Indexing Fields

It is very important to decide which fields you want to index. Adding indexes to fields that do not need it will result in longer load times and a larger disk footprint with no discernible benefit.

Fields that are candidates for indexing:

• Any field that is used as a Link Key that comprises the 'one' side of a link must be indexed.
• Any field that is going to be queried as part of a segment document, or a filter in a crosstab should be indexed to achieve maximum query speed. Note: Lower cardinality columns of less than 32,000 discrete values do not necessarily benefit from indexing, so this should be tested in specific cases. The general rule is that large numbers of table rows will benefit from faster query speeds with indexing.
• Any High cardinality columns of greater than 32,000 discrete values that are used as a Dimension in a crosstab must be indexed. Indexing on Low cardinality columns is not required.

Conversely, indexing would provide no benefit for:

• Columns that are only going to be viewed in Record Viewer.
• Columns that are only going to be Output.
• Columns on tables that are receiving rapidly changing data, for example, Campaign History tables. This will avoid the burden of frequent index re-creation.

Changing an Index

For a new table or field, the index is set in the Table Definition file.

Any types declared with a 'U' prefix such as UINTEGER or UTEXT are imported as unindexed.

For an existing field, the import will inherit the index level of the field at the time of the load, regardless of the setting in the script file, or the type of load being executed. Therefore to change an index level on a existing field you would need to change the index in AMC or Campaign Manager. This ensures that the next load keeps that index level. It is also recommended that the script file is changed in case the table is ever loaded from scratch.

• Editing Scripts
  • Using The iLoader Editing Tools
  • Using the Table Declaration Wizard
  • Table Declaration File Structure
  • Table Declaration Example
  • Using the Table Definition Wizard
  • Table Definition File Structure
  • Table Definition Example
  • Indexing Fields
  • Creating Scripts Manually