Is there a limit to size of data stored in update_option()?

Question

I've checked out several* questions and WP docs and I have some idea of the answer but am looking for a specific number on the following questions:

• 1- Is there a limit to the size of data (kb,mb, ect) that can be stored in update_option/add_option?
• 2- Is it reasonable to store 350kb to 500kb using update_option?
• 3- should I be using some other system or angle of the WP cache?

Should I assume its 4G since thats the limit of MySQL in this case?

Specific details: I have a custom DB query that pre-loads 350,000 or so bytes of data which contains ~100,000 or so lat/lng pairs (and some other data) which were queried using a custom WPquery based on the Haversine formula (part of a custom 'Dealer Locator' type system).

The data is simply an array (not json, maybe it should be?)

I am using Map Clustering to output top level items on the Google Map (moot perhaps as the google Maps API is not my concern here)

This query is taxing of course and I do not want it running on every page load, so naturally I want to store/cache it. Currently I am stuffing it into update_option via an Admin AJAX action that is triggered manually from WPadmin so it can be flushed as needed.

My current method to handling speed works fine, I get the results I want at 350kb no problem. I am mostly concerned with the limit to this approach.

References I checked out (also did some googling):

• Excessive memory used by update_option() (this one is interesting, 17M+ characters long he managed to get in there?)

• Is there a limit to the length/size of serialized data that can be stored as user meta? length-size-of-serialized-data-that-can-be-stored-as-use

• store simple data in get_option()

• http://codex.wordpress.org/Function_Reference/get_option

• http://codex.wordpress.org/Function_Reference/add_option

• http://codex.wordpress.org/Function_Reference/update_option

Answer 1

The option_value column in the database is LONGTEXT, meaning it can hold up to 4GB of text.

But keep in mind that WordPress loads all options on every page load by default, and storing large values for options you only intend to use on a single page is inefficient. Either set the autoload argument of update_option() and add_option() to false, or store the data in a custom table and only query it when you need it.