I was trying to use pt-online-schema-change to alter a big table, and it result on a segfault.
The table size is 12G, when I run pt-online-schema-change, it increase up to the max memory available on the server (4Gb), then it’s killed by the kernel.
I’ve already limited the memory used by mysql, but it’s the perl process of pt-online-schema-change that consume the memory.
Since the problem is not from mysql, the options --max-load and --critical-load have no effect. They mesure the mysql load, and this load is not huge, it’s only the ram consumed by the pt-online-schema-change that make problems (the ram consumed by the mysql process is low).
Is there any way to limit the ram used by the pt-online-schema-change ? Does it always try to store all the table in the ram ? The alter i’m trying (for testing purposes) to do is only to add a column.