| Oracle® Database PL/SQL Packages and Types Reference 10g Release 2 (10.2) Part Number B14258-01 |
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| Oracle® Database PL/SQL Packages and Types Reference 10g Release 2 (10.2) Part Number B14258-01 |
|
|
View PDF |
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:
Overview
Operational Notes
The DBMS_XDBT package can be used in the following fashion:
Customize the package to set up the appropriate configuration.
DROPPREFERENCES ProcedureDrop any existing index preferences using the procedure.
Create new index preferences using the CREATEPREFERENCES Procedure procedure.
Create the CONTEXT index using the CREATEINDEX Procedure procedure.
Set up automatic synchronization of the index using the CONFIGUREAUTOSYNC Procedureprocedure.
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. This section describes the configuration settings, or package variables, available to customize the DBMS_XDBT package.
Table 122-1 General Indexing Settings for Customizing DBMS_XDBT
| Parameter | Default Value | Description |
|---|---|---|
IndexName |
XDB$CI |
The name of the CONTEXT index. |
IndexTablespace |
XDB$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 122-2 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$CI_FILTER |
Name of the filter preference. |
Table 122-3 Stoplist Settings for Customizing DBMS_XDBT
| Parameter | Default Value | Description |
|---|---|---|
StoplistPref |
XDB$CI_STOPLIST |
Name of the stoplist. |
StopWords |
0..9; 'a'..'z'; 'A'..'Z' |
List of stopwords, in excess of CTXSYS.DEFAULT_STOPLIST. |
Table 122-4 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$CI_SECTIONGROUP |
Name of the section group. |
Table 122-5 Other Index Preference Settings for Customizing DBMS_XDBT
| Parameter | Default Value | Description |
|---|---|---|
DatastorePref |
XDB$CI_DATASTORE |
The name of the datastore preference. |
StoragePref |
XDB$CI_STORAGE |
The name of the storage preference. |
WordlistPref |
XDB$CI_WORDLIST |
The name of the wordlist preference. |
DefaultLexerPref |
XDB$CI_DEFAULT_LEXER |
The name of the default lexer preference. |
Table 122-6 SYNC (CONTEXT Synchronization) Settings for Customizing DBMS_XDBT
Table 122-7 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 |
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 CheckPendingCountInterval configuration parameter) to determine if the number of documents exceeds the threshold. |
SYNC_BY_TIME |
The SYNC is triggered at regular intervals. (See the SyncInterval configuration parameter). |
SYNC_BY_PENDING_COUNT_AND_TIME |
A combination of both of the preceding options. |
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.
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.
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.
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.
This procedure creates a set of default preferences based on the configuration settings.
Syntax
DBMS_XDBT.CREATEPREFERENCES;
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.
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.
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.
This procedure creates a wordlist preference for the CONTEXT index on the XML DB hierarchy.
Syntax
DBMS_XDBT.CREATEWORDLISTPREF;
Usage Notes
The name of the wordlist 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)
This procedure drops any previously created preferences for the CONTEXT index on the XML DB hierarchy.
Syntax
DBMS_XDBT.DROPPREFERENCES;
