Difference between revisions of "PostgreSQL 13 Open Items"

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(add 2nd thread)
(Open Issues)
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** "despite writing about twice as much data, the hashagg cost is estimated to be much lower than the sort".
 
** "despite writing about twice as much data, the hashagg cost is estimated to be much lower than the sort".
 
** At the very low end, the amount of I/O performed by hash aggregate can significantly exceed what we see with the equivalent Group agg + sort.
 
** At the very low end, the amount of I/O performed by hash aggregate can significantly exceed what we see with the equivalent Group agg + sort.
 +
** Original commit: {{PgCommitURL|1f39bce0}}
 +
** Owner: Jeff Davis
  
* [https://www.postgresql.org/message-id/20200619040358.GZ17995@telsasoft.com EXPLAIN ANALYZE's non-text output should consistently include all fields for incremental sort, meaning fields "not applicable" to text format output should be shown as 0]
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* [https://www.postgresql.org/message-id/CAH2-Wzn5PCBLUrrds=hD439LtWP+PD7ekRTd=8LdtqJ+KO5D1Q@mail.gmail.com HashAggs-that-spill preallocation subtly broke trace_sort and EXPLAIN ANALYZE "%u disk blocks used" statistics]
** We fixed more or less the same issue in hash agg already, but we still need to fix incremental sort.
+
** We should account for "preallocated" though unused blocks, which currently get included in the instrumentation.
** [https://www.postgresql.org/message-id/CAApHDvo_dmNozQQTmN-2jGp1vT%3Ddxx7Q0vd%2BMvD1cGpv2HU%3DSg%40mail.gmail.com 2nd thread about same]
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** Original commit: {{PgCommitURL|896ddf9b}}
** Original commit: {{PgCommitURL|d2d8a229}}
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** Owner: Jeff Davis
** Owner: James Coleman, Tomas Vondra
 
  
 
== Older Bugs ==
 
== Older Bugs ==
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=== Live issues ===
 
=== Live issues ===
  
* [https://www.postgresql.org/message-id/20200728151002.GE20393%40telsasoft.com ItemPointer values should never be equal in an index]
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* [https://www.postgresql.org/message-id/CAH2-WzkjjCoq5Y4LeeHJcjYJVxGm3M3SAWZ0%3D6J8K1FPSC9K0w%40mail.gmail.com REINDEX on a system catalog can leave index with two index tuples whose heap TIDs match]
** Apparently system catalog index builds can sometimes create an index that breaks the HOT invariant by having two index tuples with the same identical heap TID value.
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** In other words, there is a rare case where the HOT invariant is violated. Same HOT chain is indexed twice due to confusion about which precise heap tuple should be indexed.
** Affects all stable branches
+
** Unclear what the user impact is.
 +
** Affects all stable branches.
  
* [https://www.postgresql.org/message-id/flat/CAKcux6k2KoQ%3DWjvNdW_Jyct7HuoVvqdgj-bEiXavS1BqOPzi%2Bw%40mail.gmail.com ERROR with FOR UPDATE/SHARE for partitioned table.]
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* [https://www.postgresql.org/message-id/flat/CAKcux6k2KoQ%3DWjvNdW_Jyct7HuoVvqdgj-bEiXavS1BqOPzi%2Bw%40mail.gmail.com ERROR with FOR UPDATE/SHARE for partitioned table]
 
** Affects v12 and probably v11 (partition pruning)
 
** Affects v12 and probably v11 (partition pruning)
  
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=== resolved before 13beta3 ===
 
=== resolved before 13beta3 ===
 +
 +
* [https://www.postgresql.org/message-id/CAAaqYe97a3xf=5Q0ZjPcQQGX-rAPL9CNFkfupqzCt7g4TrVLrA@mail.gmail.com EXPLAIN ANALYZE's non-text output should consistently include all fields for incremental sort, meaning fields "not applicable" to text format output should be shown as 0]
 +
** [https://www.postgresql.org/message-id/CAApHDvo_dmNozQQTmN-2jGp1vT%3Ddxx7Q0vd%2BMvD1cGpv2HU%3DSg%40mail.gmail.com Nothing to do for incremental sort], which at least manages to show EXPLAIN ANALYZE output that's consistent with regular sort nodes.
 +
** Original commit: {{PgCommitURL|d2d8a229}}
  
 
* [https://www.postgresql.org/message-id/20200625203629.7m6yvut7eqblgmfo@alap3.anarazel.de Many users rely on hashagg exceeding work_mem, regardless of whether or not that is the intended behavior in Postgres 12]
 
* [https://www.postgresql.org/message-id/20200625203629.7m6yvut7eqblgmfo@alap3.anarazel.de Many users rely on hashagg exceeding work_mem, regardless of whether or not that is the intended behavior in Postgres 12]

Revision as of 01:49, 31 July 2020

Open Issues

NOTE: Please place new open items at the end of the list.

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