Igor's Blog
Programming, DIY, Games, Hacks, and Tech

We use partitioning in at least one of the databases at work, changing to partitioned tables has allowed us to keep the system running within our imposed SLAs. Recently I've started to wonder however, what happens when we start hammering individual partitions more than others. The data distribution would be skewed and the benefits of partitioning lost. I decided to put together a bit of SQL and then use gnuplot to show me how well our data is distributed.

These results are from a development environment where I was testing out my scripts, but it clearly shows how some partitions can get filled at a much quicker rate than others. Each of the bars is an individual partition, the height of the bar represents the number of rows of data in that partition.
dbpartplot.png


The SQL behind this graph is very simple...adjust the like statement to suit. In my case I get data for multiple tables and then filter it later in a shell script.
 SQL
select up.table_name, up.partition_name, up.num_rows
from user_tab_partitions up
where table_name like 'MY_TABLES_%'
order by up.table_name, up.partition_name asc;


I export the result of this query to a file called export.d. This has to be a tab-delimited file that doesn't use quotes around each of the data values. The data looks something like this...
 export.d
...
MY_TABLES_TBL1 SYS_P42665 822568
MY_TABLES_TBL1 SYS_P42666 394797
...


This is then processed by a shell script.



To make the graph, I used gnuplot with the following shell script to generate the image...
 Bash Script
#!/bin/bash
function plot {
gp_table=$1
gp_file=$2.$1
grep $1 $2 > $gp_file
gp_95pct=`cat $gp_file|awk '{print $3}' |sort -n|awk 'BEGIN{i=0} {s[i]=$1; i++;} END{print s[int(NR*0.95-0.5)]}'`
gp_99pct=`cat $gp_file|awk '{print $3}' |sort -n|awk 'BEGIN{i=0} {s[i]=$1; i++;} END{print s[int(NR*0.99-0.5)]}'`
$GNU_PLOT << EOF
set terminal svg size 800,400 noenhanced font "Verdana,10"
set output "export_$gp_table.svg"
set title "Table Partitions Row Sizing: $gp_table"
set ylabel "Data Rows"
set grid y
set format x ''
set style fill solid 1.0
set palette defined (0 "red", 1 "#FFA500", 2 "#555577")
unset colorbox
plot "$gp_file" using 0:3:(\$3 > $gp_99pct ? 0 : (\$3 > $gp_95pct ? 1 : 2)) with boxes palette notitle
EOF
rm $gp_file
}
GNU_PLOT=gnuplot
plot MY_TABLES_TBL1 export.d



What this bash script does is define a function called plot, then it defines the gnuplot executable and calls the plot function passing in the name of the table to filter by and the name of the data file.

Inside the plot function, I use grep to get the data for the table that's been passed in. Then awk is used to calculate the 95th and 99th percentile values for the data points in the filtered file. These are used for colouring the bars. 95th percentile bars are orange and 99th are red, others are blue-gray.

This is all followed by calling gnuplot to generate the bar graph, and then the filtered file is cleaned up.

It's all quite simple, it did take me a long time to get the syntax right for gnuplot however. In my actual script I also have a loop to process all of the tables in the exported file all in one go.

-i

Please leave your comments or feedback below!
comments powered by Disqus
Other posts you may like...

Recent Blog Posts

How to enable the full stack trace in Maven's Surefire plugin for JUnit testing

Twelve elements of the Burst Mining Pool interface explained

TPG FTTB settings for the Billion BiPAC 8700AXL 1600 modem router

Protecting old Atari Lynx game boxes with snug fit plastic sleeves

How to fix SoapUI javax.net.ssl.SSLHandshakeException calling WebLogic 12.2 web services on Java 8

Woolworths (WOW) shares disappeared from Computer Share Investor Centre

Connecting the Dell UltraSharp U3415W monitor to a MacBookPro via USB-C

How to add/change PHP versions appearing in MAMP preferences

Fix the ORA-00904: ORA_ROWSCN: invalid identifier error in SQLDeveloper with a few easy steps

G Suite Gmail is broken on Safari due to new Google Content Security Policy settings

Recent Galleries

Protecting old Atari Lynx game boxes with snug fit plastic sleeves

Monument Valley 2 is released and does not disappoint

Space Food - Chocolate Ice Cream with Chocolate Chips

Legeod Star Wars AT-DP kit

DIY spare parts computer build with a RAIDMAX Anura case

Fake 'Lepin' brand Lego packaging

Hardwood garden bench with clear resin void filler

Fixing a 3D printer extruder that stopped heating up

Easily increase disk space in a Lenovo Ideapad 100S 14" laptop with an M.2 SSD

Making a multi-piece 3D printed solder spool holder stand

My Other Web Sites

Igor and Elise's Travels
Riverside Expressway Cam
300 George St Blogumentary

My Online Tools

UUID to OID Converter
Guru JSON-RPC Tester
Extrudifier Object Designer
Travel ┬ÁBlog

Blogs and Friends

Matt Moores Blog
Georgi's FlatPress Guide
Perplexing Permutations
The Security Sleuth
Ilia Rogatchevski
Travelling Fairy

Blog Activity

Blog Activity
Don't forget to
my Facebook page for more great articles!
Don't show this again