What is the maximum number of columns allowed on a table in MySQL MEMORY storage engine? The official MySQL documentation the the MEMORY storage engine covers maximum table size (in MB) but the maximum number of columns that can be defined on a table is not specified.

This question is specifically about the MEMORY storage engine - not InnoDB or MySQL in general.
From This MySQL link


  There is a hard limit of 4096 columns per table, but the effective
  maximum may be less for a given table. The exact limit depends on
  several interacting factors.
  
  
  Every table (regardless of storage engine) has a maximum row size of 65,535 bytes. Storage engines may place additional constraints on this limit, reducing the effective maximum row size.
  
  
  ...


These are engine-independent MySQL limits. As you say the MEMORY engine specific manual pages do not seem to specify any additional restrictions for size or count.