perf(export): export generates unnecessary files content

[Always-prog]

SUMMARY

Currently, exporting models functionality is slower than it can be.

Model export is slow because models export their related models, and since related models cannot check if they have already been exported to the final archive, they are exported anyway. This leads to generating unnecessary export model files.
For example, exporting a dashboard with 2 charts will generate 4 files - a dashboard, two charts, a dataset, and a database, but ““behind the scenes” there will actually be 7 files generated, since each chart will re-export the dataset and database, and at the end, the highest-level export model (dashboard export) will remove these duplicates.

To solve this problem, it is proposed to start generating export files not immediately, but only when they are written to a file, by convert file_content to function that generates content when we call it.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

pay attention to speed up of generating an dashboard export archive!

Before

without-perf.mp4

After

with-perf.mp4

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[geido]

Hello @Always-prog thanks for the PR! Would you mind taking a look at the failing CI steps?

[codecov]

Codecov Report

Attention: Patch coverage is 87.82609% with 14 lines in your changes missing coverage. Please review.

Project coverage is 69.51%. Comparing base (4796484) to head (9d2e16e).
Report is 1562 commits behind head on master.

Files with missing lines	Patch %	Lines
superset/commands/dashboard/export.py	59.25%	11 Missing ⚠️
superset/commands/export/models.py	80.00%	2 Missing ⚠️
superset/commands/export/assets.py	96.15%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #26765      +/-   ##
==========================================
+ Coverage   67.18%   69.51%   +2.33%     
==========================================
  Files        1900     1900              
  Lines       74443    74491      +48     
  Branches     8293     8293              
==========================================
+ Hits        50012    51785    +1773     
+ Misses      22376    20651    -1725     
  Partials     2055     2055              

Flag	Coverage Δ
hive	53.82% <46.08%> (?)
mysql	78.04% <78.26%> (+0.01%)	⬆️
postgres	78.14% <78.26%> (+0.01%)	⬆️
presto	53.77% <46.08%> (?)
python	83.09% <87.82%> (+4.83%)	⬆️
sqlite	77.66% <78.26%> (+0.01%)	⬆️
unit	56.49% <60.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[Always-prog]

@betodealmeida Hi! Thanks for review! I have committed fixes by your comments.

But the only thing that pre-commit fails due to file .github/workflows/update-monorepo-lockfiles.yml, which I have not fixed.

[geido]

Hi @Always-prog it seems you have a conflicting file. Can you fix it, please? I am adding myself as a reviewer and checking back on this asap. Thank you!

[geido]

👀

[Always-prog]

@geido Hi! Rebased!

[geido]

/testenv up

[github-actions]

@geido Ephemeral environment spinning up at http://54.191.84.78:8080. Credentials are admin/admin. Please allow several minutes for bootstrapping and startup.

[michael-s-molina]

I tested the PR and was able to successfully export/import dashboards.

Thank you for the work @Always-prog, the performance improvements are impressive!

[Always-prog]

@michael-s-molina Thank you for testing my PR. Can I get merge?

[github-actions]

Ephemeral environment shutdown and build artifacts deleted.