Option to disable auto indexing.

[ghost]

What's the problem? Indexing large projects ex. linux kernel takes many hours and it's frustrating not able to use bloop because its re-indexing the repo.

What's the solution? To have an on-off switch for the auto indexing.

[ggordonhall]

After an initial index, bloop should only index files that have been modified by new commits, not the whole repo. However, it may re-index every file if bloop itself has been upgraded and the index schema has changed.

Do you notice the re-indexing after bloop upgrades?