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                合規國際互聯網加速 OSASE為企業客戶提供高速穩定SD-WAN國際加速解決方案。 廣告
                TokuDB除了有著較好的寫性能外,還有一個重要的特性:壓縮,而且大部分情況下壓縮效果很不錯。 目前TokuDB有4種壓縮算法: ~~~ tokudb_lzma: 壓縮比高,CPU消耗也高 tokudb_zlib: 壓縮比和CPU消耗持中(默認壓縮算法) tokudb_quicklz: 壓縮比低,CPU消耗低 tokudb_uncompressed:無壓縮 ~~~ 使用上也比較簡單: ~~~ MariaDB: CREATE TABLE `t_quicklz` ( `x` int(11) DEFAULT NULL, `y` int(11) DEFAULT NULL ) ENGINE=TokuDB `compression`='tokudb_quicklz' ~~~ ~~~ MySQL(Percona Server): CREATE TABLE `t_quicklz` ( `x` int(11) DEFAULT NULL, `y` int(11) DEFAULT NULL ) ENGINE=TokuDB DEFAULT CHARSET=latin1 ROW_FORMAT=TOKUDB_QUICKLZ ~~~ 可能大家會有一個疑問:如果一個表創建的時候壓縮算法是tokudb_quicklz,我可以通過ALERT TABLE改成其他算法嗎?答案是:可以的! TokuDB在底層實現上,用1byte來標記當前block的壓縮算法,并持久化到磁盤,當壓縮算法改變后,從磁盤讀取數據然后解壓縮的代碼類似: ~~~ switch (block_buffer[0] & 0xF) { case TOKU_NO_COMPRESSION: ... break; case TOKU_ZLIB_METHOD: ... break; case TOKU_QUICKLZ_METHOD: ... break; case TOKU_LZMA_METHOD: ... break; } ~~~ 是不是很機智? 在使用TokuDB的過程中,一般不會改變壓縮算法,除非默認的tokudb_zlib不給力,TokuDB是大block(4MB),壓縮效果較好,enjoy~
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