SQLite

**    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
** to handle INSERT statements in SQLite.
**
** $Id: insert.c,v 1.173 2007/02/13 15:01:11 drh Exp $
*/
#include "sqliteInt.h"

/*
** Set P3 of the most recently inserted opcode to a column affinity
** string for index pIdx. A column affinity string has one character
** for each column in the table, according to the affinity of the column:

    }else{
      if( pItem->pTab->pSchema==pSchema && pItem->pTab->tnum==iTab ) return 1;
    }
  }
  return 0;
}

#ifndef SQLITE_OMIT_AUTOINCREMENT
/*
** Write out code to initialize the autoincrement logic.  This code
** looks up the current autoincrement value in the sqlite_sequence
** table and stores that value in a memory cell.  Code generated by
** autoIncStep() will keep that memory cell holding the largest
** rowid value.  Code generated by autoIncEnd() will write the new
** largest value of the counter back into the sqlite_sequence table.
**
** This routine returns the index of the mem[] cell that contains
** the maximum rowid counter.
**
** Two memory cells are allocated.  The next memory cell after the
** one returned holds the rowid in sqlite_sequence where we will
** write back the revised maximum rowid.
*/
static int autoIncBegin(
  Parse *pParse,      /* Parsing context */
  int iDb,            /* Index of the database holding pTab */
  Table *pTab         /* The table we are writing to */
){
  int memId = 0;
  if( pTab->autoInc ){
    Vdbe *v = pParse->pVdbe;
    Db *pDb = &pParse->db->aDb[iDb];
    int iCur = pParse->nTab;
    int addr;
    assert( v );
    addr = sqlite3VdbeCurrentAddr(v);
    memId = pParse->nMem+1;
    pParse->nMem += 2;
    sqlite3OpenTable(pParse, iCur, iDb, pDb->pSchema->pSeqTab, OP_OpenRead);
    sqlite3VdbeAddOp(v, OP_Rewind, iCur, addr+13);
    sqlite3VdbeAddOp(v, OP_Column, iCur, 0);
    sqlite3VdbeOp3(v, OP_String8, 0, 0, pTab->zName, 0);
    sqlite3VdbeAddOp(v, OP_Ne, 0x100, addr+12);
    sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
    sqlite3VdbeAddOp(v, OP_MemStore, memId-1, 1);
    sqlite3VdbeAddOp(v, OP_Column, iCur, 1);
    sqlite3VdbeAddOp(v, OP_MemStore, memId, 1);
    sqlite3VdbeAddOp(v, OP_Goto, 0, addr+13);
    sqlite3VdbeAddOp(v, OP_Next, iCur, addr+4);
    sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
  }
  return memId;
}

/*
** Update the maximum rowid for an autoincrement calculation.
**
** This routine should be called when the top of the stack holds a
** new rowid that is about to be inserted.  If that new rowid is
** larger than the maximum rowid in the memId memory cell, then the
** memory cell is updated.  The stack is unchanged.
*/
static void autoIncStep(Parse *pParse, int memId){
  if( memId>0 ){
    sqlite3VdbeAddOp(pParse->pVdbe, OP_MemMax, memId, 0);
  }
}

/*
** After doing one or more inserts, the maximum rowid is stored
** in mem[memId].  Generate code to write this value back into the
** the sqlite_sequence table.
*/
static void autoIncEnd(
  Parse *pParse,     /* The parsing context */
  int iDb,           /* Index of the database holding pTab */
  Table *pTab,       /* Table we are inserting into */
  int memId          /* Memory cell holding the maximum rowid */
){
  if( pTab->autoInc ){
    int iCur = pParse->nTab;
    Vdbe *v = pParse->pVdbe;
    Db *pDb = &pParse->db->aDb[iDb];
    int addr;
    assert( v );
    addr = sqlite3VdbeCurrentAddr(v);
    sqlite3OpenTable(pParse, iCur, iDb, pDb->pSchema->pSeqTab, OP_OpenWrite);
    sqlite3VdbeAddOp(v, OP_MemLoad, memId-1, 0);
    sqlite3VdbeAddOp(v, OP_NotNull, -1, addr+7);
    sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
    sqlite3VdbeAddOp(v, OP_NewRowid, iCur, 0);
    sqlite3VdbeOp3(v, OP_String8, 0, 0, pTab->zName, 0);
    sqlite3VdbeAddOp(v, OP_MemLoad, memId, 0);
    sqlite3VdbeAddOp(v, OP_MakeRecord, 2, 0);
    sqlite3VdbeAddOp(v, OP_Insert, iCur, 0);
    sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
  }
}
#else
/*
** If SQLITE_OMIT_AUTOINCREMENT is defined, then the three routines
** above are all no-ops
*/
# define autoIncBegin(A,B,C) (0)
# define autoIncStep(A,B)
# define autoIncEnd(A,B,C,D)
#endif /* SQLITE_OMIT_AUTOINCREMENT */


/* Forward declaration */
static int xferOptimization(
  Parse *pParse,        /* Parser context */
  Table *pDest,         /* The table we are inserting into */
  Select *pSelect,      /* A SELECT statement to use as the data source */
  int onError,          /* How to handle constraint errors */
  int iDbDest           /* The database of pDest */
);

/*
** This routine is call to handle SQL of the following forms:
**
**    insert into TABLE (IDLIST) values(EXPRLIST)
**    insert into TABLE (IDLIST) select
**
** The IDLIST following the table name is always optional.  If omitted,
** then a list of all columns for the table is substituted.  The IDLIST
** appears in the pColumn parameter.  pColumn is NULL if IDLIST is omitted.
**
** The pList parameter holds EXPRLIST in the first form of the INSERT
** statement above, and pSelect is NULL.  For the second form, pList is
** NULL and pSelect is a pointer to the select statement used to generate
** data for the insert.
**
** The code generated follows one of four templates.  For a simple
** select with data coming from a VALUES clause, the code executes
** once straight down through.  The template looks like this:
**
**         open write cursor to <table> and its indices
**         puts VALUES clause expressions onto the stack
**         write the resulting record into <table>
**         cleanup
**
** The three remaining templates assume the statement is of the form
**
**   INSERT INTO <table> SELECT ...
**
** If the SELECT clause is of the restricted form "SELECT * FROM <table2>" -
** in other words if the SELECT pulls all columns from a single table
** and there is no WHERE or LIMIT or GROUP BY or ORDER BY clauses, and
** if <table2> and <table1> are distinct tables but have identical
** schemas, including all the same indices, then a special optimization
** is invoked that copies raw records from <table2> over to <table1>.
** See the xferOptimization() function for the implementation of this
** template.  This is the second template.
**
**         open a write cursor to <table>
**         open read cursor on <table2>
**         transfer all records in <table2> over to <table>
**         close cursors
**         foreach index on <table>
**           open a write cursor on the <table> index
**           open a read cursor on the corresponding <table2> index
**           transfer all records from the read to the write cursors
**           close cursors
**         end foreach
**
** The third template is for when the second template does not apply
** and the SELECT clause does not read from <table> at any time.
** The generated code follows this template:
**
**         goto B
**      A: setup for the SELECT
**         loop over the rows in the SELECT
**           gosub C
**         end loop
**         cleanup after the SELECT
**         goto D
**      B: open write cursor to <table> and its indices
**         goto A
**      C: insert the select result into <table>
**         return
**      D: cleanup
**
** The fourth template is used if the insert statement takes its
** values from a SELECT but the data is being inserted into a table
** that is also read as part of the SELECT.  In the third form,
** we have to use a intermediate table to store the results of
** the select.  The template is like this:
**
**         goto B
**      A: setup for the SELECT

  int iDb;

#ifndef SQLITE_OMIT_TRIGGER
  int isView;                 /* True if attempting to insert into a view */
  int triggers_exist = 0;     /* True if there are FOR EACH ROW triggers */
#endif





  if( pParse->nErr || sqlite3MallocFailed() ){
    goto insert_cleanup;
  }
  db = pParse->db;

  /* Locate the table into which we will be inserting new information.
  */

  sqlite3BeginWriteOperation(pParse, pSelect || triggers_exist, iDb);

  /* if there are row triggers, allocate a temp table for new.* references. */
  if( triggers_exist ){
    newIdx = pParse->nTab++;
  }

#ifndef SQLITE_OMIT_XFER_OPT
  /* If the statement is of the form
  **
  **       INSERT INTO <table1> SELECT * FROM <table2>;
  **
  ** Then special optimizations can be applied that make the transfer
  ** very fast and which reduce fragmentation of indices.
  */
  if( pColumn==0 && xferOptimization(pParse, pTab, pSelect, onError, iDb) ){
    assert( !triggers_exist );
    assert( pList==0 );
    goto insert_cleanup;
  }
#endif /* SQLITE_OMIT_XFER_OPT */

  /* If this is an AUTOINCREMENT table, look up the sequence number in the
  ** sqlite_sequence table and store it in memory cell counterMem.  Also
  ** remember the rowid of the sqlite_sequence table entry in memory cell
  ** counterRowid.
  */




  counterMem = autoIncBegin(pParse, iDb, pTab);















  /* Figure out how many columns of data are supplied.  If the data
  ** is coming from a SELECT statement, then this step also generates
  ** all the code to implement the SELECT statement and invoke a subroutine
  ** to process each row of the result. (Template 2.) If the SELECT
  ** statement uses the the table that is being inserted into, then the
  ** subroutine is also coded here.  That subroutine stores the SELECT

      sqlite3VdbeAddOp(v, OP_NewRowid, base, counterMem);
      sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
    }else if( IsVirtual(pTab) ){
      sqlite3VdbeAddOp(v, OP_Null, 0, 0);
    }else{
      sqlite3VdbeAddOp(v, OP_NewRowid, base, counterMem);
    }


    autoIncStep(pParse, counterMem);



    /* Push onto the stack, data for all columns of the new entry, beginning
    ** with the first column.
    */
    for(i=0; i<pTab->nCol; i++){
      if( i==pTab->iPKey ){
        /* The value of the INTEGER PRIMARY KEY column is always a NULL.

    /* Close all tables opened */
    sqlite3VdbeAddOp(v, OP_Close, base, 0);
    for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
      sqlite3VdbeAddOp(v, OP_Close, idx+base, 0);
    }
  }


  /* Update the sqlite_sequence table by storing the content of the
  ** counter value in memory counterMem back into the sqlite_sequence
  ** table.
  */
  autoIncEnd(pParse, iDb, pTab, counterMem);















  /*
  ** Return the number of rows inserted. If this routine is 
  ** generating code because of a call to sqlite3NestedParse(), do not
  ** invoke the callback function.
  */
  if( db->flags & SQLITE_CountRows && pParse->nested==0 && !pParse->trigStack ){

    VdbeComment((v, "# %s", pIdx->zName));
    sqlite3VdbeOp3(v, op, i+base, pIdx->tnum, (char*)pKey, P3_KEYINFO_HANDOFF);
  }
  if( pParse->nTab<=base+i ){
    pParse->nTab = base+i;
  }
}

#ifndef SQLITE_OMIT_XFER_OPT
/*
** Check to collation names to see if they are compatible.
*/
static int xferCompatibleCollation(const char *z1, const char *z2){
  if( z1==0 ){
    return z2==0;
  }
  if( z2==0 ){
    return 0;
  }
  return sqlite3StrICmp(z1, z2)==0;
}


/*
** Check to see if index pSrc is compatible as a source of data
** for index pDest in an insert transfer optimization.  The rules
** for a compatible index:
**
**    *   The index is over the same set of columns
**    *   The same DESC and ASC markings occurs on all columns
**    *   The same onError processing (OE_Abort, OE_Ignore, etc)
**    *   The same collating sequence on each column
*/
static int xferCompatibleIndex(Index *pDest, Index *pSrc){
  int i;
  assert( pDest && pSrc );
  assert( pDest->pTable!=pSrc->pTable );
  if( pDest->nColumn!=pSrc->nColumn ){
    return 0;   /* Different number of columns */
  }
  if( pDest->onError!=pSrc->onError ){
    return 0;   /* Different conflict resolution strategies */
  }
  for(i=0; i<pSrc->nColumn; i++){
    if( pSrc->aiColumn[i]!=pDest->aiColumn[i] ){
      return 0;   /* Different columns indexed */
    }
    if( pSrc->aSortOrder[i]!=pDest->aSortOrder[i] ){
      return 0;   /* Different sort orders */
    }
    if( pSrc->azColl[i]!=pDest->azColl[i] ){
      return 0;   /* Different sort orders */
    }
  }

  /* If no test above fails then the indices must be compatible */
  return 1;
}

/*
** Attempt the transfer optimization on INSERTs of the form
**
**     INSERT INTO tab1 SELECT * FROM tab2;
**
** This optimization is only attempted if
**
**    (1)  tab1 and tab2 have identical schemas including all the
**         same indices
**
**    (2)  tab1 and tab2 are different tables
**
**    (3)  There must be no triggers on tab1
**
**    (4)  The result set of the SELECT statement is "*"
**
**    (5)  The SELECT statement has no WHERE, HAVING, ORDER BY, GROUP BY,
**         or LIMIT clause.
**
**    (6)  The SELECT statement is a simple (not a compound) select that
**         contains only tab2 in its FROM clause
**
** This method for implementing the INSERT transfers raw records from
** tab2 over to tab1.  The columns are not decoded.  Raw records from
** the indices of tab2 are transfered to tab1 as well.  In so doing,
** the resulting tab1 has much less fragmentation.
**
** This routine returns TRUE if the optimization is attempted.  If any
** of the conditions above fail so that the optimization should not
** be attempted, then this routine returns FALSE.
*/
static int xferOptimization(
  Parse *pParse,        /* Parser context */
  Table *pDest,         /* The table we are inserting into */
  Select *pSelect,      /* A SELECT statement to use as the data source */
  int onError,          /* How to handle constraint errors */
  int iDbDest           /* The database of pDest */
){
  ExprList *pEList;                /* The result set of the SELECT */
  Table *pSrc;                     /* The table in the FROM clause of SELECT */
  Index *pSrcIdx, *pDestIdx;       /* Source and destination indices */
  struct SrcList_item *pItem;      /* An element of pSelect->pSrc */
  int i;                           /* Loop counter */
  int iDbSrc;                      /* The database of pSrc */
  int iSrc, iDest;                 /* Cursors from source and destination */
  int addr1, addr2;                /* Loop addresses */
  int emptyDestTest;               /* Address of test for empty pDest */
  int emptySrcTest;                /* Address of test for empty pSrc */
  int memRowid;                    /* A memcell containing a rowid from pSrc */
  Vdbe *v;                         /* The VDBE we are building */
  KeyInfo *pKey;                   /* Key information for an index */
  int counterMem;                  /* Memory register used by AUTOINC */

  if( pSelect==0 ){
    return 0;   /* Must be of the form  INSERT INTO ... SELECT ... */
  }
  if( pDest->pTrigger ){
    return 0;   /* tab1 must not have triggers */
  }
#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( pDest->isVirtual ){
    return 0;   /* tab1 must not be a virtual table */
  }
#endif
  if( onError==OE_Default ){
    onError = OE_Abort;
  }
  if( onError!=OE_Abort && onError!=OE_Rollback ){
    return 0;   /* Cannot do OR REPLACE or OR IGNORE or OR FAIL */
  }
  if( pSelect->pSrc==0 ){
    return 0;   /* SELECT must have a FROM clause */
  }
  if( pSelect->pSrc->nSrc!=1 ){
    return 0;   /* FROM clause must have exactly one term */
  }
  if( pSelect->pSrc->a[0].pSelect ){
    return 0;   /* FROM clause cannot contain a subquery */
  }
  if( pSelect->pWhere ){
    return 0;   /* SELECT may not have a WHERE clause */
  }
  if( pSelect->pOrderBy ){
    return 0;   /* SELECT may not have an ORDER BY clause */
  }
  if( pSelect->pHaving ){
    return 0;   /* SELECT may not have a HAVING clause */
  }
  if( pSelect->pGroupBy ){
    return 0;   /* SELECT may not have a GROUP BY clause */
  }
  if( pSelect->pLimit ){
    return 0;   /* SELECT may not have a LIMIT clause */
  }
  if( pSelect->pOffset ){
    return 0;   /* SELECT may not have an OFFSET clause */
  }
  if( pSelect->pPrior ){
    return 0;   /* SELECT may not be a compound query */
  }
  if( pSelect->isDistinct ){
    return 0;   /* SELECT may not be DISTINCT */
  }
  pEList = pSelect->pEList;
  assert( pEList!=0 );
  if( pEList->nExpr!=1 ){
    return 0;   /* The result set must have exactly one column */
  }
  assert( pEList->a[0].pExpr );
  if( pEList->a[0].pExpr->op!=TK_ALL ){
    return 0;   /* The result set must be the special operator "*" */
  }

  /* At this point we have established that the statement is of the
  ** correct syntactic form to participate in this optimization.  Now
  ** we have to check the semantics.
  */
  pItem = pSelect->pSrc->a;
  pSrc = sqlite3LocateTable(pParse, pItem->zName, pItem->zDatabase);
  if( pSrc==0 ){
    return 0;   /* FROM clause does not contain a real table */
  }
  if( pSrc==pDest ){
    return 0;   /* tab1 and tab2 may not be the same table */
  }
#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( pSrc->isVirtual ){
    return 0;   /* tab2 must not be a virtual table */
  }
#endif
  if( pSrc->pSelect ){
    return 0;   /* tab2 may not be a view */
  }
  if( pDest->nCol!=pSrc->nCol ){
    return 0;   /* Number of columns must be the same in tab1 and tab2 */
  }
  if( pDest->iPKey!=pSrc->iPKey ){
    return 0;   /* Both tables must have the same INTEGER PRIMARY KEY */
  }
  for(i=0; i<pDest->nCol; i++){
    if( pDest->aCol[i].affinity!=pSrc->aCol[i].affinity ){
      return 0;    /* Affinity must be the same on all columns */
    }
    if( !xferCompatibleCollation(pDest->aCol[i].zColl, pSrc->aCol[i].zColl) ){
      return 0;    /* Collating sequence must be the same on all columns */
    }
    if( pDest->aCol[i].notNull && !pSrc->aCol[i].notNull ){
      return 0;    /* tab2 must be NOT NULL if tab1 is */
    }
  }
  for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
    for(pSrcIdx=pSrc->pIndex; pSrcIdx; pSrcIdx=pSrcIdx->pNext){
      if( xferCompatibleIndex(pDestIdx, pSrcIdx) ) break;
    }
    if( pSrcIdx==0 ){
      return 0;    /* pDestIdx has no corresponding index in pSrc */
    }
  }

  /* If we get this far, it means either:
  **
  **    *   We can always do the transfer if the table contains an
  **        an integer primary key
  **
  **    *   We can conditionally do the transfer if the destination
  **        table is empty.
  */
  iDbSrc = sqlite3SchemaToIndex(pParse->db, pSrc->pSchema);
  v = sqlite3GetVdbe(pParse);
  iSrc = pParse->nTab++;
  iDest = pParse->nTab++;
  counterMem = autoIncBegin(pParse, iDbDest, pDest);
  sqlite3OpenTable(pParse, iDest, iDbDest, pDest, OP_OpenWrite);
  if( pDest->iPKey<0 ){
    /* The tables do not have an INTEGER PRIMARY KEY so that
    ** transfer optimization is only allowed if the destination
    ** table is initially empty
    */
    addr1 = sqlite3VdbeAddOp(v, OP_Rewind, iDest, 0);
    emptyDestTest = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
    sqlite3VdbeJumpHere(v, addr1);
  }else{
    emptyDestTest = 0;
  }
  sqlite3OpenTable(pParse, iSrc, iDbSrc, pSrc, OP_OpenRead);
  emptySrcTest = sqlite3VdbeAddOp(v, OP_Rewind, iSrc, 0);
  memRowid = pParse->nMem++;
  sqlite3VdbeAddOp(v, OP_Rowid, iSrc, 0);
  sqlite3VdbeAddOp(v, OP_MemStore, memRowid, 1);
  addr1 = sqlite3VdbeAddOp(v, OP_Rowid, iSrc, 0);
  sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
  addr2 = sqlite3VdbeAddOp(v, OP_NotExists, iDest, 0);
  sqlite3VdbeOp3(v, OP_Halt, SQLITE_CONSTRAINT, onError, 
                    "PRIMARY KEY must be unique", P3_STATIC);
  sqlite3VdbeJumpHere(v, addr2);
  autoIncStep(pParse, counterMem);
  sqlite3VdbeAddOp(v, OP_RowData, iSrc, 0);
  sqlite3VdbeOp3(v, OP_Insert, iDest, OPFLAG_NCHANGE|OPFLAG_LASTROWID,
                    pDest->zName, 0);
  sqlite3VdbeAddOp(v, OP_Next, iSrc, addr1);
  autoIncEnd(pParse, iDbDest, pDest, counterMem);
  for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
    for(pSrcIdx=pSrc->pIndex; pSrcIdx; pSrcIdx=pSrcIdx->pNext){
      if( xferCompatibleIndex(pDestIdx, pSrcIdx) ) break;
    }
    assert( pSrcIdx );
    sqlite3VdbeAddOp(v, OP_Close, iSrc, 0);
    sqlite3VdbeAddOp(v, OP_Close, iDest, 0);
    sqlite3VdbeAddOp(v, OP_Integer, iDbSrc, 0);
    pKey = sqlite3IndexKeyinfo(pParse, pSrcIdx);
    VdbeComment((v, "# %s", pSrcIdx->zName));
    sqlite3VdbeOp3(v, OP_OpenRead, iSrc, pSrcIdx->tnum, 
                   (char*)pKey, P3_KEYINFO_HANDOFF);
    sqlite3VdbeAddOp(v, OP_Integer, iDbDest, 0);
    pKey = sqlite3IndexKeyinfo(pParse, pDestIdx);
    VdbeComment((v, "# %s", pDestIdx->zName));
    sqlite3VdbeOp3(v, OP_OpenWrite, iDest, pDestIdx->tnum, 
                   (char*)pKey, P3_KEYINFO_HANDOFF);
    addr1 = sqlite3VdbeAddOp(v, OP_Rewind, iSrc, 0);
    sqlite3VdbeAddOp(v, OP_RowKey, iSrc, 0);
    if( pDestIdx->onError!=OE_None ){
      sqlite3VdbeAddOp(v, OP_MemLoad, memRowid, 0);
      addr2 = sqlite3VdbeAddOp(v, OP_IsUnique, iDest, 0);
      sqlite3VdbeOp3(v, OP_Halt, SQLITE_CONSTRAINT, onError, 
                    "UNIQUE constraint failed", P3_STATIC);
      sqlite3VdbeJumpHere(v, addr2);
    }
    sqlite3VdbeAddOp(v, OP_IdxInsert, iDest, 0);
    sqlite3VdbeAddOp(v, OP_Next, iSrc, addr1+1);
    sqlite3VdbeJumpHere(v, addr1);
  }
  sqlite3VdbeJumpHere(v, emptySrcTest);
  sqlite3VdbeAddOp(v, OP_Close, iSrc, 0);
  sqlite3VdbeAddOp(v, OP_Close, iDest, 0);
  if( emptyDestTest ){
    sqlite3VdbeAddOp(v, OP_Halt, SQLITE_OK, 0);
    sqlite3VdbeJumpHere(v, emptyDestTest);
    sqlite3VdbeAddOp(v, OP_Close, iDest, 0);
    return 0;
  }else{
    return 1;
  }
}
#endif /* SQLITE_OMIT_XFER_OPT */