Do DELETE instead of TRUNCATE when locks aren't acquired #7785
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## main #7785 +/- ##
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+ Coverage 80.06% 81.90% +1.83%
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After compression, the uncompressed part of the chunk is truncated. This requires upgrading the `ExclusiveLock` to an `AccessExclusiveLock` and hence is sometimes blocked by other other operations, including reads, on the chunk. This leads to longer compress times or potential deadlocks. Instead of this, we fall back to deleting the tuples in the chunk row-by-row when the upgraded lock isn't immediately acquired.
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kpan2034
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Mar 4, 2025
| # until the end when we drop the compressed chunk | ||
| # which happens after updates to the chunk catalog tuple | ||
| permutation "CA1" "CAc" "LockChunkTuple" "DA1" "SA" "SF" "UnlockChunkTuple" "DAc" | ||
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| # Compressing a chunk should not stop any reads | ||
| # until it comes to truncating the uncompressed chunk |
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Is there a way to check whether truncate or deletion is happening during compression? Using a log here seems unnecessary.
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After compression, the uncompressed part of the chunk is truncated. This requires upgrading the
ExclusiveLockto anAccessExclusiveLockand hence is sometimes blocked by other other operations, including reads, on the chunk. This leads to longer compress times or potential deadlocks.Instead of this, we fall back to deleting the tuples in the chunk row-by-row when the upgraded lock isn't immediately acquired.