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Overview
Comment:Fix sessions module handling of sqlite_stat1 rows with (idx IS NULL).
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA3-256:0e916416331d7948b312a5dd58ac0c145030bb3b47a37dab2636564397249a86
User & Date: dan 2018-01-18 16:59:52
Context
2018-01-18
17:09
Update the autoconf configure.ac script and Makefile.am templates so that ZLIB is automatically detected and used. check-in: 41bfb6b8 user: drh tags: trunk
16:59
Fix sessions module handling of sqlite_stat1 rows with (idx IS NULL). check-in: 0e916416 user: dan tags: trunk
16:56
Clarify the handling of the sqlite_stat1 table by legacy versions of the sessions module. Closed-Leaf check-in: dc7c48cb user: dan tags: sessions-stat1
16:52
Fix to the documentation for sqlite3_trace_v2(). No changes to code. check-in: 6fbd0a11 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to ext/session/sessionstat1.test.

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do_execsql_test -db db2 2.4 {
  SELECT * FROM sqlite_stat1
} {
}

do_execsql_test -db db2 2.5 { SELECT count(*) FROM t1 } 32



























































































































































































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do_execsql_test -db db2 2.4 {
  SELECT * FROM sqlite_stat1
} {
}

do_execsql_test -db db2 2.5 { SELECT count(*) FROM t1 } 32

#-------------------------------------------------------------------------
db2 close
forcedelete test.db2
reset_db
sqlite3 db2 test.db2

do_test 3.0 {
  do_common_sql {
    CREATE TABLE t1(a, b, c);
    ANALYZE;
    DELETE FROM sqlite_stat1;
  }
  execsql {
    INSERT INTO t1 VALUES(1, 1, 1);
    INSERT INTO t1 VALUES(2, 2, 2);
    INSERT INTO t1 VALUES(3, 3, 3);
    INSERT INTO t1 VALUES(4, 4, 4);
  }
} {} 

do_iterator_test 3.1 {} {
  ANALYZE
} {
  {INSERT sqlite_stat1 0 XX. {} {t t1 b {} t 4}}
}
db null null
db2 null null
do_execsql_test 3.2 {
  SELECT * FROM sqlite_stat1;
} {t1 null 4}
do_test 3.3 {
  execsql { DELETE FROM sqlite_stat1 }
  do_then_apply_sql { ANALYZE }
  execsql { SELECT * FROM sqlite_stat1 } db2
} {t1 null 4}
do_test 3.4 {
  execsql { INSERT INTO t1 VALUES(5,5,5) }
  do_then_apply_sql { ANALYZE }
  execsql { SELECT * FROM sqlite_stat1 } db2
} {t1 null 5}
do_test 3.5 {
  do_then_apply_sql { DROP TABLE t1 }
  execsql { SELECT * FROM sqlite_stat1 } db2
} {}

do_test 3.6.1 {
  execsql { 
    CREATE TABLE t1(a, b, c);
    CREATE TABLE t2(x, y, z);
    INSERT INTO t1 VALUES(1,1,1), (2,2,2), (3,3,3), (4,4,4), (5,5,5);
    INSERT INTO t2 SELECT * FROM t1;
    DELETE FROM sqlite_stat1;
  }
  sqlite3session S db main
  S attach sqlite_stat1
  execsql { ANALYZE }
} {}
do_changeset_test 3.6.2 S {
  {INSERT sqlite_stat1 0 XX. {} {t t2 b {} t 5}}
  {INSERT sqlite_stat1 0 XX. {} {t t1 b {} t 5}}
}
do_changeset_invert_test 3.6.3 S {
  {DELETE sqlite_stat1 0 XX. {t t2 b {} t 5} {}}
  {DELETE sqlite_stat1 0 XX. {t t1 b {} t 5} {}}
}
do_test 3.6.4 { S delete } {}

proc sql_changeset_concat {args} {
  foreach sql $args {
    sqlite3session S db main
    S attach sqlite_stat1
    execsql $sql
    set change [S changeset]
    S delete

    if {[info vars ret]!=""} {
      set ret [sqlite3changeset_concat $ret $change]
    } else {
      set ret $change
    }
  }

  changeset_to_list $ret
}

proc do_scc_test {tn args} {
  uplevel [list \
    do_test $tn [concat sql_changeset_concat [lrange $args 0 end-1]] \
    [list {*}[ lindex $args end ]]
  ]
}

do_execsql_test 3.7.0 {
  DELETE FROM sqlite_stat1;
}
do_scc_test 3.7.1 {
  ANALYZE;
} {
  INSERT INTO t2 VALUES(6,6,6);
  ANALYZE;
} {
  {INSERT sqlite_stat1 0 XX. {} {t t1 b {} t 5}}
  {INSERT sqlite_stat1 0 XX. {} {t t2 b {} t 6}}
}

#-------------------------------------------------------------------------
catch { db2 close }
reset_db
forcedelete test.db2
sqlite3 db2 test.db2

do_test 4.1.0 {
  do_common_sql {
    CREATE TABLE t1(a, b);
    CREATE INDEX i1 ON t1(a);
    CREATE INDEX i2 ON t1(b);
    INSERT INTO t1 VALUES(1,1), (2,2);
    ANALYZE;
  }
  execsql { DELETE FROM sqlite_stat1 }
} {}

do_test 4.1.1 {
  execsql { INSERT INTO t1 VALUES(3,3); }
  set C [changeset_from_sql {ANALYZE}]
  set ::c [list]
  proc xConflict {args} {
    lappend ::c $args
    return "OMIT"
  }
  sqlite3changeset_apply db2 $C xConflict
  set ::c
} [list {*}{
  {INSERT sqlite_stat1 CONFLICT {t t1 t i1 t {3 1}} {t t1 t i1 t {2 1}}}
  {INSERT sqlite_stat1 CONFLICT {t t1 t i2 t {3 1}} {t t1 t i2 t {2 1}}}
}]

do_execsql_test -db db2 4.1.2 {
  SELECT * FROM sqlite_stat1 ORDER BY 1,2;
} {t1 i1 {2 1} t1 i2 {2 1}}

do_test 4.1.3 {
  proc xConflict {args} {
    return "REPLACE"
  }
  sqlite3changeset_apply db2 $C xConflict
  execsql { SELECT * FROM sqlite_stat1 ORDER BY 1,2 } db2
} {t1 i1 {3 1} t1 i2 {3 1}}

do_test 4.2.0 {
  do_common_sql { 
    DROP TABLE t1;
    CREATE TABLE t3(x,y);
    INSERT INTO t3 VALUES('a','a');
    INSERT INTO t3 VALUES('b','b');
    ANALYZE;
  }
  execsql { DELETE FROM sqlite_stat1 }
} {}
do_test 4.2.1 {
  execsql { INSERT INTO t3 VALUES('c','c'); }
  set C [changeset_from_sql {ANALYZE}]
  set ::c [list]
  proc xConflict {args} {
    lappend ::c $args
    return "OMIT"
  }
  sqlite3changeset_apply db2 $C xConflict
  set ::c
} [list {*}{
  {INSERT sqlite_stat1 CONFLICT {t t3 b {} t 3} {t t3 b {} t 2}}
}]

db2 null null
do_execsql_test -db db2 4.2.2 {
  SELECT * FROM sqlite_stat1 ORDER BY 1,2;
} {t3 null 2}

do_test 4.2.3 {
  proc xConflict {args} {
    return "REPLACE"
  }
  sqlite3changeset_apply db2 $C xConflict
  execsql { SELECT * FROM sqlite_stat1 ORDER BY 1,2 } db2
} {t3 null 3}

finish_test

Changes to ext/session/sqlite3session.c.

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  char *zDb;                      /* Name of database session is attached to */
  int bEnable;                    /* True if currently recording */
  int bIndirect;                  /* True if all changes are indirect */
  int bAutoAttach;                /* True to auto-attach tables */
  int rc;                         /* Non-zero if an error has occurred */
  void *pFilterCtx;               /* First argument to pass to xTableFilter */
  int (*xTableFilter)(void *pCtx, const char *zTab);

  sqlite3_session *pNext;         /* Next session object on same db. */
  SessionTable *pTable;           /* List of attached tables */
  SessionHook hook;               /* APIs to grab new and old data with */
};

/*
** Instances of this structure are used to build strings or binary records.
................................................................................
** a subset of the initial values that the modified row contained at the
** start of the session. Or no initial values if the row was inserted.
*/
struct SessionTable {
  SessionTable *pNext;
  char *zName;                    /* Local name of table */
  int nCol;                       /* Number of columns in table zName */

  const char **azCol;             /* Column names */
  u8 *abPK;                       /* Array of primary key flags */
  int nEntry;                     /* Total number of entries in hash table */
  int nChange;                    /* Size of apChange[] array */
  SessionChange **apChange;       /* Hash table buckets */
};

................................................................................
          z = (const u8 *)sqlite3_value_blob(pVal);
        }
        n = sqlite3_value_bytes(pVal);
        if( !z && (eType!=SQLITE_BLOB || n>0) ) return SQLITE_NOMEM;
        h = sessionHashAppendBlob(h, n, z);
      }else{
        assert( eType==SQLITE_NULL );

        *pbNullPK = 1;
      }
    }
  }

  *piHash = (h % pTab->nChange);
  return SQLITE_OK;
................................................................................
      int i;
      for(i=0; i<pTab->nCol; i++){
        if( abPK[i] ){
          pTab->abPK = abPK;
          break;
        }
      }


    }
  }

  return (pSession->rc || pTab->abPK==0);
}










































/*
** This function is only called from with a pre-update-hook reporting a 
** change on table pTab (attached to session pSession). The type of change
** (UPDATE, INSERT, DELETE) is specified by the first argument.
**
** Unless one is already present or an error occurs, an entry is added
................................................................................
  int op,                         /* One of SQLITE_UPDATE, INSERT, DELETE */
  sqlite3_session *pSession,      /* Session object pTab is attached to */
  SessionTable *pTab              /* Table that change applies to */
){
  int iHash; 
  int bNull = 0; 
  int rc = SQLITE_OK;


  if( pSession->rc ) return;

  /* Load table details if required */
  if( sessionInitTable(pSession, pTab) ) return;

  /* Check the number of columns in this xPreUpdate call matches the 
................................................................................
  }

  /* Grow the hash table if required */
  if( sessionGrowHash(0, pTab) ){
    pSession->rc = SQLITE_NOMEM;
    return;
  }




















  /* Calculate the hash-key for this change. If the primary key of the row
  ** includes a NULL value, exit early. Such changes are ignored by the
  ** session module. */
  rc = sessionPreupdateHash(pSession, pTab, op==SQLITE_INSERT, &iHash, &bNull);
  if( rc!=SQLITE_OK ) goto error_out;

................................................................................
        pC->bIndirect = 0;
      }
    }
  }

  /* If an error has occurred, mark the session object as failed. */
 error_out:



  if( rc!=SQLITE_OK ){
    pSession->rc = rc;
  }
}

static int sessionFindTable(
  sqlite3_session *pSession, 
................................................................................
    if( (*pp)==pSession ){
      *pp = (*pp)->pNext;
      if( pHead ) sqlite3_preupdate_hook(db, xPreUpdate, (void*)pHead);
      break;
    }
  }
  sqlite3_mutex_leave(sqlite3_db_mutex(db));


  /* Delete all attached table objects. And the contents of their 
  ** associated hash-tables. */
  sessionDeleteTable(pSession->pTable);

  /* Free the session object itself. */
  sqlite3_free(pSession);
................................................................................
  const char *zTab,               /* Table name */
  int nCol,                       /* Number of columns in table */
  const char **azCol,             /* Names of table columns */
  u8 *abPK,                       /* PRIMARY KEY  array */
  sqlite3_stmt **ppStmt           /* OUT: Prepared SELECT statement */
){
  int rc = SQLITE_OK;









  int i;
  const char *zSep = "";
  SessionBuffer buf = {0, 0, 0};

  sessionAppendStr(&buf, "SELECT * FROM ", &rc);
  sessionAppendIdent(&buf, zDb, &rc);
  sessionAppendStr(&buf, ".", &rc);
  sessionAppendIdent(&buf, zTab, &rc);
  sessionAppendStr(&buf, " WHERE ", &rc);
  for(i=0; i<nCol; i++){
    if( abPK[i] ){
      sessionAppendStr(&buf, zSep, &rc);
      sessionAppendIdent(&buf, azCol[i], &rc);
      sessionAppendStr(&buf, " = ?", &rc);
      sessionAppendInteger(&buf, i+1, &rc);
      zSep = " AND ";
    }
  }




  if( rc==SQLITE_OK ){
    rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, ppStmt, 0);
  }
  sqlite3_free(buf.aBuf);
  return rc;
}

/*
** Bind the PRIMARY KEY values from the change passed in argument pChange
** to the SELECT statement passed as the first argument. The SELECT statement
** is as prepared by function sessionSelectStmt().
................................................................................
  sqlite3_stmt *pDelete;          /* DELETE statement */
  sqlite3_stmt *pUpdate;          /* UPDATE statement */
  sqlite3_stmt *pInsert;          /* INSERT statement */
  sqlite3_stmt *pSelect;          /* SELECT statement */
  int nCol;                       /* Size of azCol[] and abPK[] arrays */
  const char **azCol;             /* Array of column names */
  u8 *abPK;                       /* Boolean array - true if column is in PK */

  int bDeferConstraints;          /* True to defer constraints */
  SessionBuffer constraints;      /* Deferred constraints are stored here */
};

/*
** Formulate a statement to DELETE a row from database db. Assuming a table
** structure like this:
................................................................................
  if( rc==SQLITE_OK ){
    rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, &p->pUpdate, 0);
  }
  sqlite3_free(buf.aBuf);

  return rc;
}


/*
** Formulate and prepare an SQL statement to query table zTab by primary
** key. Assuming the following table structure:
**
**     CREATE TABLE x(a, b, c, d, PRIMARY KEY(a, c));
**
................................................................................

  if( rc==SQLITE_OK ){
    rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, &p->pInsert, 0);
  }
  sqlite3_free(buf.aBuf);
  return rc;
}










































/*
** A wrapper around sqlite3_bind_value() that detects an extra problem. 
** See comments in the body of this function for details.
*/
static int sessionBindValue(
  sqlite3_stmt *pStmt,            /* Statement to bind value to */
................................................................................
      rc = sessionConflictHandler(
          SQLITE_CHANGESET_CONFLICT, p, pIter, xConflict, pCtx, 0
      );
    }

  }else{
    assert( op==SQLITE_INSERT );












    rc = sessionBindRow(pIter, sqlite3changeset_new, nCol, 0, p->pInsert);
    if( rc!=SQLITE_OK ) return rc;

    sqlite3_step(p->pInsert);
    rc = sqlite3_reset(p->pInsert);


    if( (rc&0xff)==SQLITE_CONSTRAINT ){
      rc = sessionConflictHandler(
          SQLITE_CHANGESET_CONFLICT, p, pIter, xConflict, pCtx, pbReplace
      );
    }
  }

................................................................................
          schemaMismatch = 1;
          sqlite3_log(SQLITE_SCHEMA, "sqlite3changeset_apply(): "
              "primary key mismatch for table %s", zTab
          );
        }
        else{
          sApply.nCol = nCol;






          if((rc = sessionSelectRow(db, zTab, &sApply))
          || (rc = sessionUpdateRow(db, zTab, &sApply))
          || (rc = sessionDeleteRow(db, zTab, &sApply))
          || (rc = sessionInsertRow(db, zTab, &sApply))
          ){
            break;


          }
        }
        nTab = sqlite3Strlen30(zTab);
      }
    }

    /* If there is a schema mismatch on the current table, proceed to the







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....
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....
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....
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....
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  char *zDb;                      /* Name of database session is attached to */
  int bEnable;                    /* True if currently recording */
  int bIndirect;                  /* True if all changes are indirect */
  int bAutoAttach;                /* True to auto-attach tables */
  int rc;                         /* Non-zero if an error has occurred */
  void *pFilterCtx;               /* First argument to pass to xTableFilter */
  int (*xTableFilter)(void *pCtx, const char *zTab);
  sqlite3_value *pZeroBlob;       /* Value containing X'' */
  sqlite3_session *pNext;         /* Next session object on same db. */
  SessionTable *pTable;           /* List of attached tables */
  SessionHook hook;               /* APIs to grab new and old data with */
};

/*
** Instances of this structure are used to build strings or binary records.
................................................................................
** a subset of the initial values that the modified row contained at the
** start of the session. Or no initial values if the row was inserted.
*/
struct SessionTable {
  SessionTable *pNext;
  char *zName;                    /* Local name of table */
  int nCol;                       /* Number of columns in table zName */
  int bStat1;                     /* True if this is sqlite_stat1 */
  const char **azCol;             /* Column names */
  u8 *abPK;                       /* Array of primary key flags */
  int nEntry;                     /* Total number of entries in hash table */
  int nChange;                    /* Size of apChange[] array */
  SessionChange **apChange;       /* Hash table buckets */
};

................................................................................
          z = (const u8 *)sqlite3_value_blob(pVal);
        }
        n = sqlite3_value_bytes(pVal);
        if( !z && (eType!=SQLITE_BLOB || n>0) ) return SQLITE_NOMEM;
        h = sessionHashAppendBlob(h, n, z);
      }else{
        assert( eType==SQLITE_NULL );
        assert( pTab->bStat1==0 || i!=1 );
        *pbNullPK = 1;
      }
    }
  }

  *piHash = (h % pTab->nChange);
  return SQLITE_OK;
................................................................................
      int i;
      for(i=0; i<pTab->nCol; i++){
        if( abPK[i] ){
          pTab->abPK = abPK;
          break;
        }
      }
      if( 0==sqlite3_stricmp("sqlite_stat1", pTab->zName) ){
        pTab->bStat1 = 1;
      }
    }
  }
  return (pSession->rc || pTab->abPK==0);
}

/*
** Versions of the four methods in object SessionHook for use with the
** sqlite_stat1 table. The purpose of this is to substitute a zero-length
** blob each time a NULL value is read from the "idx" column of the
** sqlite_stat1 table.
*/
typedef struct SessionStat1Ctx SessionStat1Ctx;
struct SessionStat1Ctx {
  SessionHook hook;
  sqlite3_session *pSession;
};
static int sessionStat1Old(void *pCtx, int iCol, sqlite3_value **ppVal){
  SessionStat1Ctx *p = (SessionStat1Ctx*)pCtx;
  sqlite3_value *pVal = 0;
  int rc = p->hook.xOld(p->hook.pCtx, iCol, &pVal);
  if( rc==SQLITE_OK && iCol==1 && sqlite3_value_type(pVal)==SQLITE_NULL ){
    pVal = p->pSession->pZeroBlob;
  }
  *ppVal = pVal;
  return rc;
}
static int sessionStat1New(void *pCtx, int iCol, sqlite3_value **ppVal){
  SessionStat1Ctx *p = (SessionStat1Ctx*)pCtx;
  sqlite3_value *pVal = 0;
  int rc = p->hook.xNew(p->hook.pCtx, iCol, &pVal);
  if( rc==SQLITE_OK && iCol==1 && sqlite3_value_type(pVal)==SQLITE_NULL ){
    pVal = p->pSession->pZeroBlob;
  }
  *ppVal = pVal;
  return rc;
}
static int sessionStat1Count(void *pCtx){
  SessionStat1Ctx *p = (SessionStat1Ctx*)pCtx;
  return p->hook.xCount(p->hook.pCtx);
}
static int sessionStat1Depth(void *pCtx){
  SessionStat1Ctx *p = (SessionStat1Ctx*)pCtx;
  return p->hook.xDepth(p->hook.pCtx);
}


/*
** This function is only called from with a pre-update-hook reporting a 
** change on table pTab (attached to session pSession). The type of change
** (UPDATE, INSERT, DELETE) is specified by the first argument.
**
** Unless one is already present or an error occurs, an entry is added
................................................................................
  int op,                         /* One of SQLITE_UPDATE, INSERT, DELETE */
  sqlite3_session *pSession,      /* Session object pTab is attached to */
  SessionTable *pTab              /* Table that change applies to */
){
  int iHash; 
  int bNull = 0; 
  int rc = SQLITE_OK;
  SessionStat1Ctx stat1;

  if( pSession->rc ) return;

  /* Load table details if required */
  if( sessionInitTable(pSession, pTab) ) return;

  /* Check the number of columns in this xPreUpdate call matches the 
................................................................................
  }

  /* Grow the hash table if required */
  if( sessionGrowHash(0, pTab) ){
    pSession->rc = SQLITE_NOMEM;
    return;
  }

  if( pTab->bStat1 ){
    stat1.hook = pSession->hook;
    stat1.pSession = pSession;
    pSession->hook.pCtx = (void*)&stat1;
    pSession->hook.xNew = sessionStat1New;
    pSession->hook.xOld = sessionStat1Old;
    pSession->hook.xCount = sessionStat1Count;
    pSession->hook.xDepth = sessionStat1Depth;
    if( pSession->pZeroBlob==0 ){
      sqlite3_value *p = sqlite3ValueNew(0);
      if( p==0 ){
        rc = SQLITE_NOMEM;
        goto error_out;
      }
      sqlite3ValueSetStr(p, 0, "", 0, SQLITE_STATIC);
      pSession->pZeroBlob = p;
    }
  }

  /* Calculate the hash-key for this change. If the primary key of the row
  ** includes a NULL value, exit early. Such changes are ignored by the
  ** session module. */
  rc = sessionPreupdateHash(pSession, pTab, op==SQLITE_INSERT, &iHash, &bNull);
  if( rc!=SQLITE_OK ) goto error_out;

................................................................................
        pC->bIndirect = 0;
      }
    }
  }

  /* If an error has occurred, mark the session object as failed. */
 error_out:
  if( pTab->bStat1 ){
    pSession->hook = stat1.hook;
  }
  if( rc!=SQLITE_OK ){
    pSession->rc = rc;
  }
}

static int sessionFindTable(
  sqlite3_session *pSession, 
................................................................................
    if( (*pp)==pSession ){
      *pp = (*pp)->pNext;
      if( pHead ) sqlite3_preupdate_hook(db, xPreUpdate, (void*)pHead);
      break;
    }
  }
  sqlite3_mutex_leave(sqlite3_db_mutex(db));
  sqlite3ValueFree(pSession->pZeroBlob);

  /* Delete all attached table objects. And the contents of their 
  ** associated hash-tables. */
  sessionDeleteTable(pSession->pTable);

  /* Free the session object itself. */
  sqlite3_free(pSession);
................................................................................
  const char *zTab,               /* Table name */
  int nCol,                       /* Number of columns in table */
  const char **azCol,             /* Names of table columns */
  u8 *abPK,                       /* PRIMARY KEY  array */
  sqlite3_stmt **ppStmt           /* OUT: Prepared SELECT statement */
){
  int rc = SQLITE_OK;
  char *zSql = 0;
  int nSql = -1;

  if( 0==sqlite3_stricmp("sqlite_stat1", zTab) ){
    zSql = sqlite3_mprintf(
        "SELECT tbl, ?2, stat FROM %Q.sqlite_stat1 WHERE tbl IS ?1 AND "
        "idx IS (CASE WHEN ?2=X'' THEN NULL ELSE ?2 END)", zDb
    );
  }else{
    int i;
    const char *zSep = "";
    SessionBuffer buf = {0, 0, 0};

    sessionAppendStr(&buf, "SELECT * FROM ", &rc);
    sessionAppendIdent(&buf, zDb, &rc);
    sessionAppendStr(&buf, ".", &rc);
    sessionAppendIdent(&buf, zTab, &rc);
    sessionAppendStr(&buf, " WHERE ", &rc);
    for(i=0; i<nCol; i++){
      if( abPK[i] ){
        sessionAppendStr(&buf, zSep, &rc);
        sessionAppendIdent(&buf, azCol[i], &rc);
        sessionAppendStr(&buf, " IS ?", &rc);
        sessionAppendInteger(&buf, i+1, &rc);
        zSep = " AND ";
      }
    }
    zSql = (char*)buf.aBuf;
    nSql = buf.nBuf;
  }

  if( rc==SQLITE_OK ){
    rc = sqlite3_prepare_v2(db, zSql, nSql, ppStmt, 0);
  }
  sqlite3_free(zSql);
  return rc;
}

/*
** Bind the PRIMARY KEY values from the change passed in argument pChange
** to the SELECT statement passed as the first argument. The SELECT statement
** is as prepared by function sessionSelectStmt().
................................................................................
  sqlite3_stmt *pDelete;          /* DELETE statement */
  sqlite3_stmt *pUpdate;          /* UPDATE statement */
  sqlite3_stmt *pInsert;          /* INSERT statement */
  sqlite3_stmt *pSelect;          /* SELECT statement */
  int nCol;                       /* Size of azCol[] and abPK[] arrays */
  const char **azCol;             /* Array of column names */
  u8 *abPK;                       /* Boolean array - true if column is in PK */
  int bStat1;                     /* True if table is sqlite_stat1 */
  int bDeferConstraints;          /* True to defer constraints */
  SessionBuffer constraints;      /* Deferred constraints are stored here */
};

/*
** Formulate a statement to DELETE a row from database db. Assuming a table
** structure like this:
................................................................................
  if( rc==SQLITE_OK ){
    rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, &p->pUpdate, 0);
  }
  sqlite3_free(buf.aBuf);

  return rc;
}


/*
** Formulate and prepare an SQL statement to query table zTab by primary
** key. Assuming the following table structure:
**
**     CREATE TABLE x(a, b, c, d, PRIMARY KEY(a, c));
**
................................................................................

  if( rc==SQLITE_OK ){
    rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, &p->pInsert, 0);
  }
  sqlite3_free(buf.aBuf);
  return rc;
}

static int sessionPrepare(sqlite3 *db, sqlite3_stmt **pp, const char *zSql){
  return sqlite3_prepare_v2(db, zSql, -1, pp, 0);
}

/*
** Prepare statements for applying changes to the sqlite_stat1 table.
** These are similar to those created by sessionSelectRow(),
** sessionInsertRow(), sessionUpdateRow() and sessionDeleteRow() for 
** other tables.
*/
static int sessionStat1Sql(sqlite3 *db, SessionApplyCtx *p){
  int rc = sessionSelectRow(db, "sqlite_stat1", p);
  if( rc==SQLITE_OK ){
    rc = sessionPrepare(db, &p->pInsert,
        "INSERT INTO main.sqlite_stat1 VALUES(?1, "
        "CASE WHEN length(?2)=0 AND typeof(?2)='blob' THEN NULL ELSE ?2 END, "
        "?3)"
    );
  }
  if( rc==SQLITE_OK ){
    rc = sessionPrepare(db, &p->pUpdate,
        "UPDATE main.sqlite_stat1 SET "
        "tbl = CASE WHEN ?2 THEN ?3 ELSE tbl END, "
        "idx = CASE WHEN ?5 THEN ?6 ELSE idx END, "
        "stat = CASE WHEN ?8 THEN ?9 ELSE stat END  "
        "WHERE tbl=?1 AND idx IS "
        "CASE WHEN length(?4)=0 AND typeof(?4)='blob' THEN NULL ELSE ?4 END "
        "AND (?10 OR ?8=0 OR stat IS ?7)"
    );
  }
  if( rc==SQLITE_OK ){
    rc = sessionPrepare(db, &p->pDelete,
        "DELETE FROM main.sqlite_stat1 WHERE tbl=?1 AND idx IS "
        "CASE WHEN length(?2)=0 AND typeof(?2)='blob' THEN NULL ELSE ?2 END "
        "AND (?4 OR stat IS ?3)"
    );
  }
  assert( rc==SQLITE_OK );
  return rc;
}

/*
** A wrapper around sqlite3_bind_value() that detects an extra problem. 
** See comments in the body of this function for details.
*/
static int sessionBindValue(
  sqlite3_stmt *pStmt,            /* Statement to bind value to */
................................................................................
      rc = sessionConflictHandler(
          SQLITE_CHANGESET_CONFLICT, p, pIter, xConflict, pCtx, 0
      );
    }

  }else{
    assert( op==SQLITE_INSERT );
    if( p->bStat1 ){
      /* Check if there is a conflicting row. For sqlite_stat1, this needs
      ** to be done using a SELECT, as there is no PRIMARY KEY in the 
      ** database schema to throw an exception if a duplicate is inserted.  */
      rc = sessionSeekToRow(p->db, pIter, p->abPK, p->pSelect);
      if( rc==SQLITE_ROW ){
        rc = SQLITE_CONSTRAINT;
        sqlite3_reset(p->pSelect);
      }
    }

    if( rc==SQLITE_OK ){
      rc = sessionBindRow(pIter, sqlite3changeset_new, nCol, 0, p->pInsert);
      if( rc!=SQLITE_OK ) return rc;

      sqlite3_step(p->pInsert);
      rc = sqlite3_reset(p->pInsert);
    }

    if( (rc&0xff)==SQLITE_CONSTRAINT ){
      rc = sessionConflictHandler(
          SQLITE_CHANGESET_CONFLICT, p, pIter, xConflict, pCtx, pbReplace
      );
    }
  }

................................................................................
          schemaMismatch = 1;
          sqlite3_log(SQLITE_SCHEMA, "sqlite3changeset_apply(): "
              "primary key mismatch for table %s", zTab
          );
        }
        else{
          sApply.nCol = nCol;
          if( 0==sqlite3_stricmp(zTab, "sqlite_stat1") ){
            if( (rc = sessionStat1Sql(db, &sApply) ) ){
              break;
            }
            sApply.bStat1 = 1;
          }else{
            if((rc = sessionSelectRow(db, zTab, &sApply))
                || (rc = sessionUpdateRow(db, zTab, &sApply))
                || (rc = sessionDeleteRow(db, zTab, &sApply))
                || (rc = sessionInsertRow(db, zTab, &sApply))
              ){
              break;
            }
            sApply.bStat1 = 0;
          }
        }
        nTab = sqlite3Strlen30(zTab);
      }
    }

    /* If there is a schema mismatch on the current table, proceed to the

Changes to ext/session/sqlite3session.h.

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** no changes will be recorded in either of these scenarios.
**
** Changes are not recorded for individual rows that have NULL values stored
** in one or more of their PRIMARY KEY columns.
**
** SQLITE_OK is returned if the call completes without error. Or, if an error 
** occurs, an SQLite error code (e.g. SQLITE_NOMEM) is returned.





























*/
int sqlite3session_attach(
  sqlite3_session *pSession,      /* Session object */
  const char *zTab                /* Table name */
);

/*







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** no changes will be recorded in either of these scenarios.
**
** Changes are not recorded for individual rows that have NULL values stored
** in one or more of their PRIMARY KEY columns.
**
** SQLITE_OK is returned if the call completes without error. Or, if an error 
** occurs, an SQLite error code (e.g. SQLITE_NOMEM) is returned.
**
** <h3>Special sqlite_stat1 Handling</h3>
**
** As of SQLite version 3.22.0, the "sqlite_stat1" table is an exception to 
** some of the rules above. In SQLite, the schema of sqlite_stat1 is:
**  <pre>
**  &nbsp;     CREATE TABLE sqlite_stat1(tbl,idx,stat)  
**  </pre>
**
** Even though sqlite_stat1 does not have a PRIMARY KEY, changes are 
** recorded for it as if the PRIMARY KEY is (tbl,idx). Additionally, changes 
** are recorded for rows for which (idx IS NULL) is true. However, for such
** rows a zero-length blob (SQL value X'') is stored in the changeset or
** patchset instead of a NULL value. This allows such changesets to be
** manipulated by legacy implementations of sqlite3changeset_invert(),
** concat() and similar.
**
** The sqlite3changeset_apply() function automatically converts the 
** zero-length blob back to a NULL value when updating the sqlite_stat1
** table. However, if the application calls sqlite3changeset_new(),
** sqlite3changeset_old() or sqlite3changeset_conflict on a changeset 
** iterator directly (including on a changeset iterator passed to a
** conflict-handler callback) then the X'' value is returned. The application
** must translate X'' to NULL itself if required.
**
** Legacy (older than 3.22.0) versions of the sessions module cannot capture
** changes made to the sqlite_stat1 table. Legacy versions of the
** sqlite3changeset_apply() function silently ignore any modifications to the
** sqlite_stat1 table that are part of a changeset or patchset.
*/
int sqlite3session_attach(
  sqlite3_session *pSession,      /* Session object */
  const char *zTab                /* Table name */
);

/*

Changes to src/analyze.c.

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1312
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    jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regStat1); VdbeCoverage(v);
    sqlite3VdbeAddOp2(v, OP_Null, 0, regIdxname);
    assert( "BBB"[0]==SQLITE_AFF_TEXT );
    sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regTemp, "BBB", 0);
    sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid);
    sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regTemp, regNewRowid);
    sqlite3VdbeChangeP5(v, OPFLAG_APPEND);



    sqlite3VdbeJumpHere(v, jZeroRows);
  }
}


/*
** Generate code that will cause the most recent index analysis to







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    jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regStat1); VdbeCoverage(v);
    sqlite3VdbeAddOp2(v, OP_Null, 0, regIdxname);
    assert( "BBB"[0]==SQLITE_AFF_TEXT );
    sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regTemp, "BBB", 0);
    sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid);
    sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regTemp, regNewRowid);
    sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
    sqlite3VdbeChangeP4(v, -1, (char*)pStat1, P4_TABLE);
#endif
    sqlite3VdbeJumpHere(v, jZeroRows);
  }
}


/*
** Generate code that will cause the most recent index analysis to