Release 9.2
Part Number A96518-01
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| Oracle Text Reference Release 9.2 Part Number A96518-01 |
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This chapter provides reference information for using the CTX_DDL PL/SQL package to create and manage the preferences, section groups, and stoplists required for Text indexes.
CTX_DDL contains the following stored procedures and functions:
Adds an attribute section to an XML section group. This procedure is useful for defining attributes in XML documents as sections. This allows you to search XML attribute text with the WITHIN operator.
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Note: When you use |
CTX_DDL.ADD_ATTR_SECTION( group_name in varchar2, section_name in varchar2, tag in varchar2);
Specify the name of the XML section group. You can add attribute sections only to XML section groups.
Specify the name of the attribute section. This is the name used for WITHIN queries on the attribute text.
The section name you specify cannot contain the colon (:), comma (,), or dot (.) characters. The section name must also be unique within group_name. Section names are case-insensitive.
Attribute section names can be no more than 64 bytes long.
Specify the name of the attribute in tag@attr form. This parameter is case-sensitive.
Consider an XML file that defines the BOOK tag with a TITLE attribute as follows:
<BOOK TITLE="Tale of Two Cities"> It was the best of times. </BOOK>
To define the title attribute as an attribute section, create an XML_SECTION_GROUP and define the attribute section as follows:
begin ctx_ddl_create_section_group('myxmlgroup', 'XML_SECTION_GROUP'); ctx_ddl.add_attr_section('myxmlgroup', 'booktitle', 'BOOK@TITLE'); end;
When you define the TITLE attribute section as such and index the document set, you can query the XML attribute text as follows:
'Cities within booktitle'
Creates a field section and adds the section to an existing section group. This enables field section searching with the WITHIN operator.
Field sections are delimited by start and end tags. By default, the text within field sections are indexed as a sub-document separate from the rest of the document.
Unlike zone sections, field sections cannot nest or overlap. As such, field sections are best suited for non-repeating, non-overlapping sections such as TITLE and AUTHOR markup in email- or news-type documents.
Because of how field sections are indexed, WITHIN queries on field sections are usually faster than WITHIN queries on zone sections.
CTX_DDL.ADD_FIELD_SECTION( group_name in varchar2, section_name in varchar2, tag in varchar2, visible in boolean default FALSE );
Specify the name of the section group to which section_name is added. You can add up to 64 field sections to a single section group. Within the same group, section zone names and section field names cannot be the same.
Specify the name of the section to add to the group_name. You use this name to identify the section in queries. Avoid using names that contain non-alphanumeric characters such as _, since these characters must be escaped in queries. Section names are case-insensitive.
Within the same group, zone section names and field section names cannot be the same. The terms Paragraph and Sentence are reserved for special sections.
Section names need not be unique across tags. You can assign the same section name to more than one tag, making details transparent to searches.
Specify the tag which marks the start of a section. For example, if the tag is <H1>, specify H1. The start tag you specify must be unique within a section group.
If group_name is an HTML_SECTION_GROUP, you can create field sections for the META tag's NAME/CONTENT attribute pairs. To do so, specify tag as meta@namevalue where namevalue is the value of the NAME attribute whose CONTENT attribute is to be indexed as a section. Refer to the example.
Oracle knows what the end tags look like from the group_type parameter you specify when you create the section group.
Specify TRUE to make the text visible within rest of document.
By default the visible flag is FALSE. This means that Oracle indexes the text within field sections as a sub-document separate from the rest of the document. However, you can set the visible flag to TRUE if you want text within the field section to be indexed as part of the enclosing document.
The following code defines a section group basicgroup of the BASIC_SECTION_GROUP type. It then creates a field section in basicgroup called Author for the <A> tag. It also sets the visible flag to FALSE:
begin ctx_ddl.create_section_group('basicgroup', 'BASIC_SECTION_GROUP'); ctx_ddl.add_field_section('basicgroup', 'Author', 'A', FALSE);end;
Because the Author field section is not visible, to find text within the Author section, you must use the WITHIN operator as follows:
'(Martin Luther King) WITHIN Author'
A query of Martin Luther King without the WITHIN operator does not return instances of this term in field sections. If you want to query text within field sections without specifying WITHIN, you must set the visible flag to TRUE when you create the section as follows:
begin ctx_ddl.add_field_section('basicgroup', 'Author', 'A', TRUE); end;
When you use the HTML_SECTION _GROUP, you can create sections for META tags.
Consider an HTML document that has a META tag as follows:
<META NAME="author" CONTENT="ken">
To create a field section that indexes the CONTENT attribute for the <META NAME="author"> tag:
begin ctx_ddl.create_section_group('myhtmlgroup', 'HTML_SECTION_GROUP'); ctx_ddl.add_field_section('myhtmlgroup', 'author', 'META@AUTHOR'); end
After indexing with section group mygroup, you can query the document as follows:
'ken WITHIN author'
Field sections cannot be nested. For example, if you define a field section to start with <TITLE> and define another field section to start with <FOO>, the two sections cannot be nested as follows:
<TITLE> dog <FOO> cat </FOO> </TITLE>
To work with nested section define them as zone sections.
Repeated field sections are allowed, but WITHIN queries treat them as a single section. The following is an example of repeated field section in a document:
<TITLE> cat </TITLE> <TITLE> dog </TITLE>
The query dog and cat within title returns the document, even though these words occur in different sections.
To have WITHIN queries distinguish repeated sections, define them as zone sections.
WITHIN operator in Chapter 3, "CONTAINS Query Operators".
"Section Group Types" in Chapter 2, "Indexing".
Use this procedure to add an index to a catalog index preference. You create this preference to create catalog indexes of type CTXCAT.
CTX_DDL.ADD_INDEX(set_name in varchar2, column_list varchar2, storage_clause varchar2);
Specify the name of the index set.
Specify a comma separated list of columns to index.
Specify a storage clause.
Consider a table called AUCTION with the following schema:
create table auction( item_id number, title varchar2(100), category_id number, price number, bid_close date);
Assume that queries on the table involve a mandatory text query clause and optional structured conditions on category_id. Results must be sorted based on bid_close.
You can create a catalog index to support the different types of structured queries a user might enter.
To create the indexes, first create the index set preference then add the required indexes to it:
begin ctx_ddl.create_index_set('auction_iset'); ctx_ddl.add_index('auction_iset','bid_close'); ctx_ddl.add_index('auction_iset','category_id, bid_close'); ctx_ddl.add_index('auction_iset','price, bid_close'); end;
Create the combined catalog index with CREATE INDEX as follows:
create index auction_titlex on AUCTION(title) indextype is CTXCAT parameters ('index set auction_iset');
To query the title column for the word pokemon, you can issue regular and mixed queries as follows:
select * from AUCTION where CATSEARCH(title, 'pokemon',NULL)> 0; select * from AUCTION where CATSEARCH(title, 'pokemon', 'category_id=99 order by bid_close desc')> 0;
Adds a special section, either SENTENCE or PARAGRAPH, to a section group. This enables searching within sentences or paragraphs in documents with the WITHIN operator.
A special section in a document is a section which is not explicitly tagged like zone and field sections. The start and end of special sections are detected when the index is created. Oracle supports two such sections: paragraph and sentence.
The sentence and paragraph boundaries are determined by the lexer.For example, the lexer recognizes sentence and paragraph section boundaries as follows:
| Special Section | Boundary |
|---|---|
|
SENTENCE |
WORD/PUNCT/WHITESPACE |
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WORD/PUNCT/NEWLINE |
|
|
PARAGRAPH |
WORD/PUNCT/NEWLINE/WHITESPACE (indented paragraph) |
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WORD/PUNCT/NEWLINE/NEWLINE (block paragraph) |
The punctuation, whitespace, and newline characters are determined by your lexer settings and can be changed.
If the lexer cannot recognize the boundaries, no sentence or paragraph sections are indexed.
CTX_DDL.ADD_SPECIAL_SECTION( group_name IN VARCHAR2, section_name IN VARCHAR2);
Specify the name of the section group.
Specify SENTENCE or PARAGRAPH.
The following code enables searching within sentences within HTML documents:
begin ctx_ddl.create_section_group('htmgroup', 'HTML_SECTION_GROUP'); ctx_ddl.add_special_section('htmgroup', 'SENTENCE'); end;
You can also add zone sections to the group to enable zone searching in addition to sentence searching. The following example adds the zone section Headline to the section group htmgroup:
begin ctx_ddl.create_section_group('htmgroup', 'HTML_SECTION_GROUP'); ctx_ddl.add_special_section('htmgroup', 'SENTENCE'); ctx_ddl.add_zone_section('htmgroup', 'Headline', 'H1'); end;
If you are only interested in sentence or paragraph searching within documents and not interested in defining zone or field sections, you can use the NULL_SECTION_GROUP as follows:
begin ctx_ddl.create_section_group('nullgroup', 'NULL_SECTION_GROUP'); ctx_ddl.add_special_section('nullgroup', 'SENTENCE'); end;
WITHIN operator in Chapter 3, "CONTAINS Query Operators".
"Section Group Types" in Chapter 2, "Indexing".
Adds a stopclass to a stoplist. A stopclass is a class of tokens that is not to be indexed.
CTX_DDL.ADD_STOPCLASS( stoplist_name in varchar2, stopclass in varchar2 );
Specify the name of the stoplist.
Specify the stopclass to be added to stoplist_name. Currently, only the NUMBERS class is supported.
The maximum number of stopwords, stopthemes, and stopclasses you can add to a stoplist is 4095.
The following code adds a stopclass of NUMBERS to the stoplist mystop:
begin ctx_ddl.add_stopclass('mystop', 'NUMBERS'); end;
Adds a stop section to an automatic section group. Adding a stop section causes the automatic section indexing operation to ignore the specified section in XML documents.
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Note: Adding a stop section causes no section information to be created in the index. However, the text within a stop section is always searchable. |
Adding a stop section is useful when your documents contain many low information tags. Adding stop sections also improves indexing performance with the automatic section group.
The number of stop sections you can add is unlimited.
Stop sections do not have section names and hence are not recorded in the section views.
CTX_DDL.ADD_STOP_SECTION( section_group IN VARCHAR2, tag IN VARCHAR2);
Specify the name of the automatic section group. If you do not specify an automatic section group, this procedure returns an error.
Specify the tag to ignore during indexing. This parameter is case-sensitive. Defining a stop tag as such also stops the tag's attribute sections, if any.
You can qualify the tag with document type in the form (doctype)tag. For example, if you wanted to make the <fluff> tag a stop section only within the mydoc document type, specify (mydoc)fluff for tag.
The following code adds a stop section identified by the tag <fluff> to the automatic section group myauto:
begin ctx_ddl.add_stop_section('myauto', 'fluff'); end;
This code also stops any attribute sections contained within <fluff>. For example, if a document contained:
<fluff type="computer">
Then the above code also stops the attribute section fluff@type.
The following code creates a stop section for the tag <fluff> only in documents that have a root element of mydoc:
begin ctx_ddl.add_stop_section('myauto', '(mydoc)fluff'); end;
ALTER INDEX in Chapter 1, "SQL Statements and Operators".
Adds a single stoptheme to a stoplist. A stoptheme is a theme that is not to be indexed.
In English, you query on indexed themes using the ABOUT operator.
CTX_DDL.ADD_STOPTHEME( stoplist_name in varchar2, stoptheme in varchar2 );
Specify the name of the stoplist.
Specify the stoptheme to be added to stoplist_name. The system normalizes the stoptheme you enter using the knowledge base. If the normalized theme is more than one theme, the system does not process your stoptheme. For this reason, Oracle recommends that you submit single stopthemes.
The maximum number of stopwords, stopthemes, and stopclasses you can add to a stoplist is 4095.
The following example adds the stoptheme banking to the stoplist mystop:
begin ctx_ddl.add_stoptheme('mystop', 'banking'); end;
ABOUT operator in Chapter 3, "CONTAINS Query Operators".
Use this procedure to add a single stopword to a stoplist.
To create a list of stopwords, you must call this procedure once for each word.
CTX_DDL.ADD_STOPWORD( stoplist_name in varchar2, stopword in varchar2, language in varchar2 default NULL);
Specify the name of the stoplist.
Specify the stopword to be added.
Language-specific stopwords must be unique across the other stopwords specific to the language. For example, it is valid to have a German die and an English die in the same stoplist.
The maximum number of stopwords, stopthemes, and stopclasses you can add to a stoplist is 4095.
Specify the language of stopword when the stoplist you specify with stoplist_name is of type MULTI_STOPLIST. You must specify the Globalization Support name or abbreviation of an Oracle-supported language.
To make a stopword active in multiple languages, specify ALL for this parameter. For example, defining ALL stopwords is useful when you have international documents that contain English fragments that need to be stopped in any language.
An ALL stopword is active in all languages. If you use the multi-lexer, the language-specific lexing of the stopword occurs, just as if it had been added multiple times in multiple specific languages.
Otherwise, specify NULL.
The following example adds the stopwords because, notwithstanding, nonetheless, and therefore to the stoplist mystop:
begin ctx_ddl.add_stopword('mystop', 'because'); ctx_ddl.add_stopword('mystop', 'notwithstanding'); ctx_ddl.add_stopword('mystop', 'nonetheless'); ctx_ddl.add_stopword('mystop', 'therefore');end;
The following example adds the German word die to a multi-language stoplist:
begin ctx_ddl.add_stopword('mystop', 'Die','german');end;
The following adds the word the as an ALL stopword to the multi-language stoplist globallist:
begin ctx_ddl.add_stopword('globallist','the','ALL');end;
ALTER INDEX in Chapter 1, "SQL Statements and Operators".
Appendix D, "Supplied Stoplists"
Add a sub-lexer to a multi-lexer preference. A sub-lexer identifies a language in a multi-lexer (multi-language) preference. Use a multi-lexer preference when you want to index more than one language.
The following restrictions apply to using CTX_DDL.ADD_SUB_LEXER:
CTXSYS.CTX_DDL.ADD_SUB_LEXER records only a reference. The sub-lexer values are copied at create index time to index value storage.CTX_DDL.ADD_SUB_LEXER( lexer_name in varchar2, language in varchar2, sub_lexer in varchar2, alt_value in varchar2 default null );
Specify the name of the multi-lexer preference.
Specify the Globalization Support language name or abbreviation of the sub-lexer. For example, you can specify ENGLISH or EN for English.
The sub-lexer you specify with sub_lexer is used when the language column has a value case-insensitive equal to the Globalization Support name of abbreviation of language.
Specify DEFAULT to assign a default sub-lexer to use when the value of the language column in the base table is null, invalid, or unmapped to a sub-lexer. The DEFAULT lexer is also used to parse stopwords.
If a sub-lexer definition for language already exists, then it is replaced by this call.
Specify the name of the sub-lexer to use for this language.
Optionally specify an alternate value for language.
If you specify DEFAULT for language, you cannot specify an alt_value.
The alt_value is limited to 30 bytes and cannot be an Globalization Support language name, abbreviation, or DEFAULT.
This example shows how to create a multi-language text table and how to set up the multi-lexer to index the table.
Create the multi-language table with a primary key, a text column, and a language column as follows:
create table globaldoc ( doc_id number primary key, lang varchar2(3), text clob );
Assume that the table holds mostly English documents, with the occasional German or Japanese document. To handle the three languages, you must create three sub-lexers, one for English, one for German, and one for Japanese:
ctx_ddl.create_preference('english_lexer','basic_lexer'); ctx_ddl.set_attribute('english_lexer','index_themes','yes'); ctx_ddl.set_attribtue('english_lexer','theme_language','english'); ctx_ddl.create_preference('german_lexer','basic_lexer'); ctx_ddl.set_attribute('german_lexer','composite','german'); ctx_ddl.set_attribute('german_lexer','mixed_case','yes'); ctx_ddl.set_attribute('german_lexer','alternate_spelling','german'); ctx_ddl.create_preference('japanese_lexer','japanese_vgram_lexer');
Create the multi-lexer preference:
ctx_ddl.create_preference('global_lexer', 'multi_lexer');
Since the stored documents are mostly English, make the English lexer the default:
ctx_ddl.add_sub_lexer('global_lexer','default','english_lexer');
Add the German and Japanese lexers in their respective languages. Also assume that the language column is expressed in ISO 639-2, so we add those as alternate values.
ctx_ddl.add_sub_lexer('global_lexer','german','german_lexer','ger'); ctx_ddl.add_sub_lexer('global_lexer','japanese','japanese_lexer','jpn');
Create the index globalx, specifying the multi-lexer preference and the language column in the parameters string as follows:
create index globalx on globaldoc(text) indextype is ctxsys.context parameters ('lexer global_lexer language column lang');
Creates a zone section and adds the section to an existing section group. This enables zone section searching with the WITHIN operator.
Zone sections are sections delimited by start and end tags. The <B> and </B> tags in HTML, for instance, marks a range of words which are to be rendered in boldface.
Zone sections can be nested within one another, can overlap, and can occur more than once in a document.
CTX_DDL.ADD_ZONE_SECTION( group_name in varchar2, section_name in varchar2, tag in varchar2 );
Specify the name of the section group to which section_name is added.
Specify the name of the section to add to the group_name. You use this name to identify the section in WITHIN queries. Avoid using names that contain non-alphanumeric characters such as _, since most of these characters are special must be escaped in queries. Section names are case-insensitive.
Within the same group, zone section names and field section names cannot be the same. The terms Paragraph and Sentence are reserved for special sections.
Section names need not be unique across tags. You can assign the same section name to more than one tag, making details transparent to searches.
Specify the pattern which marks the start of a section. For example, if <H1> is the HTML tag, specify H1 for tag. The start tag you specify must be unique within a section group.
Oracle knows what the end tags look like from the group_type parameter you specify when you create the section group.
If group_name is an HTML_SECTION_GROUP, you can create zone sections for the META tag's NAME/CONTENT attribute pairs. To do so, specify tag as meta@namevalue where namevalue is the value of the NAME attribute whose CONTENT attributes are to be indexed as a section. Refer to the example.
If group_name is an XML_SECTION_GROUP, you can optionally qualify tag with a document type (root element) in the form (doctype)tag. Doing so makes section_name sensitive to the XML document type declaration. Refer to the example.
The following code defines a section group called htmgroup of type HTML_SECTION_GROUP. It then creates a zone section in htmgroup called headline identified by the <H1> tag:
begin ctx_ddl.create_section_group('htmgroup', 'HTML_SECTION_GROUP'); ctx_ddl.add_zone_section('htmgroup', 'heading', 'H1'); end;
After indexing with section group htmgroup, you can query within the heading section by issuing a query as follows:
'Oracle WITHIN heading'
You can create zone sections for HTML META tags when you use the HTML_SECTION_GROUP.
Consider an HTML document that has a META tag as follows:
<META NAME="author" CONTENT="ken">
To create a zone section that indexes all CONTENT attributes for the META tag whose NAME value is author:
begin ctx_ddl.create_section_group('htmgroup', 'HTML_SECTION_GROUP'); ctx_ddl.add_zone_section('htmgroup', 'author', 'meta@author'); end
After indexing with section group htmgroup, you can query the document as follows:
'ken WITHIN author'
You have an XML document set that contains the <book> tag declared for different document types. You want to create a distinct book section for each document type.
Assume that mydocname is declared as an XML document type (root element) as follows:
<!DOCTYPE mydocname ... [...
Within mydocname, the element <book> is declared. For this tag, you can create a section named mybooksec that is sensitive to the tag's document type as follows:
begin ctx_ddl.create_section_group('myxmlgroup', 'XML_SECTION_GROUP'); ctx_ddl.add_zone_section('myxmlgroup', 'mybooksec', '(mydocname)book'); end;
Zone sections can repeat. Each occurrence is treated as a separate section. For example, if <H1> denotes a heading section, they can repeat in the same documents as follows:
<H1> The Brown Fox </H1>
<H1> The Gray Wolf </H1>
Assuming that these zone sections are named Heading, the query Brown WITHIN Heading returns this document. However, a query of (Brown and Gray) WITHIN Heading does not.
Zone sections can overlap each other. For example, if <B> and <I> denote two different zone sections, they can overlap in document as follows:
plain <B> bold <I> bold and italic </B> only italic </I> plain
Zone sections can nest, including themselves as follows:
<TD> <TABLE><TD>nested cell</TD></TABLE></TD>
Using the WITHIN operator, you can write queries to search for text in sections within sections. For example, assume the BOOK1, BOOK2, and AUTHOR zone sections occur as follows in documents doc1 and doc2:
doc1:
<book1> <author>Scott Tiger</author> This is a cool book to read.<book1>
doc2:
<book2> <author>Scott Tiger</author> This is a great book to read.<book2>
Consider the nested query:
'Scott within author within book1'
This query returns only doc1.
WITHIN operator in Chapter 3, "CONTAINS Query Operators".
"Section Group Types" in Chapter 2, "Indexing".
Creates an index set for CTXCAT index types. You name this index set in the parameter clause of CREATE INDEX when you create a CTXCAT index.
CTX_DDL.CREATE_INDEX_SET(set_name in varchar2);
Specify the name of the index set. You name this index set in the parameter clause of CREATE INDEX when you create a CTXCAT index.
Creates a policy to use with the ORA:CONTAINS function. ORA:CONTAINS is a function you use within an XPATH query expression with existsNode.
CTX_DDL.CREATE_POLICY( policy_name IN VARCHAR2 DEFAULT NULL, filter IN VARCHAR2 DEFAULT NULL, section_group IN VARCHAR2 DEFAULT NULL, lexer IN VARCHAR2 DEFAULT NULL, stoplist IN VARCHAR2 DEFAULT NULL, wordlist IN VARCHAR2 DEFAULT NULL);
Specify the name for the new policy.
Specify the filter preference to use.
Specify the section group to use. You can specify only NULL_SECTION_GROUP. Only special (sentence and paragraph) section are supported.
Specify the lexer preference to use. Your INDEX_THEMES attribute must be disabled.
specify the stoplist to use.
Specify the wordlist to use.
Create mylex lexer preference named mylex.
begin ctx_ddl.create_preference('mylex', 'BASIC_LEXER'); ctx_ddl.set_attribute('mylex', 'printjoins', '_-'); ctx_ddl.set_attribute ( 'mylex', 'index_themes', 'NO'); ctx_ddl.set_attribute ( 'mylex', 'index_text', 'YES'); end;
Create a stoplist preference named mystop.
begin ctx_ddl.create_stoplist('mystop', 'BASIC_STOPLIST'); ctx_ddl.add_stopword('mystop', 'because'); ctx_ddl.add_stopword('mystop', 'nonetheless'); ctx_ddl.add_stopword('mystop', 'therefore'); end;
Create a wordlist preference named 'mywordlist'.
begin ctx_ddl.create_preference('mywordlist', 'BASIC_WORDLIST'); ctx_ddl.set_attribute('mywordlist','FUZZY_MATCH','ENGLISH'); ctx_ddl.set_attribute('mywordlist','FUZZY_SCORE','0'); ctx_ddl.set_attribute('mywordlist','FUZZY_NUMRESULTS','5000'); ctx_ddl.set_attribute('mywordlist','SUBSTRING_INDEX','TRUE'); ctx_ddl.set_attribute('mywordlist','STEMMER','ENGLISH'); end;
exec ctx_ddl.create_policy('my_policy', NULL, NULL, 'mylex', 'mystop', 'mywordlist');
or
exec ctx_ddl.create_policy(policy_name => 'my_policy', lexer => 'mylex', stoplist => 'mystop', wordlist => 'mywordlist');
Then you can issue the following ExistsNode() query with your own defined policy:
select id from xmltab where existsNode(doc, '/book/chapter[ ora:contains(summary,"dog or cat", "my_ policy") >0 ]' );
You can update your policy by doing:
exec ctx_ddl.update_policy(policy_name => 'my_policy', lexer => 'my_new_lex');
You can drop your policy by doing:
exec ctx_ddl.drop_policy(policy_name => 'my_policy');
Creates a preference in the Text data dictionary. You specify preferences in the parameter string of CREATE INDEX or ALTER INDEX.
CTX_DDL.CREATE_PREFERENCE(preference_name in varchar2, object_name in varchar2);
Specify the name of the preference to be created.
Specify the name of the preference type.
| See Also:
For a complete list of preference types and their associated attributes, see Chapter 2, "Indexing". |
The following example creates a lexer preference that specifies a text-only index. It does so by creating a BASIC_LEXER preference called my_lexer with CTX_DDL.CREATE_PREFERENCE. It then calls CTX_DDL.SET_ATTRIBUTE twice, first specifying Y for the INDEX_TEXT attribute, then specifying N for the INDEX_THEMES attribute.
begin ctx_ddl.create_preference('my_lexer', 'BASIC_LEXER'); ctx_ddl.set_attribute('my_lexer', 'INDEX_TEXT', 'YES'); ctx_ddl.set_attribute('my_lexer', 'INDEX_THEMES', 'NO'); end;
The following example creates a data storage preference called mypref that tells the system that the files to be indexed are stored in the operating system. The example then uses CTX_DDL.SET_ATTRIBUTE to set the PATH attribute of to the directory /docs.
begin ctx_ddl.create_preference('mypref', 'FILE_DATASTORE'); ctx_ddl.set_attribute('mypref', 'PATH', '/docs'); end;
| See Also:
For more information about data storage, see "Datastore Types" in Chapter 2, "Indexing". |
You can use CTX_DDL.CREATE_PREFERENCE to create a preference with DETAIL_DATASTORE. You use CTX_DDL.SET_ATTRIBUTE to set the attributes for this preference. The following example shows how this is done:
begin ctx_ddl.create_preference('my_detail_pref', 'DETAIL_DATASTORE'); ctx_ddl.set_attribute('my_detail_pref', 'binary', 'true'); ctx_ddl.set_attribute('my_detail_pref', 'detail_table', 'my_detail'); ctx_ddl.set_attribute('my_detail_pref', 'detail_key', 'article_id'); ctx_ddl.set_attribute('my_detail_pref', 'detail_lineno', 'seq'); ctx_ddl.set_attribute('my_detail_pref', 'detail_text', 'text'); end;
| See Also:
For more information about master/detail, see "DETAIL_DATASTORE" in Chapter 2, "Indexing". |
The following examples specify that the index tables are to be created in the foo tablespace with an initial extent of 1K:
begin ctx_ddl.create_preference('mystore', 'BASIC_STORAGE'); ctx_ddl.set_attribute('mystore', 'I_TABLE_CLAUSE', 'tablespace foo storage (initial 1K)'); ctx_ddl.set_attribute('mystore', 'K_TABLE_CLAUSE', 'tablespace foo storage (initial 1K)'); ctx_ddl.set_attribute('mystore', 'R_TABLE_CLAUSE', 'tablespace foo storage (initial 1K)'); ctx_ddl.set_attribute('mystore', 'N_TABLE_CLAUSE', 'tablespace foo storage (initial 1K)'); ctx_ddl.set_attribute('mystore', 'I_INDEX_CLAUSE', 'tablespace foo storage (initial 1K)'); end;
When you create preferences with types that have no attributes, you need only create the preference, as in the following example which sets the filter to the NULL_FILTER:
begin ctx_ddl.create_preference('my_null_filter', 'NULL_FILTER'); end;
CREATE INDEX in Chapter 1, "SQL Statements and Operators".
ALTER INDEX in Chapter 1, "SQL Statements and Operators".
Creates a section group for defining sections in a text column.
When you create a section group, you can add to it zone, field, or special sections with ADD_ZONE_SECTION, ADD_FIELD_SECTION, or ADD_SPECIAL_SECTION.
When you index, you name the section group in the parameter string of CREATE INDEX or ALTER INDEX.
After indexing, you can query within your defined sections with the WITHIN operator.
CTX_DDL.CREATE_SECTION_GROUP( group_name in varchar2, group_type in varchar2 );
Specify the section group name to create as [user.]section_group_name. This parameter must be unique within an owner.
Specify section group type. The group_type parameter can be one of:
The following command creates a section group called htmgroup with the HTML group type.
begin ctx_ddl.create_section_group('htmgroup', 'HTML_SECTION_GROUP');end;
The following command creates a section group called auto with the AUTO_SECTION_GROUP group type to be used to automatically index tags in XML documents.
begin ctx_ddl.create_section_group('auto', 'AUTO_SECTION_GROUP');end;
WITHIN operator in Chapter 3, "CONTAINS Query Operators".
"Section Group Types" in Chapter 2, "Indexing".
Use this procedure to create a new, empty stoplist. Stoplists can contain words or themes that are not to be indexed.
You can also create multi-language stoplists to hold language-specific stopwords. A multi-language stoplist is useful when you index a table that contains documents in different languages, such as English, German, and Japanese. When you do so, you text table must contain a language column.
You can add either stopwords, stopclasses, or stopthemes to a stoplist using ADD_STOPWORD, ADD_STOPCLASS, or ADD_STOPTHEME.
You can specify a stoplist in the parameter string of CREATE INDEX or ALTER INDEX to override the default stoplist CTXSYS.DEFAULT_STOPLIST.
CTX_DDL.CREATE_STOPLIST( stoplist_name IN VARCHAR2, stoplist_type IN VARCHAR2 DEFAULT 'BASIC_STOPLIST');
Specify the name of the stoplist to be created.
Specify BASIC_STOPLIST to create a stoplist for a single language. This is the default.
Specify MULTI_STOPLIST to create a stoplist with language-specific stopwords.
At indexing time, the language column of each document is examined, and only the stopwords for that language are eliminated. At query time, the session language setting determines the active stopwords, like it determines the active lexer when using the multi-lexer.
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Note: When indexing a multi-language table with a multi-language stoplist, your table must have a language column. |
The following code creates a stoplist called mystop:
begin ctx_ddl.create_stoplist('mystop', 'BASIC_STOPLIST'); end;
The following code creates a multi-language stoplist called multistop and then adds tow language-specific stopwords:
begin ctx_ddl.create_stoplist('multistop', 'MULTI_STOPLIST'); ctx_ddl.add_stopword('mystop', 'Die','german'); ctx_ddl.add_stopword('mystop', 'Or','english'); end;
CREATE INDEX in Chapter 1, "SQL Statements and Operators".
ALTER INDEX in Chapter 1, "SQL Statements and Operators".
Appendix D, "Supplied Stoplists"
Drops an index set.
CTX_DDL.DROP_INDEX_SET(set_name in varchar2);
Specify the name of the index set to drop.
Drops a policy create with CREATE_POLICY.
CTX_DDL.DROP_POLICY(policy_name IN VARCHAR2);
Specify the name of the policy to drop.
The DROP_PREFERENCE procedure deletes the specified preference from the Text data dictionary. Dropping a preference does not affect indexes that have already been created using that preference.
CTX_DDL.DROP_PREFERENCE(preference_name IN VARCHAR2);
Specify the name of the preference to be dropped.
The following code drops the preference my_lexer.
begin ctx_ddl.drop_preference('my_lexer'); end;
The DROP_SECTION_GROUP procedure deletes the specified section group, as well as all the sections in the group, from the Text data dictionary.
CTX_DDL.DROP_SECTION_GROUP(group_name IN VARCHAR2);
Specify the name of the section group to delete.
The following code drops the section group htmgroup and all its sections:
begin ctx_ddl.drop_section_group('htmgroup'); end;
Drops a stoplist from the Text data dictionary. When you drop a stoplist, you must re-create or rebuild the index for the change to take effect.
CTX_DDL.DROP_STOPLIST(stoplist_name in varchar2);
Specify the name of the stoplist.
The following code drops the stoplist mystop:
begin ctx_ddl.drop_stoplist('mystop'); end;
Use this procedure to optimize the index. You optimize your index after you synchronize it. Optimizing the index removes old data and minimizes index fragmentation. Optimizing the index can improve query response time.
You can optimize in fast, full, or token mode. In token mode, you specify a specific token to be optimized. You can use token mode to optimize index tokens that are frequently searched, without spending time on optimizing tokens that are rarely referenced. An optimized token can improve query response time for that token.
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Note: Optimizing an index can result in better response time only if you insert, delete, or update documents in your base table after your initial indexing operation. |
Using this procedure to optimize your index is recommended over using the ALTER INDEX statement.
The CTX_DDL.OPTIMIZE_INDEX procedure optimizes at most 16,000 document ids. To continue optimizing more document ids, re-run this procedure.
CTX_DDL.OPTIMIZE_INDEX( idx_name IN VARCHAR2, optlevel IN VARCHAR2, maxtime IN NUMBER DEFAULT NULL, token IN VARCHAR2 DEFAULT NULL, part_name IN VARCHAR2 DEFAULT NULL, parallel_degree IN VARCHAR2););
Specify the name of the index. If you do not specify an index name, Oracle chooses a single index to optimize.
Specify optimization level as a string. You can specify one of the following methods for optimization:
Specify maximum optimization time, in minutes, for FULL optimize.
When you specify the symbol CTX_DDL.MAXTIME_UNLIMITED (or pass in NULL), the entire index is optimized. This is the default.
Specify the token to be optimized.
Specify the name of the index partition to optimize.
Specify the parallel degree as a number for parallel optimization. The actual parallel degree depends on your resources.
The following two examples optimize the index for fast optimization.
begin ctx_ddl.optimize_index('myidx','FAST'); end; begin ctx_ddl.optimize_index('myidx',CTX_DDL.OPTLEVEL_FAST); end;
The following example optimizes the index token Oracle:
begin ctx_ddl.optimize_index('myidx','token', TOKEN=>'Oracle'); end;
ALTER INDEX in Chapter 1, "SQL Statements and Operators".
Removes the index with the specified column list from a CTXCAT index set preference.
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Note: This procedure does not remove a |
CTX_DDL.REMOVE_INDEX( set_name in varchar2, column_list in varchar2 language in varchar2 default NULL );
Specify the name of the index set
Specify the name of the column list to remove.
The REMOVE_SECTION procedure removes the specified section from the specified section group. You can specify the section by name or by id. You can view section id with the CTX_USER_SECTIONS view.
Use the following syntax to remove a section by section name:
CTX_DDL.REMOVE_SECTION( group_name in varchar2, section_name in varchar2 );
Specify the name of the section group from which to delete section_name.
Specify the name of the section to delete from group_name.
Use the following syntax to remove a section by section id:
CTX_DDL.REMOVE_SECTION( group_name in varchar2, section_id in number );
Specify the name of the section group from which to delete section_id.
Specify the section id of the section to delete from group_name.
The following code drops a section called Title from the htmgroup:
begin ctx_ddl.remove_section('htmgroup', 'Title'); end;
Removes a stopclass from a stoplist.
CTX_DDL.REMOVE_STOPCLASS( stoplist_name in varchar2, stopclass in varchar2 );
Specify the name of the stoplist.
Specify the name of the stopclass to be removed.
The following code removes the stopclass NUMBERS from the stoplist mystop.
begin ctx_ddl.remove_stopclass('mystop', 'NUMBERS'); end;
Removes a stoptheme from a stoplist.
CTX_DDL.REMOVE_STOPTHEME( stoplist_name in varchar2, stoptheme in varchar2 );
Specify the name of the stoplist.
Specify the stoptheme to be removed from stoplist_name.
The following code removes the stoptheme banking from the stoplist mystop:
begin ctx_ddl.remove_stoptheme('mystop', 'banking'); end;
Removes a stopword from a stoplist. To have the removal of a stopword be reflected in the index, you must rebuild your index.
CTX_DDL.REMOVE_STOPWORD( stoplist_name in varchar2, stopword in varchar2, language in varchar2 default NULL);
Specify the name of the stoplist.
Specify the stopword to be removed from stoplist_name.
Specify the language of stopword to remove when the stoplist you specify with stoplist_name is of type MULTI_STOPLIST. You must specify the Globalization Support name or abbreviation of an Oracle-supported language. You can also remove ALL stopwords.
The following code removes a stopword because from the stoplist mystop:
begin ctx_ddl.remove_stopword('mystop','because');end;
Sets a preference attribute. You use this procedure after you have created a preference with CTX_DDL.CREATE_PREFERENCE.
ctx_ddl.set_attribute(preference_name in varchar2, attribute_name in varchar2, attribute_value in varchar2);
Specify the name of the preference.
Specify the name of the attribute.
Specify the attribute value. You can specify boolean values as TRUE or FALSE, T or F, YES or NO, Y or N, ON or OFF, or 1 or 0.
The following example creates a data storage preference called filepref that tells the system that the files to be indexed are stored in the operating system. The example then uses CTX_DDL.SET_ATTRIBUTE to set the PATH attribute to the directory /docs.
begin ctx_ddl.create_preference('filepref', 'FILE_DATASTORE'); ctx_ddl.set_attribute('filepref', 'PATH', '/docs'); end;
| See Also:
For more information about data storage, see "Datastore Types" in Chapter 2, "Indexing". For more examples of using |
Synchronizes the index to process inserts, updates, and deletes to the base table.
ctx_ddl.sync_index( idx_name IN VARCHAR2 DEFAULT NULL memory IN VARCHAR2 DEFAULT NULL, part_name IN VARCHAR2 DEFAULT NULL parallel_degree IN NUMBER DEFAULT 1);
Specify the name of the index.
Specify the runtime memory to use for synchronization. This value overrides the DEFAULT_INDEX_MEMORY system parameter.
The memory parameter specifies the amount of memory Oracle uses for the synchronization operation before flushing the index to disk. Specifying a large amount of memory:
Specifying smaller amounts of memory increases disk I/O and index fragmentation, but might be useful when runtime memory is scarce.
Specify the name of the index partition to synchronize.
Specify the degree to run parallel synchronize. A number greater than 1 turns on parallel synchronize. The actual degree of parallelism might be smaller depending on your resources.
The following example synchronizes the index myindex with 2 megabytes of memory:
begin ctx_ddl.sync_index('myindex', '2M');end;
The following example synchronizes the part1 index partition with 2 megabytes of memory:
begin ctx_ddl.sync_index('myindex', '2M', 'part1');end;
ALTER INDEX in Chapter 1, "SQL Statements and Operators".
Removes a set attribute from a preference.
CTX_DDL.UNSET_ATTRIBUTE(preference_name varchar2, attribute_name varchar2);
Specify the name of the preference.
Specify the name of the attribute.
The following example shows how you can enable alternate spelling for German and disable alternate spelling with CTX_DDL.UNSET_ATTRIBUTE:
begin ctx_ddl.create_preference('GERMAN_LEX', 'BASIC_LEXER'); ctx_ddl.set_attribute('GERMAN_LEX', 'ALTERNATE_SPELLING', 'GERMAN'); end;
To disable alternate spelling, use the CTX_DDL.UNSET_ATTRIBUTE procedure as follows:
begin ctx_ddl.unset_attribute('GERMAN_LEX', 'ALTERNATE_SPELLING'); end;
Updates a policy created with CREATE_POLICY. Replaces the preferences of the policy. Null arguments are not replaced.
CTX_DDL.UPDATE_POLICY( policy_name IN VARCHAR2 DEFAULT NULL, filter IN VARCHAR2 DEFAULT NULL, section_group IN VARCHAR2 DEFAULT NULL, lexer IN VARCHAR2 DEFAULT NULL, stoplist IN VARCHAR2 DEFAULT NULL, wordlist IN VARCHAR2 DEFAULT NULL);
Specify the name of the policy to update.
Specify the filter preference to use.
Specify the section group to use.
Specify the lexer preference to use.
specify the stoplist to use.
Specify the wordlist to use.
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