Difference between revisions of "PostgreSQL 13 Open Items"

From PostgreSQL wiki
Jump to: navigation, search
(Open Issues: Added item about unnecessary variations between Hash Agg and Hash Join EXPLAIN ANALYZE output)
Line 33: Line 33:
 
** Original commit: {{PgCommitURL|d2d8a229}}
 
** Original commit: {{PgCommitURL|d2d8a229}}
 
** Owner: James Coleman, Tomas Vondra
 
** Owner: James Coleman, Tomas Vondra
 +
 +
* [https://www.postgresql.org/message-id/CAApHDvqTvD3bXBiC5cmuoATFYeP%2BRSkv5WTgfyuBb6JpwKmSoQ%40mail.gmail.com EXPLAIN ANALYZE output for HashAgg could be better aligned to Hash Join's output]
 +
** Owner: David Rowley
  
 
== Older Bugs ==
 
== Older Bugs ==

Revision as of 23:01, 26 July 2020

Open Issues

NOTE: Please place new open items at the end of the list (within its applicable open item category).

Hash Aggs that spill (commit 1f39bce0) issues

  • Default setting for hashagg_avoid_disk_plan GUC (the GUC formerly known as enable_hashagg_disk, renamed by 92c58fd9)
    • This thread is now mostly a discussion of the preceding "Many users rely on hashagg exceeding work_mem, regardless of whether or not that is the intended behavior in Postgres 12" item.
    • You can think of this hashagg_avoid_disk_plan item as being about providing users with a mechanism to avoid hash aggregation when planning, without reliably ensuring that it is avoided at execution time.
    • In other words, it preserves the plan time behavior from Postgres 12, but not the execution time behavior.
    • In theory there should be no difference (in theory these two open items are one and the same). In practice there is a huge difference, because group estimates are frequently off by orders of magnitude, and because hash aggs greatly benefit from more memory (unlike the equivalent group aggregate + sort plan).
    • We have a pending patch that removes the hashagg_avoid_disk_plan GUC (which is part of a patch series that also adds the hash_mem_multiplier GUC).

Other issues

Older Bugs

Live issues

Fixed issues

Nothing to do

Non-bugs

Resolved Issues

resolved before 13beta3

  • Review the decision to enable deduplication by default (i.e. use 'on' as the default setting for the 'deduplicate_items' B-Tree storage parameter).

resolved before 13beta2

  • Should we rename effective_io_concurrency? It now has a different meaning and you might want to turn it up higher, though the default behaviour hasn't changed.
    • Commit: b09ff536
    • No one argued strongly in favour of changing it, so let's leave it as it is.

resolved before 13beta1

Won't Fix

Important Dates

Current schedule:

  • Feature Freeze: April 7, 2020 (Last Day to Commit Features)
  • Beta 1: May 21, 2020
  • Beta 2: June 25, 2020
  • Beta 3: August 13, 2020