* for dead-tuple TIDs, invoke lazy_vacuum to vacuum indexes and vacuum
* heap relation during its own second pass over the heap.
*
- * If the table has at least two indexes, we execute both index vacuum
- * and index cleanup with parallel workers unless parallel vacuum is
- * disabled. In a parallel vacuum, we enter parallel mode and then
- * create both the parallel context and the DSM segment before starting
- * heap scan so that we can record dead tuples to the DSM segment. All
- * parallel workers are launched at beginning of index vacuuming and
- * index cleanup and they exit once done with all indexes. At the end of
- * this function we exit from parallel mode. Index bulk-deletion results
- * are stored in the DSM segment and we update index statistics for all
- * the indexes after exiting from parallel mode since writes are not
- * allowed during parallel mode.
- *
* If there are no indexes then we can reclaim line pointers on the fly;
* dead line pointers need only be retained until all index pointers that
* reference them have been killed.