MDATA
Use the MDATA operator to query documents that contain MDATA sections. MDATA sections are metadata that have been added to documents to speed up mixed querying.
MDATA queries are treated exactly as literals. For example, with the query:
MDATA(price, $1.24)the $ is not interpreted as a stem operator, nor is the . (period) transformed into whitespace. A right (close) parenthesis terminates the MDATA operator, so that MDATA values that have close parentheses cannot be searched.
Syntax
MDATA(sectionname, value)sectionname
The name of the MDATA section(s) to search. MDATA will also search DATE or numerical equality if the sectionname parameter is mapped to a FILTER BY column of DATE or some numerical type.
value
The value of the MDATA section. For example, if an MDATA section called Booktype has been created, it might have a value of paperback.
For MDATA operator on MDATA sections that are mapped to a DATE FILTER BY column, the MDATA value must follow the Date format: YYYY-MM-DD HH24:MI:SS. Otherwise, the expected rows will not be returned. If the time component is omitted, it will default to 00:00:00, according to SQL semantics.
Example for MDATA Operator
Suppose you want to query for books written by the writer Nigella Lawson that contain the word summer. Assuming that an MDATA section called AUTHOR has been declared, you can query as follows:
SELECT id FROM idx_docs
WHERE CONTAINS(text, 'summer AND MDATA(author, Nigella Lawson)')>0This query will only be successful if an AUTHOR tag has the exact value Nigella Lawson (after simplified tokenization). Nigella or Ms. Nigella Lawson will not work.
Notes
MDATA query values ignore stopwords.
The MDATA operator returns an unlimited number of results or 0, depending on whether the document is a match. You can set the maximum.
The MDATA operator is not supported for CTXCAT and CTXRULE indexes.
Table 3-2 shows how MDATA interacts with some other query operators:
Table 2 MDATA and Other Query Operators
| Operator | Example | Allowed? |
|---|---|---|
| AND | dog & MDATA(a, b) | yes |
| OR | dog | MDATA(a, b) | yes |
| NOT | dog ~ MDATA(a, b) | yes |
| MINUS | dog - MDATA(a, b) | yes |
| ACCUM | dog , MDATA(a, b) | yes |
| PHRASE | MDATA(a, b) dog | no |
| NEAR | MDATA(a, b) ; dog | no |
| WITHIN, HASPATH, INPATH | MDATA(a, b) WITHIN c | no |
| Thesaurus | MDATA(a, SYN(b)) | no |
| expansion | MDATA(a, $b) MDATA(a, b%) MDATA(a, !b) MDATA(a, ?b) |
no (syntactically allowed, but the inner operator is treated as literal text) |
| ABOUT | ABOUT(MDATA(a,b)) MDATA(ABOUT(a)) |
no (syntactically allowed, but the inner operator is treated as literal text) |
When MDATA sections repeat, each instance is a separate and independent value. For instance, the document
<AUTHOR>Terry Pratchett</AUTHOR><AUTHOR>Douglas Adams</AUTHOR>can be found with any of the following queries:
MDATA(author, Terry Pratchett)
MDATA(author, Douglas Adams)
MDATA(author, Terry Pratchett) and MDATA(author, Douglas Adams)but not any of the following:
MDATA(author, Terry Pratchett Douglas Adams)
MDATA(author, Terry Pratchett & Douglas Adams)
MDATA(author, Pratchett Douglas)Related Topics
See Also: Oracle Text Application Developer’s Guide for information about section searching