```
SELECT version();

┌─version()────┐
│ 21.10.1.8002 │
└──────────────┘

WITH lower('\RealVNC\WinVNC4 /v password') as CommandLine
SELECT 
    CommandLine,
    CommandLine LIKE '%\\\\realvnc\\\\winvnc4%password%' as t1,
    CommandLine LIKE '%\\\\realvnc\\\\winvnc4 %password%' as t2,
    CommandLine LIKE '%\\\\realvnc\\\\winvnc4%password' as t3,
    CommandLine LIKE '%\\\\realvnc\\\\winvnc4 %password' as t4,
    CommandLine LIKE '%realvnc%winvnc4%password%' as t5,
    CommandLine LIKE '%\\\\winvnc4%password%' as t6;

┌─CommandLine──────────────────┬─t1─┬─t2─┬─t3─┬─t4─┬─t5─┬─t6─┐
│ \realvnc\winvnc4 /v password │  0 │  1 │  1 │  1 │  1 │  1 │
└──────────────────────────────┴────┴────┴────┴────┴────┴────┘

1 rows in set. Elapsed: 0.001 sec. 
```

All should match.

http://sqlfiddle.com/#!9/73f0c6/2
*  so that it can match when `required_substring` occurs into the string several times,
                              *  and at the first occurrence, the regexp is not a match.
                              */
                            if (required_substring_is_prefix)
                                res[i] = revert
                                    ^ regexp->getRE2()->Match(
                                          re2_st::StringPiece(str_data, str_size),
                                          reinterpret_cast<const char *>(pos) - str_data,
                                          str_size,
                                          re2_st::RE2::UNANCHORED,
                                          nullptr,
                                          0);
                            else
                                res[i] = revert
                                    ^ regexp->getRE2()->Match(
                                          re2_st::StringPiece(str_data, str_size), 0, str_size, re2_st::RE2::UNANCHORED, nullptr, 0);
                        }
                    }
                    else
                        res[i] = revert;
                    pos = begin + offsets[i];
                    ++i;
                }
                if (i < res.size())
                    memset(&res[i], revert, (res.size() - i) * sizeof(res[0]));
            }
        }
    }
    
    static void vectorFixedConstant(