从分区表删除查询失败后，Postgres处于恢复模式(PG 12)

Question

我有一个用于处理简单表的代码，当同一个表被分区到多个子分区时，就停止工作了。

在分布式应用程序(Spark)中，我们有代码可以在同一时间并行执行来自不同计算机的批删除查询(删除不同的记录)。

大多数查询都正常工作，但其中一个查询似乎在套接字连接超时上失败：

java.sql.BatchUpdateException: Batch entry 0 DELETE FROM my_table WHERE vessel_id='xxxxxx' AND day='2020-09-15 00:00:00+00'::timestamp was aborted: An I/O error occurred while sending to the backend.  Call getNextException to see other errors in the batch.

Caused by: java.net.SocketException: Connection reset
        at java.net.SocketInputStream.read(SocketInputStream.java:210)
        at java.net.SocketInputStream.read(SocketInputStream.java:141)

When the code retries to run the task the connection fails on 
:FATAL:  the database system is in recovery mode

在数据库日志中，我看到：

2020-09-21 16:44:27 UTC::@:[26848]:DETAIL:  Failed process was running: DELETE FROM my_table WHERE vessel_id=$1 AND day=$2
2020-09-21 16:44:27 UTC::@:[26848]:LOG:  terminating any other active server processes
2020-09-21 16:44:27 UTC:172.31.4.110(59468):postgres@postgres:[27705]:WARNING:  terminating connection because of crash of another server process
2020-09-21 16:44:27 UTC:172.31.4.110(59468):postgres@postgres:[27705]:DETAIL:  The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
2020-09-21 16:44:27 UTC:172.31.4.110(59468):postgres@postgres:[27705]:HINT:  In a moment you should be able to reconnect to the database and repeat your command.
2020-09-21 16:44:27 UTC:10.3.1.138(57926):rdsrepladmin@[unknown]:[26740]:WARNING:  terminating connection because of crash of another server process
2020-09-21 16:44:27 UTC:10.3.1.138(57926):rdsrepladmin@[unknown]:[26740]:DETAIL:  The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
2020-09-21 16:44:27 UTC:10.3.1.138(57926):rdsrepladmin@[unknown]:[26740]:HINT:  In a moment you should be able to reconnect to the database and repeat your command.
2020-09-21 16:44:27 UTC::@:[22480]:WARNING:  terminating connection because of crash of another server process
2020-09-21 16:44:27 UTC::@:[22480]:DETAIL:  The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
2020-09-21 16:44:27 UTC::@:[22480]:HINT:  In a moment you should be able to reconnect to the database and repeat your command.
2020-09-21 16:44:27 UTC:127.0.0.1(31826):rdsadmin@rdsadmin:[27967]:FATAL:  the database system is in recovery mode

知道当表被分区时数据库为什么会失败吗？为什么其他计算机上的所有其他连接都关闭，数据库进入恢复模式？

Answer 1

在查看了日志之后，我发现这个问题已经没有记忆了。这个数据库实例是主要的实例，它负责编写、复制和删除，并且没有足够的内存同时处理所有这些任务。

修复方法是简单地添加更多内存。没什么花哨的。