This preface describes changes in Oracle Text for this release.
Changes in Oracle Text 12c Release 2 (184.108.40.206)
The changes in Oracle Text for Oracle Database 12c Release 2 (220.127.116.11) are described in this topic.
This section describes the primary new features for Oracle Text introduced in Oracle Database 12c Release 2 (18.104.22.168).
SDATA Section Improvements
Oracle Text provides enhancements to the
SDATA section operations. A new kind of
SDATA section is added.
Keep Updated Documents in Index
Oracle Text can optionally keep updated index entries to search for original content with the
Oracle Text supports a new storage preference
SMALL_R_ROW for indexed lookups.
Oracle Text provides an enhancement to indexing by getting rid of the locking of base table rows. A new table
$U for each index or partition is introduced which keeps track of all the concurrent updates and also introduces a new storage clause,
$U_TABLE_CLAUSE for this
Reverse Token Index for Left-Truncated Queries
Oracle Text provides the new attribute
REVERSE_INDEX for left-truncated queries. This attribute is a part of the wordlist preference and can be set to
FALSE. It is set to
FALSE by default, which means that the new feature is disabled. You can set this attribute using
CTX_DDL.SET_ATTRIBUTE procedure. It can also be added using
ALTER INDEX REBUILD just like any other wordlist preference. Use this attribute if you want better query performance for left-truncated queries.
Oracle Text Reference for more information about the
BASIC_WORDLIST attributes table and the
Partition-Specific Near Real Time Indexes
Oracle Text supports partition-specific
STAGE_ITAB option. The
STAGE_ITAB option provides a two-level index mechanism that prevents fragmentation of the main index under heavy DML. In some circumstances, it is desirable to set this option at a partition level. For example, some partitions can contain mostly static data whereas other partitions can contain rapidly-changing data.
The storage option
STAGE_ITAB_PARALLEL controls the level of parallelism used to merge the data from the
$G staging table back into the
A maximum size for the near real-time
$G index table can be specified. This prevents the near real-time
$G index table from getting too large to fit into memory.
Sentiment Analysis and Collocates
Oracle Text supports sentiment analysis and collocates. Sentiment analysis enables the identification of positive and negative trends associated with search terms. Collocates enable you to identify other keywords that are related to or used frequently with a specified keyword.
NEAR2 Operator and NDATA Operator Enhancements
Oracle Text provides a new operator,
NEAR2. It is an enhanced version of the existing
NEAR operator. The
NEAR2 operator aims to combine the semantics of
PHRASE, NEAR and
NDATA operator now provides more control on the similarity scoring of character and phonetic matches as well as on the overall ranked results returned by the operation.
Join Character Support for Japanese VGRAM Lexer and WORLD LEXER
Oracle Text provides join character support for Japanese
VGRAM lexer and
New Document Formats
Oracle Text provides new text filters to support new document formats.
Extract Synonyms of Words in Documents
Oracle Text provides new options in the
CTX_DOC package to enable thesaurus support. You can use the
CTX_DOC.POLICY_TOKENS procedures to extract synonyms of index tokens.
Read-only MDATA Sections
Oracle Text supports read-only
MDATA sections. You can create a non-updatable MDATA section such that when queried, there will not be an extra cursor opened for each MDATA operator. A non-updatable MDATA section is different from a regular MDATA section in that it does not allow you to add or remove MDATA values, and therefore, queries run faster because there is no extra overhead in tracking the updated MDATA values.
Index Name Length and Long Identifier Support for Oracle Text Objects
Oracle Text index names can be as long as the database object names. The length is 128 bytes for Oracle Database release 12.2 compatible and above and is 30 bytes for earlier releases. Oracle Text supports long identifiers for Oracle Text objects, increasing the current maximum to 128 bytes.
Increased Default Value and Upper Limit of MAX_INDEX_MEMORY Parameter
Oracle Text provides an increase in the default value and the upper limit of the
MAX_INDEX_MEMORY parameter that can be allocated for indexing purpose to 256 GB.
You can use a simpler alternative syntax to create a search index on JSON.
See Also:Oracle Database JSON Developer's Guide for more information about creating search index for JSON