Performance, Reliability, Flexibility – Pick Any Three!

• JSONB- json Binary Storage

• Replication improvements- Replication Slots

• Logical Decoding in WAL log

• Time Lagging Replica

• pg_prewarm

• ALTER SYSTEM Command

• Great new enhancements in aggregation features

Wasn’t JSON was introduced in v9.2? Well it just got better

JSONB is much more optimized and faster for lookup

New functions to extract and manipulate the json data

You have the flexibility without compromising on Reliability!

Non-relational data with ACID compliance!

row_to_json – to convert a row to json

json_object – Create json object out of text array

json_build_object – Create json object out of variadic argument list

array_to_json – to conver an array to JSON

json_each and json_each_text – convert json objects in key-value pair

json_extract_path- Get value of a json object

json_populate_record and json_populate_recordset - Convert json object to records

Operator Operand Type Purpose

-> int Get JSON arrary element

-> text Get JSON object field

->> int Get JSON array element as text

->> text Get JSON object field as text

#> array of text Get JSON object at specified path

#>> array of text Get JSON object at specified path as text

@> jsonb Does the left JSON value contain within it the right value?

<@ jsonb Is the left JSON value contained within the right value?

? text Does the key/element string exist within the JSON value?

?| text[] Do any of these key/element strings exist?

?& text[] Do all of these key/element strings exist?

JSONB in action!

select data from Table as a json object-

SELECT

JSON_BUILD_OBJECT( 'name',name )

FROM books;

Convert a row to json

SELECT ROW_TO_JSON(my_row)

FROM ( SELECT ROW(books.*)

FROM books )my_row;

Select output of join as a json object-

SELECT JSON_BUILD_OBJECT( 'name', name, 'author', name_arr )

FROM(

SELECT ARRAY_AGG( a.name ) AS name_arr, b.name AS name

FROM authors a JOIN author_book_map ab ON a.id=ab.author_id

JOIN books b ON b.id=ab.book_id

GROUP BY b.name ) books_authors_join;

Now you need to guess “wal_keep_segment” to avoid wal files from getting removed

Simply create a replication slot and WAL which are yet not replicated to the slot will not be removed from live WAL location

Time Lagging Replica- You can define a lag period for your replica

This can be used for back-dated reporting

Or recover from a user error – an accidentally dropped table or a truncated table

Set WAL level to ‘logical’ to do more verbose recoding in WAL files

This will also record table and relation level details in each WAL entry

These WAL files can be used for logical decoding and logical replication to replicate changes on a particular table

There are commercial and open source solutions which are in beta stage and are based on this approach

ALTER SYSTEM Command- Now a DBA can alter the configuration with ALTER SYSTEM command and avoid changing it in postgresql.conf

pg_prewarm- now a DBA can load certain relations and blocks in cache after startup and avoid performance issues due to cold-reboot

https://wiki.postgresql.org/wiki/What's_new_in_PostgreSQL_9.4

Hangout Recording for Replication Features in v9.4-https://www.youtube.com/watch?v=-HkrXwaWCb8

EnterpriseDB Whitepaper- http://www.enterprisedb.com/nosql-for-enterprise

http://www.craigkerstiens.com/2014/03/24/Postgres-9.4-Looking-up/

Or just mail me…

sameer.kasi200x@gmail.com

sameer.kumar@ashnik.com