hello, sorry if i should just rtfm but i was wondering, last night i heard that you could set up an index on multiple columns without storing the concatenation of those columns.
I was wondering, how would you set up such an index and how would you use it in your selects?
Alan,
Technically, if it can, R:BASE will do index-only retrieval. This is the fastest method of retrieving data.
When the columns selected for display are limited to the column or columns in the index used in the WHERE clause, R:BASE will retrieve the data as it reads the index information from file 3. It does not need to look at the data stored in file 2.
Index-only retrieval is done only when the columns to be retrieved are all included in the index.
Multi-Column Indexes are also very useful. If you routinely select the same set of columns (up to eight), consider defining a multi-column index for use with index-only retrieval.
Keep in mind that only full-text indexed and non-text indexes can be used for index-only retrieval -- thus all pieces of the multi-column index must be full-text or non-text to store the actual data values in file 3.
When defining a multi-column index, you are limited to a total of 200 bytes for the index value. Text values store the index value in a 4-byte segments, therefor a TEXT 6 column defined as a full-text index actually is stored as 8-bytes in file 3.
Database with INDEXes will also require a regular maintenance of database.
R:BASE 6.5++ (Build:1.866xRT03) and R:BASE 7.0 for Windows includes *new* PACK INDEX command in a multi-user environment.
Example 01:
PACK INDEX FOR TableName
This will pack all the indices for the specified table, even in a Multi-User environment.
Example 02:
PACK INDEX
This will pack all the indices for currently CONNected database, even in a Multi-User environment.
Hope that helps!
Very Best R:egards,
Razzak.
