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Comment:Avoid updating unaffected indexes on a table as part of an UPDATE that requires foreign key processing in some cases.
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SHA3-256: 477bea9ed0dd0fa69896bfd16d9b1d22170cbab784e3279ce65c29c47e032f34
User & Date: dan 2017-04-11 19:58:55
Context
2017-04-11
20:48
Avoid updating unaffected indexes on a table as part of an UPDATE that requires foreign key processing in some cases. check-in: 7aae5c0f user: dan tags: trunk
19:58
Avoid updating unaffected indexes on a table as part of an UPDATE that requires foreign key processing in some cases. Closed-Leaf check-in: 477bea9e user: dan tags: fkey-optimization
18:55
Limit the depth of recursion for valid JSON in the JSON1 extension in order to avoid using excess stack space in the recursive descent parser. Fix for ticket [981329adeef51011052667a9]. check-in: 1f68c184 user: drh tags: trunk
Changes
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Changes to src/fkey.c.

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** to an array of size N, where N is the number of columns in table pTab.
** If the i'th column is not modified by the UPDATE, then the corresponding 
** entry in the aChange[] array is set to -1. If the column is modified,
** the value is 0 or greater. Parameter chngRowid is set to true if the
** UPDATE statement modifies the rowid fields of the table.
**
** If any foreign key processing will be required, this function returns
** true. If there is no foreign key related processing, this function 
** returns false.








*/
int sqlite3FkRequired(
  Parse *pParse,                  /* Parse context */
  Table *pTab,                    /* Table being modified */
  int *aChange,                   /* Non-NULL for UPDATE operations */
  int chngRowid                   /* True for UPDATE that affects rowid */
){

  if( pParse->db->flags&SQLITE_ForeignKeys ){
    if( !aChange ){
      /* A DELETE operation. Foreign key processing is required if the 
      ** table in question is either the child or parent table for any 
      ** foreign key constraint.  */
      return (sqlite3FkReferences(pTab) || pTab->pFKey);
    }else{
      /* This is an UPDATE. Foreign key processing is only required if the
      ** operation modifies one or more child or parent key columns. */
      FKey *p;

      /* Check if any child key columns are being modified. */
      for(p=pTab->pFKey; p; p=p->pNextFrom){

        if( fkChildIsModified(pTab, p, aChange, chngRowid) ) return 1;


      }

      /* Check if any parent key columns are being modified. */
      for(p=sqlite3FkReferences(pTab); p; p=p->pNextTo){
        if( fkParentIsModified(pTab, p, aChange, chngRowid) ) return 1;



      }
    }
  }
  return 0;
}

/*
** This function is called when an UPDATE or DELETE operation is being 
** compiled on table pTab, which is the parent table of foreign-key pFKey.
** If the current operation is an UPDATE, then the pChanges parameter is
** passed a pointer to the list of columns being modified. If it is a







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** to an array of size N, where N is the number of columns in table pTab.
** If the i'th column is not modified by the UPDATE, then the corresponding 
** entry in the aChange[] array is set to -1. If the column is modified,
** the value is 0 or greater. Parameter chngRowid is set to true if the
** UPDATE statement modifies the rowid fields of the table.
**
** If any foreign key processing will be required, this function returns
** non-zero. If there is no foreign key related processing, this function 
** returns zero.
**
** For an UPDATE, this function returns 2 if:
**
**   * There are any FKs for which pTab is the child and the parent table, or
**   * the UPDATE modifies one or more parent keys for which the action is
**     not "NO ACTION" (i.e. is CASCADE, SET DEFAULT or SET NULL).
**
** Or, assuming some other foreign key processing is required, 1.
*/
int sqlite3FkRequired(
  Parse *pParse,                  /* Parse context */
  Table *pTab,                    /* Table being modified */
  int *aChange,                   /* Non-NULL for UPDATE operations */
  int chngRowid                   /* True for UPDATE that affects rowid */
){
  int eRet = 0;
  if( pParse->db->flags&SQLITE_ForeignKeys ){
    if( !aChange ){
      /* A DELETE operation. Foreign key processing is required if the 
      ** table in question is either the child or parent table for any 
      ** foreign key constraint.  */
      eRet = (sqlite3FkReferences(pTab) || pTab->pFKey);
    }else{
      /* This is an UPDATE. Foreign key processing is only required if the
      ** operation modifies one or more child or parent key columns. */
      FKey *p;

      /* Check if any child key columns are being modified. */
      for(p=pTab->pFKey; p; p=p->pNextFrom){
        if( 0==sqlite3_stricmp(pTab->zName, p->zTo) ) return 2;
        if( fkChildIsModified(pTab, p, aChange, chngRowid) ){
          eRet = 1;
        }
      }

      /* Check if any parent key columns are being modified. */
      for(p=sqlite3FkReferences(pTab); p; p=p->pNextTo){
        if( fkParentIsModified(pTab, p, aChange, chngRowid) ){
          if( p->aAction[1]!=OE_None ) return 2;
          eRet = 1;
        }
      }
    }
  }
  return eRet;
}

/*
** This function is called when an UPDATE or DELETE operation is being 
** compiled on table pTab, which is the parent table of foreign-key pFKey.
** If the current operation is an UPDATE, then the pChanges parameter is
** passed a pointer to the list of columns being modified. If it is a

Changes to src/update.c.

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  ** being updated.  Fill in aRegIdx[] with a register number that will hold
  ** the key for accessing each index.
  **
  ** FIXME:  Be smarter about omitting indexes that use expressions.
  */
  for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
    int reg;
    if( chngKey || hasFK || pIdx->pPartIdxWhere || pIdx==pPk ){
      reg = ++pParse->nMem;
      pParse->nMem += pIdx->nColumn;
    }else{
      reg = 0;
      for(i=0; i<pIdx->nKeyCol; i++){
        i16 iIdxCol = pIdx->aiColumn[i];
        if( iIdxCol<0 || aXRef[iIdxCol]>=0 ){
................................................................................
    ** pre-update hook. If the caller invokes preupdate_new(), the returned
    ** value is copied from memory cell (regNewRowid+1+iCol), where iCol
    ** is the column index supplied by the user.
    */
    assert( regNew==regNewRowid+1 );
#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
    sqlite3VdbeAddOp3(v, OP_Delete, iDataCur,
        OPFLAG_ISUPDATE | ((hasFK || chngKey) ? 0 : OPFLAG_ISNOOP),
        regNewRowid
    );
    if( eOnePass==ONEPASS_MULTI ){
      assert( hasFK==0 && chngKey==0 );
      sqlite3VdbeChangeP5(v, OPFLAG_SAVEPOSITION);
    }
    if( !pParse->nested ){
      sqlite3VdbeAppendP4(v, pTab, P4_TABLE);
    }
#else
    if( hasFK || chngKey ){
      sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, 0);
    }
#endif
    if( bReplace || chngKey ){
      sqlite3VdbeJumpHere(v, addr1);
    }








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  ** being updated.  Fill in aRegIdx[] with a register number that will hold
  ** the key for accessing each index.
  **
  ** FIXME:  Be smarter about omitting indexes that use expressions.
  */
  for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
    int reg;
    if( chngKey || hasFK>1 || pIdx->pPartIdxWhere || pIdx==pPk ){
      reg = ++pParse->nMem;
      pParse->nMem += pIdx->nColumn;
    }else{
      reg = 0;
      for(i=0; i<pIdx->nKeyCol; i++){
        i16 iIdxCol = pIdx->aiColumn[i];
        if( iIdxCol<0 || aXRef[iIdxCol]>=0 ){
................................................................................
    ** pre-update hook. If the caller invokes preupdate_new(), the returned
    ** value is copied from memory cell (regNewRowid+1+iCol), where iCol
    ** is the column index supplied by the user.
    */
    assert( regNew==regNewRowid+1 );
#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
    sqlite3VdbeAddOp3(v, OP_Delete, iDataCur,
        OPFLAG_ISUPDATE | ((hasFK>1 || chngKey) ? 0 : OPFLAG_ISNOOP),
        regNewRowid
    );
    if( eOnePass==ONEPASS_MULTI ){
      assert( hasFK==0 && chngKey==0 );
      sqlite3VdbeChangeP5(v, OPFLAG_SAVEPOSITION);
    }
    if( !pParse->nested ){
      sqlite3VdbeAppendP4(v, pTab, P4_TABLE);
    }
#else
    if( hasFK>1 || chngKey ){
      sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, 0);
    }
#endif
    if( bReplace || chngKey ){
      sqlite3VdbeJumpHere(v, addr1);
    }