fix(trigger): add size threshold to table bloat trigger#34
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Small tables that are frequently rewritten can trivially have > 50 % table bloat even though the absolute size of the bloat is just a few kB. This is the normal, stable, desirable condition for such tables. In those cases, the suggested VACUUM FULL is an incorrect response. The common solution to this is to add a size threshold to the table bloat trigger. There's no strict guidance for such a threshold, and different sources use different thresholds: - pgexperts/pgx_scripts needs 10 MB of table bloat to trigger by default - keithf4/pg_bloat_check lists example triggers of 10 MB and 1 GB - Heroku's documentation suggests a threshold of 100 MB This commit is written with a conservative threshold to catch obvious false alarms without deviating too far from the function's earlier behaviour.
kqr
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Jul 22, 2026
| q | ||
| where | ||
| bloat_pct > 50.0 | ||
| and schemaname not like all(array['information_schema', 'pg_catalog', 'pg_toast', 'pg_temp%']) |
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I adjusted the indentation of this filter so it's aligned with the rest of the where clause expression. Not strictly necessary, but I figured I might as well when I'm in there anyway.
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Small tables that are frequently rewritten can trivially have > 50 % table bloat even though the absolute size of the bloat is just a few kB. This is the normal, stable, desirable condition for such tables. In those cases, the suggested VACUUM FULL is an incorrect response.
The common solution to this is to add a size threshold to the table bloat trigger. There's no strict guidance for such a threshold, and different sources use different thresholds:
This commit is written with a conservative threshold to catch obvious false alarms without deviating too far from the function's earlier behaviour.
Type of Change
Related Issues
n/a
Testing
PostgreSQL Version Compatibility
Has this code been tested against the following PostgreSQL versions?
Testing notes:
Very small change and little scope for what could go wrong. It seems to work as expected.
Managed Database Platforms
Has this code been deployed and tested on the following platforms?
Platform-specific notes:
Unfortunately not been able to do any testing on managed platforms.
Additional Notes