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I have installed both pgpool and postgresql via apt.

In pgpool.conf, I have made the changes necessary to use replication mode, as well as my two postgresql databases (currently all running on the same host).

I am unable to figure out what I need to add to my pg_hba.conf files in order to have pgpool connect to them. I keep getting this error

createdb: could not connect to database postgres: ERROR:  MD5 authentication 
is unsupported in replication, master-slave and parallel modes.
HINT:  check pg_hba.conf

both of my pg_hba.conf files look like

local   all             postgres                                peer

local   all             all                                     peer
local   all             postgres                                md5

host    all             all               md5

host    all             all             ::1/128                 md5

local   replication     postgres                                peer
host    replication     postgres            md5

and my pool_hba.conf looks like

local   all         all                               trust
local   all         postgres                          md5
local   all         all                               md5     

host    all         all          trust

What am I missing in order to have pgpool connect to my databases?

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Have you read the relevant parts of the docs? – Milen A. Radev Feb 10 '14 at 15:47
@MilenA.Radev Yes I have. – Justin Wood Feb 10 '14 at 15:58
You are executing createdb. Please try a simple psql connection first. I went through some issues while trying to set up pgpool with replication and made a note of the debugging process I used - – Jayadevan Feb 11 '14 at 3:50

3 Answers 3

It looks like your default authentication mode for TCP/IP connections (host) is md5. So at a guess, you have PgPool connecting over TCP/IP.

Change the auth mode for loopback connections on tcp/ip, or use unix sockets with pgpool (usually by omitting the host setting).

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Thanks for the input. I am still new to DB administration. Would you be able to tell me which line to change, and to what? – Justin Wood Feb 11 '14 at 2:09
@JustinWood If you're still stuck after reading and, and you can't find answers elsewhere (there are lots of related questions on stackoverflow), let me know and I'll give you a step by step if I have a chance. – Craig Ringer Feb 11 '14 at 2:48

I messed around with this problem for several hours and then finally found the solution.

Read the pgpool-II FAQ and look at the table.

You cannot leave the default entries of trust in pool_hba.conf. I commented out the trust entries and added my md5 entries.

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As an additional check, after ensuring matching MD5 METHODS in pg_hba.conf and pool_hba.conf,

make sure to set

 enable_pool_hba = on 

in pgpool.conf

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