1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963
|
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>7.14. Regular expression — Groonga v10.1.1-31-g1e46ba6 documentation</title>
<link rel="stylesheet" href="../_static/groonga.css" type="text/css" />
<link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
<script id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script>
<script src="../_static/jquery.js"></script>
<script src="../_static/underscore.js"></script>
<script src="../_static/doctools.js"></script>
<script src="../_static/language_data.js"></script>
<link rel="shortcut icon" href="../_static/favicon.ico"/>
<link rel="index" title="Index" href="../genindex.html" />
<link rel="search" title="Search" href="../search.html" />
<link rel="next" title="7.15. Function" href="function.html" />
<link rel="prev" title="7.13.2. Script syntax" href="grn_expr/script_syntax.html" />
</head><body>
<div class="header">
<h1 class="title">
<a id="top-link" href="../index.html">
<span class="project">groonga</span>
<span class="separator">-</span>
<span class="description">An open-source fulltext search engine and column store.</span>
</a>
</h1>
<div class="other-language-links">
<ul>
<li><a href="../../../ja/html/reference/regular_expression.html">日本語</a></li>
</ul>
</div>
</div>
<div class="related" role="navigation" aria-label="related navigation">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
accesskey="I">index</a></li>
<li class="right" >
<a href="function.html" title="7.15. Function"
accesskey="N">next</a> |</li>
<li class="right" >
<a href="grn_expr/script_syntax.html" title="7.13.2. Script syntax"
accesskey="P">previous</a> |</li>
<li class="nav-item nav-item-0"><a href="../index.html">Groonga v10.1.1-31-g1e46ba6 documentation</a> »</li>
<li class="nav-item nav-item-1"><a href="../reference.html" accesskey="U"><span class="section-number">7. </span>Reference manual</a> »</li>
<li class="nav-item nav-item-this"><a href=""><span class="section-number">7.14. </span>Regular expression</a></li>
</ul>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body" role="main">
<div class="section" id="regular-expression">
<h1><span class="section-number">7.14. </span>Regular expression<a class="headerlink" href="#regular-expression" title="Permalink to this headline">¶</a></h1>
<div class="section" id="summary">
<h2><span class="section-number">7.14.1. </span>Summary<a class="headerlink" href="#summary" title="Permalink to this headline">¶</a></h2>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Regular expression support is an experimental feature.</p>
</div>
<div class="versionadded">
<p><span class="versionmodified added">New in version 5.0.1.</span></p>
</div>
<p>Groonga supports pattern match by regular expression. Regular
expression is widely used format to describe a pattern. Regular
expression is useful to represent complex pattern.</p>
<p>In most cases, pattern match by regular expression is evaluated as
sequential search. It’ll be slow for many records and many texts.</p>
<p>In some cases, pattern match by regular expression can be evaluated
by index. It’s very fast rather than sequential search. Patterns
that can be evaluated by index are described later.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 5.0.7: </span>Groonga normalizes match target text by <a class="reference internal" href="normalizers/normalizer_auto.html#normalizer-auto"><span class="std std-ref">NormalizerAuto</span></a>
normalizer when Groonga doesn’t use index for regular expression
search. It means that regular expression that has upper case such
as <code class="docutils literal notranslate"><span class="pre">Groonga</span></code> never match. Because <a class="reference internal" href="normalizers/normalizer_auto.html#normalizer-auto"><span class="std std-ref">NormalizerAuto</span></a>
normalizer normalizes all alphabets to lower case. <code class="docutils literal notranslate"><span class="pre">groonga</span></code>
matches to both <code class="docutils literal notranslate"><span class="pre">Groonga</span></code> and <code class="docutils literal notranslate"><span class="pre">groonga</span></code>.</p>
<p>Why is match target text normalizered? It’s for increasing index
search-able patterns. If Groonga doesn’t normalize match target
text, you need to write complex regular expression such as
<code class="docutils literal notranslate"><span class="pre">[Dd][Ii][Ss][Kk]</span></code> and <code class="docutils literal notranslate"><span class="pre">(?i)disk</span></code> for case-insensitive match.
Groonga can’t use index against complex regular expression.</p>
<p>If you write <code class="docutils literal notranslate"><span class="pre">disk</span></code> regular expression for case-insensitive
match, Groonga can search the pattern with index. It’s fast.</p>
<p>By full text search normally, Groonga normalize search keywords
using the normalizer specified in a lexicon.
By using regular expression search, Groonga doesn’t normalize search
keywords.
Because the regular expression has specified meaning in uppercase and
lowercase.</p>
<p>So, if you regular expression search that doesn’t use the index,
we suggest that use <a class="reference internal" href="commands/normalize.html"><span class="doc">normalize</span></a> command to
normalize search keywords before a search.
By using <a class="reference internal" href="commands/normalize.html"><span class="doc">normalize</span></a> command, you don’t have
to need to think about how to normalize search keywords.</p>
<p>You may feel the behavior is strange. But fast search based on this
behavior will help you.</p>
</div>
<p>There are many regular expression syntaxes. Groonga uses the same
syntax in Ruby. Because Groonga uses the same regular expression
engine as Ruby. The regular expression engine is <a class="reference external" href="https://github.com/k-takata/Onigmo/">Onigmo</a>. Characteristic difference
with other regular expression syntax is <code class="docutils literal notranslate"><span class="pre">^</span></code> and <code class="docutils literal notranslate"><span class="pre">$</span></code>. The regular
expression syntax in Ruby, <code class="docutils literal notranslate"><span class="pre">^</span></code> means the beginning of line and <code class="docutils literal notranslate"><span class="pre">$</span></code>
means the end of line. <code class="docutils literal notranslate"><span class="pre">^</span></code> means the beginning of text and <code class="docutils literal notranslate"><span class="pre">$</span></code>
means the end of text in other most regular expression syntaxes. The regular
expression syntax in Ruby uses <code class="docutils literal notranslate"><span class="pre">\A</span></code> for the beginning of text and
<code class="docutils literal notranslate"><span class="pre">\z</span></code> for the end of text.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 5.0.6: </span>Groonga uses multiline mode since 5.0.6. It means that <code class="docutils literal notranslate"><span class="pre">.</span></code>
matches on <code class="docutils literal notranslate"><span class="pre">\n</span></code>.</p>
<p>But it’s meaningless. Because <code class="docutils literal notranslate"><span class="pre">\n</span></code> is removed by
<a class="reference internal" href="normalizers/normalizer_auto.html#normalizer-auto"><span class="std std-ref">NormalizerAuto</span></a> normalizer.</p>
</div>
<p>You can use regular expression in <a class="reference internal" href="commands/select.html#select-query"><span class="std std-ref">query</span></a> and
<a class="reference internal" href="commands/select.html#select-filter"><span class="std std-ref">filter</span></a> options of <a class="reference internal" href="commands/select.html"><span class="doc">select</span></a>
command.</p>
</div>
<div class="section" id="usage">
<h2><span class="section-number">7.14.2. </span>Usage<a class="headerlink" href="#usage" title="Permalink to this headline">¶</a></h2>
<p>Here are a schema definition and sample data to show usage. There is
only one table, <code class="docutils literal notranslate"><span class="pre">Logs</span></code>. <code class="docutils literal notranslate"><span class="pre">Logs</span></code> table has only <code class="docutils literal notranslate"><span class="pre">message</span></code>
column. Log messages are stored into the <code class="docutils literal notranslate"><span class="pre">message</span></code> column.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>table_create Logs TABLE_NO_KEY
# [[0, 1337566253.89858, 0.000355720520019531], true]
column_create Logs message COLUMN_SCALAR Text
# [[0, 1337566253.89858, 0.000355720520019531], true]
load --table Logs
[
{"message": "host1:[error]: No memory"},
{"message": "host1:[warning]: Remained disk space is less than 30%"},
{"message": "host1:[error]: Disk full"},
{"message": "host2:[error]: No memory"},
{"message": "host2:[info]: Shutdown"}
]
# [[0, 1337566253.89858, 0.000355720520019531], 5]
</pre></div>
</div>
<p>Here is an example that uses regular expression in
<a class="reference internal" href="commands/select.html#select-query"><span class="std std-ref">query</span></a>. You need to use
<code class="docutils literal notranslate"><span class="pre">${COLUMN}:~${REGULAR_EXPRESSION}</span></code> syntax.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --query 'message:~"disk (space|full)"'
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 2
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 2,
# "host1:[warning]: Remained disk space is less than 30%"
# ],
# [
# 3,
# "host1:[error]: Disk full"
# ]
# ]
# ]
# ]
</pre></div>
</div>
<p>Here is an example that uses regular expression in
<a class="reference internal" href="commands/select.html#select-filter"><span class="std std-ref">filter</span></a>. You need to use
<code class="docutils literal notranslate"><span class="pre">${COLUMN}</span> <span class="pre">@~</span> <span class="pre">${REGULAR_EXPRESSION}</span></code> syntax.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --filter 'message @~ "disk (space|full)"'
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 2
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 2,
# "host1:[warning]: Remained disk space is less than 30%"
# ],
# [
# 3,
# "host1:[error]: Disk full"
# ]
# ]
# ]
# ]
</pre></div>
</div>
</div>
<div class="section" id="index">
<span id="regular-expression-index"></span><h2><span class="section-number">7.14.3. </span>Index<a class="headerlink" href="#index" title="Permalink to this headline">¶</a></h2>
<p>Groonga can search records by regular expression with index. It’s very
fast rather than sequential search.</p>
<p>But it doesn’t support all regular expression patterns. It supports
only the following regular expression patterns. The patterns will be
increased in the future.</p>
<blockquote>
<div><ul class="simple">
<li><p>Literal only pattern such as <code class="docutils literal notranslate"><span class="pre">disk</span></code></p></li>
<li><p>The begging of text and literal only pattern such as <code class="docutils literal notranslate"><span class="pre">\Adisk</span></code></p></li>
<li><p>The end of text and literal only pattern such as <code class="docutils literal notranslate"><span class="pre">disk\z</span></code></p></li>
</ul>
</div></blockquote>
<p>You need to create an index for fast regular expression search. Here
are requirements of index:</p>
<blockquote>
<div><ul class="simple">
<li><p>Lexicon must be <a class="reference internal" href="tables.html#table-pat-key"><span class="std std-ref">TABLE_PAT_KEY</span></a> table.</p></li>
<li><p>Lexicon must use <a class="reference internal" href="tokenizers/token_regexp.html#token-regexp"><span class="std std-ref">TokenRegexp</span></a> tokenizer.</p></li>
<li><p>Index column must has <code class="docutils literal notranslate"><span class="pre">WITH_POSITION</span></code> flag.</p></li>
</ul>
</div></blockquote>
<p>Other configurations such as lexicon’s normalizer are optional. You
can choose what you like. If you want to use case-insensitive search,
use <a class="reference internal" href="normalizers/normalizer_auto.html#normalizer-auto"><span class="std std-ref">NormalizerAuto</span></a> normalizer.</p>
<p>Here are recommended index definitions. In general, it’s reasonable
index definitions.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>table_create RegexpLexicon TABLE_PAT_KEY ShortText \
--default_tokenizer TokenRegexp \
--normalizer NormalizerAuto
# [[0, 1337566253.89858, 0.000355720520019531], true]
column_create RegexpLexicon logs_message_index \
COLUMN_INDEX|WITH_POSITION Logs message
# [[0, 1337566253.89858, 0.000355720520019531], true]
</pre></div>
</div>
<p>Now, you can use index for regular expression search. The following
regular expression can be evaluated by index because it uses only “the
beginning of text” and “literal”.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --query message:~\\\\Ahost1
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 3
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 1,
# "host1:[error]: No memory"
# ],
# [
# 2,
# "host1:[warning]: Remained disk space is less than 30%"
# ],
# [
# 3,
# "host1:[error]: Disk full"
# ]
# ]
# ]
# ]
</pre></div>
</div>
<p>Here is an example that uses <a class="reference internal" href="commands/select.html#select-filter"><span class="std std-ref">filter</span></a> instead of
<a class="reference internal" href="commands/select.html#select-query"><span class="std std-ref">query</span></a>. It uses the same regular expression as the
previous example.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --filter 'message @~ "\\\\Ahost1:"'
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 3
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 1,
# "host1:[error]: No memory"
# ],
# [
# 2,
# "host1:[warning]: Remained disk space is less than 30%"
# ],
# [
# 3,
# "host1:[error]: Disk full"
# ]
# ]
# ]
# ]
</pre></div>
</div>
<p><code class="docutils literal notranslate"><span class="pre">\</span></code> escape will confuse you because there are some steps that
require escape between you and Groonga. Here are steps that require
<code class="docutils literal notranslate"><span class="pre">\</span></code> escape:</p>
<blockquote>
<div><ul>
<li><p>Shell only when you pass Groonga command from command line the
following:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>% groonga /tmp/db select Logs --filter '"message @~ \"\\\\Ahost1:"\"'
</pre></div>
</div>
<p><code class="docutils literal notranslate"><span class="pre">--filter</span> <span class="pre">'"message</span> <span class="pre">@~</span> <span class="pre">\"\\\\Ahost1:\""'</span></code> is evaluated as the
following two arguments by shell:</p>
<blockquote>
<div><ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">--filter</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">"message</span> <span class="pre">@~</span> <span class="pre">\"\\\\Ahost1:\""</span></code></p></li>
</ul>
</div></blockquote>
</li>
<li><p>Groonga command parser only when you pass Groonga command by
command line style (<code class="docutils literal notranslate"><span class="pre">COMMAND</span> <span class="pre">ARG1_VALUE</span> <span class="pre">ARG2_VALUE</span> <span class="pre">...</span></code>) not
HTTP path style
(<code class="docutils literal notranslate"><span class="pre">/d/COMMAND?ARG1_NAME=ARG1_VALUE&ARG2_NAME=ARG3_VALUE</span></code>).</p>
<p><code class="docutils literal notranslate"><span class="pre">"message</span> <span class="pre">@~</span> <span class="pre">\"\\\\Ahost1:\""</span></code> is evaluated as the following
value by Groonga command parser:</p>
<blockquote>
<div><ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">message</span> <span class="pre">@~</span> <span class="pre">"\\Ahost1:"</span></code></p></li>
</ul>
</div></blockquote>
</li>
<li><p><a class="reference internal" href="grn_expr.html"><span class="doc">grn_expr</span></a> parser. <code class="docutils literal notranslate"><span class="pre">\</span></code> escape is required in both
<a class="reference internal" href="grn_expr/query_syntax.html"><span class="doc">Query syntax</span></a> and
<a class="reference internal" href="grn_expr/script_syntax.html"><span class="doc">Script syntax</span></a>.</p>
<p><code class="docutils literal notranslate"><span class="pre">"\\Ahost1:"</span></code> string literal in script syntax is evaluated as
the following value:</p>
<blockquote>
<div><ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">\Ahost1</span></code></p></li>
</ul>
</div></blockquote>
<p>The value is evaluated as regular expression.</p>
</li>
</ul>
</div></blockquote>
</div>
<div class="section" id="syntax">
<span id="regular-expression-syntax"></span><h2><span class="section-number">7.14.4. </span>Syntax<a class="headerlink" href="#syntax" title="Permalink to this headline">¶</a></h2>
<p>This section describes about only commonly used syntaxes. See <a class="reference external" href="https://github.com/k-takata/Onigmo/blob/master/doc/RE">Onigmo
syntax documentation</a> for other
syntaxes and details.</p>
<div class="section" id="escape">
<span id="regular-expression-escape"></span><h3><span class="section-number">7.14.4.1. </span>Escape<a class="headerlink" href="#escape" title="Permalink to this headline">¶</a></h3>
<p>In regular expression, there are the following special characters:</p>
<blockquote>
<div><ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">\</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">|</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">(</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">)</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">[</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">]</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">.</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">*</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">+</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">?</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">{</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">}</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">^</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">$</span></code></p></li>
</ul>
</div></blockquote>
<p>If you want to write pattern that matches these special character as
is, you need to escape them.</p>
<p>You can escape them by putting <code class="docutils literal notranslate"><span class="pre">\</span></code> before special character. Here
are regular expressions that match special character itself:</p>
<blockquote>
<div><ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">\\</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\|</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\(</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\)</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\[</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\]</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\.</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\*</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\+</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\?</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\{</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\}</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\^</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\$</span></code></p></li>
</ul>
</div></blockquote>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --filter 'message @~ "warning|info"'
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 2
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 2,
# "host1:[warning]: Remained disk space is less than 30%"
# ],
# [
# 5,
# "host2:[info]: Shutdown"
# ]
# ]
# ]
# ]
</pre></div>
</div>
<p>If your regular expression doesn’t work as you expected, confirm that
some special characters are used without escaping.</p>
</div>
<div class="section" id="choice">
<span id="regular-expression-choice"></span><h3><span class="section-number">7.14.4.2. </span>Choice<a class="headerlink" href="#choice" title="Permalink to this headline">¶</a></h3>
<p>Choice syntax is <code class="docutils literal notranslate"><span class="pre">A|B</span></code>. The regular expression matches when either
<code class="docutils literal notranslate"><span class="pre">A</span></code> pattern or <code class="docutils literal notranslate"><span class="pre">B</span></code> pattern is matched.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --filter 'message @~ "warning|info"'
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 2
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 2,
# "host1:[warning]: Remained disk space is less than 30%"
# ],
# [
# 5,
# "host2:[info]: Shutdown"
# ]
# ]
# ]
# ]
</pre></div>
</div>
<div class="admonition caution">
<p class="admonition-title">Caution</p>
<p>Regular expression that uses this syntax can’t be evaluated by
index.</p>
</div>
</div>
<div class="section" id="group">
<span id="regular-expression-group"></span><h3><span class="section-number">7.14.4.3. </span>Group<a class="headerlink" href="#group" title="Permalink to this headline">¶</a></h3>
<p>Group syntax is <code class="docutils literal notranslate"><span class="pre">(...)</span></code>. Group provides the following features:</p>
<blockquote>
<div><ul class="simple">
<li><p>Back reference</p></li>
<li><p>Scope reducing</p></li>
</ul>
</div></blockquote>
<p>You can refer matched groups by <code class="docutils literal notranslate"><span class="pre">\n</span></code> (<code class="docutils literal notranslate"><span class="pre">n</span></code> is the group number)
syntax. For example, <code class="docutils literal notranslate"><span class="pre">e(r)\1o\1</span></code> matches <code class="docutils literal notranslate"><span class="pre">error</span></code>. Because <code class="docutils literal notranslate"><span class="pre">\1</span></code>
is replaced with match result (<code class="docutils literal notranslate"><span class="pre">r</span></code>) of the first group <code class="docutils literal notranslate"><span class="pre">(r)</span></code>.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --filter 'message @~ "e(r)\\\\1o\\\\1"'
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 3
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 1,
# "host1:[error]: No memory"
# ],
# [
# 3,
# "host1:[error]: Disk full"
# ],
# [
# 4,
# "host2:[error]: No memory"
# ]
# ]
# ]
# ]
</pre></div>
</div>
<p>You can also use more powerful back reference features. See <a class="reference external" href="https://github.com/k-takata/Onigmo/blob/master/doc/RE#L302">“8. Back
reference” section in Onigmo documentation</a> for
details.</p>
<p>Group syntax reduces scope. For example, <code class="docutils literal notranslate"><span class="pre">\[(warning|info)\]</span></code>
reduces choice syntax scope. The regular expression matches
<code class="docutils literal notranslate"><span class="pre">[warning]</span></code> and <code class="docutils literal notranslate"><span class="pre">[info]</span></code>.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --filter 'message @~ "\\\\[(warning|info)\\\\]"'
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 2
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 2,
# "host1:[warning]: Remained disk space is less than 30%"
# ],
# [
# 5,
# "host2:[info]: Shutdown"
# ]
# ]
# ]
# ]
</pre></div>
</div>
<p>You can also use more powerful group related features. See
<a class="reference external" href="https://github.com/k-takata/Onigmo/blob/master/doc/RE#L225">“7. Extended groups” section in Onigmo documentation</a> for
details.</p>
<div class="admonition caution">
<p class="admonition-title">Caution</p>
<p>Regular expression that uses this syntax can’t be evaluated by
index.</p>
</div>
</div>
<div class="section" id="character-class">
<span id="regular-expression-character-class"></span><h3><span class="section-number">7.14.4.4. </span>Character class<a class="headerlink" href="#character-class" title="Permalink to this headline">¶</a></h3>
<p>Character class syntax is <code class="docutils literal notranslate"><span class="pre">[...]</span></code>. Character class is useful to
specify multiple characters to be matched.</p>
<p>For example, <code class="docutils literal notranslate"><span class="pre">[12]</span></code> matches <code class="docutils literal notranslate"><span class="pre">1</span></code> or <code class="docutils literal notranslate"><span class="pre">2</span></code>.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --filter 'message @~ "host[12]"'
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 5
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 1,
# "host1:[error]: No memory"
# ],
# [
# 2,
# "host1:[warning]: Remained disk space is less than 30%"
# ],
# [
# 3,
# "host1:[error]: Disk full"
# ],
# [
# 4,
# "host2:[error]: No memory"
# ],
# [
# 5,
# "host2:[info]: Shutdown"
# ]
# ]
# ]
# ]
</pre></div>
</div>
<p>You can specify characters by range. For example, <code class="docutils literal notranslate"><span class="pre">[0-9]</span></code> matches
one digit.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --filter 'message @~ "[0-9][0-9]%"'
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 1
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 2,
# "host1:[warning]: Remained disk space is less than 30%"
# ]
# ]
# ]
# ]
</pre></div>
</div>
<p>You can also use more powerful character class related features. See
<a class="reference external" href="https://github.com/k-takata/Onigmo/blob/master/doc/RE#L164">“6. Character class” section in Onigmo documentation</a> for
details.</p>
<div class="admonition caution">
<p class="admonition-title">Caution</p>
<p>Regular expression that uses this syntax can’t be evaluated by
index.</p>
</div>
</div>
<div class="section" id="anchor">
<span id="regular-expression-anchor"></span><h3><span class="section-number">7.14.4.5. </span>Anchor<a class="headerlink" href="#anchor" title="Permalink to this headline">¶</a></h3>
<p>There are the following commonly used anchor syntaxes. Some anchors
can be evaluated by index.</p>
<table class="docutils align-default">
<colgroup>
<col style="width: 33%" />
<col style="width: 33%" />
<col style="width: 33%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head"><p>Anchor</p></th>
<th class="head"><p>Description</p></th>
<th class="head"><p>Index ready</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">^</span></code></p></td>
<td><p>The beginning of line</p></td>
<td><p>o</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">$</span></code></p></td>
<td><p>The end of line</p></td>
<td><p>x</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">\A</span></code></p></td>
<td><p>The beginning of text</p></td>
<td><p>o</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">\z</span></code></p></td>
<td><p>The end of text</p></td>
<td><p>x</p></td>
</tr>
</tbody>
</table>
<p>Here is an example that uses <code class="docutils literal notranslate"><span class="pre">\z</span></code>.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --filter 'message @~ "%\\\\z"'
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 1
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 2,
# "host1:[warning]: Remained disk space is less than 30%"
# ]
# ]
# ]
# ]
</pre></div>
</div>
<p>You can also use more anchors. See <a class="reference external" href="https://github.com/k-takata/Onigmo/blob/master/doc/RE#L152">“5. Anchors” section in Onigmo
documentation</a> for
details.</p>
<div class="admonition caution">
<p class="admonition-title">Caution</p>
<p>Regular expression that uses this syntax except <code class="docutils literal notranslate"><span class="pre">\A</span></code> and <code class="docutils literal notranslate"><span class="pre">\z</span></code>
can’t be evaluated by index.</p>
</div>
</div>
<div class="section" id="quantifier">
<span id="regular-expression-quantifier"></span><h3><span class="section-number">7.14.4.6. </span>Quantifier<a class="headerlink" href="#quantifier" title="Permalink to this headline">¶</a></h3>
<p>There are the following commonly used quantifier syntaxes.</p>
<table class="docutils align-default">
<colgroup>
<col style="width: 50%" />
<col style="width: 50%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head"><p>Quantifier</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">?</span></code></p></td>
<td><p>0 or 1 time</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">*</span></code></p></td>
<td><p>0 or more times</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">+</span></code></p></td>
<td><p>1 or more times</p></td>
</tr>
</tbody>
</table>
<p>For example, <code class="docutils literal notranslate"><span class="pre">er+or</span></code> matches <code class="docutils literal notranslate"><span class="pre">error</span></code>, <code class="docutils literal notranslate"><span class="pre">errror</span></code> and so on.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>select Logs --filter 'message @~ "er+or"'
# [
# [
# 0,
# 1337566253.89858,
# 0.000355720520019531
# ],
# [
# [
# [
# 3
# ],
# [
# [
# "_id",
# "UInt32"
# ],
# [
# "message",
# "Text"
# ]
# ],
# [
# 1,
# "host1:[error]: No memory"
# ],
# [
# 3,
# "host1:[error]: Disk full"
# ],
# [
# 4,
# "host2:[error]: No memory"
# ]
# ]
# ]
# ]
</pre></div>
</div>
<p>You can also use more quantifiers. See <a class="reference external" href="https://github.com/k-takata/Onigmo/blob/master/doc/RE#L119">“4. Quantifier” section in Onigmo
documentation</a> for
details.</p>
<div class="admonition caution">
<p class="admonition-title">Caution</p>
<p>Regular expression that uses this syntax can’t be evaluated by
index.</p>
</div>
</div>
<div class="section" id="others">
<h3><span class="section-number">7.14.4.7. </span>Others<a class="headerlink" href="#others" title="Permalink to this headline">¶</a></h3>
<p>There are more syntaxes. If you’re interested in them, see <a class="reference external" href="https://github.com/k-takata/Onigmo/blob/master/doc/RE">Onigmo
documentation</a> for
details. You may be interested in “character type” and “character”
syntaxes.</p>
</div>
</div>
</div>
<div class="clearer"></div>
</div>
</div>
</div>
<div class="sphinxsidebar" role="navigation" aria-label="main navigation">
<div class="sphinxsidebarwrapper">
<h3><a href="../index.html">Table of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">7.14. Regular expression</a><ul>
<li><a class="reference internal" href="#summary">7.14.1. Summary</a></li>
<li><a class="reference internal" href="#usage">7.14.2. Usage</a></li>
<li><a class="reference internal" href="#index">7.14.3. Index</a></li>
<li><a class="reference internal" href="#syntax">7.14.4. Syntax</a><ul>
<li><a class="reference internal" href="#escape">7.14.4.1. Escape</a></li>
<li><a class="reference internal" href="#choice">7.14.4.2. Choice</a></li>
<li><a class="reference internal" href="#group">7.14.4.3. Group</a></li>
<li><a class="reference internal" href="#character-class">7.14.4.4. Character class</a></li>
<li><a class="reference internal" href="#anchor">7.14.4.5. Anchor</a></li>
<li><a class="reference internal" href="#quantifier">7.14.4.6. Quantifier</a></li>
<li><a class="reference internal" href="#others">7.14.4.7. Others</a></li>
</ul>
</li>
</ul>
</li>
</ul>
<h4>Previous topic</h4>
<p class="topless"><a href="grn_expr/script_syntax.html"
title="previous chapter"><span class="section-number">7.13.2. </span>Script syntax</a></p>
<h4>Next topic</h4>
<p class="topless"><a href="function.html"
title="next chapter"><span class="section-number">7.15. </span>Function</a></p>
<div id="searchbox" style="display: none" role="search">
<h3 id="searchlabel">Quick search</h3>
<div class="searchformwrapper">
<form class="search" action="../search.html" method="get">
<input type="text" name="q" aria-labelledby="searchlabel" />
<input type="submit" value="Go" />
</form>
</div>
</div>
<script>$('#searchbox').show(0);</script>
</div>
</div>
<div class="clearer"></div>
</div>
<div class="related" role="navigation" aria-label="related navigation">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
>index</a></li>
<li class="right" >
<a href="function.html" title="7.15. Function"
>next</a> |</li>
<li class="right" >
<a href="grn_expr/script_syntax.html" title="7.13.2. Script syntax"
>previous</a> |</li>
<li class="nav-item nav-item-0"><a href="../index.html">Groonga v10.1.1-31-g1e46ba6 documentation</a> »</li>
<li class="nav-item nav-item-1"><a href="../reference.html" ><span class="section-number">7. </span>Reference manual</a> »</li>
<li class="nav-item nav-item-this"><a href=""><span class="section-number">7.14. </span>Regular expression</a></li>
</ul>
</div>
<div class="footer" role="contentinfo">
© Copyright 2009-2021, Brazil, Inc.
</div>
</body>
</html>
|