「PGError：到服務器的連接」試圖創建或保存

Question

1.9.1 + ActiveRecord的2.3.5 + Postgres的8.3.7

這裏是我的代碼的草圖。忽略任何明顯的語法細節。下面的模型繼承自ActiveRecord :: Base，通過ActiveRecord 2.3.5連接到Postgres 8.3.7數據庫。

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 

什麼總是會發生的是我得到了下面的堆棧跟蹤：

/...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!' 

....不管我打電話保存，保存！或做一個創造，而不是新的和保存。

strace顯示我只能得到一個BEGIN..INSERT..COMMIT事務爲每次運行這個工作。在發送COMMIT之前，在循環的相同運行或下一個事件中，任何後續對事務中INSERT的嘗試都以連接被丟棄結束。顯然，我在這裏做錯了我如何加入ActiveRecord模型。

我只在設置第一個成功的INSERT語句之前看到以下strace。 ActiveRecord中有什麼東西可以讓我保留這一點，當我逐步瀏覽表格，或者我只是做錯了嗎？

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 

在這裏的任何幫助，非常感謝。

Answer 1

謝謝大家。我很抱歉花時間來解決這個問題。這個postgres實例依賴於第二個運行來處理將觸發事件推送到其他進程的進程。該進程沒有運行，所以數據庫服務器在第一次提交INSERT後啓動。這是一種自定義的內部類型的事情。