** auxiliary databases added using the ATTACH command.
**
** See also sqlite3LocateTable().
*/
Table *sqlite3FindTable(sqlite3 *db, const char *zName, const char *zDatabase){
  Table *p = 0;
  int i;
  int nName;
  assert( zName!=0 );
  nName = sqlite3Strlen30(zName);
  /* All mutexes are required for schema access.  Make sure we hold them. */
  assert( zDatabase!=0 || sqlite3BtreeHoldsAllMutexes(db) );
  for(i=OMIT_TEMPDB; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;   /* Search TEMP before MAIN */
    if( zDatabase!=0 && sqlite3StrICmp(zDatabase, db->aDb[j].zName) ) continue;
    assert( sqlite3SchemaMutexHeld(db, j, 0) );
    p = sqlite3HashFind(&db->aDb[j].pSchema->tblHash, zName, nName);
    if( p ) break;
  }
  return p;
}

/*
** Locate the in-memory structure that describes a particular database
................................................................................
** for duplicate index names is done.)  The search order is
** TEMP first, then MAIN, then any auxiliary databases added
** using the ATTACH command.
*/
Index *sqlite3FindIndex(sqlite3 *db, const char *zName, const char *zDb){
  Index *p = 0;
  int i;
  int nName = sqlite3Strlen30(zName);
  /* All mutexes are required for schema access.  Make sure we hold them. */
  assert( zDb!=0 || sqlite3BtreeHoldsAllMutexes(db) );
  for(i=OMIT_TEMPDB; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
    Schema *pSchema = db->aDb[j].pSchema;
    assert( pSchema );
    if( zDb && sqlite3StrICmp(zDb, db->aDb[j].zName) ) continue;
    assert( sqlite3SchemaMutexHeld(db, j, 0) );
    p = sqlite3HashFind(&pSchema->idxHash, zName, nName);
    if( p ) break;
  }
  return p;
}

/*
** Reclaim the memory used by an index
................................................................................
** For the index called zIdxName which is found in the database iDb,
** unlike that index from its Table then remove the index from
** the index hash table and free all memory structures associated
** with the index.
*/
void sqlite3UnlinkAndDeleteIndex(sqlite3 *db, int iDb, const char *zIdxName){
  Index *pIndex;
  int len;
  Hash *pHash;

  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  pHash = &db->aDb[iDb].pSchema->idxHash;
  len = sqlite3Strlen30(zIdxName);
  pIndex = sqlite3HashInsert(pHash, zIdxName, len, 0);
  if( ALWAYS(pIndex) ){
    if( pIndex->pTable->pIndex==pIndex ){
      pIndex->pTable->pIndex = pIndex->pNext;
    }else{
      Index *p;
      /* Justification of ALWAYS();  The index must be on the list of
      ** indices. */
................................................................................
  /* Delete all indices associated with this table. */
  for(pIndex = pTable->pIndex; pIndex; pIndex=pNext){
    pNext = pIndex->pNext;
    assert( pIndex->pSchema==pTable->pSchema );
    if( !db || db->pnBytesFreed==0 ){
      char *zName = pIndex->zName; 
      TESTONLY ( Index *pOld = ) sqlite3HashInsert(
         &pIndex->pSchema->idxHash, zName, sqlite3Strlen30(zName), 0
      );
      assert( db==0 || sqlite3SchemaMutexHeld(db, 0, pIndex->pSchema) );
      assert( pOld==pIndex || pOld==0 );
    }
    freeIndex(db, pIndex);
  }

................................................................................

  assert( db!=0 );
  assert( iDb>=0 && iDb<db->nDb );
  assert( zTabName );
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  testcase( zTabName[0]==0 );  /* Zero-length table names are allowed */
  pDb = &db->aDb[iDb];
  p = sqlite3HashInsert(&pDb->pSchema->tblHash, zTabName,
                        sqlite3Strlen30(zTabName),0);
  sqlite3DeleteTable(db, p);
  db->flags |= SQLITE_InternChanges;
}

/*
** Given a token, return a string that consists of the text of that
** token.  Space to hold the returned string
................................................................................

  /* Add the table to the in-memory representation of the database.
  */
  if( db->init.busy ){
    Table *pOld;
    Schema *pSchema = p->pSchema;
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
    pOld = sqlite3HashInsert(&pSchema->tblHash, p->zName,
                             sqlite3Strlen30(p->zName),p);
    if( pOld ){
      assert( p==pOld );  /* Malloc must have failed inside HashInsert() */
      db->mallocFailed = 1;
      return;
    }
    pParse->pNewTable = 0;
    db->flags |= SQLITE_InternChanges;
................................................................................
  }
  pFKey->isDeferred = 0;
  pFKey->aAction[0] = (u8)(flags & 0xff);            /* ON DELETE action */
  pFKey->aAction[1] = (u8)((flags >> 8 ) & 0xff);    /* ON UPDATE action */

  assert( sqlite3SchemaMutexHeld(db, 0, p->pSchema) );
  pNextTo = (FKey *)sqlite3HashInsert(&p->pSchema->fkeyHash, 
      pFKey->zTo, sqlite3Strlen30(pFKey->zTo), (void *)pFKey
  );
  if( pNextTo==pFKey ){
    db->mallocFailed = 1;
    goto fk_end;
  }
  if( pNextTo ){
    assert( pNextTo->pPrevTo==0 );
................................................................................
  /* Link the new Index structure to its table and to the other
  ** in-memory database structures. 
  */
  if( db->init.busy ){
    Index *p;
    assert( sqlite3SchemaMutexHeld(db, 0, pIndex->pSchema) );
    p = sqlite3HashInsert(&pIndex->pSchema->idxHash, 
                          pIndex->zName, sqlite3Strlen30(pIndex->zName),
                          pIndex);
    if( p ){
      assert( p==pIndex );  /* Malloc must have failed */
      db->mallocFailed = 1;
      goto exit_create_index;
    }
    db->flags |= SQLITE_InternChanges;
    if( pTblName!=0 ){

** auxiliary databases added using the ATTACH command.
**
** See also sqlite3LocateTable().
*/
Table *sqlite3FindTable(sqlite3 *db, const char *zName, const char *zDatabase){
  Table *p = 0;
  int i;

  assert( zName!=0 );

  /* All mutexes are required for schema access.  Make sure we hold them. */
  assert( zDatabase!=0 || sqlite3BtreeHoldsAllMutexes(db) );
  for(i=OMIT_TEMPDB; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;   /* Search TEMP before MAIN */
    if( zDatabase!=0 && sqlite3StrICmp(zDatabase, db->aDb[j].zName) ) continue;
    assert( sqlite3SchemaMutexHeld(db, j, 0) );
    p = sqlite3HashFind(&db->aDb[j].pSchema->tblHash, zName);
    if( p ) break;
  }
  return p;
}

/*
** Locate the in-memory structure that describes a particular database
................................................................................
** for duplicate index names is done.)  The search order is
** TEMP first, then MAIN, then any auxiliary databases added
** using the ATTACH command.
*/
Index *sqlite3FindIndex(sqlite3 *db, const char *zName, const char *zDb){
  Index *p = 0;
  int i;

  /* All mutexes are required for schema access.  Make sure we hold them. */
  assert( zDb!=0 || sqlite3BtreeHoldsAllMutexes(db) );
  for(i=OMIT_TEMPDB; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
    Schema *pSchema = db->aDb[j].pSchema;
    assert( pSchema );
    if( zDb && sqlite3StrICmp(zDb, db->aDb[j].zName) ) continue;
    assert( sqlite3SchemaMutexHeld(db, j, 0) );
    p = sqlite3HashFind(&pSchema->idxHash, zName);
    if( p ) break;
  }
  return p;
}

/*
** Reclaim the memory used by an index
................................................................................
** For the index called zIdxName which is found in the database iDb,
** unlike that index from its Table then remove the index from
** the index hash table and free all memory structures associated
** with the index.
*/
void sqlite3UnlinkAndDeleteIndex(sqlite3 *db, int iDb, const char *zIdxName){
  Index *pIndex;

  Hash *pHash;

  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  pHash = &db->aDb[iDb].pSchema->idxHash;

  pIndex = sqlite3HashInsert(pHash, zIdxName, 0);
  if( ALWAYS(pIndex) ){
    if( pIndex->pTable->pIndex==pIndex ){
      pIndex->pTable->pIndex = pIndex->pNext;
    }else{
      Index *p;
      /* Justification of ALWAYS();  The index must be on the list of
      ** indices. */
................................................................................
  /* Delete all indices associated with this table. */
  for(pIndex = pTable->pIndex; pIndex; pIndex=pNext){
    pNext = pIndex->pNext;
    assert( pIndex->pSchema==pTable->pSchema );
    if( !db || db->pnBytesFreed==0 ){
      char *zName = pIndex->zName; 
      TESTONLY ( Index *pOld = ) sqlite3HashInsert(
         &pIndex->pSchema->idxHash, zName, 0
      );
      assert( db==0 || sqlite3SchemaMutexHeld(db, 0, pIndex->pSchema) );
      assert( pOld==pIndex || pOld==0 );
    }
    freeIndex(db, pIndex);
  }

................................................................................

  assert( db!=0 );
  assert( iDb>=0 && iDb<db->nDb );
  assert( zTabName );
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  testcase( zTabName[0]==0 );  /* Zero-length table names are allowed */
  pDb = &db->aDb[iDb];
  p = sqlite3HashInsert(&pDb->pSchema->tblHash, zTabName, 0);

  sqlite3DeleteTable(db, p);
  db->flags |= SQLITE_InternChanges;
}

/*
** Given a token, return a string that consists of the text of that
** token.  Space to hold the returned string
................................................................................

  /* Add the table to the in-memory representation of the database.
  */
  if( db->init.busy ){
    Table *pOld;
    Schema *pSchema = p->pSchema;
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
    pOld = sqlite3HashInsert(&pSchema->tblHash, p->zName, p);

    if( pOld ){
      assert( p==pOld );  /* Malloc must have failed inside HashInsert() */
      db->mallocFailed = 1;
      return;
    }
    pParse->pNewTable = 0;
    db->flags |= SQLITE_InternChanges;
................................................................................
  }
  pFKey->isDeferred = 0;
  pFKey->aAction[0] = (u8)(flags & 0xff);            /* ON DELETE action */
  pFKey->aAction[1] = (u8)((flags >> 8 ) & 0xff);    /* ON UPDATE action */

  assert( sqlite3SchemaMutexHeld(db, 0, p->pSchema) );
  pNextTo = (FKey *)sqlite3HashInsert(&p->pSchema->fkeyHash, 
      pFKey->zTo, (void *)pFKey
  );
  if( pNextTo==pFKey ){
    db->mallocFailed = 1;
    goto fk_end;
  }
  if( pNextTo ){
    assert( pNextTo->pPrevTo==0 );
................................................................................
  /* Link the new Index structure to its table and to the other
  ** in-memory database structures. 
  */
  if( db->init.busy ){
    Index *p;
    assert( sqlite3SchemaMutexHeld(db, 0, pIndex->pSchema) );
    p = sqlite3HashInsert(&pIndex->pSchema->idxHash, 

                          pIndex->zName, pIndex);
    if( p ){
      assert( p==pIndex );  /* Malloc must have failed */
      db->mallocFailed = 1;
      goto exit_create_index;
    }
    db->flags |= SQLITE_InternChanges;
    if( pTblName!=0 ){

*/
static CollSeq *findCollSeqEntry(
  sqlite3 *db,          /* Database connection */
  const char *zName,    /* Name of the collating sequence */
  int create            /* Create a new entry if true */
){
  CollSeq *pColl;
  int nName = sqlite3Strlen30(zName);
  pColl = sqlite3HashFind(&db->aCollSeq, zName, nName);

  if( 0==pColl && create ){

    pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName + 1 );
    if( pColl ){
      CollSeq *pDel = 0;
      pColl[0].zName = (char*)&pColl[3];
      pColl[0].enc = SQLITE_UTF8;
      pColl[1].zName = (char*)&pColl[3];
      pColl[1].enc = SQLITE_UTF16LE;
      pColl[2].zName = (char*)&pColl[3];
      pColl[2].enc = SQLITE_UTF16BE;
      memcpy(pColl[0].zName, zName, nName);
      pColl[0].zName[nName] = 0;
      pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, nName, pColl);

      /* If a malloc() failure occurred in sqlite3HashInsert(), it will 
      ** return the pColl pointer to be deleted (because it wasn't added
      ** to the hash table).
      */
      assert( pDel==0 || pDel==pColl );
      if( pDel!=0 ){

*/
static CollSeq *findCollSeqEntry(
  sqlite3 *db,          /* Database connection */
  const char *zName,    /* Name of the collating sequence */
  int create            /* Create a new entry if true */
){
  CollSeq *pColl;

  pColl = sqlite3HashFind(&db->aCollSeq, zName);

  if( 0==pColl && create ){
    int nName = sqlite3Strlen30(zName);
    pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName + 1);
    if( pColl ){
      CollSeq *pDel = 0;
      pColl[0].zName = (char*)&pColl[3];
      pColl[0].enc = SQLITE_UTF8;
      pColl[1].zName = (char*)&pColl[3];
      pColl[1].enc = SQLITE_UTF16LE;
      pColl[2].zName = (char*)&pColl[3];
      pColl[2].enc = SQLITE_UTF16BE;
      memcpy(pColl[0].zName, zName, nName);
      pColl[0].zName[nName] = 0;
      pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, pColl);

      /* If a malloc() failure occurred in sqlite3HashInsert(), it will 
      ** return the pColl pointer to be deleted (because it wasn't added
      ** to the hash table).
      */
      assert( pDel==0 || pDel==pColl );
      if( pDel!=0 ){

** Calling this function with table "t1" as an argument returns a pointer
** to the FKey structure representing the foreign key constraint on table
** "t2". Calling this function with "t2" as the argument would return a
** NULL pointer (as there are no FK constraints for which t2 is the parent
** table).
*/
FKey *sqlite3FkReferences(Table *pTab){
  int nName = sqlite3Strlen30(pTab->zName);
  return (FKey *)sqlite3HashFind(&pTab->pSchema->fkeyHash, pTab->zName, nName);
}

/*
** The second argument is a Trigger structure allocated by the 
** fkActionTrigger() routine. This function deletes the Trigger structure
** and all of its sub-components.
**
................................................................................
    /* Remove the FK from the fkeyHash hash table. */
    if( !db || db->pnBytesFreed==0 ){
      if( pFKey->pPrevTo ){
        pFKey->pPrevTo->pNextTo = pFKey->pNextTo;
      }else{
        void *p = (void *)pFKey->pNextTo;
        const char *z = (p ? pFKey->pNextTo->zTo : pFKey->zTo);
        sqlite3HashInsert(&pTab->pSchema->fkeyHash, z, sqlite3Strlen30(z), p);
      }
      if( pFKey->pNextTo ){
        pFKey->pNextTo->pPrevTo = pFKey->pPrevTo;
      }
    }

    /* EV: R-30323-21917 Each foreign key constraint in SQLite is

** Calling this function with table "t1" as an argument returns a pointer
** to the FKey structure representing the foreign key constraint on table
** "t2". Calling this function with "t2" as the argument would return a
** NULL pointer (as there are no FK constraints for which t2 is the parent
** table).
*/
FKey *sqlite3FkReferences(Table *pTab){

  return (FKey *)sqlite3HashFind(&pTab->pSchema->fkeyHash, pTab->zName);
}

/*
** The second argument is a Trigger structure allocated by the 
** fkActionTrigger() routine. This function deletes the Trigger structure
** and all of its sub-components.
**
................................................................................
    /* Remove the FK from the fkeyHash hash table. */
    if( !db || db->pnBytesFreed==0 ){
      if( pFKey->pPrevTo ){
        pFKey->pPrevTo->pNextTo = pFKey->pNextTo;
      }else{
        void *p = (void *)pFKey->pNextTo;
        const char *z = (p ? pFKey->pNextTo->zTo : pFKey->zTo);
        sqlite3HashInsert(&pTab->pSchema->fkeyHash, z, p);
      }
      if( pFKey->pNextTo ){
        pFKey->pNextTo->pPrevTo = pFKey->pPrevTo;
      }
    }

    /* EV: R-30323-21917 Each foreign key constraint in SQLite is

  }
  pH->count = 0;
}

/*
** The hashing function.
*/
static unsigned int strHash(const char *z, int nKey){
  unsigned int h = 0;
  assert( nKey>=0 );
  while( nKey > 0  ){
    h = (h<<3) ^ h ^ sqlite3UpperToLower[(unsigned char)*z++];
    nKey--;
  }
  return h;
}


/* Link pNew element into the hash table pH.  If pEntry!=0 then also
** insert pNew into the pEntry hash bucket.
................................................................................

  if( new_ht==0 ) return 0;
  sqlite3_free(pH->ht);
  pH->ht = new_ht;
  pH->htsize = new_size = sqlite3MallocSize(new_ht)/sizeof(struct _ht);
  memset(new_ht, 0, new_size*sizeof(struct _ht));
  for(elem=pH->first, pH->first=0; elem; elem = next_elem){
    unsigned int h = strHash(elem->pKey, elem->nKey) % new_size;
    next_elem = elem->next;
    insertElement(pH, &new_ht[h], elem);
  }
  return 1;
}

/* This function (for internal use only) locates an element in an
** hash table that matches the given key.  The hash for this key has
** already been computed and is passed as the 4th parameter.
*/
static HashElem *findElementGivenHash(
  const Hash *pH,     /* The pH to be searched */
  const char *pKey,   /* The key we are searching for */
  int nKey,           /* Bytes in key (not counting zero terminator) */
  unsigned int h      /* The hash for this key. */
){
  HashElem *elem;                /* Used to loop thru the element list */
  int count;                     /* Number of elements left to test */


  if( pH->ht ){


    struct _ht *pEntry = &pH->ht[h];
    elem = pEntry->chain;
    count = pEntry->count;
  }else{

    elem = pH->first;
    count = pH->count;
  }

  while( count-- && ALWAYS(elem) ){

    if( elem->nKey==nKey && sqlite3StrNICmp(elem->pKey,pKey,nKey)==0 ){ 
      return elem;
    }
    elem = elem->next;
  }
  return 0;
}

................................................................................
    assert( pH->first==0 );
    assert( pH->count==0 );
    sqlite3HashClear(pH);
  }
}

/* Attempt to locate an element of the hash table pH with a key
** that matches pKey,nKey.  Return the data for this element if it is
** found, or NULL if there is no match.
*/
void *sqlite3HashFind(const Hash *pH, const char *pKey, int nKey){
  HashElem *elem;    /* The element that matches key */
  unsigned int h;    /* A hash on key */

  assert( pH!=0 );
  assert( pKey!=0 );
  assert( nKey>=0 );
  if( pH->ht ){
    h = strHash(pKey, nKey) % pH->htsize;
  }else{
    h = 0;
  }
  elem = findElementGivenHash(pH, pKey, nKey, h);
  return elem ? elem->data : 0;
}

/* Insert an element into the hash table pH.  The key is pKey,nKey
** and the data is "data".
**
** If no element exists with a matching key, then a new
** element is created and NULL is returned.
**
** If another element already exists with the same key, then the
** new data replaces the old data and the old data is returned.
** The key is not copied in this instance.  If a malloc fails, then
** the new data is returned and the hash table is unchanged.
**
** If the "data" parameter to this function is NULL, then the
** element corresponding to "key" is removed from the hash table.
*/
void *sqlite3HashInsert(Hash *pH, const char *pKey, int nKey, void *data){
  unsigned int h;       /* the hash of the key modulo hash table size */
  HashElem *elem;       /* Used to loop thru the element list */
  HashElem *new_elem;   /* New element added to the pH */

  assert( pH!=0 );
  assert( pKey!=0 );
  assert( nKey>=0 );
  if( pH->htsize ){
    h = strHash(pKey, nKey) % pH->htsize;
  }else{
    h = 0;
  }
  elem = findElementGivenHash(pH,pKey,nKey,h);
  if( elem ){
    void *old_data = elem->data;
    if( data==0 ){
      removeElementGivenHash(pH,elem,h);
    }else{
      elem->data = data;
      elem->pKey = pKey;
      assert(nKey==elem->nKey);
    }
    return old_data;
  }
  if( data==0 ) return 0;
  new_elem = (HashElem*)sqlite3Malloc( sizeof(HashElem) );
  if( new_elem==0 ) return data;
  new_elem->pKey = pKey;
  new_elem->nKey = nKey;
  new_elem->data = data;
  pH->count++;
  if( pH->count>=10 && pH->count > 2*pH->htsize ){
    if( rehash(pH, pH->count*2) ){
      assert( pH->htsize>0 );
      h = strHash(pKey, nKey) % pH->htsize;
    }
  }
  if( pH->ht ){
    insertElement(pH, &pH->ht[h], new_elem);
  }else{
    insertElement(pH, 0, new_elem);
  }
  return 0;
}

  }
  pH->count = 0;
}

/*
** The hashing function.
*/
static unsigned int strHash(const char *z){
  unsigned int h = 0;
  unsigned char c;
  while( (c = (unsigned char)*z++)!=0 ){
    h = (h<<3) ^ h ^ sqlite3UpperToLower[c];

  }
  return h;
}


/* Link pNew element into the hash table pH.  If pEntry!=0 then also
** insert pNew into the pEntry hash bucket.
................................................................................

  if( new_ht==0 ) return 0;
  sqlite3_free(pH->ht);
  pH->ht = new_ht;
  pH->htsize = new_size = sqlite3MallocSize(new_ht)/sizeof(struct _ht);
  memset(new_ht, 0, new_size*sizeof(struct _ht));
  for(elem=pH->first, pH->first=0; elem; elem = next_elem){
    unsigned int h = strHash(elem->pKey) % new_size;
    next_elem = elem->next;
    insertElement(pH, &new_ht[h], elem);
  }
  return 1;
}

/* This function (for internal use only) locates an element in an
** hash table that matches the given key.  The hash for this key is
** also computed and returned in the *pH parameter.
*/
static HashElem *findElementWithHash(
  const Hash *pH,     /* The pH to be searched */
  const char *pKey,   /* The key we are searching for */
  unsigned int *pHash /* Write the hash value here */

){
  HashElem *elem;                /* Used to loop thru the element list */
  int count;                     /* Number of elements left to test */
  unsigned int h;                /* The computed hash */

  if( pH->ht ){
    struct _ht *pEntry;
    h = strHash(pKey) % pH->htsize;
    pEntry = &pH->ht[h];
    elem = pEntry->chain;
    count = pEntry->count;
  }else{
    h = 0;
    elem = pH->first;
    count = pH->count;
  }
  *pHash = h;
  while( count-- ){
    assert( elem!=0 );
    if( sqlite3StrICmp(elem->pKey,pKey)==0 ){ 
      return elem;
    }
    elem = elem->next;
  }
  return 0;
}

................................................................................
    assert( pH->first==0 );
    assert( pH->count==0 );
    sqlite3HashClear(pH);
  }
}

/* Attempt to locate an element of the hash table pH with a key
** that matches pKey.  Return the data for this element if it is
** found, or NULL if there is no match.
*/
void *sqlite3HashFind(const Hash *pH, const char *pKey){
  HashElem *elem;    /* The element that matches key */
  unsigned int h;    /* A hash on key */

  assert( pH!=0 );
  assert( pKey!=0 );






  elem = findElementWithHash(pH, pKey, &h);
  return elem ? elem->data : 0;
}

/* Insert an element into the hash table pH.  The key is pKey
** and the data is "data".
**
** If no element exists with a matching key, then a new
** element is created and NULL is returned.
**
** If another element already exists with the same key, then the
** new data replaces the old data and the old data is returned.
** The key is not copied in this instance.  If a malloc fails, then
** the new data is returned and the hash table is unchanged.
**
** If the "data" parameter to this function is NULL, then the
** element corresponding to "key" is removed from the hash table.
*/
void *sqlite3HashInsert(Hash *pH, const char *pKey, void *data){
  unsigned int h;       /* the hash of the key modulo hash table size */
  HashElem *elem;       /* Used to loop thru the element list */
  HashElem *new_elem;   /* New element added to the pH */

  assert( pH!=0 );
  assert( pKey!=0 );






  elem = findElementWithHash(pH,pKey,&h);
  if( elem ){
    void *old_data = elem->data;
    if( data==0 ){
      removeElementGivenHash(pH,elem,h);
    }else{
      elem->data = data;
      elem->pKey = pKey;

    }
    return old_data;
  }
  if( data==0 ) return 0;
  new_elem = (HashElem*)sqlite3Malloc( sizeof(HashElem) );
  if( new_elem==0 ) return data;
  new_elem->pKey = pKey;

  new_elem->data = data;
  pH->count++;
  if( pH->count>=10 && pH->count > 2*pH->htsize ){
    if( rehash(pH, pH->count*2) ){
      assert( pH->htsize>0 );
      h = strHash(pKey) % pH->htsize;
    }
  }



  insertElement(pH, pH->ht ? &pH->ht[h] : 0, new_elem);

  return 0;
}

**
** Again, this structure is intended to be opaque, but it can't really
** be opaque because it is used by macros.
*/
struct HashElem {
  HashElem *next, *prev;       /* Next and previous elements in the table */
  void *data;                  /* Data associated with this element */
  const char *pKey; int nKey;  /* Key associated with this element */
};

/*
** Access routines.  To delete, insert a NULL pointer.
*/
void sqlite3HashInit(Hash*);
void *sqlite3HashInsert(Hash*, const char *pKey, int nKey, void *pData);
void *sqlite3HashFind(const Hash*, const char *pKey, int nKey);
void sqlite3HashClear(Hash*);

/*
** Macros for looping over all elements of a hash table.  The idiom is
** like this:
**
**   Hash h;

**
** Again, this structure is intended to be opaque, but it can't really
** be opaque because it is used by macros.
*/
struct HashElem {
  HashElem *next, *prev;       /* Next and previous elements in the table */
  void *data;                  /* Data associated with this element */
  const char *pKey;            /* Key associated with this element */
};

/*
** Access routines.  To delete, insert a NULL pointer.
*/
void sqlite3HashInit(Hash*);
void *sqlite3HashInsert(Hash*, const char *pKey, void *pData);
void *sqlite3HashFind(const Hash*, const char *pKey);
void sqlite3HashClear(Hash*);

/*
** Macros for looping over all elements of a hash table.  The idiom is
** like this:
**
**   Hash h;

  u8 enc,
  void* pCtx,
  int(*xCompare)(void*,int,const void*,int,const void*),
  void(*xDel)(void*)
){
  CollSeq *pColl;
  int enc2;
  int nName = sqlite3Strlen30(zName);
  
  assert( sqlite3_mutex_held(db->mutex) );

  /* If SQLITE_UTF16 is specified as the encoding type, transform this
  ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
  ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
  */
................................................................................
    /* If collation sequence pColl was created directly by a call to
    ** sqlite3_create_collation, and not generated by synthCollSeq(),
    ** then any copies made by synthCollSeq() need to be invalidated.
    ** Also, collation destructor - CollSeq.xDel() - function may need
    ** to be called.
    */ 
    if( (pColl->enc & ~SQLITE_UTF16_ALIGNED)==enc2 ){
      CollSeq *aColl = sqlite3HashFind(&db->aCollSeq, zName, nName);
      int j;
      for(j=0; j<3; j++){
        CollSeq *p = &aColl[j];
        if( p->enc==pColl->enc ){
          if( p->xDel ){
            p->xDel(p->pUser);
          }

  u8 enc,
  void* pCtx,
  int(*xCompare)(void*,int,const void*,int,const void*),
  void(*xDel)(void*)
){
  CollSeq *pColl;
  int enc2;

  
  assert( sqlite3_mutex_held(db->mutex) );

  /* If SQLITE_UTF16 is specified as the encoding type, transform this
  ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
  ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
  */
................................................................................
    /* If collation sequence pColl was created directly by a call to
    ** sqlite3_create_collation, and not generated by synthCollSeq(),
    ** then any copies made by synthCollSeq() need to be invalidated.
    ** Also, collation destructor - CollSeq.xDel() - function may need
    ** to be called.
    */ 
    if( (pColl->enc & ~SQLITE_UTF16_ALIGNED)==enc2 ){
      CollSeq *aColl = sqlite3HashFind(&db->aCollSeq, zName);
      int j;
      for(j=0; j<3; j++){
        CollSeq *p = &aColl[j];
        if( p->enc==pColl->enc ){
          if( p->xDel ){
            p->xDel(p->pUser);
          }

  /* Check that the trigger name is not reserved and that no trigger of the
  ** specified name exists */
  zName = sqlite3NameFromToken(db, pName);
  if( !zName || SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
    goto trigger_cleanup;
  }
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  if( sqlite3HashFind(&(db->aDb[iDb].pSchema->trigHash),
                      zName, sqlite3Strlen30(zName)) ){
    if( !noErr ){
      sqlite3ErrorMsg(pParse, "trigger %T already exists", pName);
    }else{
      assert( !db->init.busy );
      sqlite3CodeVerifySchema(pParse, iDb);
    }
    goto trigger_cleanup;
................................................................................
        sqlite3MPrintf(db, "type='trigger' AND name='%q'", zName));
  }

  if( db->init.busy ){
    Trigger *pLink = pTrig;
    Hash *pHash = &db->aDb[iDb].pSchema->trigHash;
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
    pTrig = sqlite3HashInsert(pHash, zName, sqlite3Strlen30(zName), pTrig);
    if( pTrig ){
      db->mallocFailed = 1;
    }else if( pLink->pSchema==pLink->pTabSchema ){
      Table *pTab;
      int n = sqlite3Strlen30(pLink->table);
      pTab = sqlite3HashFind(&pLink->pTabSchema->tblHash, pLink->table, n);
      assert( pTab!=0 );
      pLink->pNext = pTab->pTrigger;
      pTab->pTrigger = pLink;
    }
  }

triggerfinish_cleanup:
................................................................................
** instead of the trigger name.
**/
void sqlite3DropTrigger(Parse *pParse, SrcList *pName, int noErr){
  Trigger *pTrigger = 0;
  int i;
  const char *zDb;
  const char *zName;
  int nName;
  sqlite3 *db = pParse->db;

  if( db->mallocFailed ) goto drop_trigger_cleanup;
  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
    goto drop_trigger_cleanup;
  }

  assert( pName->nSrc==1 );
  zDb = pName->a[0].zDatabase;
  zName = pName->a[0].zName;
  nName = sqlite3Strlen30(zName);
  assert( zDb!=0 || sqlite3BtreeHoldsAllMutexes(db) );
  for(i=OMIT_TEMPDB; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
    if( zDb && sqlite3StrICmp(db->aDb[j].zName, zDb) ) continue;
    assert( sqlite3SchemaMutexHeld(db, j, 0) );
    pTrigger = sqlite3HashFind(&(db->aDb[j].pSchema->trigHash), zName, nName);
    if( pTrigger ) break;
  }
  if( !pTrigger ){
    if( !noErr ){
      sqlite3ErrorMsg(pParse, "no such trigger: %S", pName, 0);
    }else{
      sqlite3CodeVerifyNamedSchema(pParse, zDb);
................................................................................
}

/*
** Return a pointer to the Table structure for the table that a trigger
** is set on.
*/
static Table *tableOfTrigger(Trigger *pTrigger){
  int n = sqlite3Strlen30(pTrigger->table);
  return sqlite3HashFind(&pTrigger->pTabSchema->tblHash, pTrigger->table, n);
}


/*
** Drop a trigger given a pointer to that trigger. 
*/
void sqlite3DropTriggerPtr(Parse *pParse, Trigger *pTrigger){
................................................................................
*/
void sqlite3UnlinkAndDeleteTrigger(sqlite3 *db, int iDb, const char *zName){
  Trigger *pTrigger;
  Hash *pHash;

  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  pHash = &(db->aDb[iDb].pSchema->trigHash);
  pTrigger = sqlite3HashInsert(pHash, zName, sqlite3Strlen30(zName), 0);
  if( ALWAYS(pTrigger) ){
    if( pTrigger->pSchema==pTrigger->pTabSchema ){
      Table *pTab = tableOfTrigger(pTrigger);
      Trigger **pp;
      for(pp=&pTab->pTrigger; *pp!=pTrigger; pp=&((*pp)->pNext));
      *pp = (*pp)->pNext;
    }

  /* Check that the trigger name is not reserved and that no trigger of the
  ** specified name exists */
  zName = sqlite3NameFromToken(db, pName);
  if( !zName || SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
    goto trigger_cleanup;
  }
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  if( sqlite3HashFind(&(db->aDb[iDb].pSchema->trigHash),zName) ){

    if( !noErr ){
      sqlite3ErrorMsg(pParse, "trigger %T already exists", pName);
    }else{
      assert( !db->init.busy );
      sqlite3CodeVerifySchema(pParse, iDb);
    }
    goto trigger_cleanup;
................................................................................
        sqlite3MPrintf(db, "type='trigger' AND name='%q'", zName));
  }

  if( db->init.busy ){
    Trigger *pLink = pTrig;
    Hash *pHash = &db->aDb[iDb].pSchema->trigHash;
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
    pTrig = sqlite3HashInsert(pHash, zName, pTrig);
    if( pTrig ){
      db->mallocFailed = 1;
    }else if( pLink->pSchema==pLink->pTabSchema ){
      Table *pTab;

      pTab = sqlite3HashFind(&pLink->pTabSchema->tblHash, pLink->table);
      assert( pTab!=0 );
      pLink->pNext = pTab->pTrigger;
      pTab->pTrigger = pLink;
    }
  }

triggerfinish_cleanup:
................................................................................
** instead of the trigger name.
**/
void sqlite3DropTrigger(Parse *pParse, SrcList *pName, int noErr){
  Trigger *pTrigger = 0;
  int i;
  const char *zDb;
  const char *zName;

  sqlite3 *db = pParse->db;

  if( db->mallocFailed ) goto drop_trigger_cleanup;
  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
    goto drop_trigger_cleanup;
  }

  assert( pName->nSrc==1 );
  zDb = pName->a[0].zDatabase;
  zName = pName->a[0].zName;

  assert( zDb!=0 || sqlite3BtreeHoldsAllMutexes(db) );
  for(i=OMIT_TEMPDB; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
    if( zDb && sqlite3StrICmp(db->aDb[j].zName, zDb) ) continue;
    assert( sqlite3SchemaMutexHeld(db, j, 0) );
    pTrigger = sqlite3HashFind(&(db->aDb[j].pSchema->trigHash), zName);
    if( pTrigger ) break;
  }
  if( !pTrigger ){
    if( !noErr ){
      sqlite3ErrorMsg(pParse, "no such trigger: %S", pName, 0);
    }else{
      sqlite3CodeVerifyNamedSchema(pParse, zDb);
................................................................................
}

/*
** Return a pointer to the Table structure for the table that a trigger
** is set on.
*/
static Table *tableOfTrigger(Trigger *pTrigger){

  return sqlite3HashFind(&pTrigger->pTabSchema->tblHash, pTrigger->table);
}


/*
** Drop a trigger given a pointer to that trigger. 
*/
void sqlite3DropTriggerPtr(Parse *pParse, Trigger *pTrigger){
................................................................................
*/
void sqlite3UnlinkAndDeleteTrigger(sqlite3 *db, int iDb, const char *zName){
  Trigger *pTrigger;
  Hash *pHash;

  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  pHash = &(db->aDb[iDb].pSchema->trigHash);
  pTrigger = sqlite3HashInsert(pHash, zName, 0);
  if( ALWAYS(pTrigger) ){
    if( pTrigger->pSchema==pTrigger->pTabSchema ){
      Table *pTab = tableOfTrigger(pTrigger);
      Trigger **pp;
      for(pp=&pTab->pTrigger; *pp!=pTrigger; pp=&((*pp)->pNext));
      *pp = (*pp)->pNext;
    }

  void (*xDestroy)(void *)        /* Module destructor function */
){
  int rc = SQLITE_OK;
  int nName;

  sqlite3_mutex_enter(db->mutex);
  nName = sqlite3Strlen30(zName);
  if( sqlite3HashFind(&db->aModule, zName, nName) ){
    rc = SQLITE_MISUSE_BKPT;
  }else{
    Module *pMod;
    pMod = (Module *)sqlite3DbMallocRaw(db, sizeof(Module) + nName + 1);
    if( pMod ){
      Module *pDel;
      char *zCopy = (char *)(&pMod[1]);
      memcpy(zCopy, zName, nName+1);
      pMod->zName = zCopy;
      pMod->pModule = pModule;
      pMod->pAux = pAux;
      pMod->xDestroy = xDestroy;
      pDel = (Module *)sqlite3HashInsert(&db->aModule,zCopy,nName,(void*)pMod);
      assert( pDel==0 || pDel==pMod );
      if( pDel ){
        db->mallocFailed = 1;
        sqlite3DbFree(db, pDel);
      }
    }
  }
................................................................................
  ** the first time the virtual table is used in an SQL statement. This
  ** allows a schema that contains virtual tables to be loaded before
  ** the required virtual table implementations are registered.  */
  else {
    Table *pOld;
    Schema *pSchema = pTab->pSchema;
    const char *zName = pTab->zName;
    int nName = sqlite3Strlen30(zName);
    assert( sqlite3SchemaMutexHeld(db, 0, pSchema) );
    pOld = sqlite3HashInsert(&pSchema->tblHash, zName, nName, pTab);
    if( pOld ){
      db->mallocFailed = 1;
      assert( pTab==pOld );  /* Malloc must have failed inside HashInsert() */
      return;
    }
    pParse->pNewTable = 0;
  }
................................................................................
  assert( pTab );
  if( (pTab->tabFlags & TF_Virtual)==0 || sqlite3GetVTable(db, pTab) ){
    return SQLITE_OK;
  }

  /* Locate the required virtual table module */
  zMod = pTab->azModuleArg[0];
  pMod = (Module*)sqlite3HashFind(&db->aModule, zMod, sqlite3Strlen30(zMod));

  if( !pMod ){
    const char *zModule = pTab->azModuleArg[0];
    sqlite3ErrorMsg(pParse, "no such module: %s", zModule);
    rc = SQLITE_ERROR;
  }else{
    char *zErr = 0;
................................................................................
  const char *zMod;

  pTab = sqlite3FindTable(db, zTab, db->aDb[iDb].zName);
  assert( pTab && (pTab->tabFlags & TF_Virtual)!=0 && !pTab->pVTable );

  /* Locate the required virtual table module */
  zMod = pTab->azModuleArg[0];
  pMod = (Module*)sqlite3HashFind(&db->aModule, zMod, sqlite3Strlen30(zMod));

  /* If the module has been registered and includes a Create method, 
  ** invoke it now. If the module has not been registered, return an 
  ** error. Otherwise, do nothing.
  */
  if( !pMod ){
    *pzErr = sqlite3MPrintf(db, "no such module: %s", zMod);

  void (*xDestroy)(void *)        /* Module destructor function */
){
  int rc = SQLITE_OK;
  int nName;

  sqlite3_mutex_enter(db->mutex);
  nName = sqlite3Strlen30(zName);
  if( sqlite3HashFind(&db->aModule, zName) ){
    rc = SQLITE_MISUSE_BKPT;
  }else{
    Module *pMod;
    pMod = (Module *)sqlite3DbMallocRaw(db, sizeof(Module) + nName + 1);
    if( pMod ){
      Module *pDel;
      char *zCopy = (char *)(&pMod[1]);
      memcpy(zCopy, zName, nName+1);
      pMod->zName = zCopy;
      pMod->pModule = pModule;
      pMod->pAux = pAux;
      pMod->xDestroy = xDestroy;
      pDel = (Module *)sqlite3HashInsert(&db->aModule,zCopy,(void*)pMod);
      assert( pDel==0 || pDel==pMod );
      if( pDel ){
        db->mallocFailed = 1;
        sqlite3DbFree(db, pDel);
      }
    }
  }
................................................................................
  ** the first time the virtual table is used in an SQL statement. This
  ** allows a schema that contains virtual tables to be loaded before
  ** the required virtual table implementations are registered.  */
  else {
    Table *pOld;
    Schema *pSchema = pTab->pSchema;
    const char *zName = pTab->zName;

    assert( sqlite3SchemaMutexHeld(db, 0, pSchema) );
    pOld = sqlite3HashInsert(&pSchema->tblHash, zName, pTab);
    if( pOld ){
      db->mallocFailed = 1;
      assert( pTab==pOld );  /* Malloc must have failed inside HashInsert() */
      return;
    }
    pParse->pNewTable = 0;
  }
................................................................................
  assert( pTab );
  if( (pTab->tabFlags & TF_Virtual)==0 || sqlite3GetVTable(db, pTab) ){
    return SQLITE_OK;
  }

  /* Locate the required virtual table module */
  zMod = pTab->azModuleArg[0];
  pMod = (Module*)sqlite3HashFind(&db->aModule, zMod);

  if( !pMod ){
    const char *zModule = pTab->azModuleArg[0];
    sqlite3ErrorMsg(pParse, "no such module: %s", zModule);
    rc = SQLITE_ERROR;
  }else{
    char *zErr = 0;
................................................................................
  const char *zMod;

  pTab = sqlite3FindTable(db, zTab, db->aDb[iDb].zName);
  assert( pTab && (pTab->tabFlags & TF_Virtual)!=0 && !pTab->pVTable );

  /* Locate the required virtual table module */
  zMod = pTab->azModuleArg[0];
  pMod = (Module*)sqlite3HashFind(&db->aModule, zMod);

  /* If the module has been registered and includes a Create method, 
  ** invoke it now. If the module has not been registered, return an 
  ** error. Otherwise, do nothing.
  */
  if( !pMod ){
    *pzErr = sqlite3MPrintf(db, "no such module: %s", zMod);