Solved

Limit on number of values in mysql in clause

Posted on 2016-09-30
3
98 Views
Last Modified: 2016-10-06
HI,
On this page :
http://dev.mysql.com/doc/refman/5.7/en/comparison-operators.html#function_in
its mentioned that :
The number of values in the IN list is only limited by the max_allowed_packet value.
what does this means ??
On my mysql i have the following value of this variable :
mysql> show variables like 'max_allowed_packet'
    -> ;
+--------------------+---------+
| Variable_name      | Value   |
+--------------------+---------+
| max_allowed_packet | 4194304 |
+--------------------+---------+
1 row in set (0.01 sec)

Open in new window

This is the default 4MB.
I dont understand the relation between the number of value and 4MB.

What limit does mysql produce on the number of values in the IN clause ?

Thanks
0
Comment
Question by:Rohit Bajaj
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 23

Accepted Solution

by:
Ferruccio Accalai earned 500 total points
ID: 41823034
When you create an IN list you generally write strings that are buffered, so the limit is to have a buffer size not larger than max_allowed_packet.
Anyway there's not a sure limit number for arguments passed in the IN list: it depends on the size of the sent packet that is limited by max_allowed_packet.
http://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_max_allowed_packet
0
 

Author Comment

by:Rohit Bajaj
ID: 41823040
So is it like If i am using a query : select * from note where id in (id1, id2,....)
And say each id is a string of 10 chars
so each id is approx 10 bytes and if the number of elements in the list is 1000. Then total buffer size will be = 10000 bytes = 10 KB ??
which is smaller than 4 MB so it is fine ?

Also the link mentions something about if you are using large columns...
So for queries like select * from note where a column type is TEXT this max_allowed_packet comes into play ???
If i have to move from TEXT to LONGTEXT do i need to change max_allowed_packet ??
0
 
LVL 23

Expert Comment

by:Ferruccio Accalai
ID: 41823059
@will be = 10000 bytes = 10 KB ??
which is smaller than 4 MB so it is fine ?

more or less yes.

To better understand how datas are stored  in blob or longtext field take a look here http://dev.mysql.com/doc/refman/5.7/en/blob.html and
also the Data Type Storage Requirements here http://dev.mysql.com/doc/refman/5.7/en/storage-requirements.html
0

Featured Post

Get 15 Days FREE Full-Featured Trial

Benefit from a mission critical IT monitoring with Monitis Premium or get it FREE for your entry level monitoring needs.
-Over 200,000 users
-More than 300,000 websites monitored
-Used in 197 countries
-Recommended by 98% of users

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Does the idea of dealing with bits scare or confuse you? Does it seem like a waste of time in an age where we all have terabytes of storage? If so, you're missing out on one of the core tools in every professional programmer's toolbox. Learn how to …
This post contains step-by-step instructions for setting up alerting in Percona Monitoring and Management (PMM) using Grafana.
Monitoring a network: why having a policy is the best policy? Michael Kulchisky, MCSE, MCSA, MCP, VTSP, VSP, CCSP outlines the enormous benefits of having a policy-based approach when monitoring medium and large networks. Software utilized in this v…
In this brief tutorial Pawel from AdRem Software explains how you can quickly find out which services are running on your network, or what are the IP addresses of servers responsible for each service. Software used is freeware NetCrunch Tools (https…

623 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question