About the LightDB-A Database Utilities

General information about using the LightDB-A Database utility programs.

Parent topic: LightDB-A Database Utility Guide

Referencing IP Addresses

When you reference IPv6 addresses in LightDB-A Database utility programs, or when you use numeric IP addresses instead of hostnames in any management utility, always enclose the IP address in brackets. When specifying an IP address at the command line, the best practice is to escape any brackets or enclose them in single quotes. For example, use either:

\[2620:0:170:610::11\]

Or:

'[2620:0:170:610::11]'

Running Backend Server Programs

LightDB-A Database has modified certain PostgreSQL backend server programs to handle the parallelism and distribution of a LightDB-A Database system. You access these programs only through the LightDB-A Database management tools and utilities. Do not run these programs directly.

The following table identifies certain PostgreSQL backend server programs and the LightDB-A Database utility command to run instead.

PostgreSQL Program Name	Description	Use Instead
`initdb`	This program is called by `gpinitsystem` when initializing a LightDB-A Database array. It is used internally to create the individual segment instances and the coordinator instance.	gpinitsystem
`ipcclean`	Not used in LightDB-A Database	N/A
`pg_basebackup`	This program makes a binary copy of a single database instance. LightDB-A Database uses it for tasks such as creating a standby coordinator instance, or recovering a mirror segment when a full copy is needed. Do not use this utility to back up LightDB-A Database segment instances because it does not produce MPP-consistent backups.	gpinitstandby, `[gprecoverseg](ref/gprecoverseg.html)`
`pg_controldata`	Not used in LightDB-A Database	gpstate
`pg_ctl`	This program is called by `gpstart` and `gpstop` when starting or stopping a LightDB-A Database array. It is used internally to stop and start the individual segment instances and the coordinator instance in parallel and with the correct options.	gpstart, gpstop
`pg_resetwal`	DO NOT USE > Caution This program might cause data loss or cause data to become unavailable. If this program is used, the VMware LightDB-A cluster is not supported. Thecluster must be reinitialized and restoredby the customer.	N/A
`postgres`	The `postgres` executable is the actual PostgreSQL server process that processes queries.	The main `postgres` process (postmaster) creates other `postgres` subprocesses and `postgres` session as needed to handle client connections.
`postmaster`	`postmaster` starts the `postgres` database server listener process that accepts client connections. In LightDB-A Database, a `postgres` database listener process runs on the LightDB-A coordinator Instance and on each Segment Instance.	In LightDB-A Database, you use gpstart and gpstop to start all postmasters (`postgres` processes) in the system at once in the correct order and with the correct options.