What’s New In PostgreSQL 9.3

What’s New In PostgreSQL 9.3 ?
Pavan Deolasee
Nov 16, 2013
India PostgreSQL UserGroup MeetUp

Who am I ?


Pavan Deolasee
–



http://www.linkedin.com/in/pavandeolasee

Contributor to PostgreSQL and Postgres-XC Global
DevelopmentBest known for development of Heap-OnlyTuple (HOT) feature of PostgreSQL 8.3 release
–

Contributed several other enhancements to PostgreSQL
and derivatives

–

Contributed to Postgres-XC's architectural design and
implementation of several features



Currently works at NTT Data as a consultant



Previously worked for EnterpriseDB and Symantec/Veritas

Credits
●

Magnus Hagander

●

Michael Paquier

●

Bruce Momjian

●

Of course, all the developers

PostgreSQL Recap
PostgreSQL
–

is world's most advanced open source database

–

is very stable

–

is fully compliant with ANSI SQL

–

supports foreign key, check constraints

–

supports various kinds of indexes

–

supports inheritance

–

is fully extensible (data types, procedural languages etc)

–

will recover your database in case of server failure

PostgreSQL Recap
PostgreSQL
–

uses write-ahead-logs for durability and recover your database
in case of server failure

–

built-in log based streaming synchronous/asynchronous
replication

–

file system level backups and archive recovery

–

point-in-time recovery

–

hot standby

–

upgrade in place

–

full-text search

What’s New Really in 9.3 ?
●

SQL features

●

Performance features

●

DBA features

●

Many more general features

Auto Updatable Views
●

Simple views are now updatable i.e. you can run
INSERT/UPDATE/DELETE queries against a view that uses a
single base relation

●

Many restrictions apply

●

More complex views can be updated via RULEs mechanism

Materialized Views
●

●

Query is executed once and result is materialized on a stable
storage
Views must be refreshed manually

CREATE MATERIALIZED VIEW
..
AS query [ WITH [ NO ] DATA ]

LATERAL Support
●

●

Subqueries appearing in FROM can be preceded by the key
word LATERAL.
This allows them to reference columns provided by
preceding FROM items.
–

●

Without LATERAL, each subquery is evaluated
independently and so cannot cross-reference any
other FROM item.

LATERAL is primarily useful when the cross-referenced
column is necessary for computing the row(s) to be joined.
–

A common application is providing an argument value for
a set-returning function

LATERAL Example
SELECT m.name FROM
manufacturers m LEFT JOIN
LATERAL get_product_names(m.id) pname
ON true WHERE pname IS NULL;

Range Type Enhancements
●

●

SP-Gist index support for range types
Statistics collection for range types thus improving query
planning and execution

JSON Enhancements
●

●

●

●

Operators and functions to extract elements from JSON
values
Allow JSON values to be converted into records
Functions to convert scalars, records and hstore values to
JSON
Aggregates

Foreign Data Wrappers
●

●

Several new features
PostgreSQL FDW (postgres_fdw) is available in core now
(forget the old dblink)

●

Writable FDWs are now reality

●

Many FDWs are already available
–

Hbase

–

MongoDB

–

MySQL

–

Oracle

COPY FREEZE
●

●

Load tuples in frozen state to avoid another rewrite of the
table
A few restrictions apply
–

●

A table must be truncated or created in the same
transaction loading the frozen data

A very useful tip to avoid significant IO overhead while
working with large tables

Background Workers
●

●

●

Step towards parallel query execution which is still a release
or two away
Background workers can be used with 9.3 if you have enough
guts to write some cool C code
Look at contrib/worker_spi for some sample code

Posix/mmap Shared Memory
●

●

A step away from SysV Shared memory
Most unix-like systems support Posix or mmap and
PostgreSQL will use them by default
–

●

A small SysV shared memory segment is still allocated for
book keeping purposes

No need to tune your kernel parameters or hit runtime issues
because of hitting kernel limits

Page Level Checksums
●

●

A great feature for checking data consistency
Can be turned on (default is of) at the initdb time and must
stay that way
–

●

Comes at a cost

Errors can’t be corrected, but corruptions can be detected
very early in the cycle

Foreign Key Locking
●

●

Improved concurrency since non-key updates don’t block
foreign key checks
New lock levels
–
–

●

●

FOR KEY SHARE
FOR NO KEY UPDATE

Foreign key triggers now take FOR KEY SHARE locks
DMLs updating non key columns should take FOR NO KEY
UPDATE locks thus avoiding blocking

Event Triggers
●

They are more like DDL triggers
–

●

●

●

Triggers are invoked when new database objects are
created, updated or dropped

Will be useful for logging, monitoring and even some
replication solutions
Three types of triggers - ddl_command_start,
ddl_command_end, sql_drop
More support expected in later releases

Parallel pg_dump
●

Faster pg_dump by using multiple processes
–
–

●

Better utilization of multiple cores
Multiple tables are dumped in parallel

Remember pg_restore can already run parallel jobs

Streaming-only Remastering
●

"Remastering" is the process whereby a replica in a set of
replicas becomes the new master for all of the other replicas.
–

Master M1 is replicating to replicas R1, R2 and R3.

–

Master M1 needs to be taken down for a hardware
upgrade.

–

The DBA promotes R1 to be the master.

–

R2 and R3 are reconfigured & restarted, and now replicate
from R1

Streaming-only Remastering
●

●

In prior versions, it wasn’t possible to stream from new
master without taking a fresh backup
That restriction is now gone

Arch Independent Streaming
●

Stream WAL from diferent OS and diferent architecture
–

pg_basebackup and pg_receivexlog can now work cross
platform

–

You can’t apply WAL from diferent architecture, but this is
still very useful for centralized backup etc

Many More
●

pg_basebackup conf setup (-R option)

●

Logging enhancements

●

Recursive views

●

COPY PIPE

●

Include_dir directive

●

Array enhancements

Resources
●

Release Notes
–

●

Planet PostgreSQL
–

●

http://planet.postgresql.org/

Documentation
–

●

http://www.postgresql.org/docs/9.3/static/release-9-3.html

http://www.postgresql.org/docs/9.3/static/index.html

Source Code
–

http://git.postgresql.org/gitweb/

Thank you
Pavan Deolasee
pavan.deolasee@gmail.com
http://www.linkedin.com/in/pavandeolasee

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