The irregular-interval time series conventions are similar to the regular-interval conventions except that an explicit date and time is stored with each data value whereas in regular-interval time series the date and time are implied by the location of the data within the block.

Irregular-interval data is stored in variable length blocks while regular-interval data is stored in fixed length blocks. The block lengths are days, months, years, decades, and centuries. Irregular-interval data is NOT compressed, as each value has an explicit date/time stored with it. Storing data as irregular-interval will generally greatly increase the record size and file size, compared to regular-interval data.


The number of values that may be stored in one record is indefinite although it is prudent to choose a size that matches typical data queries.  Usually this is less than 5000 data points. The user selects the appropriate block length. For example, if the data to be stored occurred once every 1-2 hours, a monthly block would be appropriate. If data were recorded once or twice a day, use a yearly block.

One would not want to store data that occurred 10-12 or more times a day in a yearly block (about 5000 values) because that may exceed dimension limits in some programs.


All data are stored in variable length blocks that are incremented a set amount when necessary. Initial space for 100 data values is allocated and additional increments are for 50 data values unless otherwise set. (When the 101st data value is added to the record, a new record with a length of 150 values is written.)


The E parts (blocks) for irregular-interval data are:

Block NameExample Frequency
Ir-Day10 minutes
Ir-Monthhourly
Ir-Yeardaily, semi-daily
Ir-Decademonthly
Ir-Centuryannual


Irregular interval data must always be in ascending order. When storing irregular interval data to an existing dataset, you can replace the data within your time window, or you can merge the two datasets together.


Example:   If you were to store 200 data points, that occur every hour starting in 20Jan2010 the following table shows how 'IR-Day' would result in 9 blocks, while 'IR-Month' would allow storing all the data in a single block.


IR-Day  (9 blocks, 24 points per block)IR-Month (1 block , all 200 points in a single block)
  /Basin/Location/Flow/20Jan2010/IR-Day/hourly test//Basin/Location/Flow/01Jan2010/IR-Month/hourly test/
  /Basin/Location/Flow/21Jan2010/IR-Day/hourly test/
  /Basin/Location/Flow/22Jan2010/IR-Day/hourly test/
  /Basin/Location/Flow/23Jan2010/IR-Day/hourly test/
  /Basin/Location/Flow/24Jan2010/IR-Day/hourly test/
  /Basin/Location/Flow/25Jan2010/IR-Day/hourly test/
  /Basin/Location/Flow/26Jan2010/IR-Day/hourly test/
  /Basin/Location/Flow/27Jan2010/IR-Day/hourly test/
  /Basin/Location/Flow/28Jan2010/IR-Day/hourly test/