SQLite

  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

  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] ){

    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
          )

    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;

        );
      }

      /* 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;
            }
          }

              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",