Postgres sql code to execute an array of statements in parallel based on dblink.
Returns true if all statements are executed OK.
In the example below we send 11 statements to be executed in three parallel dblink connections .
select 1, execute_parallel('{"select pg_sleep(10)","select pg_sleep(1)","select pg_sleep(1)","select pg_sleep(1)","select pg_sleep(1)","select pg_sleep(1)","select pg_sleep(1)","select pg_sleep(1)","select pg_sleep(1)","select pg_sleep(1)","select pg_sleep(1)"}'::text[],3);
In this case the following is hapning :
- The first statements takes 10 seconds and the first dblink connection works this all the time with this statement.
- The 2 other connections continue to work with the rest of the statements while the first dblink connection work the first statement.
This mean that that this jobs takes a total of 10 seconds if there are three free database connections .
If you request to run more parallel requests than there are db connections available, the number of parallel jobs will be reduced to the number of available connections.
If you have a error in one the statements only that wil fail the other statements will execute ok.
git clone https://github.com/larsop/postgres_execute_parallel.git
cat postgres_execute_parallel/src/main/sql/function*.sql | psql
psql -c'CREATE EXTENSION dblink;'
Based on initial code from Joe Conway mail@joeconway.com in https://www.postgresql-archive.org/How-to-run-in-parallel-in-Postgres-td6114510.html