205 DBMS_XDBT

The DBMS_XDBT package provides a convenient mechanism for administrators to set up a CONTEXT index on the Oracle XML DB hierarchy.

The package contains procedures to create default preferences, create the index and set up automatic synchronization of the CONTEXT index

The DBMS_XDBT package also contains a set of package variables that describe the configuration settings for the index. These are intended to cover the basic customizations that installations may require, but is by no means a complete set.

This chapter contains the following topics:

See Also:

Oracle XML DB Developer’s Guide

205.1 DBMS_XDBT Overview

The DBMS_XDBT package contains a set of package variables that describe the configuration settings for the index.

The DBMS_XDBT package can be used in the following ways:

205.2 DBMS_XDBT Security Model

Owned by XDB, the DBMS_XDBT package must be created by SYS or XDB. The EXECUTE privilege is granted to SYS or XDB. Subprograms in this package are executed using the privileges of the current user.

205.3 DBMS_XDBT Operational Notes

Configuration settings, or package variables, are available to customize the DBMS_XDBT package.

The DBMS_XDBT package can be customized by using a PL/SQL procedure or an anonymous block to set the relevant package variables, configuration settings, and then execute the procedures. A more general approach would be to introduce the appropriate customizations by modifying this package in place, or as a copy. The system must be configured to use job queues, and the jobs can be viewed through the USER_JOBS catalog views.

Table 205-1 General Indexing Settings for Customizing DBMS_XDBT

Parameter Default Value Description

IndexName

XDB$CI

Name of the CONTEXT index.

IndexTablespace

XDB$RESINFO

Tablespace used by tables and indexes comprising the CONTEXT index.

IndexMemory

128M

Memory used by index creation and SYNC; less than or equal to the MAX_INDEX_MEMORY system parameter (see the CTX_ADMIN package).

LogFile

'XdbCtxLog'

The log file used for ROWID during indexing. The LOG_DIRECTORY system parameter must be set already. NULL turn s off ROWID logging.

Table 205-2 Filtering Settings for Customizing DBMS_XDBT

Parameter Default Value Description

SkipFilter_Types

image/%, audio/%, video/%, model/%

List of mime types that should not be indexed.

NullFilter_Types

text/plain, text/html, text/xml

List of mime types that do not need to use the INSO filter. Use this for text-based documents.

FilterPref

XDB$CI_FILTER

Name of the filter preference.

Table 205-3 Stoplist Settings for Customizing DBMS_XDBT

Parameter Default Value Description

StoplistPref

XDB$CI_STOPLIST

Name of the stoplist.

StopWords

0..9; 'a'..'z'; 'A'..'Z'

List of stopwords, in excess of CTXSYS.DEFAULT_STOPLIST.

Table 205-4 Sectioning and Section Group Settings for Customizing DBMS_XDBT

Parameter Default Value Description

SectionGroup

HTML_SECTION_GROUP

Default sectioner. Use PATH_SECTION_GROUP or AUTO_SECTION_GROUP if repository contains mainly XML documents.

SectiongroupPref

XDB$CI_SECTIONGROUP

Name of the section group.

Table 205-5 Other Index Preference Settings for Customizing DBMS_XDBT

Parameter Default Value Description

DatastorePref

XDB$CI_DATASTORE

Name of the datastore preference

StoragePref

XDB$CI_STORAGE

Name of the storage preference.

WordlistPref

XDB$CI_WORDLIST

Name of the wordlist preference.

DefaultLexerPref

XDB$CI_DEFAULT_LEXER

Name of the default lexer preference.

Table 205-6 SYNC (CONTEXT Synchronization) Settings for Customizing DBMS_XDBT

Parameter Default Value Description

AutoSyncPolicy

SYNC_BY_PENDING_COUNT

Indicates when the index should be SYNCed. One of SYNC_BY_PENDING_COUNT, SYNC_BY_TIME, or SYNC_BY_PENDING_COUNT_AND_TIME.

MaxPendingCount

2

Maximum number of documents in the CTX_USER_PENDING queue before an index SYNC is triggered. Only if the AutoSyncPolicy is SYNC_BY_PENDING_COUNT or SYNC_BY_PENDING_COUNT_AND_TIME.

CheckPendingCountInterval

10 minutes

How often, in minutes, the pending queue should be checked. Only if the AutoSyncPolicy is SYNC_BY_PENDING_COUNT or SYNC_BY_PENDING_COUNT_AND_TIME.

SyncInterval

60 minutes

Indicates how often, in minutes, the index should be SYNCed. Only if the AutoSyncPolicy is SYNC_BY_TIME or SYNC_BY_PENDING_COUNT_AND_TIME

205.4 Summary of DBMS_XDBT Subprograms

This table lists the DBMS_XDBT subprograms in alphabetical order and briefly describes them.

Table 205-7 DBMS_XDBT Package Subprograms

Subprogram Description

CONFIGUREAUTOSYNC Procedure

Configures the CONTEXT index for automatic maintenance, SYNC

CREATEDATASTOREPREF Procedure

Creates a USER datastore preference for the CONTEXT index

CREATEFILTERPREF Procedure

Creates a filter preference for the CONTEXT index

CREATEINDEX Procedure

Creates the CONTEXT index on the XML DB hierarchy

CREATELEXERPREF Procedure

Creates a lexer preference for the CONTEXT index

CREATEPREFERENCES Procedure

Creates preferences required for the CONTEXT index on the XML DB hierarchy

CREATESECTIONGROUPPREF Procedure

Creates a storage preference for the CONTEXT index

CREATESTOPLISTPREF Procedure

Creates a section group for the CONTEXT index

CREATESTORAGEPREF Procedure

Creates a wordlist preference for the CONTEXT index

CREATEWORLDLISTPREF Procedure

Creates a stoplist for the CONTEXT index

DROPPREFERENCES Procedure

Drops any existing preferences

205.4.1 CONFIGUREAUTOSYNC Procedure

This procedure sets up jobs for automatic SYNCs of the CONTEXT index.

Syntax

DBMS_XDBT.CONFIGUREAUTOSYNC;

Usage Notes

  • The system must be configured for job queues for automatic synchronization. The jobs can be viewed using the USER_JOBS catalog views

  • The configuration parameter AutoSyncPolicy can be set to choose an appropriate synchronization policy.

The synchronization can be based on one of the following:

Sync Basis Description

SYNC_BY_PENDING_COUNT

The SYNC is triggered when the number of documents in the pending queue is greater than a threshold (See the MaxPendingCount configuration setting). The pending queue is polled at regular intervals (See the CheckPendingCountIntervalconfiguration parameter) to determine if the number of documents exceeds the threshold.

SYNC_BY_TIME

The SYNC is triggered at regular intervals. (See theSyncInterval configuration parameter).

SYNC_BY_PENDING_COUNT_AND_TIME

A combination of both of the preceding options.

205.4.2 CREATEDATASTOREPREF Procedure

This procedure creates a user datastore preference for the CONTEXT index on the XML DB hierarchy.

Syntax

DBMS_XDBT.CREATEDATASTOREPREF;

Usage Notes

  • The name of the datastore preference can be modified; see the DatastorePref configuration setting.

  • The default USER datastore procedure also filters the incoming document. The DBMS_XDBT package provides a set of configuration settings that control the filtering process.

  • The SkipFilter_Types array contains a list of regular expressions. Documents with a mime type that matches one of these expressions are not indexed. Some of the properties of the document metadata, such as author, remain unindexed.

    • The NullFilter_Types array contains a list of regular expressions. Documents with a mime type that matches one of these expressions are not filtered; however, they are still indexed. This is intended to be used for documents that are text-based, such as HTML, XML and plain-text.

    • All other documents use the INSO filter through the IFILTER API.

205.4.3 CREATEFILTERPREF Procedure

This procedure creates a NULL filter preference for the CONTEXT index on the XML DB hierarchy.

Syntax

DBMS_XDBT.CREATEFILTERPREF;

Usage Notes

  • The name of the filter preference can be modified; see FilterPref configuration setting.

  • The USER datastore procedure filters the incoming document; see CREATEDATASTOREPREF Procedurefor more details.

205.4.4 CREATEINDEX Procedure

This procedure creates the CONTEXT index on the XML DB hierarchy.

Syntax

DBMS_XDBT.CREATEINDEX;

Usage Notes

  • The name of the index can be changed; see the IndexName configuration setting.

  • Set the LogFile configuration parameter to enable ROWID logging during index creation.

  • Set the IndexMemory configuration parameter to determine the amount of memory that index creation, and later SYNCs, will use.

205.4.5 CREATELEXERPREF Procedure

This procedure creates a BASIC lexer preference for the CONTEXT index on the XML DB hierarchy.

Syntax

DBMS_XDBT.CREATELEXERPREF;

Usage Notes

  • The name of the lexer preference can be modified; see LexerPref configuration setting. No other configuration settings are provided.

  • MultiLexer preferences are not supported.

  • Base letter translation is turned on by default.

205.4.6 CREATEPREFERENCES Procedure

This procedure creates a set of default preferences based on the configuration settings.

Syntax

DBMS_XDBT.CREATEPREFERENCES;

205.4.7 CREATESECTIONGROUPPREF Procedure

This procedure creates a section group for the CONTEXT index on the XML DB hierarchy.

Syntax

DBMS_XDBT.CREATESECTIONGROUPPREF;

Usage Notes

  • The name of the section group can be changed; see the SectiongroupPref configuration setting.

  • The HTML sectioner is used by default. No zone sections are created by default. If the vast majority of documents are XML, consider using the AUTO_SECTION_GROUP or the PATH_SECTION_GROUP; see the SectionGroup configuration setting.

205.4.8 CREATESTOPLISTPREF Procedure

This procedure creates a stoplist for the CONTEXT index on the XML DB hierarchy.

Syntax

DBMS_XDBT.CREATESTOPLISTPREF;

Usage Notes

  • The name of the stoplist can be modified; see the StoplistPref configuration setting.

  • Numbers are not indexed.

  • The StopWords array is a configurable list of stopwords. These are meant to be stopwords in addition to the set of stopwords in CTXSYS.DEFAULT_STOPLIST.

205.4.9 CREATESTORAGEPREF Procedure

This procedure creates a BASIC_STORAGE preference for the CONTEXT index on the XML DB hierarchy.

Syntax

DBMS_XDBT.CREATESTORAGEPREF;

Usage Notes

  • The name of the storage preference can be modified; see the StoragePref configuration setting.

  • A tablespace can be specified for the tables and indexes comprising the CONTEXT index; see the IndexTablespace configuration setting.

  • Prefix and Substring indexing are not turned on by default.

  • The I_INDEX_CLAUSE uses key compression.

205.4.10 CREATEWORLDLISTPREF Procedure

This procedure creates a word list preference for the CONTEXT index on the XML DB hierarchy.

Syntax

DBMS_XDBT.CREATEWORDLISTPREF;

Usage Notes

  • The name of the word list preference can be modified; see the WordlistPref configuration setting. No other configuration settings are provided.

  • FUZZY_MATCH and STEMMER attributes are set to AUTO (auto-language detection)

205.4.11 DROPPREFERENCES Procedure

This procedure drops any previously created preferences for the CONTEXT index on the XML DB hierarchy.

Syntax

DBMS_XDBT.DROPPREFERENCES;