"PGError: no connection to the server" while trying to create or save - ruby

Question

Ruby 1.9.1 + ActiveRecord 2.3.5 + Postgres 8.3.7
Here is a rough sketch of my code. Ignore any obvious syntax details left out. The model below inherits from ActiveRecord::Base connected to a Postgres 8.3.7 database via ActiveRecord 2.3.5.
class TableA
has_many :tableB
end
class TableB
belongs_to :tableA
has_many :tableC
end
class TableC
belongs_to :tableB
has_many :tableD
end
class TableD
belongs_to :tableC
has_many :tableE
end
class TableE
belongs_to :tableD
end
# Note that tableA has fids that are referenced in tableE but is not part of this model
#
# Later in the script, in the same global scope, I want to add entries to these tables if
# I cannot find what I need. Bear in mind that this part betrays much Ruby noobiness.
toAdd.each do |widget|
add_tableA = TableA.find_by_sql().first # assumes I will get one back based on earlier sanity checks
add_tableB = TableB.find_by_sql().first
if (add_tableB == nil)
new_tableB = TableB.new( # value assignments )
new_tableB.save
add_tableB = TableB.find_by_sql().first
end
add_tableC = TableC.find_by_sql().first
if (add_tableC == nil)
new_tableC = TableC.new( # value assignments )
new_tableC.save
add_tableC = TableC.find_by_sql().first
end
add_tableD = TableD.find_by_sql().first
if (add_tableD == nil)
new_tableD = TableD.new( # value assignments )
new_tableD.save
add_tableD = TableD.find_by_sql().first
end
# I step into TableA again because items in TableE are linked to items in TableA, but they are
# distinct from the "high level" item I grabbed from TableA earlier.
add_tableA = TableA.find_by_sql().first
if (add_tableA == nil)
new_tableA = TableA.new( # value assignments )
new_tableA.save
add_tableA = TableA.find_by_sql().first
end
# Now that I have a TableA id to put into TableE, just create TableE row because I know this
# does not exist yet.
new_tableE = TableE.new( # value assignments ) # again, this is assumed to be new based on earlier checks
new_tableE.save
end
What always happens is I get the following stack trace:
/...gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract_adapter.rb:219:in `rescue in log': PGError: no connection to the server (ActiveRecord::StatementInvalid)
: ROLLBACK
from .../gems/1.9.1/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract_adapter.rb:202:in `log'
from .../gems/1.9.1/gems/activerecord-2.3.5/lib/active_record/connection_adapters/postgresql_adapter.rb:550:in `execute'
from .../gems/1.9.1/gems/activerecord-2.3.5/lib/active_record/connection_adapters/postgresql_adapter.rb:576:in `rollback_db_transaction'
from .../gems/1.9.1/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/database_statements.rb:143:in `rescue in transaction'
from .../gems/1.9.1/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/database_statements.rb:125:in `transaction'
from .../gems/1.9.1/gems/activerecord-2.3.5/lib/active_record/transactions.rb:182:in `transaction'
from .../gems/1.9.1/gems/activerecord-2.3.5/lib/active_record/transactions.rb:200:in `block in save_with_transactions!'
from .../gems/1.9.1/gems/activerecord-2.3.5/lib/active_record/transactions.rb:208:in `rollback_active_record_state!'
from .../gems/activerecord-2.3.5/lib/active_record/transactions.rb:200:in `save_with_transactions!'
.... regardless if I'm calling save, save!, or doing a create instead of new and save.
strace reveals that I can only get one BEGIN..INSERT..COMMIT transaction to work for each run of this. Any subsequent attempts to INSERT within a transaction either in the same run of the loop or the next one ends with the connection being dropped before a COMMIT is sent. Clearly, I'm doing something wrong here with how I'm stepping into the ActiveRecord model.
I see the following strace only just before the first successful INSERT statement is set up. Is there something in ActiveRecord that allows me to preserve this as I step through tables, or am I simply Doing It Wrong?
rt_sigaction(SIGPIPE, {0x1, [], SA_RESTORER|SA_RESTART, 0x3876c0eb10}, {0x4b2ff0, [], SA_RESTORER|SA_RESTART, 0x3876c0eb10}, 8) = 0
sendto(3, "Q\0\0\2e SELECT attr.attna"..., 614, 0, NULL, 0) = 614
rt_sigaction(SIGPIPE, {0x4b2ff0, [], SA_RESTORER|SA_RESTART, 0x3876c0eb10}, {0x1, [], SA_RESTORER|SA_RESTART, 0x3876c0eb10}, 8) = 0
poll([{fd=3, events=POLLIN|POLLERR}], 1, -1) = 1 ([{fd=3, revents=POLLIN}])
recvfrom(3, "T\0\0\0:\0\2attname\0\0\0\4\341\0\2\0\0\0\23\0#\377\377\377\377\0"..., 16384, 0, NULL, NULL) = 541
Any help here is greatly appreciated.

Answer 1

Thanks everyone. I apologize for taking anyone's time in trying to fix this. This instance of postgres depends upon a second process to run to handle pushing trigger events out to other processes. That process was not running, so the database server booted after the first committed INSERT. It's a custom in-house kind of thing.