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46 lines
2.5 KiB
Markdown
46 lines
2.5 KiB
Markdown
---
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slug: /en/operations/system-tables/jemalloc_bins
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---
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# jemalloc_bins
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Contains information about memory allocations done via jemalloc allocator in different size classes (bins) aggregated from all arenas.
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These statistics might not be absolutely accurate because of thread local caching in jemalloc.
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Columns:
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- `index` (UInt64) — Index of the bin ordered by size
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- `large` (Bool) — True for large allocations and False for small
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- `size` (UInt64) — Size of allocations in this bin
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- `allocations` (UInt64) — Number of allocations
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- `deallocations` (UInt64) — Number of deallocations
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**Example**
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Find the sizes of allocations that contributed the most to the current overall memory usage.
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``` sql
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SELECT
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*,
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allocations - deallocations AS active_allocations,
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size * active_allocations AS allocated_bytes
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FROM system.jemalloc_bins
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WHERE allocated_bytes > 0
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ORDER BY allocated_bytes DESC
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LIMIT 10
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```
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``` text
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┌─index─┬─large─┬─────size─┬─allocactions─┬─deallocations─┬─active_allocations─┬─allocated_bytes─┐
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│ 82 │ 1 │ 50331648 │ 1 │ 0 │ 1 │ 50331648 │
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│ 10 │ 0 │ 192 │ 512336 │ 370710 │ 141626 │ 27192192 │
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│ 69 │ 1 │ 5242880 │ 6 │ 2 │ 4 │ 20971520 │
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│ 3 │ 0 │ 48 │ 16938224 │ 16559484 │ 378740 │ 18179520 │
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│ 28 │ 0 │ 4096 │ 122924 │ 119142 │ 3782 │ 15491072 │
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│ 61 │ 1 │ 1310720 │ 44569 │ 44558 │ 11 │ 14417920 │
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│ 39 │ 1 │ 28672 │ 1285 │ 913 │ 372 │ 10665984 │
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│ 4 │ 0 │ 64 │ 2837225 │ 2680568 │ 156657 │ 10026048 │
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│ 6 │ 0 │ 96 │ 2617803 │ 2531435 │ 86368 │ 8291328 │
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│ 36 │ 1 │ 16384 │ 22431 │ 21970 │ 461 │ 7553024 │
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└───────┴───────┴──────────┴──────────────┴───────────────┴────────────────────┴─────────────────┘
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```
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