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Question Akshay Pandey · Mar 2, 2023

Stream.GlobalBinary compression

ZV = IRIS for UNIX (Red Hat Enterprise Linux for x86-64) 2021.1 (Build 215_0_21260U) Tue Nov 9 2021 19:32:21 EST

I have pdf documents stored in repo edge HS.IHE.XDSb.Repository.Documents. Is it possible that this can further compress this type of binary stream?

below is the code I can see but Is this applied on 2021.1?

Property Document As %Stream.GlobalBinary;

Class %Stream.GlobalCharacter Extends TmpCharacter [ System = 2 ]
{ Parameter COMPRESS = 1;}

Product version: IRIS 2022.1

$ZV: IRIS for UNIX (Red Hat Enterprise Linux for x86-64) 2021.1 (Build 215_0_21260U) Tue Nov 9 2021 19:32:21 EST

Discussion (1)1

Akshay Pandey · Mar 2, 2023

But any kind of compression happen the the version I put on post.

InterSystems IRIS can automatically compress stream data that is stored in a global, saving database space and reducing the size of journal files.

Compression is controlled in stream classes by a class parameter, COMPRESS.

In the classes %Stream.TmpCharacterOpens in a new tab and %Stream.TmpBinaryOpens in a new tab, COMPRESS is set to 0, meaning that the stream data is not compressed.

In the classes %Stream.GlobalCharacterOpens in a new tab and %Stream.GlobalBinaryOpens in a new tab, COMPRESS is set to 1, meaning that new stream data is automatically compressed, except for the following cases, where the data is not suitable for compression:

The stream can be stored in a single chunk less than 1024 characters long.
The stream is already compressed, that is, the first chunk of data matches a typical compressed file format, such as JPEG, MP3, or ZIP.
The first 4KB of the stream cannot be compressed by at least 20 percent.

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