|Oracle Text Reference
Part Number A96518-01
This chapter discusses the executables shipped with Oracle Text. The following topics are discussed:
ctxload to do the following with a thesaurus:
An import file is an ASCII flat file that contains entries for synonyms, broader terms, narrower terms, or related terms which can be used to expand queries.
ctxload program no longer supports the loading of text columns. To load files to a text column in batch, Oracle recommends that you use SQL*Loader.
ctxload -user username[/password][@sqlnet_address] -name object_name -file file_name [-thes] [-thescase y|n] [-thesdump] [-log file_name] [-trace] [-pk] [-export] [-update]
Specify the username and password of the user running ctxload.
The username and password can be followed immediately by @sqlnet_address to permit logon to remote databases. The value for sqlnet_address is a database connect string. If the
TWO_TASK environment variable is set to a remote database, you do not have to specify a value for sqlnet_address to connect to the database.
When you use
ctxload to export/import a thesaurus, use object_name to specify the name of the thesaurus to be exported/imported.
object_name to identify the thesaurus in queries that use thesaurus operators.
Thesaurus name must be unique. If the name specified for the thesaurus is identical to an existing thesaurus,
When you use
ctxload to update/export a text field, use object_name to specify the index associated with the text column.
ctxload is used to import a thesaurus, use file_name to specify the name of the import file which contains the thesaurus entries.
ctxload is used to export a thesaurus, use file_name to specify the name of the export file created by
If the name specified for the thesaurus dump file is identical to an existing file,
Import a thesaurus. Specify the source file with the -file argument. You specify the name of the thesaurus to be imported with -name.
Specify y to create a case-sensitive thesaurus with the name specified by -name and populate the thesaurus with entries from the thesaurus import file specified by -file. If -thescase is y (the thesaurus is case-sensitive),
ctxload enters the terms in the thesaurus exactly as they appear in the import file.
The default for -thescase is n (case-insensitive thesaurus)
Export a thesaurus. Specify the name of the thesaurus to be exported with the -name argument. Specify the destination file with the -file argument.
Specify the name of the log file to which
ctxload writes any national-language supported (Globalization Support) messages generated during processing. If you do not specify a log file name, the messages appear on the standard output.
Enables SQL statement tracing using
TRUE. This command captures all processed SQL statements in a trace file, which can be used for debugging. The location of the trace file is operating-system dependent and can be modified using the
USER_DUMP_DEST initialization parameter.
For more information about SQL trace and the
Specify the primary key value of the row to be updated or exported.
When the primary key is compound, you must enclose the values within double quotes and separate the keys with a comma.
Exports the contents of a
BLOB column in a database table into the operating system file specified by -file.
ctxload exports the
BLOB column in the row specified by -pk.
When you use the -export, you must specify a primary key with -pk.
Updates the contents of a
BLOB column in a database table with the contents of the operating system file specified by -file. ctxload updates the
CLOB or BLOB column in for the row specified by -pk.
When you use -update, you must specify a primary key with -pk.
This section provides examples for some of the operations that
ctxload can perform.
For more document loading examples, see Appendix C, "Loading Examples".
The following example imports a thesaurus named
tech_doc from an import file named
The following example dumps the contents of a thesaurus named
tech_doc into a file named
The knowledge base is the information source Oracle Text uses to perform theme analysis, such as theme indexing, processing
ABOUT queries, and document theme extraction with the
CTX_DOC package. A knowledge base is supplied for English and French.
ctxkbtc compiler, you can do the following:
For more information about the knowledge base packaged with Oracle Text, see Appendix I, "English Knowledge Base Category Hierarchy".
For more information about document services, see Chapter 8, "CTX_DOC Package".
Knowledge bases can be in any single-byte character set. Supplied knowledge bases are in WE8ISO8859P1. You can store an extended knowledge base in another character set such as US7ASCII.
ctxkbtc -user uname/passwd [-name thesname1 [thesname2 ... thesname16]] [-revert] [-stoplist stoplistname] [-verbose] [-log filename]
Specify the username and password for the administrator creating an extended knowledge base. This user must have write permission to the
Specify the name(s) of the thesauri (up to 16) to be compiled with the knowledge base to create the extended knowledge base. The thesauri you specify must already be loaded with
ctxload with the
-thescase Y option
Reverts the extended knowledge base to the default knowledge base provided by Oracle Text.
Specify the name of the stoplist. Stopwords in the stoplist are added to the knowledge base as useless words that are prevented from becoming themes or contributing to themes. You can still add stopthemes after running this command using
Displays all warnings and messages, including non-Globalization Support messages, to the standard output.
Specify the log file for storing all messages. When you specify a log file, no messages are reported to standard out.
ctxkbtc, you must set the
NLS_LANGenvironment variable to match the database character set.
ctxkbtcmust have write permission to the
ORACLE_HOME, since the program writes files to this directory.
ctxkbtctwice removes the previous extension.
ctxkbtc program has the following limitations:
Terms are case sensitive. If a thesaurus has a term in uppercase, for example, the same term present in lowercase form in a document will not be recognized.
The maximum length of a term is 80 characters.
Disambiguated homographs are not supported.
The following constraints apply to thesaurus relations:
Such violations are not recommended since they might produce undesired results.
You can extend the supplied knowledge base by compiling one or more thesauri with the Oracle Text knowledge base. The extended information can be application-specific terms and relationships. During theme analysis, the extended portion of the knowledge base overrides any terms and relationships in the knowledge base where there is overlap.
When extending the knowledge base, Oracle recommends that new terms be linked to one of the categories in the knowledge base for best results in theme proving when appropriate.
For more information about the knowledge base, see Appendix I, "English Knowledge Base Category Hierarchy"
If new terms are kept completely disjoint from existing categories, fewer themes from new terms will be proven. The result of this is poorer precision and recall with
ABOUT queries as well poor quality of gists and theme highlighting.
You link new terms to existing terms by making an existing term the broader term for the new terms.
You purchase a medical thesaurus
medthes containing a hierarchy of medical terms. The four top terms in the thesaurus are the following:
To link these terms to the existing knowledge base, add the following entries to the medical thesaurus to map the new terms to the existing health and medicine branch:
health and medicine NT Anesthesia and Analgesia NT Anti-Allergic and Respiratory System Agents NT Anti-Inflamammatory Agents, Antirheumatic Agents, and Inflamation Mediators NT Antineoplastic and Immunosuppressive Agents
Set your Globalization Support language environment variable to match the database character set. For example, if your database character set is WE8ISO8859P1 and you are using American English, set your NLS_LANG as follows:
Assuming the medical thesaurus is in a file called med.thes, you load the thesaurus as
ctxload as follows:
To link the loaded thesaurus
medthes to the knowledge base, use
ctxkbtc as follows:
You can extend theme functionality to languages other than English or French by loading your own knowledge base for any single-byte whitespace delimited language, including Spanish.
Theme functionality includes theme indexing,
ABOUT queries, theme highlighting, and the generation of themes, gists, and theme summaries with the
CTX_DOC PL/SQL package.
You extend theme functionality by adding a user-defined knowledge base. For example, you can create a Spanish knowledge base from a Spanish thesuarus.
To load your language-specific knowledge base, follow these steps:
ctxkbtc -user ctxsys/ctxsys -name my_lang_thes
This command compiles your language-specific knowledge base from the loaded thesaurus. To use this knowledge base for theme analysis during indexing and
ABOUT queries, specify the
NLS_LANG language as the
THEME_LANGUAGE attribute value for the
The following limitations hold for adding knowledge bases:
When multiple thesauri are to be compiled, precedence is determined by the order in which thesauri are listed in the arguments to the compiler (most preferred first). A user thesaurus always has precedence over the built-in knowledge base.
The following table lists the size limits associated with creating and compiling an extended knowledge base:
|Description of Parameter||Limit|
Number of RTs (from + to) per term
Number of terms per a single hierarchy (i.e., all narrower terms for a given top term)
Number of new terms in an extended knowledge base
Number of separate thesauri that can be compiled into a user extension to the KB