Content
For Oracle Text, you can useCREATE INDEXCreates many types of indexes. The following describes each index type and their purpose and supported features.
- CONTEXT Index
- CTXCAT Index
- CTXRULE index CTXXPATH Index
CONTEXT description
- When your text is composed of large, continuous text, you can use this index to create a text retrieval application. You can index files of different formats, such as MS Word, HTML, or plain text.
- You can customize indexes in different ways.
- This type of index is required after DML is executed on the base tableCTX_DDL.SYNC_INDEX.
Supported preferences and parameters
- BesidesINDEX SET, Supports allCreate index preferencesAndParameters.
- These supported parameters include the index partition clause (Index partition clause), Format (Format), Character set (Charset) And language columns (Language columns).
Query operator
CONTAINS
- The syntax isCONTEXTSyntax. It supports many operations.
- CTXCATThe syntax can contain template queries.
Note:
- All text services and query services are supported.
- Supports the indexing of Partitioned text tables.
- SupportedCREATE INDEXOfFILTERAndORDERYou can also index the structured column values to more effectively process hybrid queries.
CTXCAT description
- You can use this index type to achieve better hybrid query performance. Generally, you can create an index for a small text or text fragment. For example, other columns in the base table, such as the entry name, price, and description, can be included in the index to improve the hybrid query performance.
- This index type is transactional and automatically updated after DML without the needCTX_DDL.SYNC_INDEX.
Supported preferences and parameters
INDEX SET
LEXER
STOPLIST
STORAGE
- WORDLIST (only the prefix_index attribute supports Japanese data ).
- Format, Character Set, and language columns are not supported.
- Table and index partitions are not supported.
Query operator
CATSEARCH
- The syntax isCTXCATIt supports logical operators, phrase queries, and wildcards.
- CONTEXTThe syntax can contain template queries.
- Topic query is supported.
Note:
- This index is large and has a creation time ratio.CONTEXTLong.
- CTXCATThe index size depends on the total text size, the number of indexes in the index set, and the number of index columns. Before adding an index to an index set, consider your queries and resources carefully.
- CTXCATIndexes do not support tables and index partitions, text services (highlight, Tag, topic, and summary), or query services (explanations, query feedback, and browsing words ).
