1 <chapter id="administration">
2 <!-- $Id: administration.xml,v 1.53 2007-12-17 14:22:05 heikki Exp $ -->
3 <title>Administrating &zebra;</title>
4 <!-- ### It's a bit daft that this chapter (which describes half of
5 the configuration-file formats) is separated from
6 "recordmodel-grs.xml" (which describes the other half) by the
7 instructions on running zebraidx and zebrasrv. Some careful
8 re-ordering is required here.
12 Unlike many simpler retrieval systems, &zebra; supports safe, incremental
13 updates to an existing index.
17 Normally, when &zebra; modifies the index it reads a number of records
19 Depending on your specifications and on the contents of each record
20 one the following events take place for each record:
27 The record is indexed as if it never occurred before.
28 Either the &zebra; system doesn't know how to identify the record or
29 &zebra; can identify the record but didn't find it to be already indexed.
37 The record has already been indexed.
38 In this case either the contents of the record or the location
39 (file) of the record indicates that it has been indexed before.
47 The record is deleted from the index. As in the
48 update-case it must be able to identify the record.
56 Please note that in both the modify- and delete- case the &zebra;
57 indexer must be able to generate a unique key that identifies the record
58 in question (more on this below).
62 To administrate the &zebra; retrieval system, you run the
63 <literal>zebraidx</literal> program.
64 This program supports a number of options which are preceded by a dash,
65 and a few commands (not preceded by dash).
69 Both the &zebra; administrative tool and the &acro.z3950; server share a
70 set of index files and a global configuration file.
71 The name of the configuration file defaults to
72 <literal>zebra.cfg</literal>.
73 The configuration file includes specifications on how to index
74 various kinds of records and where the other configuration files
75 are located. <literal>zebrasrv</literal> and <literal>zebraidx</literal>
76 <emphasis>must</emphasis> be run in the directory where the
77 configuration file lives unless you indicate the location of the
78 configuration file by option <literal>-c</literal>.
81 <sect1 id="record-types">
82 <title>Record Types</title>
85 Indexing is a per-record process, in which either insert/modify/delete
86 will occur. Before a record is indexed search keys are extracted from
87 whatever might be the layout the original record (sgml,html,text, etc..).
88 The &zebra; system currently supports two fundamental types of records:
89 structured and simple text.
90 To specify a particular extraction process, use either the
91 command line option <literal>-t</literal> or specify a
92 <literal>recordType</literal> setting in the configuration file.
97 <sect1 id="zebra-cfg">
98 <title>The &zebra; Configuration File</title>
101 The &zebra; configuration file, read by <literal>zebraidx</literal> and
102 <literal>zebrasrv</literal> defaults to <literal>zebra.cfg</literal>
103 unless specified by <literal>-c</literal> option.
107 You can edit the configuration file with a normal text editor.
108 parameter names and values are separated by colons in the file. Lines
109 starting with a hash sign (<literal>#</literal>) are
114 If you manage different sets of records that share common
115 characteristics, you can organize the configuration settings for each
117 When <literal>zebraidx</literal> is run and you wish to address a
118 given group you specify the group name with the <literal>-g</literal>
120 In this case settings that have the group name as their prefix
121 will be used by <literal>zebraidx</literal>.
122 If no <literal>-g</literal> option is specified, the settings
123 without prefix are used.
127 In the configuration file, the group name is placed before the option
128 name itself, separated by a dot (.). For instance, to set the record type
129 for group <literal>public</literal> to <literal>grs.sgml</literal>
130 (the &acro.sgml;-like format for structured records) you would write:
135 public.recordType: grs.sgml
140 To set the default value of the record type to <literal>text</literal>
151 The available configuration settings are summarized below. They will be
152 explained further in the following sections.
156 FIXME - Didn't Adam make something to have multiple databases in multiple dirs...
164 <emphasis>group</emphasis>
165 .recordType[<emphasis>.name</emphasis>]:
166 <replaceable>type</replaceable>
170 Specifies how records with the file extension
171 <emphasis>name</emphasis> should be handled by the indexer.
172 This option may also be specified as a command line option
173 (<literal>-t</literal>). Note that if you do not specify a
174 <emphasis>name</emphasis>, the setting applies to all files.
175 In general, the record type specifier consists of the elements (each
176 element separated by dot), <emphasis>fundamental-type</emphasis>,
177 <emphasis>file-read-type</emphasis> and arguments. Currently, two
178 fundamental types exist, <literal>text</literal> and
179 <literal>grs</literal>.
184 <term><emphasis>group</emphasis>.recordId:
185 <replaceable>record-id-spec</replaceable></term>
188 Specifies how the records are to be identified when updated. See
189 <xref linkend="locating-records"/>.
194 <term><emphasis>group</emphasis>.database:
195 <replaceable>database</replaceable></term>
198 Specifies the &acro.z3950; database name.
199 <!-- FIXME - now we can have multiple databases in one server. -H -->
204 <term><emphasis>group</emphasis>.storeKeys:
205 <replaceable>boolean</replaceable></term>
208 Specifies whether key information should be saved for a given
209 group of records. If you plan to update/delete this type of
210 records later this should be specified as 1; otherwise it
211 should be 0 (default), to save register space.
212 <!-- ### this is the first mention of "register" -->
213 See <xref linkend="file-ids"/>.
218 <term><emphasis>group</emphasis>.storeData:
219 <replaceable>boolean</replaceable></term>
222 Specifies whether the records should be stored internally
223 in the &zebra; system files.
224 If you want to maintain the raw records yourself,
225 this option should be false (0).
226 If you want &zebra; to take care of the records for you, it
232 <!-- ### probably a better place to define "register" -->
233 <term>register: <replaceable>register-location</replaceable></term>
236 Specifies the location of the various register files that &zebra; uses
237 to represent your databases.
238 See <xref linkend="register-location"/>.
243 <term>shadow: <replaceable>register-location</replaceable></term>
246 Enables the <emphasis>safe update</emphasis> facility of &zebra;, and
247 tells the system where to place the required, temporary files.
248 See <xref linkend="shadow-registers"/>.
253 <term>lockDir: <replaceable>directory</replaceable></term>
256 Directory in which various lock files are stored.
261 <term>keyTmpDir: <replaceable>directory</replaceable></term>
264 Directory in which temporary files used during zebraidx's update
270 <term>setTmpDir: <replaceable>directory</replaceable></term>
273 Specifies the directory that the server uses for temporary result sets.
274 If not specified <literal>/tmp</literal> will be used.
279 <term>profilePath: <replaceable>path</replaceable></term>
282 Specifies a path of profile specification files.
283 The path is composed of one or more directories separated by
284 colon. Similar to <literal>PATH</literal> for UNIX systems.
290 <term>modulePath: <replaceable>path</replaceable></term>
293 Specifies a path of record filter modules.
294 The path is composed of one or more directories separated by
295 colon. Similar to <literal>PATH</literal> for UNIX systems.
296 The 'make install' procedure typically puts modules in
297 <filename>/usr/local/lib/idzebra-2.0/modules</filename>.
303 <term>staticrank: <replaceable>integer</replaceable></term>
306 Enables whether static ranking is to be enabled (1) or
307 disabled (0). If omitted, it is disabled - corresponding
309 Refer to <xref linkend="administration-ranking-static"/> .
316 <term>estimatehits:: <replaceable>integer</replaceable></term>
319 Controls whether &zebra; should calculate approximite hit counts and
320 at which hit count it is to be enabled.
321 A value of 0 disables approximiate hit counts.
322 For a positive value approximaite hit count is enabled
323 if it is known to be larger than <replaceable>integer</replaceable>.
326 Approximate hit counts can also be triggered by a particular
327 attribute in a query.
328 Refer to <xref linkend="querymodel-zebra-global-attr-limit"/>.
334 <term>attset: <replaceable>filename</replaceable></term>
337 Specifies the filename(s) of attribute set files for use in
338 searching. In many configurations <filename>bib1.att</filename>
339 is used, but that is not required. If Classic Explain
340 attributes is to be used for searching,
341 <filename>explain.att</filename> must be given.
342 The path to att-files in general can be given using
343 <literal>profilePath</literal> setting.
344 See also <xref linkend="attset-files"/>.
349 <term>memMax: <replaceable>size</replaceable></term>
352 Specifies <replaceable>size</replaceable> of internal memory
353 to use for the zebraidx program.
354 The amount is given in megabytes - default is 4 (4 MB).
355 The more memory, the faster large updates happen, up to about
356 half the free memory available on the computer.
361 <term>tempfiles: <replaceable>Yes/Auto/No</replaceable></term>
364 Tells zebra if it should use temporary files when indexing. The
365 default is Auto, in which case zebra uses temporary files only
366 if it would need more that <replaceable>memMax</replaceable>
367 megabytes of memory. This should be good for most uses.
373 <term>root: <replaceable>dir</replaceable></term>
376 Specifies a directory base for &zebra;. All relative paths
377 given (in profilePath, register, shadow) are based on this
378 directory. This setting is useful if your &zebra; server
379 is running in a different directory from where
380 <literal>zebra.cfg</literal> is located.
386 <term>passwd: <replaceable>file</replaceable></term>
389 Specifies a file with description of user accounts for &zebra;.
390 The format is similar to that known to Apache's htpasswd files
391 and UNIX' passwd files. Non-empty lines not beginning with
392 # are considered account lines. There is one account per-line.
393 A line consists of fields separate by a single colon character.
394 First field is username, second is password.
400 <term>passwd.c: <replaceable>file</replaceable></term>
403 Specifies a file with description of user accounts for &zebra;.
404 File format is similar to that used by the passwd directive except
405 that the password are encrypted. Use Apache's htpasswd or similar
412 <term>perm.<replaceable>user</replaceable>:
413 <replaceable>permstring</replaceable></term>
416 Specifies permissions (priviledge) for a user that are allowed
417 to access &zebra; via the passwd system. There are two kinds
418 of permissions currently: read (r) and write(w). By default
419 users not listed in a permission directive are given the read
420 privilege. To specify permissions for a user with no
421 username, or &acro.z3950; anonymous style use
422 <literal>anonymous</literal>. The permstring consists of
423 a sequence of characters. Include character <literal>w</literal>
424 for write/update access, <literal>r</literal> for read access and
425 <literal>a</literal> to allow anonymous access through this account.
431 <term>dbaccess <replaceable>accessfile</replaceable></term>
434 Names a file which lists database subscriptions for individual users.
435 The access file should consists of lines of the form <literal>username:
436 dbnames</literal>, where dbnames is a list of database names, seprated by
437 '+'. No whitespace is allowed in the database list.
447 <sect1 id="locating-records">
448 <title>Locating Records</title>
451 The default behavior of the &zebra; system is to reference the
452 records from their original location, i.e. where they were found when you
453 run <literal>zebraidx</literal>.
454 That is, when a client wishes to retrieve a record
455 following a search operation, the files are accessed from the place
456 where you originally put them - if you remove the files (without
457 running <literal>zebraidx</literal> again, the server will return
458 diagnostic number 14 (``System error in presenting records'') to
463 If your input files are not permanent - for example if you retrieve
464 your records from an outside source, or if they were temporarily
465 mounted on a CD-ROM drive,
466 you may want &zebra; to make an internal copy of them. To do this,
467 you specify 1 (true) in the <literal>storeData</literal> setting. When
468 the &acro.z3950; server retrieves the records they will be read from the
469 internal file structures of the system.
474 <sect1 id="simple-indexing">
475 <title>Indexing with no Record IDs (Simple Indexing)</title>
478 If you have a set of records that are not expected to change over time
479 you may can build your database without record IDs.
480 This indexing method uses less space than the other methods and
485 To use this method, you simply omit the <literal>recordId</literal> entry
486 for the group of files that you index. To add a set of records you use
487 <literal>zebraidx</literal> with the <literal>update</literal> command. The
488 <literal>update</literal> command will always add all of the records that it
489 encounters to the index - whether they have already been indexed or
490 not. If the set of indexed files change, you should delete all of the
491 index files, and build a new index from scratch.
495 Consider a system in which you have a group of text files called
496 <literal>simple</literal>.
497 That group of records should belong to a &acro.z3950; database called
498 <literal>textbase</literal>.
499 The following <literal>zebra.cfg</literal> file will suffice:
504 profilePath: /usr/local/idzebra/tab
506 simple.recordType: text
507 simple.database: textbase
513 Since the existing records in an index can not be addressed by their
514 IDs, it is impossible to delete or modify records when using this method.
519 <sect1 id="file-ids">
520 <title>Indexing with File Record IDs</title>
523 If you have a set of files that regularly change over time: Old files
524 are deleted, new ones are added, or existing files are modified, you
525 can benefit from using the <emphasis>file ID</emphasis>
526 indexing methodology.
527 Examples of this type of database might include an index of WWW
528 resources, or a USENET news spool area.
529 Briefly speaking, the file key methodology uses the directory paths
530 of the individual records as a unique identifier for each record.
531 To perform indexing of a directory with file keys, again, you specify
532 the top-level directory after the <literal>update</literal> command.
533 The command will recursively traverse the directories and compare
534 each one with whatever have been indexed before in that same directory.
535 If a file is new (not in the previous version of the directory) it
536 is inserted into the registers; if a file was already indexed and
537 it has been modified since the last update, the index is also
538 modified; if a file has been removed since the last
539 visit, it is deleted from the index.
543 The resulting system is easy to administrate. To delete a record you
544 simply have to delete the corresponding file (say, with the
545 <literal>rm</literal> command). And to add records you create new
546 files (or directories with files). For your changes to take effect
547 in the register you must run <literal>zebraidx update</literal> with
548 the same directory root again. This mode of operation requires more
549 disk space than simpler indexing methods, but it makes it easier for
550 you to keep the index in sync with a frequently changing set of data.
551 If you combine this system with the <emphasis>safe update</emphasis>
552 facility (see below), you never have to take your server off-line for
553 maintenance or register updating purposes.
557 To enable indexing with pathname IDs, you must specify
558 <literal>file</literal> as the value of <literal>recordId</literal>
559 in the configuration file. In addition, you should set
560 <literal>storeKeys</literal> to <literal>1</literal>, since the &zebra;
561 indexer must save additional information about the contents of each record
562 in order to modify the indexes correctly at a later time.
566 FIXME - There must be a simpler way to do this with Adams string tags -H
570 For example, to update records of group <literal>esdd</literal>
572 <literal>/data1/records/</literal> you should type:
574 $ zebraidx -g esdd update /data1/records
579 The corresponding configuration file includes:
582 esdd.recordType: grs.sgml
588 <para>You cannot start out with a group of records with simple
589 indexing (no record IDs as in the previous section) and then later
590 enable file record Ids. &zebra; must know from the first time that you
592 the files should be indexed with file record IDs.
597 You cannot explicitly delete records when using this method (using the
598 <literal>delete</literal> command to <literal>zebraidx</literal>. Instead
599 you have to delete the files from the file system (or move them to a
601 and then run <literal>zebraidx</literal> with the
602 <literal>update</literal> command.
604 <!-- ### what happens if a file contains multiple records? -->
607 <sect1 id="generic-ids">
608 <title>Indexing with General Record IDs</title>
611 When using this method you construct an (almost) arbitrary, internal
612 record key based on the contents of the record itself and other system
613 information. If you have a group of records that explicitly associates
614 an ID with each record, this method is convenient. For example, the
615 record format may contain a title or a ID-number - unique within the group.
616 In either case you specify the &acro.z3950; attribute set and use-attribute
617 location in which this information is stored, and the system looks at
618 that field to determine the identity of the record.
622 As before, the record ID is defined by the <literal>recordId</literal>
623 setting in the configuration file. The value of the record ID specification
624 consists of one or more tokens separated by whitespace. The resulting
625 ID is represented in the index by concatenating the tokens and
626 separating them by ASCII value (1).
630 There are three kinds of tokens:
634 <term>Internal record info</term>
637 The token refers to a key that is
638 extracted from the record. The syntax of this token is
639 <literal>(</literal> <emphasis>set</emphasis> <literal>,</literal>
640 <emphasis>use</emphasis> <literal>)</literal>,
641 where <emphasis>set</emphasis> is the
642 attribute set name <emphasis>use</emphasis> is the
643 name or value of the attribute.
648 <term>System variable</term>
651 The system variables are preceded by
656 and immediately followed by the system variable name, which
669 <term>database</term>
672 Current database specified.
689 <term>Constant string</term>
692 A string used as part of the ID — surrounded
693 by single- or double quotes.
701 For instance, the sample GILS records that come with the &zebra;
702 distribution contain a unique ID in the data tagged Control-Identifier.
703 The data is mapped to the &acro.bib1; use attribute Identifier-standard
704 (code 1007). To use this field as a record id, specify
705 <literal>(bib1,Identifier-standard)</literal> as the value of the
706 <literal>recordId</literal> in the configuration file.
707 If you have other record types that uses the same field for a
708 different purpose, you might add the record type
709 (or group or database name) to the record id of the gils
710 records as well, to prevent matches with other types of records.
711 In this case the recordId might be set like this:
714 gils.recordId: $type (bib1,Identifier-standard)
720 (see <xref linkend="grs"/>
721 for details of how the mapping between elements of your records and
722 searchable attributes is established).
726 As for the file record ID case described in the previous section,
727 updating your system is simply a matter of running
728 <literal>zebraidx</literal>
729 with the <literal>update</literal> command. However, the update with general
730 keys is considerably slower than with file record IDs, since all files
731 visited must be (re)read to discover their IDs.
735 As you might expect, when using the general record IDs
736 method, you can only add or modify existing records with the
737 <literal>update</literal> command.
738 If you wish to delete records, you must use the,
739 <literal>delete</literal> command, with a directory as a parameter.
740 This will remove all records that match the files below that root
746 <sect1 id="register-location">
747 <title>Register Location</title>
750 Normally, the index files that form dictionaries, inverted
751 files, record info, etc., are stored in the directory where you run
752 <literal>zebraidx</literal>. If you wish to store these, possibly large,
753 files somewhere else, you must add the <literal>register</literal>
754 entry to the <literal>zebra.cfg</literal> file.
755 Furthermore, the &zebra; system allows its file
756 structures to span multiple file systems, which is useful for
757 managing very large databases.
761 The value of the <literal>register</literal> setting is a sequence
762 of tokens. Each token takes the form:
765 <emphasis>dir</emphasis><literal>:</literal><emphasis>size</emphasis>
768 The <emphasis>dir</emphasis> specifies a directory in which index files
769 will be stored and the <emphasis>size</emphasis> specifies the maximum
770 size of all files in that directory. The &zebra; indexer system fills
771 each directory in the order specified and use the next specified
772 directories as needed.
773 The <emphasis>size</emphasis> is an integer followed by a qualifier
775 <literal>b</literal> for bytes,
776 <literal>k</literal> for kilobytes.
777 <literal>M</literal> for megabytes,
778 <literal>G</literal> for gigabytes.
779 Specifying a negative value disables the checking (it still needs the unit,
780 use <literal>-1b</literal>).
784 For instance, if you have allocated three disks for your register, and
785 the first disk is mounted
786 on <literal>/d1</literal> and has 2GB of free space, the
787 second, mounted on <literal>/d2</literal> has 3.6 GB, and the third,
788 on which you have more space than you bother to worry about, mounted on
789 <literal>/d3</literal> you could put this entry in your configuration file:
792 register: /d1:2G /d2:3600M /d3:-1b
797 Note that &zebra; does not verify that the amount of space specified is
798 actually available on the directory (file system) specified - it is
799 your responsibility to ensure that enough space is available, and that
800 other applications do not attempt to use the free space. In a large
801 production system, it is recommended that you allocate one or more
802 file system exclusively to the &zebra; register files.
807 <sect1 id="shadow-registers">
808 <title>Safe Updating - Using Shadow Registers</title>
810 <sect2 id="shadow-registers-description">
811 <title>Description</title>
814 The &zebra; server supports <emphasis>updating</emphasis> of the index
815 structures. That is, you can add, modify, or remove records from
816 databases managed by &zebra; without rebuilding the entire index.
817 Since this process involves modifying structured files with various
818 references between blocks of data in the files, the update process
819 is inherently sensitive to system crashes, or to process interruptions:
820 Anything but a successfully completed update process will leave the
821 register files in an unknown state, and you will essentially have no
822 recourse but to re-index everything, or to restore the register files
823 from a backup medium.
824 Further, while the update process is active, users cannot be
825 allowed to access the system, as the contents of the register files
826 may change unpredictably.
830 You can solve these problems by enabling the shadow register system in
832 During the updating procedure, <literal>zebraidx</literal> will temporarily
833 write changes to the involved files in a set of "shadow
834 files", without modifying the files that are accessed by the
835 active server processes. If the update procedure is interrupted by a
836 system crash or a signal, you simply repeat the procedure - the
837 register files have not been changed or damaged, and the partially
838 written shadow files are automatically deleted before the new updating
843 At the end of the updating procedure (or in a separate operation, if
844 you so desire), the system enters a "commit mode". First,
845 any active server processes are forced to access those blocks that
846 have been changed from the shadow files rather than from the main
847 register files; the unmodified blocks are still accessed at their
848 normal location (the shadow files are not a complete copy of the
849 register files - they only contain those parts that have actually been
850 modified). If the commit process is interrupted at any point during the
851 commit process, the server processes will continue to access the
852 shadow files until you can repeat the commit procedure and complete
853 the writing of data to the main register files. You can perform
854 multiple update operations to the registers before you commit the
855 changes to the system files, or you can execute the commit operation
856 at the end of each update operation. When the commit phase has
857 completed successfully, any running server processes are instructed to
858 switch their operations to the new, operational register, and the
859 temporary shadow files are deleted.
864 <sect2 id="shadow-registers-how-to-use">
865 <title>How to Use Shadow Register Files</title>
868 The first step is to allocate space on your system for the shadow
870 You do this by adding a <literal>shadow</literal> entry to the
871 <literal>zebra.cfg</literal> file.
872 The syntax of the <literal>shadow</literal> entry is exactly the
873 same as for the <literal>register</literal> entry
874 (see <xref linkend="register-location"/>).
875 The location of the shadow area should be
876 <emphasis>different</emphasis> from the location of the main register
877 area (if you have specified one - remember that if you provide no
878 <literal>register</literal> setting, the default register area is the
879 working directory of the server and indexing processes).
883 The following excerpt from a <literal>zebra.cfg</literal> file shows
884 one example of a setup that configures both the main register
885 location and the shadow file area.
886 Note that two directories or partitions have been set aside
887 for the shadow file area. You can specify any number of directories
888 for each of the file areas, but remember that there should be no
889 overlaps between the directories used for the main registers and the
890 shadow files, respectively.
896 shadow: /scratch1:100M /scratch2:200M
902 When shadow files are enabled, an extra command is available at the
903 <literal>zebraidx</literal> command line.
904 In order to make changes to the system take effect for the
905 users, you'll have to submit a "commit" command after a
906 (sequence of) update operation(s).
912 $ zebraidx update /d1/records
919 Or you can execute multiple updates before committing the changes:
925 $ zebraidx -g books update /d1/records /d2/more-records
926 $ zebraidx -g fun update /d3/fun-records
933 If one of the update operations above had been interrupted, the commit
934 operation on the last line would fail: <literal>zebraidx</literal>
935 will not let you commit changes that would destroy the running register.
936 You'll have to rerun all of the update operations since your last
937 commit operation, before you can commit the new changes.
941 Similarly, if the commit operation fails, <literal>zebraidx</literal>
942 will not let you start a new update operation before you have
943 successfully repeated the commit operation.
944 The server processes will keep accessing the shadow files rather
945 than the (possibly damaged) blocks of the main register files
946 until the commit operation has successfully completed.
950 You should be aware that update operations may take slightly longer
951 when the shadow register system is enabled, since more file access
952 operations are involved. Further, while the disk space required for
953 the shadow register data is modest for a small update operation, you
954 may prefer to disable the system if you are adding a very large number
955 of records to an already very large database (we use the terms
956 <emphasis>large</emphasis> and <emphasis>modest</emphasis>
957 very loosely here, since every application will have a
958 different perception of size).
959 To update the system without the use of the the shadow files,
960 simply run <literal>zebraidx</literal> with the <literal>-n</literal>
961 option (note that you do not have to execute the
962 <emphasis>commit</emphasis> command of <literal>zebraidx</literal>
963 when you temporarily disable the use of the shadow registers in
965 Note also that, just as when the shadow registers are not enabled,
966 server processes will be barred from accessing the main register
967 while the update procedure takes place.
975 <sect1 id="administration-ranking">
976 <title>Relevance Ranking and Sorting of Result Sets</title>
978 <sect2 id="administration-overview">
979 <title>Overview</title>
981 The default ordering of a result set is left up to the server,
982 which inside &zebra; means sorting in ascending document ID order.
983 This is not always the order humans want to browse the sometimes
984 quite large hit sets. Ranking and sorting comes to the rescue.
988 In cases where a good presentation ordering can be computed at
989 indexing time, we can use a fixed <literal>static ranking</literal>
990 scheme, which is provided for the <literal>alvis</literal>
991 indexing filter. This defines a fixed ordering of hit lists,
992 independently of the query issued.
996 There are cases, however, where relevance of hit set documents is
997 highly dependent on the query processed.
998 Simply put, <literal>dynamic relevance ranking</literal>
999 sorts a set of retrieved records such that those most likely to be
1000 relevant to your request are retrieved first.
1001 Internally, &zebra; retrieves all documents that satisfy your
1002 query, and re-orders the hit list to arrange them based on
1003 a measurement of similarity between your query and the content of
1008 Finally, there are situations where hit sets of documents should be
1009 <literal>sorted</literal> during query time according to the
1010 lexicographical ordering of certain sort indexes created at
1016 <sect2 id="administration-ranking-static">
1017 <title>Static Ranking</title>
1020 &zebra; uses internally inverted indexes to look up term occurencies
1021 in documents. Multiple queries from different indexes can be
1022 combined by the binary boolean operations <literal>AND</literal>,
1023 <literal>OR</literal> and/or <literal>NOT</literal> (which
1024 is in fact a binary <literal>AND NOT</literal> operation).
1025 To ensure fast query execution
1026 speed, all indexes have to be sorted in the same order.
1029 The indexes are normally sorted according to document
1030 <literal>ID</literal> in
1031 ascending order, and any query which does not invoke a special
1032 re-ranking function will therefore retrieve the result set in
1034 <literal>ID</literal>
1042 directive in the main core &zebra; configuration file, the internal document
1043 keys used for ordering are augmented by a preceding integer, which
1044 contains the static rank of a given document, and the index lists
1046 first by ascending static rank,
1047 then by ascending document <literal>ID</literal>.
1049 is the ``best'' rank, as it occurs at the
1050 beginning of the list; higher numbers represent worse scores.
1053 The experimental <literal>alvis</literal> filter provides a
1054 directive to fetch static rank information out of the indexed &acro.xml;
1055 records, thus making <emphasis>all</emphasis> hit sets ordered
1056 after <emphasis>ascending</emphasis> static
1057 rank, and for those doc's which have the same static rank, ordered
1058 after <emphasis>ascending</emphasis> doc <literal>ID</literal>.
1059 See <xref linkend="record-model-alvisxslt"/> for the gory details.
1064 <sect2 id="administration-ranking-dynamic">
1065 <title>Dynamic Ranking</title>
1067 In order to fiddle with the static rank order, it is necessary to
1068 invoke additional re-ranking/re-ordering using dynamic
1069 ranking or score functions. These functions return positive
1070 integer scores, where <emphasis>highest</emphasis> score is
1072 hit sets are sorted according to <emphasis>descending</emphasis>
1074 to the index lists which are sorted according to
1075 ascending rank number and document ID).
1078 Dynamic ranking is enabled by a directive like one of the
1079 following in the zebra configuration file (use only one of these a time!):
1081 rank: rank-1 # default TDF-IDF like
1082 rank: rank-static # dummy do-nothing
1087 Dynamic ranking is done at query time rather than
1088 indexing time (this is why we
1089 call it ``dynamic ranking'' in the first place ...)
1090 It is invoked by adding
1091 the &acro.bib1; relation attribute with
1092 value ``relevance'' to the &acro.pqf; query (that is,
1093 <literal>@attr 2=102</literal>, see also
1094 <ulink url="&url.z39.50;bib1.html">
1095 The &acro.bib1; Attribute Set Semantics</ulink>, also in
1096 <ulink url="&url.z39.50.attset.bib1;">HTML</ulink>).
1097 To find all articles with the word <literal>Eoraptor</literal> in
1098 the title, and present them relevance ranked, issue the &acro.pqf; query:
1100 @attr 2=102 @attr 1=4 Eoraptor
1104 <sect3 id="administration-ranking-dynamic-rank1">
1105 <title>Dynamically ranking using &acro.pqf; queries with the 'rank-1'
1109 The default <literal>rank-1</literal> ranking module implements a
1110 TF/IDF (Term Frequecy over Inverse Document Frequency) like
1111 algorithm. In contrast to the usual defintion of TF/IDF
1112 algorithms, which only considers searching in one full-text
1113 index, this one works on multiple indexes at the same time.
1115 &zebra; does boolean queries and searches in specific addressed
1116 indexes (there are inverted indexes pointing from terms in the
1117 dictionary to documents and term positions inside documents).
1121 <term>Query Components</term>
1124 First, the boolean query is dismantled into its principal components,
1125 i.e. atomic queries where one term is looked up in one index.
1126 For example, the query
1128 @attr 2=102 @and @attr 1=1010 Utah @attr 1=1018 Springer
1130 is a boolean AND between the atomic parts
1132 @attr 2=102 @attr 1=1010 Utah
1136 @attr 2=102 @attr 1=1018 Springer
1138 which gets processed each for itself.
1144 <term>Atomic hit lists</term>
1147 Second, for each atomic query, the hit list of documents is
1151 In this example, two hit lists for each index
1152 <literal>@attr 1=1010</literal> and
1153 <literal>@attr 1=1018</literal> are computed.
1159 <term>Atomic scores</term>
1162 Third, each document in the hit list is assigned a score (_if_ ranking
1163 is enabled and requested in the query) using a TF/IDF scheme.
1166 In this example, both atomic parts of the query assign the magic
1167 <literal>@attr 2=102</literal> relevance attribute, and are
1168 to be used in the relevance ranking functions.
1171 It is possible to apply dynamic ranking on only parts of the
1174 @and @attr 2=102 @attr 1=1010 Utah @attr 1=1018 Springer
1176 searches for all documents which have the term 'Utah' on the
1177 body of text, and which have the term 'Springer' in the publisher
1178 field, and sort them in the order of the relevance ranking made on
1179 the body-of-text index only.
1185 <term>Hit list merging</term>
1188 Fourth, the atomic hit lists are merged according to the boolean
1189 conditions to a final hit list of documents to be returned.
1192 This step is always performed, independently of the fact that
1193 dynamic ranking is enabled or not.
1199 <term>Document score computation</term>
1202 Fifth, the total score of a document is computed as a linear
1203 combination of the atomic scores of the atomic hit lists
1206 Ranking weights may be used to pass a value to a ranking
1207 algorithm, using the non-standard &acro.bib1; attribute type 9.
1208 This allows one branch of a query to use one value while
1209 another branch uses a different one. For example, we can search
1210 for <literal>utah</literal> in the
1211 <literal>@attr 1=4</literal> index with weight 30, as
1212 well as in the <literal>@attr 1=1010</literal> index with weight 20:
1214 @attr 2=102 @or @attr 9=30 @attr 1=4 utah @attr 9=20 @attr 1=1010 city
1218 The default weight is
1219 sqrt(1000) ~ 34 , as the &acro.z3950; standard prescribes that the top score
1220 is 1000 and the bottom score is 0, encoded in integers.
1224 The ranking-weight feature is experimental. It may change in future
1232 <term>Re-sorting of hit list</term>
1235 Finally, the final hit list is re-ordered according to scores.
1243 Still need to describe the exact TF/IDF formula. Here's the info, need -->
1244 <!--to extract it in human readable form .. MC
1246 static int calc (void *set_handle, zint sysno, zint staticrank,
1249 int i, lo, divisor, score = 0;
1250 struct rank_set_info *si = (struct rank_set_info *) set_handle;
1252 if (!si->no_rank_entries)
1253 return -1; /* ranking not enabled for any terms */
1255 for (i = 0; i < si->no_entries; i++)
1257 yaz_log(log_level, "calc: i=%d rank_flag=%d lo=%d",
1258 i, si->entries[i].rank_flag, si->entries[i].local_occur);
1259 if (si->entries[i].rank_flag && (lo = si->entries[i].local_occur))
1260 score += (8+log2_int (lo)) * si->entries[i].global_inv *
1261 si->entries[i].rank_weight;
1263 divisor = si->no_rank_entries * (8+log2_int (si->last_pos/si->no_entries));
1264 score = score / divisor;
1265 yaz_log(log_level, "calc sysno=" ZINT_FORMAT " score=%d", sysno, score);
1268 /* reset the counts for the next term */
1269 for (i = 0; i < si->no_entries; i++)
1270 si->entries[i].local_occur = 0;
1275 where lo = si->entries[i].local_occur is the local documents term-within-index frequency, si->entries[i].global_inv represents the IDF part (computed in static void *begin()), and
1276 si->entries[i].rank_weight is the weight assigner per index (default 34, or set in the @attr 9=xyz magic)
1278 Finally, the IDF part is computed as:
1280 static void *begin (struct zebra_register *reg,
1281 void *class_handle, RSET rset, NMEM nmem,
1282 TERMID *terms, int numterms)
1284 struct rank_set_info *si =
1285 (struct rank_set_info *) nmem_malloc (nmem,sizeof(*si));
1288 yaz_log(log_level, "rank-1 begin");
1289 si->no_entries = numterms;
1290 si->no_rank_entries = 0;
1292 si->entries = (struct rank_term_info *)
1293 nmem_malloc (si->nmem, sizeof(*si->entries)*numterms);
1294 for (i = 0; i < numterms; i++)
1296 zint g = rset_count(terms[i]->rset);
1297 yaz_log(log_level, "i=%d flags=%s '%s'", i,
1298 terms[i]->flags, terms[i]->name );
1299 if (!strncmp (terms[i]->flags, "rank,", 5))
1301 const char *cp = strstr(terms[i]->flags+4, ",w=");
1302 si->entries[i].rank_flag = 1;
1304 si->entries[i].rank_weight = atoi (cp+3);
1306 si->entries[i].rank_weight = 34; /* sqrroot of 1000 */
1307 yaz_log(log_level, " i=%d weight=%d g="ZINT_FORMAT, i,
1308 si->entries[i].rank_weight, g);
1309 (si->no_rank_entries)++;
1312 si->entries[i].rank_flag = 0;
1313 si->entries[i].local_occur = 0; /* FIXME */
1314 si->entries[i].global_occur = g;
1315 si->entries[i].global_inv = 32 - log2_int (g);
1316 yaz_log(log_level, " global_inv = %d g = " ZINT_FORMAT,
1317 (int) (32-log2_int (g)), g);
1318 si->entries[i].term = terms[i];
1319 si->entries[i].term_index=i;
1320 terms[i]->rankpriv = &(si->entries[i]);
1326 where g = rset_count(terms[i]->rset) is the count of all documents in this specific index hit list, and the IDF part then is
1328 si->entries[i].global_inv = 32 - log2_int (g);
1335 The <literal>rank-1</literal> algorithm
1336 does not use the static rank
1337 information in the list keys, and will produce the same ordering
1338 with or without static ranking enabled.
1343 <sect3 id="administration-ranking-dynamic-rank1">
1344 <title>Dynamically ranking &acro.pqf; queries with the 'rank-static'
1347 The dummy <literal>rank-static</literal> reranking/scoring
1348 function returns just
1349 <literal>score = max int - staticrank</literal>
1350 in order to preserve the static ordering of hit sets that would
1351 have been produced had it not been invoked.
1352 Obviously, to combine static and dynamic ranking usefully,
1354 to make a new ranking
1355 function; this is left
1356 as an exercise for the reader.
1363 <literal>Dynamic ranking</literal> is not compatible
1364 with <literal>estimated hit sizes</literal>, as all documents in
1365 a hit set must be accessed to compute the correct placing in a
1366 ranking sorted list. Therefore the use attribute setting
1367 <literal>@attr 2=102</literal> clashes with
1368 <literal>@attr 9=integer</literal>.
1373 we might want to add ranking like this:
1375 Simple BM25 Extension to Multiple Weighted Fields
1376 Stephen Robertson, Hugo Zaragoza and Michael Taylor
1380 mitaylor2microsoft.com
1385 <sect3 id="administration-ranking-dynamic-cql">
1386 <title>Dynamically ranking &acro.cql; queries</title>
1388 Dynamic ranking can be enabled during sever side &acro.cql;
1389 query expansion by adding <literal>@attr 2=102</literal>
1390 chunks to the &acro.cql; config file. For example
1392 relationModifier.relevant = 2=102
1394 invokes dynamic ranking each time a &acro.cql; query of the form
1397 Z> f alvis.text =/relevant house
1399 is issued. Dynamic ranking can also be automatically used on
1400 specific &acro.cql; indexes by (for example) setting
1402 index.alvis.text = 1=text 2=102
1404 which then invokes dynamic ranking each time a &acro.cql; query of the form
1407 Z> f alvis.text = house
1417 <sect2 id="administration-ranking-sorting">
1418 <title>Sorting</title>
1420 &zebra; sorts efficiently using special sorting indexes
1421 (type=<literal>s</literal>; so each sortable index must be known
1422 at indexing time, specified in the configuration of record
1423 indexing. For example, to enable sorting according to the &acro.bib1;
1424 <literal>Date/time-added-to-db</literal> field, one could add the line
1426 xelm /*/@created Date/time-added-to-db:s
1428 to any <literal>.abs</literal> record-indexing configuration file.
1429 Similarly, one could add an indexing element of the form
1431 <z:index name="date-modified" type="s">
1432 <xsl:value-of select="some/xpath"/>
1435 to any <literal>alvis</literal>-filter indexing stylesheet.
1438 Indexing can be specified at searching time using a query term
1439 carrying the non-standard
1440 &acro.bib1; attribute-type <literal>7</literal>. This removes the
1441 need to send a &acro.z3950; <literal>Sort Request</literal>
1442 separately, and can dramatically improve latency when the client
1443 and server are on separate networks.
1444 The sorting part of the query is separate from the rest of the
1445 query - the actual search specification - and must be combined
1449 A sorting subquery needs two attributes: an index (such as a
1450 &acro.bib1; type-1 attribute) specifying which index to sort on, and a
1451 type-7 attribute whose value is be <literal>1</literal> for
1452 ascending sorting, or <literal>2</literal> for descending. The
1453 term associated with the sorting attribute is the priority of
1454 the sort key, where <literal>0</literal> specifies the primary
1455 sort key, <literal>1</literal> the secondary sort key, and so
1458 <para>For example, a search for water, sort by title (ascending),
1459 is expressed by the &acro.pqf; query
1461 @or @attr 1=1016 water @attr 7=1 @attr 1=4 0
1463 whereas a search for water, sort by title ascending,
1464 then date descending would be
1466 @or @or @attr 1=1016 water @attr 7=1 @attr 1=4 0 @attr 7=2 @attr 1=30 1
1470 Notice the fundamental differences between <literal>dynamic
1471 ranking</literal> and <literal>sorting</literal>: there can be
1472 only one ranking function defined and configured; but multiple
1473 sorting indexes can be specified dynamically at search
1474 time. Ranking does not need to use specific indexes, so
1475 dynamic ranking can be enabled and disabled without
1476 re-indexing; whereas, sorting indexes need to be
1477 defined before indexing.
1485 <sect1 id="administration-extended-services">
1486 <title>Extended Services: Remote Insert, Update and Delete</title>
1490 Extended services are only supported when accessing the &zebra;
1491 server using the <ulink url="&url.z39.50;">&acro.z3950;</ulink>
1492 protocol. The <ulink url="&url.sru;">&acro.sru;</ulink> protocol does
1493 not support extended services.
1498 The extended services are not enabled by default in zebra - due to the
1499 fact that they modify the system. &zebra; can be configured
1501 search, and to allow only updates for a particular admin user
1502 in the main zebra configuration file <filename>zebra.cfg</filename>.
1503 For user <literal>admin</literal>, you could use:
1507 passwd: passwordfile
1509 And in the password file
1510 <filename>passwordfile</filename>, you have to specify users and
1511 encrypted passwords as colon separated strings.
1512 Use a tool like <filename>htpasswd</filename>
1513 to maintain the encrypted passwords.
1517 It is essential to configure &zebra; to store records internally,
1519 modifications and deletion of records:
1524 The general record type should be set to any record filter which
1525 is able to parse &acro.xml; records, you may use any of the two
1526 declarations (but not both simultaneously!)
1529 # recordType: alvis.filter_alvis_config.xml
1531 To enable transaction safe shadow indexing,
1532 which is extra important for this kind of operation, set
1534 shadow: directoryname: size (e.g. 1000M)
1536 See <xref linkend="zebra-cfg"/> for additional information on
1537 these configuration options.
1541 It is not possible to carry information about record types or
1542 similar to &zebra; when using extended services, due to
1543 limitations of the <ulink url="&url.z39.50;">&acro.z3950;</ulink>
1544 protocol. Therefore, indexing filters can not be chosen on a
1545 per-record basis. One and only one general &acro.xml; indexing filter
1547 <!-- but because it is represented as an OID, we would need some
1548 form of proprietary mapping scheme between record type strings and
1551 However, as a minimum, it would be extremely useful to enable
1552 people to use &acro.marc21;, assuming grs.marcxml.marc21 as a record
1559 <sect2 id="administration-extended-services-z3950">
1560 <title>Extended services in the &acro.z3950; protocol</title>
1563 The <ulink url="&url.z39.50;">&acro.z3950;</ulink> standard allows
1564 servers to accept special binary <emphasis>extended services</emphasis>
1565 protocol packages, which may be used to insert, update and delete
1566 records into servers. These carry control and update
1567 information to the servers, which are encoded in seven package fields:
1570 <table id="administration-extended-services-z3950-table" frame="top">
1571 <title>Extended services &acro.z3950; Package Fields</title>
1575 <entry>Parameter</entry>
1576 <entry>Value</entry>
1577 <entry>Notes</entry>
1582 <entry><literal>type</literal></entry>
1583 <entry><literal>'update'</literal></entry>
1584 <entry>Must be set to trigger extended services</entry>
1587 <entry><literal>action</literal></entry>
1588 <entry><literal>string</literal></entry>
1590 Extended service action type with
1591 one of four possible values: <literal>recordInsert</literal>,
1592 <literal>recordReplace</literal>,
1593 <literal>recordDelete</literal>,
1594 and <literal>specialUpdate</literal>
1598 <entry><literal>record</literal></entry>
1599 <entry><literal>&acro.xml; string</literal></entry>
1600 <entry>An &acro.xml; formatted string containing the record</entry>
1603 <entry><literal>syntax</literal></entry>
1604 <entry><literal>'xml'</literal></entry>
1605 <entry>XML/SUTRS/MARC. GRS-1 not supported.
1606 The default filter (record type) as given by recordType in
1607 zebra.cfg is used to parse the record.</entry>
1610 <entry><literal>recordIdOpaque</literal></entry>
1611 <entry><literal>string</literal></entry>
1613 Optional client-supplied, opaque record
1614 identifier used under insert operations.
1618 <entry><literal>recordIdNumber </literal></entry>
1619 <entry><literal>positive number</literal></entry>
1620 <entry>&zebra;'s internal system number,
1621 not allowed for <literal>recordInsert</literal> or
1622 <literal>specialUpdate</literal> actions which result in fresh
1627 <entry><literal>databaseName</literal></entry>
1628 <entry><literal>database identifier</literal></entry>
1630 The name of the database to which the extended services should be
1640 The <literal>action</literal> parameter can be any of
1641 <literal>recordInsert</literal> (will fail if the record already exists),
1642 <literal>recordReplace</literal> (will fail if the record does not exist),
1643 <literal>recordDelete</literal> (will fail if the record does not
1645 <literal>specialUpdate</literal> (will insert or update the record
1646 as needed, record deletion is not possible).
1650 During all actions, the
1651 usual rules for internal record ID generation apply, unless an
1652 optional <literal>recordIdNumber</literal> &zebra; internal ID or a
1653 <literal>recordIdOpaque</literal> string identifier is assigned.
1654 The default ID generation is
1655 configured using the <literal>recordId:</literal> from
1656 <filename>zebra.cfg</filename>.
1657 See <xref linkend="zebra-cfg"/>.
1661 Setting of the <literal>recordIdNumber</literal> parameter,
1662 which must be an existing &zebra; internal system ID number, is not
1663 allowed during any <literal>recordInsert</literal> or
1664 <literal>specialUpdate</literal> action resulting in fresh record
1669 When retrieving existing
1670 records indexed with &acro.grs1; indexing filters, the &zebra; internal
1671 ID number is returned in the field
1672 <literal>/*/id:idzebra/localnumber</literal> in the namespace
1673 <literal>xmlns:id="http://www.indexdata.dk/zebra/"</literal>,
1674 where it can be picked up for later record updates or deletes.
1678 A new element set for retrieval of internal record
1679 data has been added, which can be used to access minimal records
1680 containing only the <literal>recordIdNumber</literal> &zebra;
1681 internal ID, or the <literal>recordIdOpaque</literal> string
1682 identifier. This works for any indexing filter used.
1683 See <xref linkend="special-retrieval"/>.
1687 The <literal>recordIdOpaque</literal> string parameter
1688 is an client-supplied, opaque record
1689 identifier, which may be used under
1690 insert, update and delete operations. The
1691 client software is responsible for assigning these to
1692 records. This identifier will
1693 replace zebra's own automagic identifier generation with a unique
1694 mapping from <literal>recordIdOpaque</literal> to the
1695 &zebra; internal <literal>recordIdNumber</literal>.
1696 <emphasis>The opaque <literal>recordIdOpaque</literal> string
1698 are not visible in retrieval records, nor are
1699 searchable, so the value of this parameter is
1700 questionable. It serves mostly as a convenient mapping from
1701 application domain string identifiers to &zebra; internal ID's.
1707 <sect2 id="administration-extended-services-yaz-client">
1708 <title>Extended services from yaz-client</title>
1711 We can now start a yaz-client admin session and create a database:
1714 $ yaz-client localhost:9999 -u admin/secret
1718 Now the <literal>Default</literal> database was created,
1719 we can insert an &acro.xml; file (esdd0006.grs
1720 from example/gils/records) and index it:
1723 Z> update insert id1234 esdd0006.grs
1726 The 3rd parameter - <literal>id1234</literal> here -
1727 is the <literal>recordIdOpaque</literal> package field.
1730 Actually, we should have a way to specify "no opaque record id" for
1731 yaz-client's update command.. We'll fix that.
1734 The newly inserted record can be searched as usual:
1739 Received SearchResponse.
1740 Search was a success.
1741 Number of hits: 1, setno 1
1742 SearchResult-1: term=utah cnt=1
1749 Let's delete the beast, using the same
1750 <literal>recordIdOpaque</literal> string parameter:
1753 Z> update delete id1234
1754 No last record (update ignored)
1755 Z> update delete 1 esdd0006.grs
1756 Got extended services response
1761 Received SearchResponse.
1762 Search was a success.
1763 Number of hits: 0, setno 2
1764 SearchResult-1: term=utah cnt=0
1771 If shadow register is enabled in your
1772 <filename>zebra.cfg</filename>,
1773 you must run the adm-commit command
1779 after each update session in order write your changes from the
1780 shadow to the life register space.
1785 <sect2 id="administration-extended-services-yaz-php">
1786 <title>Extended services from yaz-php</title>
1789 Extended services are also available from the &yaz; &acro.php; client layer. An
1790 example of an &yaz;-&acro.php; extended service transaction is given here:
1793 $record = '<record><title>A fine specimen of a record</title></record>';
1795 $options = array('action' => 'recordInsert',
1797 'record' => $record,
1798 'databaseName' => 'mydatabase'
1801 yaz_es($yaz, 'update', $options);
1802 yaz_es($yaz, 'commit', array());
1805 if ($error = yaz_error($yaz))
1815 <!-- Keep this comment at the end of the file
1820 sgml-minimize-attributes:nil
1821 sgml-always-quote-attributes:t
1824 sgml-parent-document: "zebra.xml"
1825 sgml-local-catalogs: nil
1826 sgml-namecase-general:t