Db2 Text Search and Net Search Extender comparison
You should be aware of the differences in syntax, semantics, and results sets for full-text search queries that look similar in both solutions before migrating from Net Search Extender (NSE) to Db2 Text Search.
Important: Net Search Extender (NSE) is no longer supported in
Db2. Use the Db2 Text Search feature.
Review Table 1 and Table 2
to help you to determine whether you can port from NSE to Db2 Text Search.Db2 Text Search
is supported on all operating systems that NSE is supported, including Linux® on System z® (64-bit)
operating systems. The following table provides a list of install functions available in NSE and
Db2 Text Search:
| Function | NSE | Db2 Text Search | Comments and links to additional information |
|---|---|---|---|
| Local Install for Text Engine | Yes | Yes | |
| Remote Install for Text Engine | No | Yes | DB2® Text Search in a partitioned database environment |
| Database partitioning | Yes | Yes | DB2 Text Search in a partitioned database environment |
| Index on non-partitioned base tables | Yes | Yes | Text search index creation, updates, and property alterations |
| Index on partitioned base tables (Range-partitioned) | Yes | Yes | Extended text-maintained staging infrastructure for text search index incremental updates |
| Index on Nicknames (with Replication) | Deprecated | No | Deprecated in Version 9.7 |
| Index on Views | Yes | No |
Db2 Text Search provides
similar functionality to NSE functionality. The following table shows
the functionality available in NSE and Db2 Text Search:
| Functional Items | NSE | Db2 Text Search | Comments and links to additional information |
|---|---|---|---|
| Recreate on update | Yes | Yes | |
| Custom transformation functions | Yes | Yes | |
| Caching | No | No | |
| Multiple Indexes | Yes | No | |
| Pre-sorted indexes | No | No | |
| Synonym dictionary | Yes | Yes | Synonym dictionaries for DB2 Text Search |
| Thesaurus (associative, hierarchical, user-defined) | Yes | No | |
| Text, HTML, XML | Yes | Yes | Document formats supported for DB2 Text Search |
| INSO | Yes | Yes | Db2 Text Search supports INSO using the Db2 accessories suite package. See Rich text document support for details. |
| GPP | Yes | No | You can create a function in Db2 Text Search to support GPP |
| Document Models | Yes | No | |
| Linguistic processing | Yes | Yes+ | NSE linguistic process is limited to simple stemming (English only).
Db2 Text Search supports linguistic processing for 20 languages, including both morphological and n-gram segmentation support for Chinese, Japanese, and Korean. See Linguistic processing for DB2 Text Search for details. |
| CONTAINS function | Yes | Yes | CONTAINS function |
| SCORE function | Yes | Yes | Db2 Text Search uses a different algorithm that might return different results. See SCORE function for details. |
| Number of matches | No | No | |
| Highlights | No | No | |
| Stop-word processing | Yes | Yes | Stop-word tool for DB2 Text Search |
| Result limit | Yes | Yes | The CONTAINS and SCORE functions have a RESULTLIMIT parameter to indicate the maximum number of results to be returned. |
| Character normalization | Yes | Yes | |
| Escape characters | Yes | Yes | Customization is not available in Db2 Text Search. |
| Boolean search | Yes | Yes | Text search argument syntax |
| Wildcard characters | Yes | Yes | Text search argument syntax |
| Stemmed search | Yes | Yes | Stemmed search is the default for Db2 Text Search |
| Precise search | Yes | Yes | Db2 Text Search is not case-sensitive. See Precise search for details. |
| Fuzzy search | Yes | Yes | Fuzzy search |
| Proximity search | Yes | Yes | Proximity search |
| Range search | Yes | Yes, for XML | Db2 Text Search relies on XPath expressions in XML for range search. Net Search Extender supports range search via the document model. |
| Freetext search | Yes | No | |
| Fielded search | Yes | Yes, for XML | Db2 Text Search support uses XPath expressions in XML. NSE support uses the document model. See XML search configuration for DB2 Text Search and Searching XML documents using DB2 Text Search for details. |
| Attribute search | Yes | No | |
| Weights/boosting | Yes | Yes | Db2 Text Search and NSE have different algorithms. See Searching text search indexes using SCORE for details. |