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| author | Robert Haas <rhaas@postgresql.org> | 2017-01-18 16:36:48 -0500 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2017-01-18 16:36:48 -0500 |
| commit | e37360d5df240443bb6e997d26d54f59146283fc (patch) | |
| tree | 57a8ad8d71d21a4e8e444182185632ce290d4526 /src | |
| parent | 1586317c3f57e619e0cde674c6da406f9d73aaff (diff) | |
| download | postgresql-e37360d5df240443bb6e997d26d54f59146283fc.tar.gz postgresql-e37360d5df240443bb6e997d26d54f59146283fc.zip | |
Improve comment in hashsearch.c.
Typo fix from Mithun Cy; other improvements by me.
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/access/hash/hashsearch.c | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/src/backend/access/hash/hashsearch.c b/src/backend/access/hash/hashsearch.c index c0bdfe6f1fb..a59ad6ff707 100644 --- a/src/backend/access/hash/hashsearch.c +++ b/src/backend/access/hash/hashsearch.c @@ -334,19 +334,20 @@ _hash_first(IndexScanDesc scan, ScanDirection dir) so->hashso_bucket_buf = buf; /* - * If the bucket split is in progress, then while scanning the bucket - * being populated, we need to skip tuples that are moved from bucket - * being split. We need to maintain the pin on bucket being split to + * If a bucket split is in progress, then while scanning the bucket being + * populated, we need to skip tuples that were copied from bucket being + * split. We also need to maintain a pin on the bucket being split to * ensure that split-cleanup work done by vacuum doesn't remove tuples - * from it till this scan is done. We need to main to maintain the pin on + * from it till this scan is done. We need to maintain a pin on the * bucket being populated to ensure that vacuum doesn't squeeze that - * bucket till this scan is complete, otherwise the ordering of tuples + * bucket till this scan is complete; otherwise, the ordering of tuples * can't be maintained during forward and backward scans. Here, we have - * to be cautious about locking order, first acquire the lock on bucket - * being split, release the lock on it, but not pin, then acquire the lock - * on bucket being populated and again re-verify whether the bucket split - * still is in progress. First acquiring lock on bucket being split - * ensures that the vacuum waits for this scan to finish. + * to be cautious about locking order: first, acquire the lock on bucket + * being split; then, release the lock on it but not the pin; then, + * acquire a lock on bucket being populated and again re-verify whether + * the bucket split is still in progress. Acquiring the lock on bucket + * being split first ensures that the vacuum waits for this scan to + * finish. */ if (H_BUCKET_BEING_POPULATED(opaque)) { |