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Failed to Create a Database or a Table on the MPPDB Backend

Publication Date:  2019-04-12 Views:  28 Downloads:  0
Issue Description

After connecting to the postgtes database by running gsql, users fail to create a table or a database.

Handling Process

1. Connect to the database and view the following GUC parameter:

show comm_tcp_mode


2. Run the following command to check the parameter value of all data nodes as user root:

cat /sys/module/sctp/parameters/no_checksums

Root Cause

This is a problem of the Red Hat 6.4 and Red Hat 6.5 kernel protocol stacks. Red Hat has fixed this problem in 2.6.32-504 version.

Solution

Upgrade the Red Hat to resolve the problem. Alternatively, perform the following operations to handle the problem temporarily:

The rule of the current disk is sequenced in the integer order. Run the echo 1 command according to the integer order, and the path after the execution is /sys/module/sctp/parameters/no_checksums.

Suggestions

su - omm

source ${BIGDATA_HOME}/mppdb/.mppdbgs_profile

cm_ctl query -Cvd

The environment CN can be queried.

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comm_tcp_mode

Parameter description: Switch for switching between the TCP communication library and the SCTP communication library. The setting takes effect after the cluster is restarted.

This parameter is of the POSTMASTER type. Set the parameter by referring to Table 1.

Value range: Boolean type.

If the comm_tcp_mode parameter of the CN is set to on, the DN is connected in TCP mode. If the comm_tcp_mode parameter of the DN is set to on, only the TCP port is listened to and TCP communication is used between the DNs.

If the comm_tcp_mode parameter of the CN is set to off, the DN is connected in the SCTP mode. If the comm_tcp_mode parameter of the DN is set to off, the TCP and SCTP ports are monitored at the same time. The SCTP communication is used between the DNs.

Pay attention to the following:

If the comm_tcp_mode of the CN is set to off and the comm_tcp_mode of the DN is set to on, the cluster communication will be abnormal. You are advised to configure the CN and DN globally and restart the cluster for the settings to take effect.

Default value: off

END