US Army Corps of Engineers
Hydrologic Engineering Center

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HEC-DSS

The U.S. Army Corps of Engineers' Hydrologic Engineering Center Data Storage System, or HEC-DSS, is a database system designed to efficiently store and retrieve scientific data that is typically sequential. Such data types include, but are not limited to, time series data, curve data, spatial-oriented gridded data, and others. The system was designed to make it easy for users and application programs to retrieve and store data. HEC-DSS is incorporated into most of HEC’s major application programs.

Data in HEC-DSS database files can be graphed, tabulated, edited and manipulated with HEC-DSSVue, a Java-based visual utilities program. HEC-DSSVue is supported for Microsoft Windows, Sun Solaris SPARC, and Linux.

These libraries are accessed by programmers who write code for applications that access HEC-DSS files. Code that is linked with the HEC-DSS Version 7 library (DSS7) can access either Version 6 or 7 files.

HEC-DSS is intended for programmers that write programs to work with HEC-DSS files in Java, C, and C# (.net) programming languages.

What is new in DSS Version 7

DSS 7 has new features, compared to the previous version 6, described in the table below. Version 6 files need to be converted to Version 7 to utilize the new features.

FeatureDSS6DSS7
CatalogSeparate .dsc
catalog file
Catalog is faster, with new search methods, and internal to DSS7 file.
Extended datesYear: 0001 to 9999Year: –5,873,711 to 5,879,610
File efficiencyMore efficient storage. Some files are 50% smaller for the same data
Max file size8GBTested up to 125GB (can go larger)
Paired dataLimits on sizeAny length of paired data, with support for multiple curves
PathnamesUpper case 'FLOW'Case insensitive 'Flow'
Programming languageFORTRANC (with FORTRAN to also support DSS 6 alongside DSS 7)
DSS is built with
Pseudo intervals (~1Day)n/aStored as irregular but typically follows regular pattern.
ThreadingSingleMulti readers
Time series ensemblesF part has c:xxxxxx| where xxxxxx is the collection sequence. /YUBA/SMARTSVILLE/FLOW/01JAN1997/1HOUR/C:000042|OP A/
Time series profilesn/aAllows storing/plotting data such as water temperature profile. For example water temperature time series at different depths stored as a package (time series of time series)
Un-deleteDeleted records are marked unused (and could be restored)Can't un-delete. However DSS7 files often have a on disk size much smaller that DSS6.