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Message Posted: Mon, 23 May 2011 @ 17:56:15 GMT
| Subj: || || Multi value compression and presence bits |
| From: || || David W Williams |
My question is on compression and presence bits and "Multi Value Compression Break Even". I understand the more values you have compression on
a column, the more bits Teradata uses to track these values. However, aren t there are 2 bytes per row of overhead reserved for presence bits
anyway. So, whether you have zero values compressed or 255 values compressed the row overhead should be the same because 255 compressed values
still only use 8 bits.
Is that correct?