[pgpool-general: 2490] doubts concerning pgpool's configuration: black_function_lists and delay_threshold

emgvivas . emgvivas at gmail.com
Mon Jan 27 07:50:15 JST 2014

Hi, first i really appreaciate the work you have been taking to develop pgpool.

Im using pgpool 3.1.3, and 2 backends in Master -> Slave Mode. It is
working greate, but ofcourse im worried about WRITE queries being sent
to the slave, so to avoid it im thinking in adding a large list of
function names to the black_function_lists.

I shall say also that this Master -> Slave Mode is running Streaming
Replication feature of postgresql 9.1.

I run a query to list all volatile function names:
select proname from pg_proc where provolatile = 'v';

the above query lists all volatile triggers, and functions in the
database, including those in pg_catalog. the total amount of functions
is round 500.

i know that i can make use of regex to make the list shorter, also it
is good practice to make a standard when naming functions, like all
functions that do WRITES should be preceeded with a "write_" prefix or
something like that.

My question are:
1) is this the right way to go to enforce WRITE queries being sent to
the Master ONLY?
2) is there any kind of limit of function names on the
black_function_lists? is there any problem seting black_function_lists
to like 10 thousand function names?
3) What should be a reasonable value of delay_threshold in
pgpool.conf? i've set it to 5 bytes..

Thanks in advance,
emgvivas at gmail.com

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