Re: [Postgres-xc-general] pgbench suggestion

>> >> We have up to 8 servers, where each server has data
>> >> node/coorrdinator/GTM proxy. We have GTM on a seprate server. Then we
>> >> execute multiple pgbench -k -S against the servers(each pgbench
>> >> connect to different server).
>> >>
>> > OK, this should not happen...
>> > How many max connections are you using per Coordinator
>>
>> 100.
>>
>> > and how many
>> > Coordinators do you have?
>>
>> Up to 4.
>> The number of coordinators are same as data nodes. So when we test 4
>> data nodes(suppose they are d1 to d4), we are doing something like
>> this:
>>
>> on host c1: pgbench -c 100 -S -h d1
>> on host c2: pgbench -c 100 -S -h d2
>> on host c3: pgbench -c 100 -S -h d3
>> on host c4: pgbench -c 100 -S -h d4
>>
> That looks OK. I was wondering if the maximum active transactions possible
> on GTM (1024) was reached, leading to your error.
> The warning "Cannot connect to GTM..." "Xid is invalid." only happens when
> a node tries to get a connection from GTM but it cannot, making me think
> that GTM is not online or you have some firewall/network problems between
> the node and GTM.

The error seems not depending on number of node. We did the similar
way as 4 nodes above against 8 nodes configuration. Sometimes we saw
the error, sometimes not. Also we saw the error when the number of
nodes less than 4, for example 2 or 1.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
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