCol[i].notNull ){
   1718       return 0;    /* tab2 must be NOT NULL if tab1 is */
   1719     }
   1720   }
   1721   for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
   1722     if( pDestIdx->onError!=OE_None ){
   1723       destHasUniqueIdx = 1;
   1724     }
   1725     for(pSrcIdx=pSrc->pIndex; pSrcIdx; pSrcIdx=pSrcIdx->pNext){
   1726       if( xferCompatibleIndex(pDestIdx, pSrcIdx) ) break;
   1727     }
   1728     if( pSrcIdx==0 ){
   1729       return 0;    /* pDestIdx has no corresponding index in pSrc */
   1730     }
   1731   }
   1732 #ifndef SQLITE_OMIT_CHECK
   1733   if( pDest->pCheck && sqlite3ExprCompare(pSrc->pCheck, pDest->pCheck) ){
   1734     return 0;   /* Tables have different CHECK constraints.  Ticket #2252 */
   1735   }
   1736 #endif
   1737 
   1738   /* If we get this far, it means either:
   1739   **
   1740   **    *   We can always do the transfer if the table contains an
   1741   **        an integer primary key
   1742   **
   1743   **    *   We can conditionally do the transfer if the destination
   1744   **        table is empty.
   1745   */
   1746 #ifdef SQLITE_TEST
   1747   sqlite3_xferopt_count++;
   1748 #endif
   1749   iDbSrc = sqlite3SchemaToIndex(pParse->db, pSrc->pSchema);
   1750   v = sqlite3GetVdbe(pParse);
   1751   sqlite3CodeVerifySchema(pParse, iDbSrc);
   1752   iSrc = pParse->nTab++;
   1753   iDest = pParse->nTab++;
   1754   regAutoinc = autoIncBegin(pParse, iDbDest, pDest);
   1755   sqlite3OpenTable(pParse, iDest, iDbDest, pDest, OP_OpenWrite);
   1756   if( (pDest->iPKey<0 && pDest->pIndex!=0) || destHasUniqueIdx ){
   1757     /* If tables do not have an INTEGER PRIMARY KEY and there
   1758     ** are indices to be copied and the destination is not empty,
   1759     ** we have to disallow the transfer optimization because the
   1760     ** the rowids might change which will mess up indexing.
   1761     **
   1762     ** Or if the destination has a UNIQUE index and is not empty,
   1763     ** we also disallow the transfer optimization because we cannot
   1764     ** insure that all entries in the union of DEST and SRC will be
   1765     ** unique.
   1766     */
   1767     addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iDest, 0);
   1768     emptyDestTest = sqlite3VdbeAddOp2(v, OP_Goto, 0, 0);
   1769     sqlite3VdbeJumpHere(v, addr1);
   1770   }else{
   1771     emptyDestTest = 0;
   1772   }
   1773   sqlite3OpenTable(pParse, iSrc, iDbSrc, pSrc, OP_OpenRead);
   1774   emptySrcTest = sqlite3VdbeAddOp2(v, OP_Rewind, iSrc, 0);
   1775   regData = sqlite3GetTempReg(pParse);
   1776   regRowid = sqlite3GetTempReg(pParse);
   1777   if( pDest->iPKey>=0 ){
   1778     addr1 = sqlite3VdbeAddOp2(v, OP_Rowid, iSrc, regRowid);
   1779     addr2 = sqlite3VdbeAddOp3(v, OP_NotExists, iDest, 0, regRowid);
   1780     sqlite3HaltConstraint(
   1781         pParse, onError, "PRIMARY KEY must be unique", P4_STATIC);
   1782     sqlite3VdbeJumpHere(v, addr2);
   1783     autoIncStep(pParse, regAutoinc, regRowid);
   1784   }else if( pDest->pIndex==0 ){
   1785     addr1 = sqlite3VdbeAddOp2(v, OP_NewRowid, iDest, regRowid);
   1786   }else{
   1787     addr1 = sqlite3VdbeAddOp2(v, OP_Rowid, iSrc, regRowid);
   1788     assert( (pDest->tabFlags & TF_Autoincrement)==0 );
   1789   }
   1790   sqlite3VdbeAddOp2(v, OP_RowData, iSrc, regData);
   1791   sqlite3VdbeAddOp3(v, OP_Insert, iDest, regData, regRowid);
   1792   sqlite3VdbeChangeP5(v, OPFLAG_NCHANGE|OPFLAG_LASTROWID|OPFLAG_APPEND);
   1793   sqlite3VdbeChangeP4(v, -1, pDest->zName, 0);
   1794   sqlite3VdbeAddOp2(v, OP_Next, iSrc, addr1);
   1795   for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
   1796     for(pSrcIdx=pSrc->pIndex; ALWAYS(pSrcIdx); pSrcIdx=pSrcIdx->pNext){
   1797       if( xferCompatibleIndex(pDestIdx, pSrcIdx) ) break;
   1798     }
   1799     assert( pSrcIdx );
   1800     sqlite3VdbeAddOp2(v, OP_Close, iSrc, 0);
   1801     sqlite3VdbeAddOp2(v, OP_Close, iDest, 0);
   1802     pKey = sqlite3IndexKeyinfo(pParse, pSrcIdx);
   1803     sqlite3VdbeAddOp4(v, OP_OpenRead, iSrc, pSrcIdx->tnum, iDbSrc,
   1804                       (char*)pKey, P4_KEYINFO_HANDOFF);
   1805     VdbeComment((v, "%s", pSrcIdx->zName));
   1806     pKey = sqlite3IndexKeyinfo(pParse, pDestIdx);
   1807     sqlite3VdbeAddOp4(v, OP_OpenWrite, iDest, pDestIdx->tnum, iDbDest,
   1808                       (char*)pKey, P4_KEYINFO_HANDOFF);
   1809     VdbeComment((v, "%s", pDestIdx->zName));
   1810     addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iSrc, 0);
   1811     sqlite3VdbeAddOp2(v, OP_RowKey, iSrc, regData);
   1812     sqlite3VdbeAddOp3(v, OP_IdxInsert, iDest, regData, 1);
   1813     sqlite3VdbeAddOp2(v, OP_Next, iSrc, addr1+1);
   1814     sqlite3VdbeJumpHere(v, addr1);
   1815   }
   1816   sqlite3VdbeJumpHere(v, emptySrcTest);
   1817   sqlite3ReleaseTempReg(pParse, regRowid);
   1818   sqlite3ReleaseTempReg(pParse, regData);
   1819   sqlite3VdbeAddOp2(v, OP_Close, iSrc, 0);
   1820   sqlite3VdbeAddOp2(v, OP_Close, iDest, 0);
   1821   if( emptyDestTest ){
   1822     sqlite3VdbeAddOp2(v, OP_Halt, SQLITE_OK, 0);
   1823     sqlite3VdbeJumpHere(v, emptyDestTest);
   1824     sqlite3VdbeAddOp2(v, OP_Close, iDest, 0);
   1825     return 0;
   1826   }else{
   1827     return 1;
   1828   }
   1829 }
   1830 #endif /* SQLITE_OMIT_XFER_OPT */
   1831