Mysql – Large NOT IN Statement vs Creating/Populating Temp Table

This composite index will speed things up:

INDEX(ip, sid, time)

What table is clicks in?

If 1444411110 is a typical time, why is it a BIGINT?

Don't say both of these:

WHERE ID = ... -- toss this
USING (ID)     -- keep this

That is probably what is causing the query to hang.

I think of it as you can't have any duplicate names in tempdb.sys.key_constraints. Here's what's in that metadata view on one of my servers:

All of the odd names that end with _6E... were names generated automatically by SQL Server. They are not named constraints because I did not explicitly give them a name when creating them. SQL Server generates a constraint name behind the scenes that in theory avoids name collisions.

If I try to create the following table in two different sessions:

create table #x1 (
ID INT NOT NULL,
CONSTRAINT NAMED_CONSTRAINT_1 PRIMARY KEY (ID)
);

The one that runs second throws an error:

Msg 2714, Level 16, State 5, Line 1

There is already an object named 'NAMED_CONSTRAINT_1' in the database.

Msg 1750, Level 16, State 1, Line 1

Could not create constraint or index. See previous errors.

Checking out the view again:

If I try to create the following table in two sessions there's no issue:

create table #y1 (
ID INT NOT NULL,
PRIMARY KEY (ID)
);

Here's the metadata view:

Just to answer your questions directly: the part that you quoted applies to both local and global temporary tables, a named constraint is one in which you deliberately give it a name, and multiple users means multiple sessions.