1. Application Developer's Guide
  2. Changes in This Release for Oracle Text Application Developer's Guide

Changes in This Release for Oracle Text Application Developer's Guide

This preface describes changes in Oracle Text for this release.

Changes in Oracle Text 12c Release 2 (12.2.0.1)

The changes in Oracle Text for Oracle Database 12c Release 2 (12.2.0.1) are described in this topic.

New Features

This section describes the primary new features for Oracle Text introduced in Oracle Database 12c Release 2 (12.2.0.1).

SDATA Section Improvements

Oracle Text provides enhancements to the SDATA section operations. A new kind of SDATA section is added.

See Also:

SDATA Section

Keep Updated Documents in Index

Oracle Text can optionally keep updated index entries to search for original content with the ASYNCHRONOUS_UPDATE option.

See Also:

About Updates to Indexed Columns

DML Improvements

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 $U table.

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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 TRUE or 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.

See Also:

Oracle Text Reference for more information about the BASIC_WORDLIST attributes table and the REVERSE_INDEX attribute

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 $I table.

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.

See Also:

Improved Response Time Using STAGE_ITAB, STAGE_ITAB_MAX_ROWS, STAGE_ITAB_PARALLEL Options of CONTEXT Index

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.

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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 AND operators.

The 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.

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Join Character Support for Japanese VGRAM Lexer and WORLD LEXER

Oracle Text provides join character support for Japanese VGRAM lexer and WORLD lexer.

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.TOKENS and CTX_DOC.POLICY_TOKENS procedures to extract synonyms of index tokens.

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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.

See Also:

MDATA Section

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.

JSON Improvements

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