Summary:
See discussion in D4204. Facebook currently has a 314MB remarkup cache with a 55MB index, which is slow to access. Under the theory that this is an index size/quality problem (the current index is on a potentially-384-byte field, with many keys sharing prefixes), provide a more general index with fancy new features:
  - It implements PhutilKeyValueCache, so it can be a component in cache stacks and supports TTL.
  - It has a 12-byte hash-based key.
  - It automatically compresses large blocks of data (most of what we store is highly-compressible HTML).
Test Plan:
  - Basics:
    - Loaded /paste/, saw caches generate and save.
    - Reloaded /paste/, saw the page hit cache.
  - GC:
    - Ran GC daemon, saw nothing.
    - Set maximum lifetime to 1 second, ran GC daemon, saw it collect the entire cache.
  - Deflate:
    - Selected row formats from the database, saw a mixture of 'raw' and 'deflate' storage.
    - Used profiler to verify that 'deflate' is fast (12 calls @ 220us on my paste list).
  - Ran unit tests
Reviewers: vrana, btrahan
Reviewed By: vrana
CC: aran
Differential Revision: https://secure.phabricator.com/D4259
		
	
		
			
				
	
	
		
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			12 lines
		
	
	
		
			479 B
		
	
	
	
		
			SQL
		
	
	
	
	
	
CREATE TABLE {$NAMESPACE}_cache.cache_general (
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  id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
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  cacheKeyHash CHAR(12) BINARY NOT NULL,
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  cacheKey VARCHAR(128) NOT NULL COLLATE utf8_bin,
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  cacheFormat VARCHAR(16) NOT NULL COLLATE utf8_bin,
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  cacheData LONGBLOB NOT NULL,
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  cacheCreated INT UNSIGNED NOT NULL,
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  cacheExpires INT UNSIGNED,
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  KEY `key_cacheCreated` (cacheCreated),
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  UNIQUE KEY `key_cacheKeyHash` (cacheKeyHash)
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) ENGINE=InnoDB, COLLATE utf8_general_ci;
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