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@kpan2034 kpan2034 commented Aug 14, 2025

Previously a delete query was run on the bgw_job_stat_history table to
remove job history. This could be slow once the job history table became
very large. We now use a temporary table to keep recent history and
truncate the job history table instead. We also introduce a
job_history_bsearch function which finds the ids of the jobs that need
to be deleted using binary search.

This PR is based on experiments done
previously (timescale/timescaledb-extras#47).

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@kpan2034 kpan2034 force-pushed the job_stat_history branch 3 times, most recently from d7d26fd to 07d4a7c Compare August 19, 2025 17:04
@kpan2034 kpan2034 marked this pull request as ready for review August 19, 2025 17:04
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@Poroma-Banerjee, @dbeck: please review this pull request.

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codecov bot commented Aug 19, 2025

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.46%. Comparing base (883c70e) to head (96081a4).
⚠️ Report is 24 commits behind head on main.

Additional details and impacted files
@@            Coverage Diff             @@
##             main    #8494      +/-   ##
==========================================
+ Coverage   82.37%   82.46%   +0.08%     
==========================================
  Files         248      248              
  Lines       47544    47516      -28     
  Branches    12089    12085       -4     
==========================================
+ Hits        39164    39182      +18     
- Misses       3494     3504      +10     
+ Partials     4886     4830      -56     

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fabriziomello commented Aug 19, 2025

Please write a better PR and commit message describing how we improved things in this PR. For future context this is based on some experiments we've made some time ago (timescale/timescaledb-extras#47).

@fabriziomello fabriziomello added this to the v2.22.0 milestone Aug 21, 2025
@kpan2034 kpan2034 force-pushed the job_stat_history branch 2 times, most recently from 188873e to f796da6 Compare August 22, 2025 21:57
@pnthao pnthao self-requested a review August 25, 2025 16:00
@fabriziomello fabriziomello added jobs Background Worker The background worker subsystem, including the scheduler data-retention labels Aug 25, 2025
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I realized we had a constraint on execution_finish when copying rows into the temp table, which I removed. This required some minor changes in job_history_bsearch.

There was also a bug in the id_middle_next logic, which I now fixed. I also added test coverage for the job_history_bsearch function directly.

@pnthao pnthao self-requested a review August 25, 2025 20:52
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The tests need to be fixed to make sure it output deterministic results, but that could be done in a separate patch, so approving now.
I have some general thoughts about the solution and some alternatives, but we could have some follow-up discussion.

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Updated the PR to use a fixed timestamp for the tests rather than now(), to make them deterministic.

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Left some comments but LGTM.

@kpan2034 kpan2034 force-pushed the job_stat_history branch 4 times, most recently from b8cb92a to 44c524c Compare August 26, 2025 00:15
Previously a delete query was run on the `bgw_job_stat_history` table to
remove job history. This could be slow once the job history table became
very large. We now use a temporary table to keep recent history and
truncate the job history table instead. We also introduce a
`job_history_bsearch` function which finds the ids of the jobs that need
to be deleted using binary search.

This PR is based on experiments done
previously (timescale/timescaledb-extras#47).
@kpan2034 kpan2034 enabled auto-merge (squash) August 26, 2025 02:08
@kpan2034 kpan2034 merged commit 82e288b into timescale:main Aug 26, 2025
46 of 50 checks passed
@svenklemm svenklemm mentioned this pull request Aug 26, 2025
@kpan2034 kpan2034 deleted the job_stat_history branch August 26, 2025 14:43
kpan2034 added a commit to kpan2034/timescaledb that referenced this pull request Aug 27, 2025
PR timescale#8494 introduces changes to the history retention job, notably it
does a TRUNCATE instead of a DELETE. When the job is run on Tiger Cloud
it doesn't have the necessary permissions to do this, so we need to use
SECURITY DEFINER to ensure the policy can perform the TRUNCATE.
kpan2034 added a commit to kpan2034/timescaledb that referenced this pull request Aug 27, 2025
PR timescale#8494 introduces changes to the history retention job, notably it
does a TRUNCATE instead of a DELETE. When the job is run on Tiger Cloud
it doesn't have the necessary permissions to do this, so we need to use
SECURITY DEFINER to ensure the policy can perform the TRUNCATE.
kpan2034 added a commit to kpan2034/timescaledb that referenced this pull request Aug 27, 2025
PR timescale#8494 introduces changes to the history retention job, notably it
does a TRUNCATE instead of a DELETE. When the job is run on Tiger Cloud
it doesn't have the necessary permissions to do this, so we need to use
SECURITY DEFINER to ensure the policy can perform the TRUNCATE.
philkra pushed a commit that referenced this pull request Sep 2, 2025
## 2.22.0 (2025-09-02)

This release contains performance improvements and bug fixes since the 2.21.3 release. We recommend that you upgrade at the next available opportunity.

**Highlighted features in TimescaleDB v2.22.0**
* Sparse indexes on compressed hypertables can now be explicitly configured via `ALTER TABLE` rather than relying only on internal heuristics. Users can define indexes on multiple columns to improve query performance for their specific workloads.
* [Tech Preview] Continuous aggregates now support the `timescaledb.invalidate_using` option, enabling invalidations to be collected either via triggers on the hypertable or directly from WAL using logical decoding. Aggregates inherit the hypertable’s method if none is specified.  
* UUIDv7 compression and vectorization are now supported. The compression algorithm leverages the timestamp portion for delta-delta compression while storing the random portion separately. The vectorized equality/inequality filters with bulk decompression deliver ~2× faster query performance. The feature is disabled by default (`timescaledb.enable_uuid_compression`) to simplify the downgrading experience, and will be enabled out of the box in the next minor release.
* Hypertables can now be partitioned by UUIDv7 columns, leveraging their embedded timestamps for time-based chunking. We’ve also added utility functions to simplify working with UUIDv7, such as generating values or extracting timestamps - e.g., `uuid_timestamp()` returns a PostgreSQL timestamp from a UUIDv7.
* SkipScan now supports multi-column indexes in not-null mode, improving performance for distinct and ordered queries across multiple keys.  

**Removal of the hypercore table access method**
We made the decision to deprecate the hypercore table access method (TAM) with the 2.21.0 release. Hypercore TAM was an experiment and it did not show the performance improvements we hoped for. It is removed with this release. Upgrades to 2.22.0 and higher are blocked if TAM is still in use. Since TAM’s inception in [2.18.0](https://github.com/timescale/timescaledb/releases/tag/2.18.0), we learned that btrees were not the right architecture. Recent advancements in the columnstore, such as more performant backfilling, SkipScan, adding check constraints, and faster point queries, put the [columnstore](https://www.timescale.com/blog/hypercore-a-hybrid-row-storage-engine-for-real-time-analytics) close to or on par with TAM without needing to store an additional index. We apologize for the inconvenience this action potentially causes and are here to assist you during the migration process.

Migration path

```
do $$
declare
   relid regclass;
begin
   for relid in
       select cl.oid from pg_class cl
       join pg_am am on (am.oid = cl.relam)
       where am.amname = 'hypercore'
   loop
       raise notice 'converting % to heap', relid::regclass;
       execute format('alter table %s set access method heap', relid);
   end loop;
end
$$;
```

**Features**
* [#8247](#8247) Add configurable alter settings for sparse indexes
* [#8306](#8306) Add option for invalidation collection using WAL for continuous aggregates
* [#8340](#8340) Improve selectivity estimates for sparse minmax indexes, so that an index scan on a table in the columnstore is chosen more often when it's beneficial.
* [#8360](#8360) Continuous aggregate multi-hypertable invalidation processing
* [#8364](#8364) Remove hypercore table access method
* [#8371](#8371) Show available timescaledb `ALTER` options when encountering unsupported options
* [#8376](#8376) Change `DecompressChunk` custom node name to `ColumnarScan`
* [#8385](#8385) UUID v7 functions for testing pre PG18
* [#8393](#8393) Add specialized compression for UUIDs. Best suited for UUID v7, but still works with other UUID versions. This is experimental at the moment and backward compatibility is not guaranteed.
* [#8398](#8398) Set default compression settings at compress time
* [#8401](#8401) Support `ALTER TABLE RESET` for compression settings
* [#8414](#8414) Vectorised filtering of UUID Eq and Ne filters, plus bulk decompression of UUIDs
* [#8424](#8424) Block downgrade when orderby setting is `NULL`
* [#8454](#8454) Remove internal unused index helper functions
* [#8494](#8494) Improve job stat history retention policy
* [#8496](#8496) Fix dropping chunks with foreign keys
* [#8505](#8505) Add support for partitioning on UUIDv7
* [#8513](#8513) Support multikey SkipScan when all keys are guaranteed to be non-null
* [#8514](#8514) Concurrent continuous aggregates improvements
* [#8528](#8528) Add the `_timescaledb_functions.chunk_status_text` helper function
* [#8529](#8529) Optimize direct compress status handling

**Bugfixes**
* [#8422](#8422) Don't require `columnstore=false` when using the TimescaleDB Apache 2 Edition
* [#8493](#8493) Change log level of `not null` constraint message
* [#8500](#8500) Fix uniqueness check with generated columns and hypercore
* [#8545](#8545) Fix error in LOCF/Interpolate with out-of-order and repeated columns
* [#8558](#8558) Error out on bad args when processing invalidation
* [#8559](#8559) Fix `timestamp out of range` using `end_offset=NULL` on CAgg refresh policy

**GUCs**
* `enable_multikey_skipscan`: Enable SkipScan for multiple distinct keys, default: on
* `enable_uuid_compression`: Enable UUID compression functionality, default: off
* `cagg_processing_wal_batch_size`: Batch size when processing WAL entries, default: 10000
* `cagg_processing_low_work_mem`: Low working memory limit for continuous aggregate invalidation processing, default: 38.4MB
* `cagg_processing_high_work_mem`: High working memory limit for continuous aggregate invalidation processing, default: 51.2MB

**Thanks**
* @CodeTherapist for reporting an issue where foreign key checks did not work after several insert statements
* @moodgorning for reporting a bug in queries with LOCF/Interpolate using out-of-order columns
* @nofalx for reporting an error when using `end_offset=NULL` on CAgg refresh policy
* @pierreforstmann for fixing a bug that happened when dropping chunks with foreign keys
* @Zaczero for reporting a bug with CREATE TABLE WITH when using the TimescaleDB Apache 2 Edition
@timescale-automation timescale-automation added the released-2.22.0 Released in 2.22.0 label Sep 2, 2025
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