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SQLite training in Houston TX on 2019-11-05 (details)
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Overview
Comment:Optimize the restarting of an RBU vacuum.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA3-256: 82062351a62f4ccc438a2b47a22ee581bd030dec952fecd610f360a25002a5ea
User & Date: dan 2019-05-07 16:37:37
Context
2019-05-07
17:47
Strive to prevent harmless compiler warnings in GCC 4.8.5. check-in: 8b6691f6 user: drh tags: trunk
16:37
Optimize the restarting of an RBU vacuum. check-in: 82062351 user: dan tags: trunk
16:28
Remove some redundant code from sqlite3rbu.c. Add test cases for RBU vacuum. Closed-Leaf check-in: 7b051698 user: dan tags: rbu-opt
2019-05-06
16:15
Fix a problem with renaming an INTEGER PRIMARY KEY column of a WITHOUT ROWID table using ALTER TABLE. check-in: 91f701d3 user: dan tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to ext/rbu/rbu_common.tcl.

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  }
  set rc
}

proc do_rbu_vacuum_test {tn step {statedb state.db}} {
  forcedelete $statedb
  if {$statedb=="" && $step==1} breakpoint
  uplevel [list do_test $tn.1 [string map [list %state% $statedb] {
    if {$step==0} { sqlite3rbu_vacuum rbu test.db {%state%}}
    while 1 {
      if {$step==1} { sqlite3rbu_vacuum rbu test.db {%state%}}
      set state [rbu state]
      check_prestep_state test.db $state
      set rc [rbu step]
      check_poststep_state $rc test.db $state
      if {$rc!="SQLITE_OK"} break
      if {$step==1} { rbu close }
    }
    rbu close
  }] {SQLITE_DONE}]

  uplevel [list do_execsql_test $tn.2 {
    PRAGMA integrity_check
  } ok]
}








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  }
  set rc
}

proc do_rbu_vacuum_test {tn step {statedb state.db}} {
  forcedelete $statedb
  if {$statedb=="" && $step==1} breakpoint
  uplevel [list do_test $tn.1 [string map [list %state% $statedb %step% $step] {
    if {%step%==0} { sqlite3rbu_vacuum rbu test.db {%state%}}
    while 1 {
      if {%step%==1} { sqlite3rbu_vacuum rbu test.db {%state%}}
      set state [rbu state]
      check_prestep_state test.db $state
      set rc [rbu step]
      check_poststep_state $rc test.db $state
      if {$rc!="SQLITE_OK"} break
      if {%step%==1} { rbu close }
    }
    rbu close
  }] {SQLITE_DONE}]

  uplevel [list do_execsql_test $tn.2 {
    PRAGMA integrity_check
  } ok]
}

Changes to ext/rbu/rbupartial.test.

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    SELECT * FROM t1 ORDER BY %A%;
  } {
    1 10 {} b   7 8 4 d   10 11 12 e   13 14 {} f
  }

  set step 0
  do_rbu_vacuum_test $tn.1.5 0




  }]
}

finish_test







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    SELECT * FROM t1 ORDER BY %A%;
  } {
    1 10 {} b   7 8 4 d   10 11 12 e   13 14 {} f
  }

  set step 0
  do_rbu_vacuum_test $tn.1.5 0

  do_test $tn.1.6 {
    execsql { PRAGMA integrity_check }
  } {ok}
  }]
}

finish_test

Added ext/rbu/rbuvacuum4.test.























































































































































































































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# 2019 Jan 3
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# This file contains tests for the RBU module. More specifically, it
# contains tests to ensure that the sqlite3rbu_vacuum() API works as
# expected.
#

source [file join [file dirname [info script]] rbu_common.tcl]
set testprefix rbuvacuum4

set step 1

do_execsql_test 1.0 {
  CREATE TABLE t1(a PRIMARY KEY, b, c) WITHOUT ROWID;
  INSERT INTO t1 VALUES(1, 2, 3);
  INSERT INTO t1 VALUES(4, 5, 6);
  INSERT INTO t1 VALUES(7, 8, 9);
}
do_rbu_vacuum_test 1.1 1

#-------------------------------------------------------------------------
reset_db

do_execsql_test 2.0 {
  CREATE TABLE t1(a, b, c, PRIMARY KEY(a, b, c)) WITHOUT ROWID;
  INSERT INTO t1 VALUES(1, 2, 3);
  INSERT INTO t1 VALUES(4, 5, 6);
  INSERT INTO t1 VALUES(7, 8, 9);
}
do_rbu_vacuum_test 2.1 1
do_execsql_test 2.2 {
  SELECT * FROM t1;
} {1 2 3 4 5 6 7 8 9}

#-------------------------------------------------------------------------
reset_db

do_execsql_test 3.0 {
  CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c);
  CREATE INDEX i1 oN t1(b, c);
  INSERT INTO t1 VALUES(1, 2, 3);
  INSERT INTO t1 VALUES(4, 5, 6);
  INSERT INTO t1 VALUES(7, 8, 9);
}

do_rbu_vacuum_test 3.1 1

do_execsql_test 3.2 {
  SELECT * FROM t1;
} {1 2 3 4 5 6 7 8 9}

#-------------------------------------------------------------------------
reset_db
do_execsql_test 4.0 {
  CREATE TABLE x1(a, b, c, d, PRIMARY KEY(c, b)) WITHOUT ROWID;
  INSERT INTO x1 VALUES(1, 1, 1, 1);
  INSERT INTO x1 VALUES(1, 1, 2, 1);
  INSERT INTO x1 VALUES(1, 2, 2, 1);

  INSERT INTO x1 VALUES(NULL, 2, 3, NULL);
  INSERT INTO x1 VALUES(NULL, 2, 4, NULL);
  INSERT INTO x1 VALUES(NULL, 2, 5, NULL);

  CREATE INDEX x1ad ON x1(d, a);
  CREATE INDEX x1null ON x1(d, a) WHERE d>15;
}

do_rbu_vacuum_test 4.1.1 1

do_execsql_test 4.2 {
  SELECT count(*) fROM x1
} 6

do_rbu_vacuum_test 4.1.2 0

#-------------------------------------------------------------------------
reset_db
do_execsql_test 5.0 {
  CREATE TABLE "a b c"(a, "b b" PRIMARY KEY, "c c");
  CREATE INDEX abc1 ON "a b c"(a, "c c");

  INSERT INTO "a b c" VALUES(NULL, 'a', NULL);
  INSERT INTO "a b c" VALUES(NULL, 'b', NULL);
  INSERT INTO "a b c" VALUES(NULL, 'c', NULL);

  INSERT INTO "a b c" VALUES(1, 2, 3);
  INSERT INTO "a b c" VALUES(3, 9, 1);
  INSERT INTO "a b c" VALUES('aaa', 'bbb', 'ccc');

  CREATE TABLE x(a);
  INSERT INTO x VALUES('a'), ('b'), ('d');
  CREATE UNIQUE INDEX y ON x(a);
}

do_rbu_vacuum_test 5.1 1

finish_test

Changes to ext/rbu/sqlite3rbu.c.

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  sqlite3rbu *p = sqlite3_user_data(pCtx);
  const char *zIn;
  assert( argc==1 || argc==2 );

  zIn = (const char*)sqlite3_value_text(argv[0]);
  if( zIn ){
    if( rbuIsVacuum(p) ){

      if( argc==1 || 0==sqlite3_value_int(argv[1]) ){
        sqlite3_result_text(pCtx, zIn, -1, SQLITE_STATIC);
      }
    }else{
      if( strlen(zIn)>4 && memcmp("data", zIn, 4)==0 ){
        int i;
        for(i=4; zIn[i]>='0' && zIn[i]<='9'; i++);
        if( zIn[i]=='_' && zIn[i+1] ){
................................................................................

        if( i!=iOrder ){
          SWAP(int, pIter->aiSrcOrder[i], pIter->aiSrcOrder[iOrder]);
          SWAP(char*, pIter->azTblCol[i], pIter->azTblCol[iOrder]);
        }

        pIter->azTblType[iOrder] = rbuStrndup(zType, &p->rc);

        pIter->abTblPk[iOrder] = (iPk!=0);
        pIter->abNotNull[iOrder] = (u8)bNotNull || (iPk!=0);
        iOrder++;
      }
    }

    rbuFinalize(p, pStmt);
    rbuObjIterCacheIndexedCols(p, pIter);
................................................................................
  for(i=0; i<pIter->nTblCol; i++){
    const char *z = pIter->azTblCol[i];
    zList = rbuMPrintf(p, "%z%s\"%w\"", zList, zSep, z);
    zSep = ", ";
  }
  return zList;
}





















































































































































































































/*
** This function is used to create a SELECT list (the list of SQL 
** expressions that follows a SELECT keyword) for a SELECT statement 
** used to read from an data_xxx or rbu_tmp_xxx table while updating the 
** index object currently indicated by the iterator object passed as the 
** second argument. A "PRAGMA index_xinfo = <idxname>" statement is used 
................................................................................
        );
      }

      /* Create the SELECT statement to read keys in sorted order */
      if( p->rc==SQLITE_OK ){
        char *zSql;
        if( rbuIsVacuum(p) ){









          zSql = sqlite3_mprintf(
              "SELECT %s, 0 AS rbu_control FROM '%q' %s ORDER BY %s%s",
              zCollist, 
              pIter->zDataTbl,


              zPart, zCollist, zLimit
          );

        }else

        if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
          zSql = sqlite3_mprintf(
              "SELECT %s, rbu_control FROM %s.'rbu_tmp_%q' %s ORDER BY %s%s",
              zCollist, p->zStateDb, pIter->zDataTbl,
              zPart, zCollist, zLimit
................................................................................
              zCollist, p->zStateDb, pIter->zDataTbl, zPart,
              zCollist, pIter->zDataTbl, 
              zPart,
              (zPart ? "AND" : "WHERE"),
              zCollist, zLimit
          );
        }

        p->rc = prepareFreeAndCollectError(p->dbRbu, &pIter->pSelect, pz, zSql);



      }

      sqlite3_free(zImposterCols);
      sqlite3_free(zImposterPK);
      sqlite3_free(zWhere);
      sqlite3_free(zBind);
      sqlite3_free(zPart);
................................................................................

        rbuObjIterPrepareTmpInsert(p, pIter, zCollist, zRbuRowid);
      }

      /* Create the SELECT statement to read keys from data_xxx */
      if( p->rc==SQLITE_OK ){
        const char *zRbuRowid = "";


        if( bRbuRowid ){
          zRbuRowid = rbuIsVacuum(p) ? ",_rowid_ " : ",rbu_rowid";
        }

















        p->rc = prepareFreeAndCollectError(p->dbRbu, &pIter->pSelect, pz,
            sqlite3_mprintf(
              "SELECT %s,%s rbu_control%s FROM '%q'%s", 
              zCollist, 
              (rbuIsVacuum(p) ? "0 AS " : ""),
              zRbuRowid,
              pIter->zDataTbl, zLimit


            )
        );



      }

      sqlite3_free(zWhere);
      sqlite3_free(zOldlist);
      sqlite3_free(zNewlist);
      sqlite3_free(zBindings);
    }







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  sqlite3rbu *p = sqlite3_user_data(pCtx);
  const char *zIn;
  assert( argc==1 || argc==2 );

  zIn = (const char*)sqlite3_value_text(argv[0]);
  if( zIn ){
    if( rbuIsVacuum(p) ){
      assert( argc==2 );
      if( 0==sqlite3_value_int(argv[1]) ){
        sqlite3_result_text(pCtx, zIn, -1, SQLITE_STATIC);
      }
    }else{
      if( strlen(zIn)>4 && memcmp("data", zIn, 4)==0 ){
        int i;
        for(i=4; zIn[i]>='0' && zIn[i]<='9'; i++);
        if( zIn[i]=='_' && zIn[i+1] ){
................................................................................

        if( i!=iOrder ){
          SWAP(int, pIter->aiSrcOrder[i], pIter->aiSrcOrder[iOrder]);
          SWAP(char*, pIter->azTblCol[i], pIter->azTblCol[iOrder]);
        }

        pIter->azTblType[iOrder] = rbuStrndup(zType, &p->rc);
        assert( iPk>=0 );
        pIter->abTblPk[iOrder] = (u8)iPk;
        pIter->abNotNull[iOrder] = (u8)bNotNull || (iPk!=0);
        iOrder++;
      }
    }

    rbuFinalize(p, pStmt);
    rbuObjIterCacheIndexedCols(p, pIter);
................................................................................
  for(i=0; i<pIter->nTblCol; i++){
    const char *z = pIter->azTblCol[i];
    zList = rbuMPrintf(p, "%z%s\"%w\"", zList, zSep, z);
    zSep = ", ";
  }
  return zList;
}

/*
** Return a comma separated list of the quoted PRIMARY KEY column names,
** in order, for the current table. Before each column name, add the text
** zPre. After each column name, add the zPost text. Use zSeparator as
** the separator text (usually ", ").
*/
static char *rbuObjIterGetPkList(
  sqlite3rbu *p,                  /* RBU object */
  RbuObjIter *pIter,              /* Object iterator for column names */
  const char *zPre,               /* Before each quoted column name */
  const char *zSeparator,         /* Separator to use between columns */
  const char *zPost               /* After each quoted column name */
){
  int iPk = 1;
  char *zRet = 0;
  const char *zSep = "";
  while( 1 ){
    int i;
    for(i=0; i<pIter->nTblCol; i++){
      if( (int)pIter->abTblPk[i]==iPk ){
        const char *zCol = pIter->azTblCol[i];
        zRet = rbuMPrintf(p, "%z%s%s\"%w\"%s", zRet, zSep, zPre, zCol, zPost);
        zSep = zSeparator;
        break;
      }
    }
    if( i==pIter->nTblCol ) break;
    iPk++;
  }
  return zRet;
}

/*
** This function is called as part of restarting an RBU vacuum within 
** stage 1 of the process (while the *-oal file is being built) while
** updating a table (not an index). The table may be a rowid table or
** a WITHOUT ROWID table. It queries the target database to find the 
** largest key that has already been written to the target table and
** constructs a WHERE clause that can be used to extract the remaining
** rows from the source table. For a rowid table, the WHERE clause
** is of the form:
**
**     "WHERE _rowid_ > ?"
**
** and for WITHOUT ROWID tables:
**
**     "WHERE (key1, key2) > (?, ?)"
**
** Instead of "?" placeholders, the actual WHERE clauses created by
** this function contain literal SQL values.
*/
static char *rbuVacuumTableStart(
  sqlite3rbu *p,                  /* RBU handle */
  RbuObjIter *pIter,              /* RBU iterator object */
  int bRowid,                     /* True for a rowid table */
  const char *zWrite              /* Target table name prefix */
){
  sqlite3_stmt *pMax = 0;
  char *zRet = 0;
  if( bRowid ){
    p->rc = prepareFreeAndCollectError(p->dbMain, &pMax, &p->zErrmsg, 
        sqlite3_mprintf(
          "SELECT max(_rowid_) FROM \"%s%w\"", zWrite, pIter->zTbl
        )
    );
    if( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pMax) ){
      sqlite3_int64 iMax = sqlite3_column_int64(pMax, 0);
      zRet = rbuMPrintf(p, " WHERE _rowid_ > %lld ", iMax);
    }
    rbuFinalize(p, pMax);
  }else{
    char *zOrder = rbuObjIterGetPkList(p, pIter, "", ", ", " DESC");
    char *zSelect = rbuObjIterGetPkList(p, pIter, "quote(", "||','||", ")");
    char *zList = rbuObjIterGetPkList(p, pIter, "", ", ", "");

    if( p->rc==SQLITE_OK ){
      p->rc = prepareFreeAndCollectError(p->dbMain, &pMax, &p->zErrmsg, 
          sqlite3_mprintf(
            "SELECT %s FROM \"%s%w\" ORDER BY %s LIMIT 1", 
                zSelect, zWrite, pIter->zTbl, zOrder
          )
      );
      if( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pMax) ){
        const char *zVal = (const char*)sqlite3_column_text(pMax, 0);
        zRet = rbuMPrintf(p, " WHERE (%s) > (%s) ", zList, zVal);
      }
      rbuFinalize(p, pMax);
    }

    sqlite3_free(zOrder);
    sqlite3_free(zSelect);
    sqlite3_free(zList);
  }
  return zRet;
}

/*
** This function is called as part of restating an RBU vacuum when the
** current operation is writing content to an index. If possible, it
** queries the target index b-tree for the largest key already written to
** it, then composes and returns an expression that can be used in a WHERE 
** clause to select the remaining required rows from the source table. 
** It is only possible to return such an expression if:
**
**   * The index contains no DESC columns, and
**   * The last key written to the index before the operation was 
**     suspended does not contain any NULL values.
**
** The expression is of the form:
**
**   (index-field1, index-field2, ...) > (?, ?, ...)
**
** except that the "?" placeholders are replaced with literal values.
**
** If the expression cannot be created, NULL is returned. In this case,
** the caller has to use an OFFSET clause to extract only the required 
** rows from the sourct table, just as it does for an RBU update operation.
*/
char *rbuVacuumIndexStart(
  sqlite3rbu *p,                  /* RBU handle */
  RbuObjIter *pIter               /* RBU iterator object */
){
  char *zOrder = 0;
  char *zLhs = 0;
  char *zSelect = 0;
  char *zVector = 0;
  char *zRet = 0;
  int bFailed = 0;

  if( p->rc==SQLITE_OK ){
    const char *zSep = "";
    int iCol = 0;
    sqlite3_stmt *pXInfo = 0;
    p->rc = prepareFreeAndCollectError(p->dbMain, &pXInfo, &p->zErrmsg,
        sqlite3_mprintf("PRAGMA main.index_xinfo = %Q", pIter->zIdx)
    );
    while( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pXInfo) ){
      int iCid = sqlite3_column_int(pXInfo, 1);
      const char *zCollate = (const char*)sqlite3_column_text(pXInfo, 4);
      const char *zCol;
      if( sqlite3_column_int(pXInfo, 3) ){
        bFailed = 1;
        break;
      }

      if( iCid<0 ){
        if( pIter->eType==RBU_PK_IPK ){
          int i;
          for(i=0; pIter->abTblPk[i]==0; i++);
          assert( i<pIter->nTblCol );
          zCol = pIter->azTblCol[i];
        }else{
          zCol = "_rowid_";
        }
      }else{
        zCol = pIter->azTblCol[iCid];
      }

      zLhs = rbuMPrintf(p, "%z%s \"%w\" COLLATE %Q",
          zLhs, zSep, zCol, zCollate
      );
      zOrder = rbuMPrintf(p, "%z%s \"rbu_imp_%d%w\" COLLATE %Q DESC",
          zOrder, zSep, iCol, zCol, zCollate
      );
      zSelect = rbuMPrintf(p, "%z%s quote(\"rbu_imp_%d%w\")",
          zSelect, zSep, iCol, zCol
      );
      zSep = ", ";
      iCol++;
    }
    rbuFinalize(p, pXInfo);
  }
  if( bFailed ) goto index_start_out;

  if( p->rc==SQLITE_OK ){
    int iCol;
    sqlite3_stmt *pSel = 0;

    if( p->rc==SQLITE_OK ){
      p->rc = prepareFreeAndCollectError(p->dbMain, &pSel, &p->zErrmsg,
          sqlite3_mprintf("SELECT %s FROM \"rbu_imp_%w\" ORDER BY %s LIMIT 1",
            zSelect, pIter->zTbl, zOrder
          )
      );
    }
    if( p->rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pSel) ){
      const char *zSep = "";
      for(iCol=0; iCol<pIter->nCol; iCol++){
        const char *zQuoted = (const char*)sqlite3_column_text(pSel, iCol);
        if( zQuoted[0]=='N' ){
          bFailed = 1;
          break;
        }
        zVector = rbuMPrintf(p, "%z%s%s", zVector, zSep, zQuoted);
        zSep = ", ";
      }

      if( !bFailed ){
        zRet = rbuMPrintf(p, "(%s) > (%s)", zLhs, zVector);
      }
    }
    rbuFinalize(p, pSel);
  }

 index_start_out:
  sqlite3_free(zOrder);
  sqlite3_free(zSelect);
  sqlite3_free(zVector);
  sqlite3_free(zLhs);
  return zRet;
}

/*
** This function is used to create a SELECT list (the list of SQL 
** expressions that follows a SELECT keyword) for a SELECT statement 
** used to read from an data_xxx or rbu_tmp_xxx table while updating the 
** index object currently indicated by the iterator object passed as the 
** second argument. A "PRAGMA index_xinfo = <idxname>" statement is used 
................................................................................
        );
      }

      /* Create the SELECT statement to read keys in sorted order */
      if( p->rc==SQLITE_OK ){
        char *zSql;
        if( rbuIsVacuum(p) ){
          char *zStart = 0;
          if( nOffset ){
            zStart = rbuVacuumIndexStart(p, pIter);
            if( zStart ){
              sqlite3_free(zLimit);
              zLimit = 0;
            }
          }

          zSql = sqlite3_mprintf(
              "SELECT %s, 0 AS rbu_control FROM '%q' %s %s %s ORDER BY %s%s",
              zCollist, 
              pIter->zDataTbl,
              zPart, 
              (zStart ? (zPart ? "AND" : "WHERE") : ""), zStart,
              zCollist, zLimit
          );
          sqlite3_free(zStart);
        }else

        if( pIter->eType==RBU_PK_EXTERNAL || pIter->eType==RBU_PK_NONE ){
          zSql = sqlite3_mprintf(
              "SELECT %s, rbu_control FROM %s.'rbu_tmp_%q' %s ORDER BY %s%s",
              zCollist, p->zStateDb, pIter->zDataTbl,
              zPart, zCollist, zLimit
................................................................................
              zCollist, p->zStateDb, pIter->zDataTbl, zPart,
              zCollist, pIter->zDataTbl, 
              zPart,
              (zPart ? "AND" : "WHERE"),
              zCollist, zLimit
          );
        }
        if( p->rc==SQLITE_OK ){
          p->rc = prepareFreeAndCollectError(p->dbRbu,&pIter->pSelect,pz,zSql);
        }else{
          sqlite3_free(zSql);
        }
      }

      sqlite3_free(zImposterCols);
      sqlite3_free(zImposterPK);
      sqlite3_free(zWhere);
      sqlite3_free(zBind);
      sqlite3_free(zPart);
................................................................................

        rbuObjIterPrepareTmpInsert(p, pIter, zCollist, zRbuRowid);
      }

      /* Create the SELECT statement to read keys from data_xxx */
      if( p->rc==SQLITE_OK ){
        const char *zRbuRowid = "";
        char *zStart = 0;
        char *zOrder = 0;
        if( bRbuRowid ){
          zRbuRowid = rbuIsVacuum(p) ? ",_rowid_ " : ",rbu_rowid";
        }

        if( rbuIsVacuum(p) ){
          if( nOffset ){
            zStart = rbuVacuumTableStart(p, pIter, bRbuRowid, zWrite);
            if( zStart ){
              sqlite3_free(zLimit);
              zLimit = 0;
            }
          }
          if( bRbuRowid ){
            zOrder = rbuMPrintf(p, "_rowid_");
          }else{
            zOrder = rbuObjIterGetPkList(p, pIter, "", ", ", "");
          }
        }

        if( p->rc==SQLITE_OK ){
          p->rc = prepareFreeAndCollectError(p->dbRbu, &pIter->pSelect, pz,
              sqlite3_mprintf(
                "SELECT %s,%s rbu_control%s FROM '%q'%s %s %s %s",
                zCollist, 
                (rbuIsVacuum(p) ? "0 AS " : ""),
                zRbuRowid,
                pIter->zDataTbl, (zStart ? zStart : ""), 
                (zOrder ? "ORDER BY" : ""), zOrder,
                zLimit
              )
          );
        }
        sqlite3_free(zStart);
        sqlite3_free(zOrder);
      }

      sqlite3_free(zWhere);
      sqlite3_free(zOldlist);
      sqlite3_free(zNewlist);
      sqlite3_free(zBindings);
    }