This is the presentation used at Dec 2014 Meetup event for Postgres User Group, Singapore. I discussed on key highlight features of v9.4 of PostgreSQL.

1. Performance, Reliability, Flexibility –Pick Any Three!

2. •JSONB-jsonBinary Storage
•Replication improvements-Replication Slots
•Logical Decoding in WAL log
•Time Lagging Replica
•pg_prewarm
•ALTER SYSTEM Command
•Great new enhancements in aggregation features

3. 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 jsondata
You have the flexibility without compromising on Reliability!
Non-relational data with ACID compliance!

4. row_to_json–to convert a row to json
json_object–Create jsonobject out of text array
json_build_object–Create jsonobject out of variadicargument list
array_to_json–to converan array to JSON
json_eachand json_each_text–convert jsonobjects in key-value pair
json_extract_path-Get value of a jsonobject
json_populate_recordand json_populate_recordset-Convert jsonobject to records

5. Operator
Operand Type
Purpose
->
int
Get JSON arraryelement
->
text
Get JSON object field
->>
int
Get JSON array element as text
->>
text
Get JSON object fieldas text
#>
array of text
Get JSONobject 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/elementstringexist within the JSON value?
?|
text[]
Do any of these key/elementstringsexist?
?&
text[]
Do all of these key/elementstringsexist?

6. JSONB in action!

7. select data from Table as a jsonobject-
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;

8. Select output of join as a jsonobject-
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_mapab ON a.id=ab.author_id
JOIN books b ON b.id=ab.book_id
GROUP BY b.name ) books_authors_join;

9. Now you need to guess “wal_keep_segment” to avoid walfiles 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

10. 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

11. 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

12. 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