DBA Cockpit - Explain - intrepeting results

[Chris_Lumb]

Hello,

I've been using DBA Cockpit to look at how queries are being planned - the database being queried is Sybase ASE.

I did some test queries on LIPS and VBAP e.g.

SELECT lips~vbeln lips~posnr
  FROM lips
  INNER JOIN vbap
    ON lips~vgbel = vbap~vbeln AND lips~vgpos = vbap~posnr
  INTO TABLE gt_vbeln
  WHERE vbap~vbeln = p_sa_doc.

Which I could see was using a index LIPS~Z01 we have set up on fields VGBEL, VGPOS. The above query did IndexScans and then did a MergeJoin.

I then tried a similar query, but which didn't fully use the index:

SELECT lips~vbeln lips~posnr
  FROM lips
  INNER JOIN vbap
    ON lips~vgbel = vbap~vbeln 
  INTO TABLE gt_vbeln
  WHERE vbap~vbeln = p_sa_doc.

This resulted in a StoreIndex on VBAP and a NestLoopJoin.

Does anyone know some good resources for learning about the different operations that appear in the flow diagrams in DBA Cockpit e.g. 'StoreIndex', 'NestLoopJoin'.

Is there any documentation or any books you could recommend? Thank you, Chris

[former_member188958 · Accepted solution]

I suggest the "Abstract Query Plan Guide" from the Performance and Tuning manuals,

Chapter 13: Abstract Query Plan Guide

[Chris_Lumb · Accepted solution]

Thanks Brett, I'd skimmed over some of those Sybase manuals previously. I'll give the chapter you recommended a read.