Fix extra tombstones on update #197
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Our current delete scheme requires that updates write tombstones for previous values when the previous value is in an file logically older than the current write file. An unrelated change broke that logic, and now tombstones are written every single time a value is updated. This test demonstrates this by counting the number of tombstones expected for repeatedly updating the same key when two data files are created. Only a tombstone is required, but we get one per update.
An unrelated fix in commit 4ab96d4 caused updates replacing a value in the same file to write extra tombstones that serve no purpose. Updates are supposed to create a tombstone for previous values only when the previous value was stored in an older file. Multiple values for the same key in the same file do not require these extra tombstones.
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+1 a7b0c1d Review, 8 hours of QuickCheck + PULSE runs all look good |
borshop
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Sep 17, 2014
Fix extra tombstones on update Reviewed-by: slfritchie
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@borshop merge |
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An unrelated fix in commit 4ab96d4 caused updates replacing a value
in the same file to write extra tombstones that serve no purpose.
Updates are supposed to create a tombstone for previous values only
when the previous value was stored in an older file. Multiple
values for the same key in the same file do not require these extra
tombstones.
This PR demonstrates the problem with a new test in the first commit.
The second commit contains the fix to the update logic.
This addresses issue #196