input/output json is causes PHP out of memory.

Even though the fields input/output json can store very large data, using the large data in PHP would cause PHP out of memory.

2 ways to circumvent it:

1. Use stream reading, and we don't load large data into memory all at once, but load and process. However, PHP json doesn't support stream reading/writing, so basically this is a deadend.

2. Instead of dumping large data into input/output, you can write extra large data directly into relevant database tables.