示例#1
0
  @Override
  public boolean indexAccessible(final IndexInfo ii) {
    /* If the following conditions yield true, the index is accessed:
     * - all query terms are statically available
     * - no FTTimes option is specified
     * - explicitly set case, diacritics and stemming match options do not
     *   conflict with index options. */
    data = ii.ic.data;
    final MetaData md = data.meta;
    final FTOpt fto = ftt.opt;

    /* Index will be applied if no explicit match options have been set
     * that conflict with the index options. As a consequence, though, index-
     * based querying might yield other results than sequential scanning. */
    if (occ != null
        || fto.cs != null && md.casesens == (fto.cs == FTCase.INSENSITIVE)
        || fto.isSet(DC) && md.diacritics != fto.is(DC)
        || fto.isSet(ST) && md.stemming != fto.is(ST)
        || fto.ln != null && !fto.ln.equals(md.language)) return false;

    // adopt database options to tokenizer
    fto.copy(md);

    // estimate costs if text is not known at compile time
    if (tokens == null) {
      ii.costs = Math.max(2, data.meta.size / 30);
      return true;
    }

    // summarize number of hits; break loop if no hits are expected
    final FTLexer ft = new FTLexer(fto);
    ii.costs = 0;
    for (byte[] t : tokens) {
      ft.init(t);
      while (ft.hasNext()) {
        final byte[] tok = ft.nextToken();
        if (fto.sw != null && fto.sw.contains(tok)) continue;

        if (fto.is(WC)) {
          // don't use index if one of the terms starts with a wildcard
          t = ft.get();
          if (t[0] == '.') return false;
          // don't use index if certain characters or more than 1 dot are found
          int d = 0;
          for (final byte w : t) {
            if (w == '{' || w == '\\' || w == '.' && ++d > 1) return false;
          }
        }
        // favor full-text index requests over exact queries
        final int costs = data.costs(ft);
        if (costs != 0) ii.costs += Math.max(2, costs / 100);
      }
    }
    return true;
  }
示例#2
0
文件: Or.java 项目: vincentml/basex
 @Override
 public boolean indexAccessible(final IndexInfo ii) throws QueryException {
   int costs = 0;
   final ExprList el = new ExprList(exprs.length);
   for (final Expr expr : exprs) {
     // check if expression can be rewritten, and if access is not sequential
     if (!expr.indexAccessible(ii)) return false;
     // skip expressions without results
     if (ii.costs == 0) continue;
     costs += ii.costs;
     el.add(ii.expr);
   }
   // use summarized costs for estimation
   ii.costs = costs;
   // no expressions means no costs: expression will later be ignored
   ii.expr = el.size() == 1 ? el.get(0) : new Union(info, el.finish());
   return true;
 }
示例#3
0
文件: FTAnd.java 项目: BaseXdb/basex
  @Override
  public boolean indexAccessible(final IndexInfo ii) throws QueryException {
    final int es = exprs.length;
    final boolean[] ng = new boolean[es];
    int costs = 0;
    for (final FTExpr expr : exprs) {
      if (!expr.indexAccessible(ii)) return false;
      // use worst costs for estimation, as all index results may need to be scanned
      if (costs < ii.costs) costs = ii.costs;
    }

    ii.costs = costs;
    negated = ng;
    return true;
  }