MySQL Bugs: #27727: Generate a warning during implicit casts

Bug #27727	Generate a warning during implicit casts
Submitted:	10 Apr 2007 6:22	Modified:	29 Mar 2011 19:05
Reporter:	Roberto Spadim (Basic Quality Contributor)	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Data Types	Severity:	S4 (Feature request)
Version:	5.1.x	OS:	Any
Assigned to:		CPU Architecture:	Any
Tags:	partition tables, qc

Description:
hello i didn't found any partition type that could be good for strings,
for example i have an field that contain the unique id of products, an it's the primary key
i could partition this table with the substring(field,1,4) since i could partition table with strings, substring <'0001'  substring < '0005' substring <'1000' substring <'2000' and substring>='2000'

any idea on how to make this?

How to repeat:
i dont't know, may by and key partition could work but i have unique keys too, and i couldn't remove the constraint of unique value on the table

Suggested fix:
maybe a new partition type could allow us to partition a table using substrings in the future maybe regexp and like expressions... how knows..

Please, check if range partitioning over something like CAST(substring(field,1,4) as unsigned) will help you. Read http://dev.mysql.com/doc/refman/5.1/en/partitioning-range.html for the details.

Please, specify exact feature/documentation request, if any, based on your last private comment.

i don't remember but the problem was
if you don't work with only allowed functions on partition the parser return an error telling that the function used is not supported
since substr isn't supported in partition by range, just numeric functions could work, but casting the string you can use it as a number casted, if mysql cast without user know, and generate a warning could be more intelligent for begginners

Thank you for a reasonable feature request (implicit cast to number with warning for the expression used to partition by range).

Partitioning by a 'string' field can be done either by KEY partitioning in 5.1+, or by RANGE/LIST COLUMNS partitioning in 5.5.

Closing as 'Not a bug'.

nice closed
should i close it or leave as not a bug?

nice closed
should i close it or leave as not a bug?