Is there a way to set the next post ID to something very high?

by

Yes, you can increase the next post ID.

The next value is controlled by the AUTO_INCREMENT setting of the post table in your database.

If you use phpMyAdmin, you can do this by opening up the post table (my prefix is wp1, therefore my table here is wp1_posts), then select the “Operations” tab and then increase the value in the AUTO_INCREMENT field.

phpmyAdmin increase auto increment value for post table in WordPress

The alternative is doing this with an SQL query like:

ALTER TABLE `wp1_posts` AUTO_INCREMENT=900001

When I tried this out I ran into a small problem.
I got the error message:

#1067 – Invalid default value for ‘post_date’ posts

I was able to solve it by first running the following query and then the query to increase the AUTO_INCREMENT value:

ALTER TABLE `wp1_posts` 
  CHANGE `post_date` `post_date`  DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  CHANGE `post_date_gmt` `post_date_gmt`  DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  CHANGE `post_modified` `post_modified`  DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  CHANGE `post_modified_gmt` `post_modified_gmt`  DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP

That query is also necessary in case you use the “Operation” site in phpMyAdmin.

So first run it, then change the AUTO_INCREMENT setting.