The last post looked into how to upgrade PostgreSQL to a new minor version. In this post I’ll look into how to upgrade PostgreSQL to a new major version. This is not as simple as just installing the binaries and start the instance from there. For major upgrades there are two possibilities:
- dump the old version and restore into the new version by using pg_dump and pg_restore
- use pg_upgrade
I’ll only look into pg_upgrade for this post. For simplicity I’ll upgrade the 9.4.5 PostgreSQL instance from the last post to 9.5 beta2. The binaries for 9.5 beta2 are already there:
postgres@oel7:/u01/app/postgres/software/ [PG1] which pg_upgrade /u01/app/postgres/product/95/db_b2/bin/pg_upgrade
Obviously we need to stop the current version before performing the upgrade:
postgres@oel7:/u01/app/postgres/software/ [PG1] pg_ctl stop -D /u02/pgdata/PG1 waiting for server to shut down.... done server stopped
Then we need to create a new database cluster with the version we want to upgrade to (9.5 beta2 in this case):
postgres@oel7:/u01/app/postgres/software/ [PG1] mkdir /u02/pgdata/PG7
postgres@oel7:/u01/app/postgres/software/ [PG1] mkdir /u03/pgdata/PG7
postgres@oel7:/u01/app/postgres/software/ [PG1] mkdir /u90/arch/PG7
postgres@oel7:/u01/app/postgres/software/ [PG1] initdb -D /u02/pgdata/PG7 -X /u03/pgdata/PG7/
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.
The database cluster will be initialized with locales
COLLATE: en_US.UTF-8
CTYPE: en_US.UTF-8
MESSAGES: en_US.UTF-8
MONETARY: de_CH.UTF-8
NUMERIC: de_CH.UTF-8
TIME: en_US.UTF-8
The default database encoding has accordingly been set to "UTF8".
The default text search configuration will be set to "english".
Data page checksums are disabled.
fixing permissions on existing directory /u02/pgdata/PG7 ... ok
fixing permissions on existing directory /u03/pgdata/PG7 ... ok
creating subdirectories ... ok
selecting default max_connections ... 100
selecting default shared_buffers ... 128MB
selecting dynamic shared memory implementation ... posix
creating configuration files ... ok
creating template1 database in /u02/pgdata/PG7/base/1 ... ok
initializing pg_authid ... ok
initializing dependencies ... ok
creating system views ... ok
loading system objects' descriptions ... ok
creating collations ... ok
creating conversions ... ok
creating dictionaries ... ok
setting privileges on built-in objects ... ok
creating information schema ... ok
loading PL/pgSQL server-side language ... ok
vacuuming database template1 ... ok
copying template1 to template0 ... ok
copying template1 to postgres ... ok
syncing data to disk ... ok
WARNING: enabling "trust" authentication for local connections
You can change this by editing pg_hba.conf or using the option -A, or
--auth-local and --auth-host, the next time you run initdb.
Success. You can now start the database server using:
pg_ctl -D /u02/pgdata/PG7 -l logfile start
To verify the version we do a quick startup:
postgres@oel7:/u01/app/postgres/software/ [PG7] pg_ctl -D /u02/pgdata/PG7 start server starting postgres@oel7:/u01/app/postgres/software/ [PG7] LOG: database system was shut down at 2015-12-01 12:10:02 CET LOG: MultiXact member wraparound protections are now enabled LOG: database system is ready to accept connections LOG: autovacuum launcher started postgres@oel7:/u01/app/postgres/software/ [PG7] sqh Null display is "NULL". Timing is on. psql (9.5beta2) Type "help" for help. (postgres@[local]:5449) [postgres] >
Then shut it down again:
postgres@oel7:/u01/app/postgres/software/ [PG7] pg_ctl -D /u02/pgdata/PG7 stop -m fast waiting for server to shut down....LOG: received fast shutdown request LOG: aborting any active transactions LOG: autovacuum launcher shutting down LOG: shutting down LOG: database system is shut down done server stopped
Now we can begin with the upgrade by specifying four environment variables:
postgres@oel7:/u01/app/postgres/software/ [PG7] export PGDATAOLD=/u02/pgdata/PG1
postgres@oel7:/u01/app/postgres/software/ [PG7] export PGDATANEW=/u02/pgdata/PG7
postgres@oel7:/u01/app/postgres/software/ [PG7] export PGBINOLD=/u01/app/postgres/product/94/db_5/bin
postgres@oel7:/u01/app/postgres/software/ [PG7] export PGBINNEW=/u01/app/postgres/product/95/db_b2/bin/
postgres@oel7:/u01/app/postgres/software/ [PG7] pg_upgrade
Performing Consistency Checks
-----------------------------
Checking cluster versions ok
Checking database user is the install user ok
Checking database connection settings ok
Checking for prepared transactions ok
Checking for reg* system OID user data types ok
Checking for contrib/isn with bigint-passing mismatch ok
Creating dump of global objects ok
Creating dump of database schemas
ok
Checking for presence of required libraries ok
Checking database user is the install user ok
Checking for prepared transactions ok
If pg_upgrade fails after this point, you must re-initdb the
new cluster before continuing.
Performing Upgrade
------------------
Analyzing all rows in the new cluster ok
Freezing all rows on the new cluster ok
Deleting files from new pg_clog ok
Copying old pg_clog to new server ok
Setting next transaction ID and epoch for new cluster ok
Deleting files from new pg_multixact/offsets ok
Copying old pg_multixact/offsets to new server ok
Deleting files from new pg_multixact/members ok
Copying old pg_multixact/members to new server ok
Setting next multixact ID and offset for new cluster ok
Resetting WAL archives ok
Setting frozenxid and minmxid counters in new cluster ok
Restoring global objects in the new cluster ok
Restoring database schemas in the new cluster
ok
Creating newly-required TOAST tables ok
Copying user relation files
ok
Setting next OID for new cluster ok
Sync data directory to disk ok
Creating script to analyze new cluster ok
Creating script to delete old cluster ok
Upgrade Complete
----------------
Optimizer statistics are not transferred by pg_upgrade so,
once you start the new server, consider running:
./analyze_new_cluster.sh
Running this script will delete the old cluster's data files:
./delete_old_cluster.sh
Quite easy, isn’t it? As pointed out by pg_upgrade optimizer statistics need to be gathered as this is not done automatically:
postgres@oel7:/u01/app/postgres/software/ [PG7] pg_ctl -D /u02/pgdata/PG7 start
server starting
postgres@oel7:/u01/app/postgres/software/ [PG7] LOG: database system was shut down at 2015-12-01 12:18:34 CET
LOG: MultiXact member wraparound protections are now enabled
LOG: database system is ready to accept connections
LOG: autovacuum launcher started
postgres@oel7:/u01/app/postgres/software/ [PG7] ./analyze_new_cluster.sh
This script will generate minimal optimizer statistics rapidly
so your system is usable, and then gather statistics twice more
with increasing accuracy. When it is done, your system will
have the default level of optimizer statistics.
If you have used ALTER TABLE to modify the statistics target for
any tables, you might want to remove them and restore them after
running this script because they will delay fast statistics generation.
If you would like default statistics as quickly as possible, cancel
this script and run:
"/u01/app/postgres/product/95/db_b2/bin/vacuumdb" --all --analyze-only
vacuumdb: processing database "bi": Generating minimal optimizer statistics (1 target)
vacuumdb: processing database "db1": Generating minimal optimizer statistics (1 target)
vacuumdb: processing database "patch": Generating minimal optimizer statistics (1 target)
vacuumdb: processing database "postgres": Generating minimal optimizer statistics (1 target)
vacuumdb: processing database "template1": Generating minimal optimizer statistics (1 target)
vacuumdb: processing database "bi": Generating medium optimizer statistics (10 targets)
vacuumdb: processing database "db1": Generating medium optimizer statistics (10 targets)
vacuumdb: processing database "patch": Generating medium optimizer statistics (10 targets)
vacuumdb: processing database "postgres": Generating medium optimizer statistics (10 targets)
vacuumdb: processing database "template1": Generating medium optimizer statistics (10 targets)
vacuumdb: processing database "bi": Generating default (full) optimizer statistics
vacuumdb: processing database "db1": Generating default (full) optimizer statistics
vacuumdb: processing database "patch": Generating default (full) optimizer statistics
vacuumdb: processing database "postgres": Generating default (full) optimizer statistics
vacuumdb: processing database "template1": Generating default (full) optimizer statistics
Done
The output above proves that the “patch” database is really there but we can confirm that:
postgres@oel7:/u01/app/postgres/software/ [PG7] sqh Null display is "NULL". Timing is on. psql (9.5beta2) Type "help" for help. (postgres@[local]:5449) [postgres] > c patch You are now connected to database "patch" as user "postgres". (postgres@[local]:5449) > select count(*) from test; count ------- 100 (1 row) Time: 0.705 ms
And finally we can delete the old data files:
postgres@oel7:/u01/app/postgres/software/ [PG7] ./delete_old_cluster.sh postgres@oel7:/u01/app/postgres/software/ [PG7] ls -al /u02/pgdata/PG1 ls: cannot access /u02/pgdata/PG1: No such file or directory
That’s it.
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