Hi,
I know, this list is not for this, but I just couldn't resist. Please forgive
me.
Being an Oracle DBA for two decades now (back then starting with Oracle 8.0.5)
and only doing PostgreSQL since version 10.3, I feel compelled to share some of
my experiences with both.
Quick facts:
All installations were performed on the same host except for Oracle Data Guard
and Patroni with etcd, which both require at least three nodes, or an odd
number >2 respectively) to establish a democracy to determine the
master/primary and replica/standby databases. However, all machines have the
same hardware and operating system:
OS: openSUSE Leap 15.1 (server setup, not desktop)
CPU: Intel i7-7700T CPU
RAM: 32 GB
Disk Hardware: SSD
Also, Oracle requires 161 additional packages to be installed, many of which
are 32-bit packages, for a supposedly 64-bit only software! This results in 150
MB additional disk space needed and swamps the system with 32-bit packages!
PostgreSQL only requires a few packages to be installed depending on the
options one chooses to compile the source with. Anyway, none of these packages
require a 32-bit version!
Size of installation:
Software:
$ du -sh /data/postgres/12.3 /data/oracle/product/19.6
62M /data/postgres/12.3
8.5G /data/oracle/product/19.6
Databases:
$ du -sh /data/oradb/*
3.3G /data/oradb/cdb01 # Oracle Container w/ 1 PDB
1.8G /data/oradb/sdb01 # Oracle stand alone database
$ du -sh /data/pgdb/sdb01
659M /data/pgdb/sdb01 # PostgreSQL 12.3 database cluster
All databases are a clean setup, no schemas, users, tables, data, etc. Just an
empty base.
Installation:
Oracle 19c: ~2h
unzip to ORACLE_HOME
runInstaller
unzip newest OPatch p6880880_200000_Linux-x86-64
apply p30797938_190000_Linux-x86-64 (19.6.1)
PostgreSQL 12.3 compiled from source: ~3m30s
bunzip postgresql-12.3.tar.bz2 to PGHOME
make install-world
Create database:
Oracle:
create stand alone database: ~30m
create container database (cdb$root): ~47m
create pluggable database (pdb): ~26s
Memory to run a database reasonably well:
at least 1 GB SGA for a stand alone database
at least 4 GB SGA for a container database
PostgreSQL:
initdb: <1s
create database: <200ms
Memory: 128 MB db_buffers
Start/stop database:
Oracle:
startup (standard, 1 GB SGA): ~15s
shutdown immediate (standard, 1 GB SGA): ~21s
startup (container, 4 GB SGA): ~16s
shutdown immediate (container, 4 GB SGA): ~23s
PostgreSQL:
pg_ctl start: 0.1s
pg_ctl stop: 0.2s
Other discoveries/experiences:
Oracle:
Set up Data Guard (2 nodes) with observer (3. node): ~4h
Applying a PSU or RU often requires downtime of 60m-90m.
Migrating a major version often requires downtime of 60m-90m.
Migrating a new major version requires a lot of work in advance.
Switching Data Guard takes ~1m.
PostgreSQL:
Set up Patroni (2 nodes) with etcd (3 nodes): ~30m
Applying a new minor version requires downtime of <2s.
Migrating a new major version requires downtime of <20s.
Migrating a new major version requires a few minutes work in advance.
Switching Patroni takes ~1s.
Oracle has some good concepts. I like the conecpt of separate UNDO and TEMP
tablespaces and not having to care about vacuuming. Also, I like the idea of
global container/cluster-wide views such as CDB_TABLES, etc., a thing which I
definitely and seriously miss about PostgreSQL.
What I especially hate about Oracle (despite the license costs, of course) is
that it has so many bugs, bugs and even more bugs and one keeps on searching
for patches all day, generating lot of downtime. Applying a PSU or RU is mostly
not enough.
So bottom line, PostgreSQL beats Oracle by far in my opinion, at least as far
as installing it and sizes are concerned.
So, guess what I think is wrong with Oracle after 20 years of working with it...
Sorry for the rant. ;-)
Cheers,
Paul
