[Monetdb-developers] [Monetdb-pf-checkins] pathfinder/compiler/algebra algopt.c, , 1.30, 1.31 planner.c, , 1.56, 1.57 properties.c, , 1.34, 1.35

Jan Rittinger rittinge at in.tum.de
Wed Apr 2 10:10:41 CEST 2008

On 04/02/2008 09:56 AM, Keulen, M. van (Maurice) wrote with possible 
> Hi Jan,
> This one is likely to speed up my use of MXQ a lot! Does "references" 
> also mean that a lot less elements will be constructed? One of the 
> scalability bottlenecks that I frequently encounter in my experiments is 
> not that it is slow, but that I create more than 2^32 elements (which 
> doesn't fit in a bat with 32-bit oids). Avoiding subtree copies would 
> probably improve the scalability of my experiments enormously. I must 
> definitely push the move to the algebra backend :-)

Hi Maurice,

you are completely correct :)

As long as you do *not* query the constructed nodes but use them only 
for serialization the subtree copying will produce at most twice as many 
nodes (reference+original) as you construct.

Note that this checkin does not improve the performance if you query the 
constructed nodes using a downward axis (e.g., if you use the 
constructed nodes as an intermediate 'tuple' representation).


Jan Rittinger
Database Systems
Technische Universität München (Germany)

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