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[BUG] iter_start_seqnum does not work with backward iteration #6837

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wolfkdy opened this issue May 12, 2020 · 1 comment
Open

[BUG] iter_start_seqnum does not work with backward iteration #6837

wolfkdy opened this issue May 12, 2020 · 1 comment
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bug Confirmed RocksDB bugs

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@wolfkdy
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wolfkdy commented May 12, 2020

rocksdb/db/db_iter.cc

Line 74 in e45673d

start_seqnum_(read_options.iter_start_seqnum),

from ReadOptions' comment (or manual), iter_start_seqnum should work well for both forward and backward iteration.

I tried but find this parameter does not work inbackward iteration, by digging into the db_iter.cc, it seems this parameter is implemented partially, only for forward iteration.
@wolfkdy wolfkdy changed the title [BUG] iter_start_seqnum only works well with forward iteration [BUG] iter_start_seqnum does not work with backward iteration May 12, 2020
@riversand963
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@wolfkdy maybe we can update the doc for ReadOptions before it is implemented for backward iteration.

@ajkr ajkr added the bug Confirmed RocksDB bugs label Apr 6, 2021
@jay-zhuang jay-zhuang mentioned this issue Oct 29, 2021
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@jay-zhuang jay-zhuang mentioned this issue Oct 29, 2021
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jay-zhuang added a commit to jay-zhuang/rocksdb that referenced this issue Nov 19, 2021
@jay-zhuang
Deprecating iter_start_seqnum and preserve_deletes
43f6df5 
Summary:
`ReadOptions::iter_start_seqnum` and `DBOptions::preserve_deletes` are
deprecated, please try using user defined timestamp feature instead.
The feature is used to support differential snapshots, but not well
maintained (facebook#6837, facebook#8472) and the interface is not user friendly which
returns an internal key from the iterator. The user defined timestamp
feature is a more flexible feature to support similar usecase, please
switch to that if you have such usecase.
The deprecated feature will be removed in a future release.

Test Plan: check LOG

Fix facebook#9090
facebook-github-bot pushed a commit that referenced this issue Nov 20, 2021
@jay-zhuang @facebook-github-bot
Deprecating iter_start_seqnum and preserve_deletes (#9091)
6cde8d2 
Summary:
`ReadOptions::iter_start_seqnum` and `DBOptions::preserve_deletes` are
deprecated, please try using user defined timestamp feature instead.
The feature is used to support differential snapshots, but not well
maintained (#6837, #8472) and the interface is not user friendly which
returns an internal key from the iterator. The user defined timestamp
feature is a more flexible feature to support similar usecase, please
switch to that if you have such usecase.
The deprecated feature will be removed in a future release.

Pull Request resolved: #9091

Test Plan:
check LOG

Fix #9090

Reviewed By: ajkr

Differential Revision: D32071750

Pulled By: jay-zhuang

fbshipit-source-id: b882c4668dd1bf26ce03c4c192f1bba584bf6104
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@wolfkdy @ajkr @riversand963