dtSearch 7 supports a new index format, with higher capacity (up to 1 terabyte per index). In addition to higher capacity, the new format has some other advantages over the dtSearch 6 index format:

• Support for caching text in the index
• Faster indexing and searching
• Much faster incremental updates

dtSearch 7 can read and update indexes created with any of the dtSearch 6.x versions. To create an index in the old version 6 format, set the dtsIndexCreateVersion6 flag in IndexJob.IndexingFlags. 

The format of an index is automatically detected when the index is opened, so there is no need to specify when updating or searching an index what the format of the index is. 

dtSearch 6 generally cannot read version 7 indexes.

Compressing a version 6 index using version 7 of the dtSearch Engine will automatically convert the index to the version 7 format

Some dtSearch Engine 6.x versions had beta support for the version 7 index format, but only version 6.51 fully supports the final release version of the dtSearch 7 index format. Older versions of the dtSearch Engine should not be used with dtSearch 7 indexes. 

dtSearch 7 supports all of the interim versions of the dtSearch 7 index format that were used during beta testing. However, any indexes that were created with beta versions should be re-created with the release version of dtSearch 7, or at least compressed with version 7 to upgrade and optimize the index structure.

Building and Maintaining Indexes