如何在mariadb10上获得每个表大小的最大索引？

Question

I'm using mariadb10.0.3 with brew on Macosx.

One of my table has 40 boolean columns and I would like to add indices on those. However, I have an error on create index ddl. Error Message is below.

ERROR 1070 (42000): Too many key parts specified; max 32 parts allowed

How can I increate MAX-INDEXES ?

Answer 1

The limit to the number of indexes is set per storage engine and cannot be changed in regular use. There's a --with-max-indexes parameter when compiling.

But you really need to look at your table and index structure. It's unlikely that having 40 indexes to boolean fields will help in any way.

Answer 2

Unfortunately MySQL has some arbitrary compile time limits. The default limit for key parts is 16. Most RDBMS allow you to set this kind of limite at startup, not compile time. It's pretty hard to work with snowflakes in MySQL.

Unfortunately adding --with-max-indexes to the ./configure will not do the trick as many people around is suggesting:

./configure --prefix=/usr/local/mysql --with-max-indexes=N

The above line is innocuous.

Max indexes is related to foreign keys, but the smaller from MAX_REF_PARTS and MAX_INDEXES .

What appears to be effective is to change MAX_REF_PARTS from 16U to 42U on sql/sql_const.h:

$ grep -R MAX_REF_PARTS ${MYSQL_SOURCE_FOLDER}
$ ./sql/sql_const.h:#define MAX_REF_PARTS 42U           /* Max parts used as ref */

As everybody knows 42 is a much better arbitrary limit as it is the answer for the ultimate question anyway :p (this is a joke with arbitrary limits).