• kdb+

  Attributes memory overhead

  Posted by unterrainer_ale on September 1, 2023 at 12:00 am

  Out of curiosity, can anyone explain the attributes overhead as explained in the Abridged Q Language Manual? Does anyone know what the 4*u+1 is? for parted and grouped? (I know the 4byte should be probably 8 bytes after 3.0)

  example overhead
  `s#2 2 3 sorted 0
  `u#2 4 5 unique 16*u
  `p#2 2 1 parted (4*u;16*u;4*u+1)
  `g#2 1 2 grouped (4*u;16*u;4*u+1;4*n)

  The byte overheads use n(number of elements) and u(number of uniques). These are used by lookups, e.g.

  unterrainer_ale replied 9 months, 2 weeks ago 2 Members · 1 Reply
• 1 Reply

• 

  fbodon

  Member

  September 4, 2023 at 12:00 am

  You might find this document useful: https://dataintellect.com/blog/adventure-in-retrieving-memory-size-of-kdb-object/ It covers the memory need of attributes.

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