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· Aug 10, 2017

Determine the impact of CREATE-INDEX on a large file

#Beginner #Indexing #MultiValue Basic #Caché

Hi,

I am new to Cache' MV but have extensive experience with other Pick flavors especially Unidata. 

I need to determine the impact of adding several indexes to a large file with over 51,000,000 records. 

On other systems, I could use FILE.STAT, ANALYZE.FILE and shell to the OS to determine how large the index file was. 

None of those seem to be available in Cache' MV. Shelling to the OS just tells me the size of CACHE.DAT.

What is the best way to determine what the disk impact would be if I added an index (CREATE-INDEX) to a file?

TIA,

Steve

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John Murray · May 8, 2017

Steve, it may be worth you adding the "MultiValue Basic" tag to your question (which you can edit).

I haven't yet seen much MV traffic here on Developer Community. This lookup of posts with the "MultiValue Basic" tag currently only shows ones created by Community Manager. This Google Group has existed for several years, and I wonder if the folk there have yet heard about DC.

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Otto Medin · May 9, 2017

Hi Steve,

Here are a couple of ways to do this:

1. Use ^%GSIZE to look at the size of your index global before and after you populate your new index. (If you look at the class definition, the global name is listed as "IndexLocation" in the "Storage" section.)

2. Map the index global to a separate database and look at the size of the CACHE.DAT.

The advantage of the second approach is that subscript-level mapping lets you selectively isolate indices.

Otto

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