On Tue, May 1, 2018 at 10:30 PM, Justin Pryzby <pry...@telsasoft.com> wrote: > - When no tuples were deleted from the heap, B-tree indexes might still > - be scanned during <command>VACUUM</command> cleanup stage by two > - reasons. The first reason is that B-tree index contains deleted > pages > - which can be recycled during cleanup. The second reason is that > B-tree > - index statistics is stalled. The criterion of stalled index > statistics > - is number of inserted tuples since previous statistics collection > - is greater than <varname>vacuum_cleanup_index_scale_factor</varname> > - fraction of total number of heap tuples. > + When no tuples were deleted from the heap, B-tree indexes are still > + scanned during <command>VACUUM</command> cleanup stage unless > + two conditions are met. First, if a B-tree index contains no > deleted pages > + which can be recycled during cleanup. Second, if B-tree > + index statistics are not stale. Index statistics are considered > stale unless > + <varname>vacuum_cleanup_index_scale_factor</varname> is > non-negative, and the > + number of inserted tuples since the previous statistics collection is > + less than that fraction of the total number of heap tuples. > + The default is -1, meaning index scan during cleanup is not skipped.
I agree that this documentation needs to be rewritten but your rewrite doesn't strike me as very good English either. A sentence of the form "First, if I like hamburgers." is not correct English. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
