fix(queries): Optimizations on common calls

[devsjc]

Contribution Checklist

• Have you followed the Open Climate Fix Contribution Guidelines?
• Have you referenced the Issue this PR addresses, where applicable?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added a summary of the changes?
• Have you written new tests for your changes, where applicable?
• Have you successfully run make lint with your changes locally?
• Have you successfully run make test with your changes locally?

Warning

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Changes in this Pull Request

Some optimizations to the queries identified as being the slowest from pg_stat_statements.

[github-actions]

Benchmark Results

Benchmark results

?   	github.com/openclimatefix/data-platform/cmd	[no test files]
?   	github.com/openclimatefix/data-platform/internal/gen/ocf/dp	[no test files]
?   	github.com/openclimatefix/data-platform/internal/interceptors	[no test files]
PASS
ok  	github.com/openclimatefix/data-platform/internal/server/dummy	0.006s
{"level":"debug","time":"2026-03-24T17:58:54Z","message":"Completed migrations"}
goos: linux
goarch: amd64
pkg: github.com/openclimatefix/data-platform/internal/server/postgres
cpu: AMD EPYC 9V74 80-Core Processor                
BenchmarkPostgresClient/small/GetForecastAsTimeseries-4         	      68	  16991982 ns/op
BenchmarkPostgresClient/small/GetForecastAtTimestamp-4          	      84	  14078823 ns/op
BenchmarkPostgresClient/small/GetObservationsAsTimeseries-4     	     955	   1217836 ns/op
BenchmarkPostgresClient/small/CreateForecast-4                  	      99	  11889043 ns/op
PASS
ok  	github.com/openclimatefix/data-platform/internal/server/postgres	64.092s
?   	github.com/openclimatefix/data-platform/internal/server/postgres/gen	[no test files]

Benchmark vs base branch

goos: linux
goarch: amd64
pkg: github.com/openclimatefix/data-platform/internal/server/postgres
cpu: AMD EPYC 7763 64-Core Processor                
                                                   │ bench-main.txt │
                                                   │     sec/op     │
PostgresClient/small/GetForecastAsTimeseries-4         19.80m ± ∞ ¹
PostgresClient/small/GetForecastAtTimestamp-4          16.71m ± ∞ ¹
PostgresClient/small/GetObservationsAsTimeseries-4     1.323m ± ∞ ¹
PostgresClient/small/CreateForecast-4                  14.03m ± ∞ ¹
geomean                                                8.853m
¹ need >= 6 samples for confidence interval at level 0.95

cpu: AMD EPYC 9V74 80-Core Processor                
                                                   │ bench-devsjc-stat-statement-speedups.txt │
                                                   │                  sec/op                  │
PostgresClient/small/GetForecastAsTimeseries-4                                   16.99m ± ∞ ¹
PostgresClient/small/GetForecastAtTimestamp-4                                    14.08m ± ∞ ¹
PostgresClient/small/GetObservationsAsTimeseries-4                               1.218m ± ∞ ¹
PostgresClient/small/CreateForecast-4                                            11.89m ± ∞ ¹
geomean                                                                          7.672m
¹ need >= 6 samples for confidence interval at level 0.95