The display of data in virtual tables
When you create virtual tables based on time series, you can customize how time series data is shown in the virtual tables and in the results of queries on the virtual tables.
Null elements in a time series are not included in the virtual table. If a base table has a null element at a specific timepoint, the virtual table has no entry for that timepoint. You can specify that null elements appear in the virtual table.
Hidden elements are not included in the virtual table. A hidden element is marked as invisible in the base table. You can specify if hidden elements appear as null values in the virtual table, or if their values are visible in the virtual table.
When you select data from a virtual table by timestamps, the rows whose timestamps are closest to being equal to or earlier than the timestamps specified in the query are returned. If the time series is irregular, the returned rows show the same timestamps as specified in the query, regardless if the actual timestamps are the same. You can specify that when you select data from a virtual table by timestamps, only rows whose timestamps are exactly equal to the timestamps specified in the query are returned.
You control the display of data by setting the TSVTMode parameter in the TSCreateVirtualTab procedure or the TSCreateExpressionVirtualTab procedure.