Basic cluster management

YMatrix 5 launches a brand new database architecture. Under this architecture, we also provide the latest cluster operation and maintenance tools: mxstart, mxstop, mxstate. For more information about the new YMatrix 5 architecture, please see YMatrix Architecture.

Notes!
YMatrix 5 uses the new operation and maintenance tool to manage the cluster by default, and YMatrix 4 (MatrixDB 4) still uses the Greenplum series operation and maintenance tool by default. For details, please see YMatrix 4 Cluster Basic Management.

1. Operation cluster

1.1 Start

mxstart -a  # Start the cluster

1.2 Close

mxstop -a   # Stop the cluster (may hang if sessions are connected)
mxstop -a -M fast  # Fast - mode shutdown

1.3 Restart

mxstop -ar # Restart, waiting for ongoing SQL to finish (may hang if sessions are connected)
mxstop -ar -M fast # Fast - mode restart

1.4 Reload the configuration

mxstop -u  # Reload configuration files

1.5 Check cluster status

mxstate     # Check cluster status
mxstate -s  # Check the entire YMatrix cluster's status
mxstate -m  # List Mirrors
mxstate -f  # Show Standby Master info

1.6 View and modify configuration parameters

Display configuration values:

gpconfig -s {GUC}

# Example: Check the maximum number of connections allowed
gpconfig -s max_connections

Modify the configuration value:

gpconfig -c {GUC} -v {Value} -m {Value} # -m for Master, -v for Segment
gpconfig -c {GUC} -v {Value} # Same value for Master and Segment

# E.g.:
gpconfig -c max_connections -v 1000 -m 300
gpconfig -c shared_buffers -v 2GB

2. Log in to the cluster

2.1 psql login database

psql -d ${db_name} -U ${user_name} -h ${ip_addr} -p ${port}

Modify environment variables and add the default value of psql:

# You can modify the default value by modifying the environment variables
vi ~/.bash_profile  # Edit with mxadmin user, add variables:

export PGPORT=5432   # Default port
export PGUSER=mxadmin # Default user
export PGDATABASE=postgres  # Default database

Make environment variables effective immediately:

source ~/.bash_profile

# Execute psql to log in to the database
psql
# The default value at this time is
psql -d postgres -U mxadmin -h localhost -p 5432

2.2 psql metacommand

\l List all databases. 
\d List tables, views, sequences in the current database 
\d [table_name] Show table structure
\dt Show matching tables.
\di Show indexes.
\dt+ table_name Check table size.
\di+ index_name Check index size.
\ds Show sequences.
\dv Show views.
\dm Show materialized views.
\df Show functions.
\dn List schemas.
\du or \dg List roles/users.
\dp or \z Show table permissions.
\dx Show extension info.
\sf function_name Show function code.
\h Show SQL command explanation.
\? List psql commands. 
\c Show current DB and connection info.
\c [database_name] Connect to another DB. 
\e Open text editor. 
\x Set query result output
\! Execute OS command
\o /home/postgres/test.txt Save results to file (close with \o)
\drds Show RDS - related info
\s Show history
\watch 1 Repeat last command every 1 second

3. Creating and deleting libraries

3.1 Creating a library

Method 1, use the createdb tool to create:

createdb test

Method 2: Create using the CREATE DATABASE SQL statement:

psql postgres
postgres=# create database test;

3.2 Delete the library

Method 1, use the dropdb tool to delete:

dropdb test

Method 2: Create using the DROP DATABASE SQL statement:

psql postgres
postgres=# drop database test;