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Author's profile photo Mark Mumy
Mark Mumy
September 6, 2013 Less than a 1 minute read

SAP IQ 16 Indexes and Indexing Techniques

Please refer to the blog here: SAP IQ 16 Indexes and Indexing Techniques

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      Author's profile photo Former Member
      Former Member

      Hi Mark Mumy,

      Thanks so much for putting the post up. As a long time Sybase IQ user it is great to see it getting some air time in the SAP space now.

      Two quick questions based off an Advanced Tuning workshop I went to on version 15.

      1. I was under the impression that the threshold to move from LF to HG indexing was closer to the 10 000 mark in terms of uniqueness instead of 2000 ?
      2. I was also advised to stop using HNG indexes

      Really would appreciate your insight here

      Thanks

      Clint

      P.S. --> Thanks also for your sizing guide that I have used frequently over the years.. 🙂

      Author's profile photo Mark Mumy
      Mark Mumy
      Blog Post Author

      Hi Clint Vosloo,

      There are two thresholds with LF indexes.  First, you have the absolute max.  The max is 9999 values.  Second, you have the usable limit.  This is the value that is open to interpretation and experience.  My preference is in the 1500-2000 range.  That isn't an absolute, though, so feel free to play around with this.

      I, generally, advise against using HNG indexes, too.  Most of this logic is done in other index structures.  Also, the other indexes (HG, LF, n-bit) can allow for better performance in terms of parallelism, etc.  To be honest, I haven't done a POC in the last 3+ years where I found that having an HNG index greatly improved performance.  Like the LF index threshold, this is open to interpretation and experience.  I would say that you try it out to see how your system reacts to having them or not.  My experience would show that likely you won't see significant improvement. 

      Mark

      Author's profile photo Former Member
      Former Member

      Thanks for the clarification !

      Author's profile photo Former Member
      Former Member

      Sybase IQ index growing size depends from system indexes, not from LF or HG indexes. You must 'truncate table'. Table size grows , then using 'delete table' - system indexes size is growing stabile.

       

       

      RL

      2017-12-08