[IQUG] Sybase 16 - FP_NBIT_Autosize_Limit

Henderson, William L william.l.henderson at jpmorgan.com
Wed Mar 11 07:19:40 MST 2015

Hey Guys,

I notice the default max nBIT is 20 bits, before you flip to flat FP. On IQ 15 we were pretty happy with 3 Byte FPs, so I am thinking we will change FP_NBIT_Autosize_Limit to 33554431, to allow 24 byte, but flip to flat above that. Does that make sense? Does anyone know the pros/cons?

The table I am particularly interested in has about 30 billion rows (and growing), and there are some columns which will be about 22/23 bit if I do this. These columns are used as id's and occasionally will be used as SARGS or joins, but never in group bys. We have 1.5 TB of RAM.


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