Hello:
I have done the following experiment to test :
PG's activity when dealing with data which is bigger in size than total memory of the whole os system.
The result is:
PG says:
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WARNING: terminating connection because of crash of another server process
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.
HINT: In a moment you should be able to reconnect to the database and repeat your command.
The connection to the server was lost. Attempting reset: Failed.
!>
-----------------------------
In log, I can see the following:
LOG: background writer process (PID 3221) was terminated by signal 9: Killed
But why it need to kill the bgwriter ?
And that PG will use as much resource as it can to finish a sql dml , till it used almost all the resource and then crash?
I used the default checkpoint_segments(3) and shard_buffers(32MB) settings. And my machine has only 1024MB memory.
The process is as :
1) create table whose one tuple is more than 1KB:
postgres=# create table test01(id integer, val char(1024));
2) insert into the table 2457600 records, which makes totally more than 2400MB:
postgres=# insert into test01 values(generate_series(1,2457600),repeat( chr(int4(random()*26)+65),1024));
It really took a few minutes, When the sql statement run, I can see that the server process is consuming 80% of total memory of the os.
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[root@server ~]# ps aux | grep post
root 3180 0.0 0.0 105296 712 pts/1 S 16:31 0:00 su - postgres
postgres 3181 0.0 0.0 70304 676 pts/1 S+ 16:31 0:00 -bash
postgres 3219 0.0 0.2 113644 2864 pts/1 S 16:32 0:00 /usr/local/pgsql/bin/postgres -D /gao/data
postgres 3221 0.4 3.0 113724 35252 ? Ss 16:32 0:01 postgres: writer process
postgres 3222 0.2 0.1 113644 1616 ? Ds 16:32 0:00 postgres: wal writer process
postgres 3223 0.0 0.0 114380 1148 ? Ss 16:32 0:00 postgres: autovacuum launcher process
postgres 3224 0.0 0.0 73332 472 ? Ss 16:32 0:00 postgres: stats collector process
root 3252 0.0 0.0 105296 712 pts/2 S 16:32 0:00 su - postgres
postgres 3253 0.0 0.0 70304 676 pts/2 S 16:32 0:00 -bash
postgres 3285 0.0 0.0 83488 740 pts/2 S+ 16:32 0:00 ./psql
postgres 3286 14.8 80.2 2598332 924308 ? Ds 16:32 0:35 postgres: postgres postgres [local] INSERT
root 3333 0.0 0.0 65424 812 pts/3 S+ 16:36 0:00 grep post
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After a while, I found in the PG's log , the following information:
--------------------------------------------------------
LOG: autovacuum launcher started
LOG: database system is ready to accept connections
LOG: checkpoints are occurring too frequently (2 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (1 second apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (2 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (1 second apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (2 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (1 second apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (2 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (4 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (10 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (9 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (7 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (9 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (7 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (5 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (5 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (10 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (11 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (15 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (23 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (7 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (8 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (13 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (7 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (8 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (8 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (8 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (4 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (5 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: checkpoints are occurring too frequently (9 seconds apart)
HINT: Consider increasing the configuration parameter "checkpoint_segments".
LOG: background writer process (PID 3221) was terminated by signal 9: Killed
LOG: terminating any other active server processes
WARNING: terminating connection because of crash of another server process
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.
HINT: In a moment you should be able to reconnect to the database and repeat your command.
WARNING: terminating connection because of crash of another server process
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.
HINT: In a moment you should be able to reconnect to the database and repeat your command.
WARNING: terminating connection because of crash of another server process
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.
HINT: In a moment you should be able to reconnect to the database and repeat your command.
WARNING: terminating connection because of crash of another server process
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.
HINT: In a moment you should be able to reconnect to the database and repeat your command.
LOG: all server processes terminated; reinitializing
FATAL: the database system is in recovery mode
LOG: database system was interrupted; last known up at 2013-08-30 16:36:42 CST
LOG: database system was not properly shut down; automatic recovery in progress
LOG: consistent recovery state reached at 0/B7657BD0
LOG: redo starts at 0/B60FE2B8
LOG: unexpected pageaddr 0/B044C000 in log file 0, segment 184, offset 4505600
LOG: redo done at 0/B844B940
LOG: autovacuum launcher started
LOG: database system is ready to accept connections
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Best Regards
