Add PostgreSQL result for c6a.2xlarge (2026-09-18)

[KazukiKandaKK]

Adds a PostgreSQL 17.11 result on c6a.2xlarge (8 vCPU / 16 GiB, gp3 220GB). Ran the usual benchmark.sh path (43 queries × 3 runs, plus the concurrent QPS follow-up). Existing PostgreSQL results are from 2022/2025 on c6a.4xlarge only; this is a smaller machine.

• Load time: 1835.506s (99,997,497 rows)
• Data size: 95,232,178,618 bytes
• Query 10, run 3 failed (null); left as null
• The table is 68 GiB on disk and does not fit in 16 GiB RAM, so most queries here are limited by disk I/O, not query complexity.

Sorry the MonetDB result in #2082 is still unresolved on my end. I posted a working theory for the CI failure there and will follow up separately. Didn't want that to block this PostgreSQL submission.

[github-actions]

Results for postgresql are ready for: c6a.metal, c7a.metal-48xl, c8g.metal-48xl.
The result files are committed as fc0db92.
Removed manually added result files: postgresql/results/20260918/c6a.2xlarge.json.

Logs:

• postgresql on c8g.metal-48xl: benchmark log, cloud-init log
• postgresql on c7a.metal-48xl: benchmark log, cloud-init log
• postgresql on c6a.metal: benchmark log, cloud-init log

[github-actions]

The run of postgresql on c6a.2xlarge did not produce results.
The run of postgresql on c6a.4xlarge did not produce results.
The run of postgresql on c6a.large did not produce results.
The run of postgresql on c6a.xlarge did not produce results.
The run of postgresql on c8g.4xlarge did not produce results.
The run of postgresql on t3a.small did not produce results.

Logs:

• postgresql on c6a.xlarge: benchmark log, cloud-init log
• postgresql on c6a.large: benchmark log, cloud-init log
• postgresql on c6a.2xlarge: benchmark log, cloud-init log
• postgresql on c6a.4xlarge: benchmark log, cloud-init log
• postgresql on c8g.4xlarge: benchmark log, cloud-init log
• postgresql on t3a.small: benchmark log, cloud-init log

[github-actions]

Results for postgresql are ready for: c6a.2xlarge.
The result files are committed as 0eaa832.

Logs:

• postgresql on c6a.2xlarge: benchmark log, cloud-init log

[github-actions]

Results for postgresql are ready for: c6a.4xlarge, c8g.4xlarge.
The result files are committed as 50a6e71.

Logs:

• postgresql on c8g.4xlarge: benchmark log, cloud-init log
• postgresql on c6a.4xlarge: benchmark log, cloud-init log

[github-actions]

Results for postgresql are ready for: c6a.xlarge.
The result files are committed as 9173299.

Logs:

• postgresql on c6a.xlarge: benchmark log, cloud-init log

[github-actions]

Results for postgresql are ready for: c6a.large.
The result files are committed as fb42b2d.

Logs:

• postgresql on c6a.large: benchmark log, cloud-init log