SQLite

  ** written. For index b-trees, it is the root page of the associated
  ** table.  */
  if( isIndex ){
    HashElem *p;
    for(p=sqliteHashFirst(&pSchema->idxHash); p; p=sqliteHashNext(p)){
      Index *pIdx = (Index *)sqliteHashData(p);
      if( pIdx->tnum==(int)iRoot ){
        if( iTab ){
          /* Two or more indexes share the same root page.  There must
          ** be imposter tables.  So just return true.  The assert is not
          ** useful in that case. */
          return 1;
        }
        iTab = pIdx->pTable->tnum;
      }
    }
  }else{
    iTab = iRoot;
  }

    }
    pPk->nKeyCol = j;
  }
  pPk->isCovering = 1;
  assert( pPk!=0 );
  nPk = pPk->nKeyCol;

  /* Make sure every column of the PRIMARY KEY is NOT NULL.  (Except,
  ** do not enforce this for imposter tables.) */
  if( !db->init.imposterTable ){
    for(i=0; i<nPk; i++){
      pTab->aCol[pPk->aiColumn[i]].notNull = 1;
    }
    pPk->uniqNotNull = 1;
  }

  /* The root page of the PRIMARY KEY is the table root page */
  pPk->tnum = pTab->tnum;

  /* Update the in-memory representation of all UNIQUE indices by converting
  ** the final rowid column into one or more columns of the PRIMARY KEY.
  */

    ** not.
    */
    case SQLITE_TESTCTRL_ISINIT: {
      if( sqlite3GlobalConfig.isInit==0 ) rc = SQLITE_ERROR;
      break;
    }

    /*   sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, db, dbName, onOff, tnum);
    **
    ** This test control is used to create imposter tables.  "db" is a pointer
    ** to the database connection.  dbName is the database name (ex: "main" or
    ** "temp") which will receive the imposter.  "onOff" turns imposter mode on
    ** or off.  "tnum" is the root page of the b-tree to which the imposter
    ** table should connect.
    **
    ** Enable imposter mode only when the schema has already been parsed.  Then
    ** run a single CREATE TABLE statement to construct the imposter table in the
    ** parsed schema.  Then turn imposter mode back off again.
    **
    ** If onOff==0 and tnum>0 then reset the schema for all databases, causing
    ** the schema to be reparsed the next time it is needed.  This has the
    ** effect of erasing all imposter tables.
    */
    case SQLITE_TESTCTRL_IMPOSTER: {
      sqlite3 *db = va_arg(ap, sqlite3*);
      db->init.iDb = sqlite3FindDbName(db, va_arg(ap,const char*));
      db->init.busy = db->init.imposterTable = va_arg(ap,int);
      db->init.newTnum = va_arg(ap,int);
      if( db->init.busy==0 && db->init.newTnum>0 ){
        sqlite3ResetAllSchemasOfConnection(db);
      }
      break;
    }
  }
  va_end(ap);
#endif /* SQLITE_OMIT_BUILTIN_TEST */
  return rc;
}

      { "always",                SQLITE_TESTCTRL_ALWAYS                 },
      { "reserve",               SQLITE_TESTCTRL_RESERVE                },
      { "optimizations",         SQLITE_TESTCTRL_OPTIMIZATIONS          },
      { "iskeyword",             SQLITE_TESTCTRL_ISKEYWORD              },
      { "scratchmalloc",         SQLITE_TESTCTRL_SCRATCHMALLOC          },
      { "byteorder",             SQLITE_TESTCTRL_BYTEORDER              },
      { "never_corrupt",         SQLITE_TESTCTRL_NEVER_CORRUPT          },
      { "imposter",              SQLITE_TESTCTRL_IMPOSTER               },
    };
    int testctrl = -1;
    int rc = 0;
    int i, n;
    open_db(p, 0);

    /* convert testctrl text option to value. allow any unique prefix

          } else {
            fprintf(stderr,"Error: testctrl %s takes a single char * option\n",
                            azArg[1]);
          }
          break;
#endif

        case SQLITE_TESTCTRL_IMPOSTER:
          if( nArg==5 ){
            rc = sqlite3_test_control(testctrl, p->db, 
                          azArg[2],
                          integerValue(azArg[3]),
                          integerValue(azArg[4]));
          }else{
            fprintf(stderr,"Usage: .testctrl initmode dbName onoff tnum\n");
            rc = 1;
          }
          break;

        case SQLITE_TESTCTRL_BITVEC_TEST:         
        case SQLITE_TESTCTRL_FAULT_INSTALL:       
        case SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS: 

#define SQLITE_TESTCTRL_LOCALTIME_FAULT         18
#define SQLITE_TESTCTRL_EXPLAIN_STMT            19  /* NOT USED */
#define SQLITE_TESTCTRL_NEVER_CORRUPT           20
#define SQLITE_TESTCTRL_VDBE_COVERAGE           21
#define SQLITE_TESTCTRL_BYTEORDER               22
#define SQLITE_TESTCTRL_ISINIT                  23
#define SQLITE_TESTCTRL_SORTER_MMAP             24
#define SQLITE_TESTCTRL_IMPOSTER                25
#define SQLITE_TESTCTRL_LAST                    25

/*
** CAPI3REF: SQLite Runtime Status
**
** ^This interface is used to retrieve runtime status information
** about the performance of SQLite, and optionally to reset various

  int aLimit[SQLITE_N_LIMIT];   /* Limits */
  int nMaxSorterMmap;           /* Maximum size of regions mapped by sorter */
  struct sqlite3InitInfo {      /* Information used during initialization */
    int newTnum;                /* Rootpage of table being initialized */
    u8 iDb;                     /* Which db file is being initialized */
    u8 busy;                    /* TRUE if currently initializing */
    u8 orphanTrigger;           /* Last statement is orphaned TEMP trigger */
    u8 imposterTable;           /* Building an imposter table */
  } init;
  int nVdbeActive;              /* Number of VDBEs currently running */
  int nVdbeRead;                /* Number of active VDBEs that read or write */
  int nVdbeWrite;               /* Number of active VDBEs that read and write */
  int nVdbeExec;                /* Number of nested calls to VdbeExec() */
  int nExtension;               /* Number of loaded extensions */
  void **aExtension;            /* Array of shared library handles */

){
  struct Verb {
    const char *zName;
    int i;
  } aVerb[] = {
    { "SQLITE_TESTCTRL_LOCALTIME_FAULT", SQLITE_TESTCTRL_LOCALTIME_FAULT }, 
    { "SQLITE_TESTCTRL_SORTER_MMAP",     SQLITE_TESTCTRL_SORTER_MMAP     }, 
    { "SQLITE_TESTCTRL_IMPOSTER",        SQLITE_TESTCTRL_IMPOSTER        },
  };
  int iVerb;
  int iFlag;
  int rc;

  if( objc<2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "VERB ARGS...");

      }
      if( getDbPointer(interp, Tcl_GetString(objv[2]), &db) ) return TCL_ERROR;
      if( Tcl_GetIntFromObj(interp, objv[3], &val) ) return TCL_ERROR;
      sqlite3_test_control(SQLITE_TESTCTRL_SORTER_MMAP, db, val);
      break;
    }

    case SQLITE_TESTCTRL_IMPOSTER: {
      int onOff, tnum;
      const char *zDbName;
      sqlite3 *db;
      if( objc!=6 ){
        Tcl_WrongNumArgs(interp, 2, objv, "DB dbName onOff tnum");
        return TCL_ERROR;
      }
      if( getDbPointer(interp, Tcl_GetString(objv[2]), &db) ) return TCL_ERROR;
      zDbName = Tcl_GetString(objv[3]);
      if( Tcl_GetIntFromObj(interp, objv[4], &onOff) ) return TCL_ERROR;
      if( Tcl_GetIntFromObj(interp, objv[5], &tnum) ) return TCL_ERROR;
      sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER, db, zDbName, onOff, tnum);
      break;
    }
  }

  Tcl_ResetResult(interp);
  return TCL_OK;
}

#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# This file implements tests for SQLite library.
#
# The focus of this file is adding extra entries in the symbol table
# using sqlite3_test_control(SQLITE_TESTCTRL_IMPOSTER) and verifying that
# SQLite handles those as expected.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix imposter

# Create a bunch of data to sort against
#
do_test imposter-1.0 {
  execsql {
    CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c, d NOT NULL);
    CREATE INDEX t1b ON t1(b);
    CREATE UNIQUE INDEX t1c ON t1(c);
    WITH RECURSIVE c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<30)
      INSERT INTO t1(a,b,c,d) SELECT i,1000+i,2000+i,3000+i FROM c;
  }
  set t1_root [db one {SELECT rootpage FROM sqlite_master WHERE name='t1'}]
  set t1b_root [db one {SELECT rootpage FROM sqlite_master WHERE name='t1b'}]
  set t1c_root [db one {SELECT rootpage FROM sqlite_master WHERE name='t1c'}]

  # Create an imposter table that uses the same b-tree as t1 but which does
  # not have the indexes
  #
  sqlite3_test_control SQLITE_TESTCTRL_IMPOSTER db main 1 $t1_root
  db eval {CREATE TABLE xt1(a,b,c,d)}

  # And create an imposter table for the t1c index.
  sqlite3_test_control SQLITE_TESTCTRL_IMPOSTER db main 1 $t1c_root
  db eval {CREATE TABLE xt1c(c,rowid,PRIMARY KEY(c,rowid))WITHOUT ROWID;}

  # Go out of imposter mode for now.
  sqlite3_test_control SQLITE_TESTCTRL_IMPOSTER db main 0 0

  # Create triggers to record changes to xt1.
  #
  db eval {
    CREATE TEMP TABLE chnglog(desc TEXT);
    CREATE TEMP TRIGGER xt1_del AFTER DELETE ON xt1 BEGIN
      INSERT INTO chnglog VALUES(

  }
} {}

# The xt1 table has separate xt1.rowid and xt1.a columns.  The xt1.rowid
# column corresponds to t1.rowid and t1.a, but the xt1.a column is always
# NULL
#
do_execsql_test imposter-1.1 {
  SELECT rowid FROM xt1 WHERE a IS NOT NULL;
} {}
do_execsql_test imposter-1.2 {
  SELECT a,b,c,d FROM t1 EXCEPT SELECT rowid,b,c,d FROM xt1;
  SELECT rowid,b,c,d FROM xt1 EXCEPT SELECT a,b,c,d FROM t1;
} {}


# Make changes via the xt1 shadow table.  This will not update the
# indexes on t1 nor check the uniqueness constraint on t1.c nor check
# the NOT NULL constraint on t1.d, resulting in a logically inconsistent
# database.
#
do_execsql_test imposter-1.3 {
  DELETE FROM xt1 WHERE rowid=5;
  INSERT INTO xt1(rowid,a,b,c,d) VALUES(99,'hello',1099,2022,NULL);
  SELECT * FROM chnglog ORDER BY rowid;
} [list \
  {DELETE t1: rowid=5, a=NULL, b=1005, c=2005, d=3005} \
  {INSERT t1:  rowid=99, a='hello', b=1099, c=2022, d=NULL} \
]

do_execsql_test imposter-1.4a {
  PRAGMA integrity_check;
} {/NULL value in t1.d/}
do_execsql_test imposter-1.4b {
  PRAGMA integrity_check;
} {/row # missing from index t1b/}
do_execsql_test imposter-1.4c {
  PRAGMA integrity_check;
} {/row # missing from index t1c/}

# Cleanup the corruption.
# Then demonstrate that the xt1c imposter table can insert non-unique
# and NULL values into the UNIQUE index.
#
do_execsql_test imposter-2.0 {
  DELETE FROM t1;
  WITH RECURSIVE c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<10)
   INSERT INTO t1(a,b,c,d) SELECT i,i,i,i FROM c;
  UPDATE xt1c SET c=NULL WHERE rowid=5;
  PRAGMA integrity_check;
} {/row # missing from index t1c/}

do_execsql_test imposter-2.1 {
  DELETE FROM t1;
  WITH RECURSIVE c(i) AS (VALUES(1) UNION ALL SELECT i+1 FROM c WHERE i<10)
   INSERT INTO t1(a,b,c,d) SELECT i,i,i,i FROM c;
  UPDATE xt1c SET c=99 WHERE rowid IN (5,7,9);
  SELECT c FROM t1 ORDER BY c;
} {1 2 3 4 6 8 10 99 99 99}
do_execsql_test imposter-2.2 {
  UPDATE xt1 SET c=99 WHERE rowid IN (5,7,9);
  PRAGMA integrity_check;
} {/non-unique entry in index t1c/}

# Erase the imposter tables
#
do_test imposter-3.1 {
  sqlite3_test_control SQLITE_TESTCTRL_IMPOSTER db main 0 1
  db eval {
    DELETE FROM t1 WHERE rowid IN (5,7,9);
    PRAGMA integrity_check;
  }
} {ok}


finish_test