Fixed dead rows accumulating in software host counts tables

[getvictor]

Related issue: Resolves #35805

Fixed to make sure software host counts tables never have host counts of 0.
Planning to loadtest this fix along with the follow up fix for #35799

Checklist for submitter

• Changes file added for user-visible changes in changes/, orbit/changes/ or ee/fleetd-chrome/changes.

Testing

• Added/updated automated tests
• QA'd all new/changed functionality manually

Summary by CodeRabbit

• Bug Fixes
  • Fixed accumulation of dead rows in software host count tracking, improving data accuracy and system performance.
  • Enhanced validation to ensure consistent and reliable software availability records.

[getvictor]

@coderabbitai full review

[Copilot]

Pull request overview

This PR addresses accumulation of “dead” hosts_count = 0 rows in the host-count aggregation tables by switching the sync logic to an atomic swap-table approach and enforcing positive counts at the schema level.

Changes:

• Reworked SyncHostsSoftware and SyncHostsSoftwareTitles to populate swap tables and atomically rename them into place (instead of resetting counts to 0 and updating in-place).
• Updated listing/filtering SQL to no longer rely on hosts_count > 0 predicates, consistent with eliminating zero-count rows.
• Added a migration + schema constraints to delete existing zero-count rows and prevent future inserts of non-positive counts; adjusted unit test expectations accordingly.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
server/datastore/mysql/software.go	Uses swap-table + rename for software_host_counts; removes reliance on hosts_count > 0 filtering in several queries.
server/datastore/mysql/software_titles.go	Uses swap-table + rename for software_titles_host_counts; adjusts title queries to check row existence instead of hosts_count > 0.
server/datastore/mysql/migrations/tables/20260223000000_CleanupSoftwareHostCountsZeroRows.go	Cleans up accumulated zero rows and adds CHECK constraints to enforce hosts_count > 0.
server/datastore/mysql/schema.sql	Reflects new constraints and migration status in the canonical schema.
server/datastore/mysql/software_test.go	Updates expected row counts in software_host_counts due to removal of zero-count rows.
changes/35805-zero-host-counts	Adds changelog entry for the bugfix.

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[codecov]

Codecov Report

❌ Patch coverage is 68.29268% with 26 lines in your changes missing coverage. Please review.
✅ Project coverage is 65.54%. Comparing base (81c75b4) to head (1f7dc61).
⚠️ Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
server/datastore/mysql/software.go	58.82%	8 Missing and 6 partials ⚠️
server/datastore/mysql/software_titles.go	60.00%	5 Missing and 5 partials ⚠️
...0260223000000_CleanupSoftwareHostCountsZeroRows.go	91.30%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #40288      +/-   ##
==========================================
- Coverage   66.26%   65.54%   -0.73%     
==========================================
  Files        2460     2274     -186     
  Lines      197220   180111   -17109     
  Branches     8716     8593     -123     
==========================================
- Hits       130682   118046   -12636     
+ Misses      54713    50865    -3848     
+ Partials    11825    11200     -625     

Flag	Coverage Δ
backend	67.47% <68.29%> (-0.67%)	⬇️

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[getvictor]

@coderabbitai full review

[coderabbitai]

✅ Actions performed

Full review triggered.

[coderabbitai]

Walkthrough

This PR fixes dead rows accumulating in software host counts tables by implementing an atomic table swap strategy during synchronization instead of in-place updates. A new migration cleans up existing zero-count rows and adds CHECK constraints (hosts_count > 0) to both software_host_counts and software_titles_host_counts tables. The SyncHostsSoftware and SyncHostsSoftwareTitles functions are refactored to populate a temporary swap table and atomically rename it into place. Query code paths are updated to remove explicit hosts_count > 0 filters since the database now enforces positive counts. Test expectations are adjusted to reflect reduced row counts.

Possibly related PRs

• Atomic vulnerability count calculations #35317: Implements the same atomic table-swap pattern for vulnerability host counts instead of in-place updates.
• Optimize software/versions queries. #35670: Modifies the same schema and query code paths in software.go related to software_host_counts tables and filtering.
• Skip software_id=0 and log, but otherwise complete counts, when counting host software on a host_software table including rows with software ID zero #30523: Changes the SyncHostsSoftware implementation to handle software_id=0 cases with skip/log logic.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	PR description is incomplete. Multiple required sections from the template are missing or unchecked.	Complete the following unchecked items: Input data validation, SQL injection prevention, endpoint backwards compatibility check, automated test simulation for host isolation, Database migration timestamp checks, collation verification, and any GitOps/fleetd compatibility checks as applicable.
Out of Scope Changes check	❓ Inconclusive	The removal of hosts_count > 0 filters from query logic appears aligned with the issue objectives, but the removal of explicit filtering conditions requires verification that query behavior and filtering still work as intended.	Verify that removing hosts_count > 0 filters and replacing with other conditions (e.g., software_title_id IS NOT NULL) maintains correct query semantics and isolation between teams/hosts.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: fixing dead rows accumulating in software host counts tables, which aligns with the primary objective from issue #35805.
Linked Issues check	✅ Passed	The code changes implement both cleanup and atomic swap approaches from issue #35805: migration removes zero-count rows, CHECK constraints prevent future zeros, and SyncHostsSoftware/SyncHostsSoftwareTitles use atomic table swaps instead of in-place updates.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

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🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch victor/35805-zero-host-counts

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[mostlikelee]

LGTM, but looks like there are some conflicts @getvictor