You have a bad database design.
The maximum row size with MySQL = 65,535 bytes.
Assuming 1 byte per character 500 X 1000 = 50,000 bytes per line, which approaches 65,535.
For VARCHAR (L) using latin1, 1 byte per column is required to store the length of L, so now we are at 501,000.
VARCHAR, , . , utf8 .
500 X 4 X 1000 = 2 000 000 (3 char + 1 )
MySQL MySQL .
, .