Test workload for PostgreSQL MultiXact: create new mxacts

mxact_create.sql

CREATE OR REPLACE FUNCTION mxact_create(SCALE integer) RETURNS void AS $body$
declare
  default_rows_per_scale integer := 100000;
  gap integer := 3000;
  range integer := 100;
  create_base_id integer;
  segment_id integer;
begin
  -- Generate a random number to use as a segment to offset concurrent connections from hitting the same exact range of ids
  select (trunc(extract(millisecond from current_timestamp) * default_rows_per_scale, 0) % (100000 * scale)) into create_base_id;

  -- Generate a random number to use as a segment to offset concurrent connections from hitting the same exact range of ids
  select floor(random() * 10 + 1)::integer into segment_id;

  -- Execute the SQL that will generate the multixact
  perform * from pgbench_accounts where aid > (create_base_id + (segment_id * gap)) and aid < ((create_base_id + (segment_id * gap)) + range) for share;
end;
$body$ LANGUAGE PLPGSQL VOLATILE;