type:
constant
name:
MESSAGEQUEUE_PREPARE
purpose:
Run the queue in a two-process way
allowed:
true false 0 1
default:
0
category:
queue processing

This option will initially mark all subscribers that need to receive the campaign as “todo” in the table and then start processing on all the “todo” entries.

It may save a little on SQL time when you have a large amount of subscribers, as the query to search for subscribers is run fewer times.

Comparison:

When MESSAGEQUEUE_PREPARE is 0, each batch of messages is processed as
follows:

  1. Find all subscribers who need to receive the campaign and haven't received it yet
  2. Dispatch the campaign to some subscribers (batch size settings determine how many)

When MESSAGEQUEUE_PREPARE is 1, the first batch of messages is processed
as follows:

  1. Find all subscribers who need to receive the campaign (as in step 1 above)
  2. Mark the found subscribers as “todo” in the database
  3. Send some of the marked subscribers the campaign

Then for all subsequent batches:

  1. Find subscribers marked “todo”
  2. Send some of them the campaign (batch size settings determine how many)

See also MAX_SENDPROCESSES