Question

我使用以下python脚本监视postgreSQL从属服务器的复制延迟，该脚本从主服务器查询pg_current_xlog_location，并将其与从服务器上的pg_xlog_replay_location进行比较。最近，我收到了警告电子邮件，表明复制滞后在2k到70k字节之间。

这里有什么合理的期望？我假设它基于WAL缓冲区大小和检查点间隔，但我不确定如何计算它。另外，与奴隶上的pg_xlog_receive_location进行比较会更好吗？

P.S。我还通过在sent_location视图中将replay_location与pg_stat_replication进行比较来监控主服务器上的复制。另外，我检查主服务器是否处于streaming模式。该监视器从未发出警报......

#!/usr/bin/python
import subprocess

slaveXlogDiffLimitBytes = 128

try:
    repModeRes = subprocess.check_output('psql -t -p {{postgresql_port}} -c "SELECT pg_is_in_recovery()"', shell=True)
    isInRepMode = repModeRes.strip() == 't'

    masterXlogLocationRes = subprocess.check_output('psql -t -p {{postgresql_port}} -h {{postgres_basebackup_host}} -U {{postgres_basebackup_user}} {{postgres_db_name}} -c "select pg_current_xlog_location();"', shell=True)
    masterXlogLocationStr = masterXlogLocationRes.strip()

    slaveXlogDiffRes = subprocess.check_output('psql -t -p {{postgresql_port}} {{postgres_db_name}} -c "select pg_xlog_location_diff(pg_last_xlog_replay_location(), \'' + masterXlogLocationStr + '\'::pg_lsn);"', shell=True)
    slaveXlogDiffBytes = float(slaveXlogDiffRes.strip())
except subprocess.CalledProcessError as e:
    print "Error retrieving stats: {0}".format(e)
    exit(1)

if isInRepMode != True:
    print ('Slave server is not in recovery mode')
    exit(1)

if slaveXlogDiffBytes > slaveXlogDiffLimitBytes:
    print "Slave server replication is behind master by %f bytes" % slaveXlogDiffBytes
    exit(1)

print('All clear!')
exit(0)

PostgreSQL复制滞后的合理值是多少？

0 个答案: