hacking postgres hashjoin algorithm
Hello there
I am trying to play around with the hashjoin algorithm in postgres.
I am using the statement like
Select count(*) from r,s where r.id=s.id;
I looked at the function ExecHashJoin() in nodeHashjoin.c and cannot
find where the algorithm is comparing if r.id equals s.id
please advise.
Regards
hal
On Sun, Oct 15, 2006 at 11:08:18PM -0400, HS wrote:
Hello there
I am trying to play around with the hashjoin algorithm in postgres.
I am using the statement like
Select count(*) from r,s where r.id=s.id;I looked at the function ExecHashJoin() in nodeHashjoin.c and cannot
find where the algorithm is comparing if r.id equals s.id
The code doing the work is actually ExecScanHashBucket() which is in
nodeHash.c. The actual check is done by the ExecQual there...
Hope this helps,
--
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/
Show quoted text
From each according to his ability. To each according to his ability to litigate.
from my understanding, postgres first needs to partition the tables.
ExecHashTableCreate() is the function that partitions the tables right?
Martijn van Oosterhout wrote:
Show quoted text
On Sun, Oct 15, 2006 at 11:08:18PM -0400, HS wrote:
Hello there
I am trying to play around with the hashjoin algorithm in postgres.
I am using the statement like
Select count(*) from r,s where r.id=s.id;I looked at the function ExecHashJoin() in nodeHashjoin.c and cannot
find where the algorithm is comparing if r.id equals s.idThe code doing the work is actually ExecScanHashBucket() which is in
nodeHash.c. The actual check is done by the ExecQual there...Hope this helps,