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[improve](load) change memtable memory limiter policy - #41018
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| } | ||
| int64_t mem = w->active_memtable_mem_consumption(); | ||
| if (mem < sort_mem * 0.9) { | ||
| // if the memtable writer just got flushed, don't flush it again |
yiguolei
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Sep 20, 2024
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Sep 20, 2024
## Proposed changes #40912 has changed meaning of `write_mem` in memtable memory limiter. This PR is a followup to change the active memtable flush policy accordingly. It also changed: 1. The amount of memtable writers selected in one flush. 2. The memtable writers are selected in orders of its size.
liaoxin01 pushed a commit
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Sep 26, 2024
## Proposed changes #41018 used priority queue when selecting memtables to flush. But the compare function is wrong and causing the order to be the opposite. > Note that the Compare parameter is defined such that it returns true if its first argument comes before its second argument in a weak ordering. But because the priority queue outputs largest elements first, the elements that "come before" are actually output last. That is, the front of the queue contains the "last" element according to the weak ordering imposed by Compare. This PR fixes the compare function to make larger memtables come front.
kaijchen added a commit
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Oct 21, 2024
## Proposed changes apache#40912 has changed meaning of `write_mem` in memtable memory limiter. This PR is a followup to change the active memtable flush policy accordingly. It also changed: 1. The amount of memtable writers selected in one flush. 2. The memtable writers are selected in orders of its size.
kaijchen added a commit
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Oct 21, 2024
…he#41278) ## Proposed changes apache#41018 used priority queue when selecting memtables to flush. But the compare function is wrong and causing the order to be the opposite. > Note that the Compare parameter is defined such that it returns true if its first argument comes before its second argument in a weak ordering. But because the priority queue outputs largest elements first, the elements that "come before" are actually output last. That is, the front of the queue contains the "last" element according to the weak ordering imposed by Compare. This PR fixes the compare function to make larger memtables come front.
kaijchen added a commit
to kaijchen/doris
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this pull request
Nov 18, 2024
This PR is a followup to change the active memtable flush policy accordingly. It also changed: 1. The amount of memtable writers selected in one flush. 2. The memtable writers are selected in orders of its size.
kaijchen added a commit
to kaijchen/doris
that referenced
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Nov 18, 2024
…he#41278) ## Proposed changes apache#41018 used priority queue when selecting memtables to flush. But the compare function is wrong and causing the order to be the opposite. > Note that the Compare parameter is defined such that it returns true if its first argument comes before its second argument in a weak ordering. But because the priority queue outputs largest elements first, the elements that "come before" are actually output last. That is, the front of the queue contains the "last" element according to the weak ordering imposed by Compare. This PR fixes the compare function to make larger memtables come front.
kaijchen added a commit
to kaijchen/doris
that referenced
this pull request
Nov 18, 2024
This PR is a followup to change the active memtable flush policy accordingly. It also changed: 1. The amount of memtable writers selected in one flush. 2. The memtable writers are selected in orders of its size.
kaijchen added a commit
to kaijchen/doris
that referenced
this pull request
Nov 18, 2024
…he#41278) ## Proposed changes apache#41018 used priority queue when selecting memtables to flush. But the compare function is wrong and causing the order to be the opposite. > Note that the Compare parameter is defined such that it returns true if its first argument comes before its second argument in a weak ordering. But because the priority queue outputs largest elements first, the elements that "come before" are actually output last. That is, the front of the queue contains the "last" element according to the weak ordering imposed by Compare. This PR fixes the compare function to make larger memtables come front.
kaijchen added a commit
to kaijchen/doris
that referenced
this pull request
Nov 18, 2024
This PR is a followup to change the active memtable flush policy accordingly. It also changed: 1. The amount of memtable writers selected in one flush. 2. The memtable writers are selected in orders of its size.
kaijchen added a commit
to kaijchen/doris
that referenced
this pull request
Nov 18, 2024
…he#41278) ## Proposed changes apache#41018 used priority queue when selecting memtables to flush. But the compare function is wrong and causing the order to be the opposite. > Note that the Compare parameter is defined such that it returns true if its first argument comes before its second argument in a weak ordering. But because the priority queue outputs largest elements first, the elements that "come before" are actually output last. That is, the front of the queue contains the "last" element according to the weak ordering imposed by Compare. This PR fixes the compare function to make larger memtables come front.
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dataroaring pushed a commit
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Jul 11, 2025
…52906) Related PR: #41018 Problem Summary: Update the `_need_flush()` function to subtract both `_queue_mem_usage` and `_flush_mem_usage` when deciding how much memory needs to be flushed. Previously, we only subtracted `_queue_mem_usage`, which could lead to flushing more active memtables than necessary. This change ensures that only the required amount of active memtable memory is flushed, avoiding premature flushes. This helps prevent creating small segments, which can hurt performance and storage efficiency.
kaijchen added a commit
to kaijchen/doris
that referenced
this pull request
Jul 25, 2025
…pache#52906) Related PR: apache#41018 Problem Summary: Update the `_need_flush()` function to subtract both `_queue_mem_usage` and `_flush_mem_usage` when deciding how much memory needs to be flushed. Previously, we only subtracted `_queue_mem_usage`, which could lead to flushing more active memtables than necessary. This change ensures that only the required amount of active memtable memory is flushed, avoiding premature flushes. This helps prevent creating small segments, which can hurt performance and storage efficiency.
kaijchen added a commit
to kaijchen/doris
that referenced
this pull request
Jul 25, 2025
…pache#52906) Related PR: apache#41018 Problem Summary: Update the `_need_flush()` function to subtract both `_queue_mem_usage` and `_flush_mem_usage` when deciding how much memory needs to be flushed. Previously, we only subtracted `_queue_mem_usage`, which could lead to flushing more active memtables than necessary. This change ensures that only the required amount of active memtable memory is flushed, avoiding premature flushes. This helps prevent creating small segments, which can hurt performance and storage efficiency.
HappenLee pushed a commit
to HappenLee/incubator-doris
that referenced
this pull request
Apr 24, 2026
## Proposed changes apache#40912 has changed meaning of `write_mem` in memtable memory limiter. This PR is a followup to change the active memtable flush policy accordingly. It also changed: 1. The amount of memtable writers selected in one flush. 2. The memtable writers are selected in orders of its size.
HappenLee pushed a commit
to HappenLee/incubator-doris
that referenced
this pull request
Apr 24, 2026
…he#41278) ## Proposed changes apache#41018 used priority queue when selecting memtables to flush. But the compare function is wrong and causing the order to be the opposite. > Note that the Compare parameter is defined such that it returns true if its first argument comes before its second argument in a weak ordering. But because the priority queue outputs largest elements first, the elements that "come before" are actually output last. That is, the front of the queue contains the "last" element according to the weak ordering imposed by Compare. This PR fixes the compare function to make larger memtables come front.
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Proposed changes
#40912 has changed meaning of
write_memin memtable memory limiter.This PR is a followup to change the active memtable flush policy accordingly.
It also changed: