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fb1a684d98
* Fix race in PageCache * Transportation security administration * Fix test flakiness, remove accidentally left over debug logging
107 lines
4.5 KiB
SQL
107 lines
4.5 KiB
SQL
-- Tags: no-fasttest, no-parallel
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-- no-fasttest because we need an S3 storage policy
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-- no-parallel because we look at server-wide counters about page cache usage
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set use_page_cache_for_disks_without_file_cache = 1;
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set page_cache_inject_eviction = 0;
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set enable_filesystem_cache = 0;
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set use_uncompressed_cache = 0;
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create table events_snapshot engine Memory as select * from system.events;
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create view events_diff as
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-- round all stats to 70 MiB to leave a lot of leeway for overhead
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with if(event like '%Bytes%', 70*1024*1024, 35) as granularity,
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-- cache hits counter can vary a lot depending on other settings:
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-- e.g. if merge_tree_min_bytes_for_concurrent_read is small, multiple threads will read each chunk
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-- so we just check that the value is not too low
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if(event in (
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'PageCacheBytesUnpinnedRoundedToPages', 'PageCacheBytesUnpinnedRoundedToHugePages',
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'PageCacheChunkDataHits'), 1, 1000) as clamp
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select event, min2(intDiv(new.value - old.value, granularity), clamp) as diff
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from system.events new
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left outer join events_snapshot old
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on old.event = new.event
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where diff != 0 and
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event in (
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'ReadBufferFromS3Bytes', 'PageCacheChunkMisses', 'PageCacheChunkDataMisses',
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'PageCacheChunkDataHits', 'PageCacheChunkDataPartialHits',
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'PageCacheBytesUnpinnedRoundedToPages', 'PageCacheBytesUnpinnedRoundedToHugePages')
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order by event;
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drop table if exists page_cache_03055;
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create table page_cache_03055 (k Int64 CODEC(NONE)) engine MergeTree order by k settings storage_policy = 's3_cache';
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-- Write an 80 MiB file (40 x 2 MiB chunks), and a few small files.
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system stop merges page_cache_03055;
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insert into page_cache_03055 select * from numbers(10485760) settings max_block_size=100000000, preferred_block_size_bytes=1000000000;
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select * from events_diff;
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truncate table events_snapshot;
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insert into events_snapshot select * from system.events;
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system start merges page_cache_03055;
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optimize table page_cache_03055 final;
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truncate table events_snapshot;
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insert into events_snapshot select * from system.events;
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-- Cold read, should miss cache. (Populating cache on write is not implemented yet.)
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select 'cold read', sum(k) from page_cache_03055;
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select * from events_diff where event not in ('PageCacheChunkDataHits');
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truncate table events_snapshot;
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insert into events_snapshot select * from system.events;
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-- Repeat read, should hit cache.
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select 'repeat read 1', sum(k) from page_cache_03055;
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select * from events_diff;
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truncate table events_snapshot;
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insert into events_snapshot select * from system.events;
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-- Drop cache and read again, should miss. Also don't write to cache.
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system drop page cache;
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select 'dropped and bypassed cache', sum(k) from page_cache_03055 settings read_from_page_cache_if_exists_otherwise_bypass_cache = 1;
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-- Data could be read multiple times because we're not writing to cache.
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-- (Not checking PageCacheBytesUnpinned* because it's unreliable in this case because of an intentional race condition, see PageCache::evictChunk.)
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select event, if(event in ('PageCacheChunkMisses', 'ReadBufferFromS3Bytes'), diff >= 1, diff) from events_diff where event not in ('PageCacheChunkDataHits', 'PageCacheBytesUnpinnedRoundedToPages', 'PageCacheBytesUnpinnedRoundedToHugePages');
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truncate table events_snapshot;
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insert into events_snapshot select * from system.events;
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-- Repeat read, should still miss, but populate cache.
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select 'repeat read 2', sum(k) from page_cache_03055;
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select * from events_diff where event not in ('PageCacheChunkDataHits');
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truncate table events_snapshot;
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insert into events_snapshot select * from system.events;
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-- Read again, hit the cache.
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select 'repeat read 3', sum(k) from page_cache_03055 settings read_from_page_cache_if_exists_otherwise_bypass_cache = 1;
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select * from events_diff;
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truncate table events_snapshot;
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insert into events_snapshot select * from system.events;
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-- Known limitation: cache is not invalidated if a table is dropped and created again at the same path.
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-- set allow_deprecated_database_ordinary=1;
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-- create database test_03055 engine = Ordinary;
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-- create table test_03055.t (k Int64) engine MergeTree order by k settings storage_policy = 's3_cache';
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-- insert into test_03055.t values (1);
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-- select * from test_03055.t;
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-- drop table test_03055.t;
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-- create table test_03055.t (k Int64) engine MergeTree order by k settings storage_policy = 's3_cache';
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-- insert into test_03055.t values (2);
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-- select * from test_03055.t;
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drop table events_snapshot;
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drop table page_cache_03055;
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drop view events_diff;
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