1 <chapter id="administration">
2 <!-- $Id: administration.xml,v 1.13 2002-12-02 15:10:58 mike 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.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 Z39.50 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="configuration-file">
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 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 Z39.50 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 PATH for UNIX systems.
289 <term>attset: <replaceable>filename</replaceable></term>
292 Specifies the filename(s) of attribute set files for use in
293 searching. At least the Bib-1 set should be loaded
294 (<literal>bib1.att</literal>).
295 The <literal>profilePath</literal> setting is used to look for
297 See <xref linkend="attset-files"/>
302 <term>memMax: <replaceable>size</replaceable></term>
305 Specifies <replaceable>size</replaceable> of internal memory
306 to use for the zebraidx program.
307 The amount is given in megabytes - default is 4 (4 MB).
313 <term>root: <replaceable>dir</replaceable></term>
316 Specifies a directory base for Zebra. All relative paths
317 given (in profilePath, register, shadow) are based on this
318 directory. This setting is useful if your Zebra server
319 is running in a different directory from where
320 <literal>zebra.cfg</literal> is located.
326 <term>tagsysno: 0|1</term>
329 Species whether Zebra should include system-number data in XML
330 and GRS-1 records returned to clients, represented by the
331 <literal><localControlNumber></literal> element in XML
332 and the <literal>(1,14)</literal> tag in GRS-1.
333 The content of these elements is an internally-generated
334 integer uniquely identifying the record within its database.
335 It is included by default but may be turned off, with
336 <literal>tagsysno: 0</literal> for databases in which a local
337 control number is explicitly specified in the input records
348 <sect1 id="locating-records">
349 <title>Locating Records</title>
352 The default behavior of the Zebra system is to reference the
353 records from their original location, i.e. where they were found when you
354 ran <literal>zebraidx</literal>.
355 That is, when a client wishes to retrieve a record
356 following a search operation, the files are accessed from the place
357 where you originally put them - if you remove the files (without
358 running <literal>zebraidx</literal> again, the server will return
359 diagnostic number 14 (``System error in presenting records'') to
364 If your input files are not permanent - for example if you retrieve
365 your records from an outside source, or if they were temporarily
366 mounted on a CD-ROM drive,
367 you may want Zebra to make an internal copy of them. To do this,
368 you specify 1 (true) in the <literal>storeData</literal> setting. When
369 the Z39.50 server retrieves the records they will be read from the
370 internal file structures of the system.
375 <sect1 id="simple-indexing">
376 <title>Indexing with no Record IDs (Simple Indexing)</title>
379 If you have a set of records that are not expected to change over time
380 you may can build your database without record IDs.
381 This indexing method uses less space than the other methods and
386 To use this method, you simply omit the <literal>recordId</literal> entry
387 for the group of files that you index. To add a set of records you use
388 <literal>zebraidx</literal> with the <literal>update</literal> command. The
389 <literal>update</literal> command will always add all of the records that it
390 encounters to the index - whether they have already been indexed or
391 not. If the set of indexed files change, you should delete all of the
392 index files, and build a new index from scratch.
396 Consider a system in which you have a group of text files called
397 <literal>simple</literal>.
398 That group of records should belong to a Z39.50 database called
399 <literal>textbase</literal>.
400 The following <literal>zebra.cfg</literal> file will suffice:
405 profilePath: /usr/local/yaz
407 simple.recordType: text
408 simple.database: textbase
414 Since the existing records in an index can not be addressed by their
415 IDs, it is impossible to delete or modify records when using this method.
420 <sect1 id="file-ids">
421 <title>Indexing with File Record IDs</title>
424 If you have a set of files that regularly change over time: Old files
425 are deleted, new ones are added, or existing files are modified, you
426 can benefit from using the <emphasis>file ID</emphasis>
427 indexing methodology.
428 Examples of this type of database might include an index of WWW
429 resources, or a USENET news spool area.
430 Briefly speaking, the file key methodology uses the directory paths
431 of the individual records as a unique identifier for each record.
432 To perform indexing of a directory with file keys, again, you specify
433 the top-level directory after the <literal>update</literal> command.
434 The command will recursively traverse the directories and compare
435 each one with whatever have been indexed before in that same directory.
436 If a file is new (not in the previous version of the directory) it
437 is inserted into the registers; if a file was already indexed and
438 it has been modified since the last update, the index is also
439 modified; if a file has been removed since the last
440 visit, it is deleted from the index.
444 The resulting system is easy to administrate. To delete a record you
445 simply have to delete the corresponding file (say, with the
446 <literal>rm</literal> command). And to add records you create new
447 files (or directories with files). For your changes to take effect
448 in the register you must run <literal>zebraidx update</literal> with
449 the same directory root again. This mode of operation requires more
450 disk space than simpler indexing methods, but it makes it easier for
451 you to keep the index in sync with a frequently changing set of data.
452 If you combine this system with the <emphasis>safe update</emphasis>
453 facility (see below), you never have to take your server off-line for
454 maintenance or register updating purposes.
458 To enable indexing with pathname IDs, you must specify
459 <literal>file</literal> as the value of <literal>recordId</literal>
460 in the configuration file. In addition, you should set
461 <literal>storeKeys</literal> to <literal>1</literal>, since the Zebra
462 indexer must save additional information about the contents of each record
463 in order to modify the indexes correctly at a later time.
467 FIXME - There must be a simpler way to do this with Adams string tags -H
471 For example, to update records of group <literal>esdd</literal>
473 <literal>/data1/records/</literal> you should type:
475 $ zebraidx -g esdd update /data1/records
480 The corresponding configuration file includes:
483 esdd.recordType: grs.sgml
489 <para>You cannot start out with a group of records with simple
490 indexing (no record IDs as in the previous section) and then later
491 enable file record Ids. Zebra must know from the first time that you
493 the files should be indexed with file record IDs.
498 You cannot explicitly delete records when using this method (using the
499 <literal>delete</literal> command to <literal>zebraidx</literal>. Instead
500 you have to delete the files from the file system (or move them to a
502 and then run <literal>zebraidx</literal> with the
503 <literal>update</literal> command.
505 <!-- ### what happens if a file contains multiple records? -->
508 <sect1 id="generic-ids">
509 <title>Indexing with General Record IDs</title>
512 When using this method you construct an (almost) arbitrary, internal
513 record key based on the contents of the record itself and other system
514 information. If you have a group of records that explicitly associates
515 an ID with each record, this method is convenient. For example, the
516 record format may contain a title or a ID-number - unique within the group.
517 In either case you specify the Z39.50 attribute set and use-attribute
518 location in which this information is stored, and the system looks at
519 that field to determine the identity of the record.
523 As before, the record ID is defined by the <literal>recordId</literal>
524 setting in the configuration file. The value of the record ID specification
525 consists of one or more tokens separated by whitespace. The resulting
526 ID is represented in the index by concatenating the tokens and
527 separating them by ASCII value (1).
531 There are three kinds of tokens:
535 <term>Internal record info</term>
538 The token refers to a key that is
539 extracted from the record. The syntax of this token is
540 <literal>(</literal> <emphasis>set</emphasis> <literal>,</literal>
541 <emphasis>use</emphasis> <literal>)</literal>,
542 where <emphasis>set</emphasis> is the
543 attribute set name <emphasis>use</emphasis> is the
544 name or value of the attribute.
549 <term>System variable</term>
552 The system variables are preceded by
557 and immediately followed by the system variable name, which
570 <term>database</term>
573 Current database specified.
590 <term>Constant string</term>
593 A string used as part of the ID — surrounded
594 by single- or double quotes.
602 For instance, the sample GILS records that come with the Zebra
603 distribution contain a unique ID in the data tagged Control-Identifier.
604 The data is mapped to the Bib-1 use attribute Identifier-standard
605 (code 1007). To use this field as a record id, specify
606 <literal>(bib1,Identifier-standard)</literal> as the value of the
607 <literal>recordId</literal> in the configuration file.
608 If you have other record types that uses the same field for a
609 different purpose, you might add the record type
610 (or group or database name) to the record id of the gils
611 records as well, to prevent matches with other types of records.
612 In this case the recordId might be set like this:
615 gils.recordId: $type (bib1,Identifier-standard)
621 (see <xref linkend="data-model"/>
622 for details of how the mapping between elements of your records and
623 searchable attributes is established).
627 As for the file record ID case described in the previous section,
628 updating your system is simply a matter of running
629 <literal>zebraidx</literal>
630 with the <literal>update</literal> command. However, the update with general
631 keys is considerably slower than with file record IDs, since all files
632 visited must be (re)read to discover their IDs.
636 As you might expect, when using the general record IDs
637 method, you can only add or modify existing records with the
638 <literal>update</literal> command.
639 If you wish to delete records, you must use the,
640 <literal>delete</literal> command, with a directory as a parameter.
641 This will remove all records that match the files below that root
647 <sect1 id="register-location">
648 <title>Register Location</title>
651 Normally, the index files that form dictionaries, inverted
652 files, record info, etc., are stored in the directory where you run
653 <literal>zebraidx</literal>. If you wish to store these, possibly large,
654 files somewhere else, you must add the <literal>register</literal>
655 entry to the <literal>zebra.cfg</literal> file.
656 Furthermore, the Zebra system allows its file
657 structures to span multiple file systems, which is useful for
658 managing very large databases.
662 The value of the <literal>register</literal> setting is a sequence
663 of tokens. Each token takes the form:
666 <emphasis>dir</emphasis><literal>:</literal><emphasis>size</emphasis>.
669 The <emphasis>dir</emphasis> specifies a directory in which index files
670 will be stored and the <emphasis>size</emphasis> specifies the maximum
671 size of all files in that directory. The Zebra indexer system fills
672 each directory in the order specified and use the next specified
673 directories as needed.
674 The <emphasis>size</emphasis> is an integer followed by a qualifier
676 <literal>b</literal> for bytes,
677 <literal>k</literal> for kilobytes.
678 <literal>M</literal> for megabytes,
679 <literal>G</literal> for gigabytes.
683 For instance, if you have allocated two disks for your register, and
684 the first disk is mounted
685 on <literal>/d1</literal> and has 2GB of free space and the
686 second, mounted on <literal>/d2</literal> has 3.6 GB, you could
687 put this entry in your configuration file:
690 register: /d1:2G /d2:3600M
696 Note that Zebra does not verify that the amount of space specified is
697 actually available on the directory (file system) specified - it is
698 your responsibility to ensure that enough space is available, and that
699 other applications do not attempt to use the free space. In a large
700 production system, it is recommended that you allocate one or more
701 file system exclusively to the Zebra register files.
706 <sect1 id="shadow-registers">
707 <title>Safe Updating - Using Shadow Registers</title>
710 <title>Description</title>
713 The Zebra server supports <emphasis>updating</emphasis> of the index
714 structures. That is, you can add, modify, or remove records from
715 databases managed by Zebra without rebuilding the entire index.
716 Since this process involves modifying structured files with various
717 references between blocks of data in the files, the update process
718 is inherently sensitive to system crashes, or to process interruptions:
719 Anything but a successfully completed update process will leave the
720 register files in an unknown state, and you will essentially have no
721 recourse but to re-index everything, or to restore the register files
722 from a backup medium.
723 Further, while the update process is active, users cannot be
724 allowed to access the system, as the contents of the register files
725 may change unpredictably.
729 You can solve these problems by enabling the shadow register system in
731 During the updating procedure, <literal>zebraidx</literal> will temporarily
732 write changes to the involved files in a set of "shadow
733 files", without modifying the files that are accessed by the
734 active server processes. If the update procedure is interrupted by a
735 system crash or a signal, you simply repeat the procedure - the
736 register files have not been changed or damaged, and the partially
737 written shadow files are automatically deleted before the new updating
742 At the end of the updating procedure (or in a separate operation, if
743 you so desire), the system enters a "commit mode". First,
744 any active server processes are forced to access those blocks that
745 have been changed from the shadow files rather than from the main
746 register files; the unmodified blocks are still accessed at their
747 normal location (the shadow files are not a complete copy of the
748 register files - they only contain those parts that have actually been
749 modified). If the commit process is interrupted at any point during the
750 commit process, the server processes will continue to access the
751 shadow files until you can repeat the commit procedure and complete
752 the writing of data to the main register files. You can perform
753 multiple update operations to the registers before you commit the
754 changes to the system files, or you can execute the commit operation
755 at the end of each update operation. When the commit phase has
756 completed successfully, any running server processes are instructed to
757 switch their operations to the new, operational register, and the
758 temporary shadow files are deleted.
764 <title>How to Use Shadow Register Files</title>
767 The first step is to allocate space on your system for the shadow
769 You do this by adding a <literal>shadow</literal> entry to the
770 <literal>zebra.cfg</literal> file.
771 The syntax of the <literal>shadow</literal> entry is exactly the
772 same as for the <literal>register</literal> entry
773 (see <xref linkend="register-location"/>).
774 The location of the shadow area should be
775 <emphasis>different</emphasis> from the location of the main register
776 area (if you have specified one - remember that if you provide no
777 <literal>register</literal> setting, the default register area is the
778 working directory of the server and indexing processes).
782 The following excerpt from a <literal>zebra.cfg</literal> file shows
783 one example of a setup that configures both the main register
784 location and the shadow file area.
785 Note that two directories or partitions have been set aside
786 for the shadow file area. You can specify any number of directories
787 for each of the file areas, but remember that there should be no
788 overlaps between the directories used for the main registers and the
789 shadow files, respectively.
796 shadow: /scratch1:100M /scratch2:200M
802 When shadow files are enabled, an extra command is available at the
803 <literal>zebraidx</literal> command line.
804 In order to make changes to the system take effect for the
805 users, you'll have to submit a "commit" command after a
806 (sequence of) update operation(s).
812 $ zebraidx update /d1/records
819 Or you can execute multiple updates before committing the changes:
825 $ zebraidx -g books update /d1/records /d2/more-records
826 $ zebraidx -g fun update /d3/fun-records
833 If one of the update operations above had been interrupted, the commit
834 operation on the last line would fail: <literal>zebraidx</literal>
835 will not let you commit changes that would destroy the running register.
836 You'll have to rerun all of the update operations since your last
837 commit operation, before you can commit the new changes.
841 Similarly, if the commit operation fails, <literal>zebraidx</literal>
842 will not let you start a new update operation before you have
843 successfully repeated the commit operation.
844 The server processes will keep accessing the shadow files rather
845 than the (possibly damaged) blocks of the main register files
846 until the commit operation has successfully completed.
850 You should be aware that update operations may take slightly longer
851 when the shadow register system is enabled, since more file access
852 operations are involved. Further, while the disk space required for
853 the shadow register data is modest for a small update operation, you
854 may prefer to disable the system if you are adding a very large number
855 of records to an already very large database (we use the terms
856 <emphasis>large</emphasis> and <emphasis>modest</emphasis>
857 very loosely here, since every application will have a
858 different perception of size).
859 To update the system without the use of the the shadow files,
860 simply run <literal>zebraidx</literal> with the <literal>-n</literal>
861 option (note that you do not have to execute the
862 <emphasis>commit</emphasis> command of <literal>zebraidx</literal>
863 when you temporarily disable the use of the shadow registers in
865 Note also that, just as when the shadow registers are not enabled,
866 server processes will be barred from accessing the main register
867 while the update procedure takes place.
875 <!-- Keep this comment at the end of the file
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