db: drop duplicate access_tokens hash index

[ValentaTomas]

access_tokens.access_token_hash carries two identical unique indexes: the UNIQUE constraint's own and a standalone copy. Identical indexes are interchangeable to the planner, so lookups continue on the constraint's index and uniqueness is untouched; every token write stops maintaining the second copy. The standalone twin is the droppable one — the constraint-backed index refuses DROP INDEX, making a mixed-up drop fail loud instead of silently.

Schema proof, both definitions in this repo: the standalone unique index (20250825102440 L9-L10) and the column's UNIQUE constraint that already carries its own index (20250211160814 L12) — identical key (access_token_hash). Background: PostgreSQL wiki — duplicate indexes.

[cursor]

PR Summary

Low Risk
Online index drop on an auth-related table; uniqueness and lookups remain on the constraint index, with low functional risk if the correct standalone index is dropped.

Overview
Removes the redundant unique index idx_access_tokens_access_token_hash on access_tokens.access_token_hash because the column’s UNIQUE constraint already provides an equivalent index, so token writes no longer maintain a duplicate index while lookups and uniqueness stay the same. The migration uses DROP INDEX CONCURRENTLY with a bounded statement_timeout and restores the migrator’s 3h timeout afterward; rollback drops any invalid leftover index before recreating the standalone index concurrently.

^{Reviewed by Cursor Bugbot for commit 93e7824. Bugbot is set up for automated code reviews on this repo. Configure here.}

[codecov]

❌ 5 Tests Failed:

Tests completed	Failed	Passed	Skipped
3514	5	3509	7

View the top 3 failed test(s) by shortest run time

github.com/e2b-dev/infra/tests/integration/internal/tests/envd::TestListDir/depth_1_lists_root_directory

Stack Traces | 0.01s run time

=== RUN   TestListDir/depth_1_lists_root_directory
=== PAUSE TestListDir/depth_1_lists_root_directory
=== CONT  TestListDir/depth_1_lists_root_directory
    filesystem_test.go:96: 
        	Error Trace:	.../tests/envd/filesystem_test.go:96
        	Error:      	Received unexpected error:
        	            	unavailable: 502 Bad Gateway
        	Test:       	TestListDir/depth_1_lists_root_directory
--- FAIL: TestListDir/depth_1_lists_root_directory (0.01s)

github.com/e2b-dev/infra/tests/integration/internal/tests/envd::TestListDir/depth_2_lists_first_level_of_subdirectories_(in_this_case_the_root_directory)

Stack Traces | 0.01s run time

=== RUN   TestListDir/depth_2_lists_first_level_of_subdirectories_(in_this_case_the_root_directory)
=== PAUSE TestListDir/depth_2_lists_first_level_of_subdirectories_(in_this_case_the_root_directory)
=== CONT  TestListDir/depth_2_lists_first_level_of_subdirectories_(in_this_case_the_root_directory)
    filesystem_test.go:96: 
        	Error Trace:	.../tests/envd/filesystem_test.go:96
        	Error:      	Received unexpected error:
        	            	unavailable: 502 Bad Gateway
        	Test:       	TestListDir/depth_2_lists_first_level_of_subdirectories_(in_this_case_the_root_directory)
--- FAIL: TestListDir/depth_2_lists_first_level_of_subdirectories_(in_this_case_the_root_directory) (0.01s)

github.com/e2b-dev/infra/tests/integration/internal/tests/envd::TestListDir/depth_0_lists_only_root_directory

Stack Traces | 0.02s run time

=== RUN   TestListDir/depth_0_lists_only_root_directory
=== PAUSE TestListDir/depth_0_lists_only_root_directory
=== CONT  TestListDir/depth_0_lists_only_root_directory
    filesystem_test.go:96: 
        	Error Trace:	.../tests/envd/filesystem_test.go:96
        	Error:      	Received unexpected error:
        	            	unavailable: 502 Bad Gateway
        	Test:       	TestListDir/depth_0_lists_only_root_directory
--- FAIL: TestListDir/depth_0_lists_only_root_directory (0.02s)

github.com/e2b-dev/infra/tests/integration/internal/tests/envd::TestListDir

Stack Traces | 0.41s run time

=== RUN   TestListDir
=== PAUSE TestListDir
=== CONT  TestListDir
--- FAIL: TestListDir (0.41s)

View the full list of 1 ❄️ flaky test(s)

github.com/e2b-dev/infra/tests/integration/internal/tests/envd::TestListDir/depth_3_lists_all_directories_and_files

Flake rate in main: 30.77% (Passed 9 times, Failed 4 times)

Stack Traces | 0.01s run time

=== RUN   TestListDir/depth_3_lists_all_directories_and_files
=== PAUSE TestListDir/depth_3_lists_all_directories_and_files
=== CONT  TestListDir/depth_3_lists_all_directories_and_files
    filesystem_test.go:96: 
        	Error Trace:	.../tests/envd/filesystem_test.go:96
        	Error:      	Received unexpected error:
        	            	unavailable: 502 Bad Gateway
        	Test:       	TestListDir/depth_3_lists_all_directories_and_files
--- FAIL: TestListDir/depth_3_lists_all_directories_and_files (0.01s)

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[claude]

LGTM — this correctly identifies and drops the redundant standalone index, keeping the UNIQUE constraint's own index intact.

Extended reasoning...

Overview

Single new migration file that drops idx_access_tokens_access_token_hash, a standalone unique index on access_tokens.access_token_hash. I verified in the migration history that this index is genuinely redundant: 20250211160814_add_token_hashes.sql added the column as TEXT UNIQUE, which creates an implicit unique index (access_tokens_access_token_hash_key), and a later migration (20250825102440_add_hash_indexes.sql) added the standalone idx_access_tokens_access_token_hash unique index on the same column — an unintentional duplicate. This PR removes the later, non-constraint-backed duplicate, which is the correct one to drop (the constraint-backed index cannot be removed via DROP INDEX at all, so a mixed-up target would simply fail rather than silently corrupt anything).

Security risks

None. This is a pure schema/index change with no application logic, query, or auth-path modifications. Uniqueness enforcement and hash lookups continue via the constraint's index.

Level of scrutiny

Low. This is a mechanical, well-reasoned online index drop (DROP INDEX CONCURRENTLY, no transaction wrapper, bounded statement_timeout) with a symmetric and correct down migration (clears any leftover INVALID index before recreating). The change is self-contained to one file and matches established patterns in this repo's migration history.

Other factors

Codecov reports full coverage on the change; Cursor Bugbot's own summary corroborates the redundant-index analysis. No outstanding review comments to address.