kognitio-wx2


Different type of imaging techniques in kognitio


Can anyone please explain me what are all the imaging techniques available in kognitio.
Would be great if you cover the below techniques.
1) Replicated
2) REPLICATED PARTITION IMAGE BY (column_name)
3) HASHED ON (column_name) PARTITION IMAGE BY (column_name)
Thanks in advance.
We have four different Imaging options in WX2
Random – even round robin distribution (default)
Hashed – placed onto RAM stores according to key
Partial Hashed – as hashed but handles skewing attributes
Replicated – complete copy on each RAM Store
Replication puts a copy of the image on every RAM Store. It can be costly in terms of RAM and redistribution time. Good for small lookup/dimension tables
It cannot be fragmented. It is required for Theta joins. Replication is per RAM Store and not per node.
Hashing distributes the rows of a table or view image across the RAM Stores. It is dependent upon the value of one or more columns. It is good for joining large tables – hash on common key. It may lead to skewing. The number of distinct values is less than number of RAM Stores. One or two values greatly exceed the others in frequency. Partial distribution may be used to neutralize value skew
Partial hashing is a mechanism to handle joins when a large table is severely skewed on key column(s). It is an alternative to straightforward hashing. Types are Partial hashed/random RAM stores and Partial hashed/replicated across RAM stores
The Kognitio community forum article here has links to all the latest documentation.
In particular, chapter 2 of the Kognitio Guide covers the various table and view image options that exist.
The ones referred to in the original question are:
replicated - here a copy of the object is placed in every ram store process. This is typically used for dimension objects to allow them to be joined to large objects, regardless of whether those objects are randomly distributed or hashed.
partitioned (deciding whether to partition or not is independent of whether you are replicating/randomising/hashing) - this allows the ram store to partition on an attribute. The main benefit is that partitions can be eliminated on scans, reducing the amount of data processed. Note the further comments in the documentation on partitioning though.
hashed - hashing on an attribute allows data to be distributed according to that attribute value. For example, in a retail example you might hash the customer table by customer_id, and do the same with the transaction table, then any given transaction is located on the same ram store as the relevant customer record. Note that this distribution is prone to skewing; so consult the documentation for details on using partial distributions to defeat skew.

Related Links

How to find resource intensive and time consuming queries in WX2?
How to change the Queue Id in WX2?
Different type of imaging techniques in kognitio
Issue in creating image for a simple view
What are different parameter used for wxloader?
Escape double quote Character in Kognitio

Categories

HOME
opengl
xcode
functional-programming
shinyapps
clearcase
android-fragments
schema.org
tcsh
slider
google-webmaster-tools
dji-sdk
visualforce
ipv6
onvif
tweepy
telegraf
responsive-design
azure-graph-api
hystrix
alljoyn
colors
spring-amqp
closures
word2vec
tfsbuild
el
pubxml
ipa
basex
npoi
ninject
bitbake
netbios
shapeless
xmlunit
payeezy
amazon-kms
busboy
ms-dos
android-alarms
llvm-ir
android-n
task-parallel-library
plane
system-on-chip
dagger
realstudio
webalizer
watir-webdriver
exc-bad-access
test-data
word-2016
fitbit
controllers
cefpython
okio
openseadragon
qtcpsocket
android-4.2-jelly-bean
urbit
accessibilityservice
cortana
html.actionlink
astropy
auto-generate
jnlp
postal-code
flow-js
dbmigrate
tidyr
htmltidy
cakephp-2.2
nesper
webmethod
coding-efficiency
maven-central
accessory
stripe.net
.htpasswd
bittorrent-sync
oxygene
cloo
facebook-game-groups
ggts
tnt4j
insertion
delphi-xe4
cakeyframeanimation
fitch-proofs
snackjs
botnet
kernel32
chunking
aggregator
sscli
firephp
spring-modules
accumulator
ntruencrypt
autobench
server-load
activex-exe
downloadfile
service-factory

Resources

Encrypt Message