Trie غير قابل للتغيير: اعثر على شيء ، لا أعرف ماذا ، لكن سريعًا ، ولا تتخلص من القمامة

سجلات ملتصقة

2020-09-11 14:49:53.281 MSK [80927:619/4255507] [explain.tensor.ru] 10.76.182.154(59933) pgAdmin III - ???????????????????? ???????????????? LOG:  duration: 0.016 ms  plan:
	Query Text: explain analyze
	SELECT
		*
	FROM
		pg_class
	WHERE
		relname = '
	
	';
	Index Scan using pg_class_relname_nsp_index on pg_class  (cost=0.29..2.54 rows=1 width=265) (actual time=0.014..0.014 rows=0 loops=1)
	  Index Cond: (relname = '
	
	'::name)
	  Buffers: shared hit=2

SHOW log_line_prefix;
-- "%m [%p:%v] [%d] %r %a "

const reTS = "\\d{4}(?:-\\d{2}){2} \\d{2}(?::\\d{2}){2}"
  , reTSMS = reTS + "\\.\\d{3}"
  , reTZ   = "(?:[A-Za-z]{3,5}|GMT[+\\-]\\d{1,2})";

var re = {
// : log_line_prefix
      '%a' : "(?:[\\x20-\\x7F]{0,63})"
    , '%u' : "(?:[\\x20-\\x7F]{0,63})"
    , '%d' : "[\\x20-\\x7F]{0,63}?"
    , '%r' : "(?:(?:\\d{1,3}(?:\\.\\d{1,3}){3}|[\\-\\.\\_a-z0-9])\\(\\d{1,5}\\)|\\[local\\]|)"
    , '%h' : "(?:(?:\\d{1,3}(?:\\.\\d{1,3}){3}|[\\-\\.\\_a-z0-9])|\\[local\\]|)"
    , '%p' : "\\d{1,5}"
    , '%t' : reTS + ' ' + reTZ
    , '%m' : reTSMS + ' ' + reTZ
    , '%i' : "(?:SET|SELECT|DO|INSERT|UPDATE|DELETE|COPY|COMMIT|startup|idle|idle in transaction|streaming [0-9a-f]{1,8}\/[0-9a-f]{1,8}|)(?: waiting)?"
    , '%e' : "[0-9a-z]{5}"
    , '%c' : "[0-9a-f]{1,8}\\.[0-9a-f]{1,8}"
    , '%l' : "\\d+"
    , '%s' : "\\d{4}(?:-\\d{2}){2} \\d{2}(?::\\d{2}){2} [A-Z]{3}"
    , '%v' : "(?:\\d{1,9}\\/\\d{1,9}|)"
    , '%x' : "\\d+"
    , '%q' : ""
    , '%%' : "%"
// : log_min_messages
    , '%!' : "(?:DEBUG[1-5]|INFO|NOTICE|WARNING|ERROR|LOG|FATAL|PANIC)"
// : log_error_verbosity
    , '%@' : "(?:DETAIL|HINT|QUERY|CONTEXT|LOCATION|STATEMENT)"
    };
re['%#'] = "(?:" + re['%!'] + "|" + re['%@'] + ")";

//  log_line_prefix  RegExp   
let lre = self.settings['log_line_prefix'].replace(/([\[\]\(\)\{\}\|\?\$\\])/g, "\\\$1") + '%#:  ';
self.tokens = lre.match(new RegExp('(' + Object.keys(re).join('|') + ')', 'g'));

let matcher = self.tokens.reduce((str, token) => str.replace(token, '(' + re[token] + ')'), lre);
self.matcher = new RegExp('^' + matcher, '');

استخدم Trie ، Luke!

تراي ثابت

• الانضغاط
  
  لدينا عشرات / مئات العناصر المحتملة بطول محدود للغاية ، لذلك لا يمكن أن يكون هناك موقف لعدد كبير من المفاتيح الطويلة جدًا المتطابقة تقريبًا والتي تختلف فقط في الحرف الأخير. أطول مفاتيح لدينا هو على الأرجح 'Parallel Index Only Scan Backward'.
• 
  
  . .
• 
  
  . , .
• -
  
  , «» Garbage Collector'.

• String.prototype.charCodeAt(index) يسمح لك بمعرفة رمز الحرف في موضع معين في السلسلة
• String.prototype.startsWith(searchString[, position]) يتحقق مما إذا كانت بداية سلسلة [من موضع معين] تطابق البحث

بناء الخريطة

//      Longest Common Prefix
let len, lcp;
for (let key of keys) {
  //  
  if (lcp === undefined) {
    len = key.length;
    lcp = key.slice(off);
    continue;
  }

  len = Math.min(len, key.length);
  // ,   "" LCP      
  if (lcp == '' || key.startsWith(lcp, off)) {
    continue;
  }
  //  LCP   
  for (let i = 0; i < lcp.length; i++) {
    if (lcp.charCodeAt(i) != key.charCodeAt(off + i)) {
      lcp = lcp.slice(0, i);
      break;
    }
  }
}

//      
let grp = new Set();
res.pos = {};
for (let i = off + lcp.length; i < len; i++) {
  //      [i]-
  let chr = keys.reduce((rv, key) => {
    if (key.length < i) {
      return rv;
    }
    let ch = key.charCodeAt(i);
    rv[ch] = rv[ch] || [];
    rv[ch].push(key);
    return rv;
  }, {});

  //          
  let cmb = Object.values(chr)
    .map(seg => seg.join('\t'))
    .sort()
    .join('\n');
  if (grp.has(cmb)) {
    continue;
  }
  else {
    grp.add(cmb);
  }

  res.pos[i] = chr;
}

المقياس الأمثل

, 3- 's', startsWith, , 6 , , Insert.

: 1 (.charCodeAt(2)) + 6 (.startsWith('Insert')) = 7 .



'd', 7-, , 'O' 'S'. — 'Index Scan Backward' (+19 ) 'Index Scan' (+10 ).



, 'Index Scan Backward', 19 , 'Index Scan' — 19 + 10 = 29.

: 1 (.charCodeAt(2)) + 1 (.charCodeAt(6)) + 19 + 29 (.startsWith(...)) = 50 .

{
  '$pos' : 2 //  3- 
, '$chr' : Map {
    100 => {         // 'd'
      '$pos' : 6 //  7- 
    , '$chr' : Map {
        79 => [ 'Index Only Scan Backward', 'Index Only Scan' ] // 'O'
      , 83 => [ 'Index Scan Backward', 'Index Scan' ]           // 'S'
      }
    }
  , 115 => 'Insert' // 's'
  }
}

فزوحه!

//   
const fill = (obj, off, hash) => {
  off = off || 0;
  hash = hash || {};

  let keys = obj.src;

  //        
  let H = keys.join('\n');
  hash[off] = hash[off] || {};
  if (hash[off][H]) {
    obj.res = hash[off][H];
    return;
  }
  obj.res = {};
  hash[off][H] = obj.res;

  let res = obj.res;

  //    -     
  if (keys.length == 1) {
    res.lst = [...keys];
    res.cmp = res.lst[0].length;
    return;
  }

  //      Longest Common Prefix
  let len, lcp;
  for (let key of keys) {
    //  
    if (lcp == undefined) {
      len = key.length;
      lcp = key.slice(off);
      continue;
    }

    len = Math.min(len, key.length);
    // ,   "" LCP      
    if (lcp == '' || key.startsWith(lcp, off)) {
      continue;
    }
    //  LCP   
    for (let i = 0; i < lcp.length; i++) {
      if (lcp.charCodeAt(i) != key.charCodeAt(off + i)) {
        lcp = lcp.slice(0, i);
        break;
      }
    }
  }

  //       
  if (off + lcp.length == len) {
    let cmp = 0;
    //       - 
    if (keys.length == 2) {
      res.lst = [...keys];
    }
    //  " "   
    else {
      res.src = keys.filter(key => key.length > off + lcp.length);
      res.lst = keys.filter(key => key.length <= off + lcp.length);
    }

    //    ,     ,   
    res.lst.sort((x, y) => y.length - x.length); // s.length DESC
    cmp += res.lst.reduce((rv, key, idx, keys) => rv + (keys.length - idx + 1) * key.length, 0);

    //    -  
    if (res.src && res.src.length) {
      fill(res, off + lcp.length + 1, hash);
      cmp += res.res.cmp;
    }
    res.cmp = cmp + 1;
    return;
  }

  //      
  let grp = new Set();
  res.pos = {};
  for (let i = off + lcp.length; i < len; i++) {
    //      [i]-
    let chr = keys.reduce((rv, key) => {
      if (key.length < i) {
        return rv;
      }
      let ch = key.charCodeAt(i);
      rv[ch] = rv[ch] || [];
      rv[ch].push(key);
      return rv;
    }, {});

    //          
    let cmb = Object.values(chr)
      .map(seg => seg.join('\t'))
      .sort()
      .join('\n');
    if (grp.has(cmb)) {
      continue;
    }
    else {
      grp.add(cmb);
    }

    let fl = true;
    let cmp = 0;
    for (let [ch, keys] of Object.entries(chr)) {
      //     
      if (keys.length == 1) {
        let key = keys[0];
        chr[ch] = key;
        cmp += key.length;
      }
      //       
      else {
        fl = false;
        chr[ch] = {src : keys};
        fill(chr[ch], i + 1, hash);
        cmp += chr[ch].res.cmp;
      }
    }

    res.pos[i] = {
      chr
    , cmp
    };

    //   "" 
    if (res.cmp === undefined || cmp + 1 < res.cmp) {
      res.cmp = cmp + 1;
      res.bst = i;
    }

    //       ,      
    if (fl) {
      res.bst = i;
      for (let j = off; j < i; j++) {
        delete res.pos[j];
      }
      break;
    }
  }
};

//      
const comp = obj => {
  //   
  delete obj.src;
  delete obj.cmp;
  if (obj.res) {
    let res = obj.res;
    if (res.pos !== undefined) {
      //      
      obj.$pos = res.bst;
      let $chr = res.pos[res.bst].chr;
      Object.entries($chr).forEach(([key, val]) => {
        //   
        comp(val);
        //      - ""    
        let keys = Object.keys(val);
        if (keys.length == 1 && keys[0] == '$lst') {
          $chr[key] = val.$lst;
        }
      });
      //    -  Map  -
      obj.$chr = new Map(Object.entries($chr).map(([key, val]) => [Number(key), val]));
    }
    //    ""     
    if (res.lst !== undefined) {
      obj.$lst = res.lst;
      delete res.lst;
      if (res.res !== undefined) {
        comp(res);
        Object.assign(obj, res);
      }
    }
    delete obj.res;
  }
};

//    -     
const find = (str, off, map) => {
  let curr = map;
  do {
    //    
    let $pos = curr.$pos;
    if ($pos !== undefined) {
      let next = curr.$chr.get(str.charCodeAt(off + $pos));
      if (typeof next === 'string') {   //  
        if (str.startsWith(next, off)) {
          return next;
        }
      }
      else if (next instanceof Array) { //    
        for (let key of next) {
          if (str.startsWith(key, off)) {
            return key;
          }
        }
      }
      else if (next !== undefined) {    //  map,  
        curr = next;
        continue;
      }
    }
    //    ,   
    if (curr.$lst) {
      for (let key of curr.$lst) {
        if (str.startsWith(key, off)) {
          return key;
        }
      }
    }
    return;
  }
  while (true);
};

function ImmutableTrie(keys) {
  this.map = {src : keys.sort((x, y) => x < y ? -1 : +1)};
  fill(this.map);
  comp(this.map);
}

const p = ImmutableTrie.prototype;

p.get = function(line, off) {
  return find(line, off || 0, this.map);
};

p.has = function(line, off) {
  return this.get(line, off) !== undefined;
};

module.exports = ImmutableTrie;

const nodeIT = new ImmutableTrie(...);
nodeIT.get('  ->  Parallel Seq Scan on abc', 6); // 'Parallel Seq Scan'

Index Scan using pg_class_relname_nsp_index on pg_class  (cost=0.29..2.54 rows=1 width=265) (actual time=0.014..0.014 rows=0 loops=1)
  Index Cond: (relname = '\n\n'::name)
  Buffers: shared hit=2