Splitting the main query can result in long query strings that segfault

[ryan]

When paging hierarchical post types, edit.php via wp_edit_posts_query() can create very long query strings that enumerate every post ID to fetch. If a limit is not present or very large, the query may beed to fallback to the old single query style.

See #20621

[ryan]

split_the_query filter. Don't split if no limit.

[nacin]

Looks good. Should probably also pick an arbitrary limit like 500 at which point we no longer try to split the query.

[ryan]

In [20740]:

Don't split the main query if there is no limit. This helps avoid extremely long query strings that could cause segfaults. Allow plugins to control splitting via split_the_query filter. see #20628

[ryan]

Still need to check the limit if anyone cares to patch that.

[scribu]

+1 for 'split_the_query'.

Still need to check the limit if anyone cares to patch that.

I already see !empty( $limits ) in there, so what's left?

[scribu]

Oh, to not split the query if 'posts_per_page' => 500+? I don't know, that seems an unlikely edge case.

[scribu]

You usually either want paging (i.e a reasonable number), or you don't. Plus, it can be handled with 'split_the_query'.

[nacin]

Replying to scribu:

You usually either want paging (i.e a reasonable number), or you don't. Plus, it can be handled with 'split_the_query'.

While it *can* be handled with split the query, surely we've all seen posts_per_page = 99999 before — we should try to catch this by default.

[scribu]

How about we catch it earlier on, say in parse_query()?

if ( $q['posts_per_page'] >= 9999 )
  $q['posts_per_page'] = -1;

[SergeyBiryukov]

Check $limits (potentially filtered, e.g. via post_limits)

[SergeyBiryukov]

Just check posts_per_page

[ryan]

In [20756]:

Set split_the_query to false if more than 500 rows requested. Props SergeyBiryukov. fixes #20628