Re: POC: make mxidoff 64 bits

[Maxim Orlov]

Here is the test scripts.
The generate.sh script is used to generate data dir with multimple clusters
in it. This script will call multixids.py in order to generate data. If you
are not use system psql consider using LD_LIBRARY_PATH env to specify path
to the lib directory.
OLDBIN=/.../pgsql-new ./generate.sh

Then the test.sh is used to run various upgrades.
OLDBIN=/.../pgsql-old NEWBIN=/.../pgsql-new ./test.sh

I hope that helps!

-- 
Best regards,
Maxim Orlov.

#!/usr/bin/env python3

import sys;
import threading;
import psycopg2;

def test_multixact(tblname: str):
    with psycopg2.connect(dbname="postgres") as conn:
        cur = conn.cursor()
        cur.execute(
            f"""
            DROP TABLE IF EXISTS {tblname};
            CREATE TABLE {tblname}(i int primary key, n_updated int) WITH (autovacuum_enabled=false);
            INSERT INTO {tblname} select g, 0 from generate_series(1, 50) g;
            """
        )

    # Lock entries using parallel connections in a round-robin fashion.
    nclients = 50
    update_every = 97
    connections = []
    for _ in range(nclients):
        # Do not turn on autocommit. We want to hold the key-share locks.
        conn = psycopg2.connect(dbname="postgres")
        connections.append(conn)

    # On each iteration, we commit the previous transaction on a connection,
    # and issue another select. Each SELECT generates a new multixact that
    # includes the new XID, and the XIDs of all the other parallel transactions.
    # This generates enough traffic on both multixact offsets and members SLRUs
    # to cross page boundaries.
    for i in range(20000):
        conn = connections[i % nclients]
        conn.commit()

        # Perform some non-key UPDATEs too, to exercise different multixact
        # member statuses.
        if i % update_every == 0:
            conn.cursor().execute(f"update {tblname} set n_updated = n_updated + 1 where i = {i % 50}")
        else:
            conn.cursor().execute(f"select * from {tblname} for key share")

test_multixact(sys.argv[1])

generate.sh
Description: Bourne shell script

test.sh
Description: Bourne shell script