{"id":18056,"date":"2018-12-18T09:00:08","date_gmt":"2018-12-18T00:00:08","guid":{"rendered":"http:\/\/www.techscore.com\/blog\/?p=18056"},"modified":"2018-12-18T09:43:30","modified_gmt":"2018-12-18T00:43:30","slug":"postgresql-vacuum%e3%81%a7%e5%b9%b4%e6%9c%ab%e5%a4%a7%e6%8e%83%e9%99%a4","status":"publish","type":"post","link":"https:\/\/www.techscore.com\/blog\/2018\/12\/18\/postgresql-vacuum%e3%81%a7%e5%b9%b4%e6%9c%ab%e5%a4%a7%e6%8e%83%e9%99%a4\/","title":{"rendered":"PostgreSQL VACUUM \u3067\u5e74\u672b\u5927\u6383\u9664"},"content":{"rendered":"

\u3053\u308c\u306f TECHSCORE Advent Calendar 2018<\/a> \u306e18\u65e5\u76ee\u306e\u8a18\u4e8b\u3067\u3059\u3002<\/p>\n

\u4eca\u56de\u306fPostgreSQL\u3092\u904b\u7528\u3059\u308b\u4e0a\u3067\u7d76\u5bfe\u306b\u7121\u8996\u3067\u304d\u306a\u3044\u300cVACUUM\u300d\u306b\u3064\u3044\u3066\u3001\u305d\u306e\u6a5f\u80fd\u3068\u5f79\u5272\u3092\u78ba\u8a8d\u3057\u3066\u3044\u304d\u305f\u3044\u3068\u601d\u3044\u307e\u3059\u3002<\/p>\n

VACUUM\u3068\u306f<\/h2>\n

VACUUM\u306f\u3001\u30c6\u30fc\u30d6\u30eb\u306e\u5b9f\u4f53\u3068\u306a\u308b\u30d5\u30a1\u30a4\u30eb\u306e\u4e2d\u304b\u3089\u3001\u4e0d\u8981\u9818\u57df\u3092\u63a2\u7d22\u3057\u3001\u518d\u5229\u7528\u53ef\u80fd\u306a\u72b6\u614b\u306b\u3057\u3066\u3044\u304f\u3082\u306e\u3067\u3059\u3002VACUUM\u3092\u5168\u304f\u5b9f\u884c\u3057\u306a\u3044\u5834\u5408\u3001\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u304c\u5897\u3048\u7d9a\u3051\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u4f4e\u4e0b\u3001\u30c7\u30a3\u30b9\u30af\u30b9\u30da\u30fc\u30b9\u306e\u5727\u8feb\u3078\u3068\u3064\u306a\u304c\u308a\u307e\u3059\u3002<\/p>\n

AUTO VACUUM\u6a5f\u80fd<\/h2>\n

PostgreSQL\u306b\u306f\u300cAUTO VACUUM\u300d\u6a5f\u80fd\u304c\u642d\u8f09\u3055\u308c\u3066\u304a\u308a\u3001\u81ea\u52d5\u3067\u968f\u6642VACUUM\u304c\u5b9f\u884c\u3055\u308c\u308b\u305f\u3081\u3001\u591a\u304f\u306e\u5834\u5408\u554f\u984c\u3068\u306a\u308a\u307e\u305b\u3093\u3002\u3057\u304b\u3057\u3001AUTO VACUUM\u3082\u4e07\u80fd\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u30c6\u30fc\u30d6\u30eb\u306b\u3088\u3063\u3066\u8ffd\u52a0\u30fb\u66f4\u65b0\u30fb\u524a\u9664\u306e\u983b\u5ea6\u3001\u898f\u6a21\u306f\u69d8\u3005\u3067\u3042\u308b\u305f\u3081\u3001AUTO VACUUM\u6a5f\u80fd\u306b\u3088\u308bVACUUM\u5b9f\u884c\u306e\u30bf\u30a4\u30df\u30f3\u30b0\u304c\u9069\u5207\u3067\u306a\u3044\u30b1\u30fc\u30b9\u304c\u3067\u3066\u304d\u307e\u3059\u3002
\n\uff08AUTO VACUUM\u306b\u3088\u308bVACUUM\u5b9f\u884c\u306e\u30bf\u30a4\u30df\u30f3\u30b0\u306f\u8a2d\u5b9a\u306b\u3088\u308a\u8abf\u6574\u304c\u53ef\u80fd\u3067\u3059\u3002autovacuum_vacuum_threshold\u3001autovacuum_vacuum_scale_factor\u7b49\uff09<\/p>\n

\u306a\u305cVACUUM\u304c\u5fc5\u8981\u304b<\/h2>\n

PostgreSQL\u306f\u8ffd\u8a18\u578b\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3\u3092\u63a1\u7528\u3057\u3066\u3044\u308b\u305f\u3081\u3067\u3059\u3002PostgreSQL\u304c\u884c\u306e\u8ffd\u52a0\u30fb\u66f4\u65b0\u30fb\u524a\u9664\u3092\u3069\u306e\u3088\u3046\u306b\u884c\u3046\u304b\u3001\u304a\u304a\u3056\u3063\u3071\u306b\u3067\u3059\u304c\u78ba\u8a8d\u3057\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n

PostgreSQL\u306f\u30c7\u30fc\u30bf\u30928KB\u5358\u4f4d\u3067\u7ba1\u7406\u3057\u307e\u3059\u3002\u7a7a\u306e\u30c6\u30fc\u30d6\u30eb\u306b1\u884cINSERT\u3059\u308b\u5834\u5408\u30018KB\u306e\u7a7a\u304d\u9818\u57df\u3092\u6e96\u5099\u3057\u3001\u305d\u3053\u306b\u30c7\u30fc\u30bf\u3092\u683c\u7d0d\u3057\u307e\u3059\u3002
\n\u3055\u3089\u306bINSERT\u3092\u7d9a\u3051\u30018KB\u306e\u7a7a\u304d\u9818\u57df\u304c\u4e0d\u8db3\u3057\u305f\u5834\u5408\u3001\u8ffd\u52a0\u30678KB\u306e\u9818\u57df\u3092\u78ba\u4fdd\u3057\u307e\u3059\u3002\u3053\u306e\u30bf\u30a4\u30df\u30f3\u30b0\u3067\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u304c\u5927\u304d\u304f\u306a\u308b\u3053\u3068\u306b\u306a\u308a\u307e\u3059\u3002
\n\"\"<\/a><\/p>\n

\u6b21\u306bDELETE\u3067\u3059\u304c\u3001DELETE\u306f\u5bfe\u8c61\u306e\u884c\u306b\u300c\u4e0d\u8981\u300d\u3068\u3044\u3046\u5370\u4ed8\u3051\u3092\u884c\u3046\u306e\u307f\u3067\u3001\u5b9f\u969b\u306b\u6d88\u3048\u308b\u3053\u3068\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u5370\u4ed8\u3051\u3089\u308c\u305f\u884c\u306f\u305d\u308c\u4ee5\u964d\u306e\u30c8\u30e9\u30f3\u30b6\u30af\u30b7\u30e7\u30f3\u304b\u3089\u898b\u3048\u306a\u304f\u306a\u308a\u3001\u7d50\u679c\u3068\u3057\u3066\u524a\u9664\u3055\u308c\u305f\u3053\u3068\u3068\u306a\u308a\u307e\u3059\u3002
\n\"\"<\/a><\/p>\n

\u6b21\u306bUPDATE\u3067\u3059\u304c\u3001DELETE + INSERT\u306e\u3088\u3046\u306a\u52d5\u4f5c\u3068\u306a\u308a\u307e\u3059\u3002UPDATE\u5bfe\u8c61\u306e\u884c\u306b\u300c\u4e0d\u8981\u300d\u3068\u3044\u3046\u5370\u4ed8\u3051\u3092\u884c\u3044\u3001\u66f4\u65b0\u5185\u5bb9\u3092\u65b0\u3057\u3044\u884c\u3068\u3057\u3066\u8ffd\u52a0\u3057\u307e\u3059\u3002
\n\"\"<\/a><\/p>\n

\u305d\u306e\u305f\u3081\u3001INSERT\/UPDATE\/DELETE\u3092\u7d9a\u3051\u308b\u3068\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u304c\u5927\u304d\u304f\u306a\u308a\u7d9a\u3051\u307e\u3059\u3002\u305d\u3053\u3067\u3001VACUUM\u3067\u3059\u3002
\nVACUUM\u3067\u306f\u300c\u4e0d\u8981\u300d\u3068\u5370\u4ed8\u3051\u3055\u308c\u305f\u9818\u57df\u3092\u300c\u518d\u5229\u7528\u53ef\u80fd\u300d\u3068\u3057\u3066\u5370\u4ed8\u3051\u307e\u3059\u3002\u518d\u5229\u7528\u53ef\u80fd\u306a\u9818\u57df\u306f\u3001\u4ee5\u964d\u306eINSERT\/UPDATE\u6642\u306b\u5229\u7528\u3055\u308c\u307e\u3059\u3002
\n\"\"<\/a><\/p>\n

\u5b9f\u969b\u306b\u8a66\u3057\u3066\u307f\u308b\uff08VACUUM\uff09<\/h2>\n

\u30c6\u30fc\u30d6\u30eb\u306b\u5927\u91cf\u30c7\u30fc\u30bf\u3092\u5165\u308c\u3001VACUUM\u306e\u6319\u52d5\u3092\u5b9f\u969b\u306b\u78ba\u8a8d\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002
\n\uff08\u3053\u3053\u3067\u306e\u691c\u8a3c\u306b\u306fPostgreSQL\u30d0\u30fc\u30b8\u30e7\u30f311.1\u3092\u4f7f\u7528\u3057\u307e\u3057\u305f\u3002\uff09<\/p>\n

\u30c6\u30b9\u30c8\u7528\u306e\u30c6\u30fc\u30d6\u30eb\u3092\u6e96\u5099\u3057\u307e\u3059\u3002<\/p>\n

\ntest=# CREATE TABLE foobar(id INTEGER, val TEXT);\nCREATE TABLE\n<\/pre>\n
\u30c6\u30fc\u30d6\u30eb\u306e\u5b9f\u30d5\u30a1\u30a4\u30eb\u3092\u78ba\u8a8d\u3057\u307e\u3059\u3002
\n\u5b9f\u30d5\u30a1\u30a4\u30eb\u306f\u30c7\u30d5\u30a9\u30eb\u30c8\u3067$PGDATA\u4ee5\u4e0b\u306ebase\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u4ee5\u4e0b\u306b\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u3054\u3068\u306b\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u304c\u5207\u3089\u308c\u3001\u30c6\u30fc\u30d6\u30eb\u306erelfilenode\u304c\u30d5\u30a1\u30a4\u30eb\u540d\u3068\u306a\u3063\u3066\u914d\u7f6e\u3055\u308c\u307e\u3059\u3002<\/p>\n
\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306eID\u3068\u3001\u30c6\u30fc\u30d6\u30eb\u306erelfilenode\u3092\u78ba\u8a8d\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n
\ntest=# SELECT datid, datname FROM pg_stat_database WHERE datname = 'test';\n datid | datname\n-------+---------\n 16384 | test\n(1 row)\n\ntest=# SELECT relfilenode,relname FROM pg_class WHERE relname = 'foobar';\n relfilenode | relname\n-------------+---------\n       16418 | foobar\n(1 row)\n<\/pre>\n
\u4ee5\u4e0a\u304b\u3089\u3001\u30c6\u30fc\u30d6\u30eb\u306e\u30d5\u30a1\u30a4\u30eb\u306f $PGDATA\/base\/16384\/16418 \u306b\u3042\u308b\u3053\u3068\u304c\u308f\u304b\u308a\u307e\u3059\u3002\u78ba\u8a8d\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n
\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16418*\n-rw------- 1 postgres postgres 0 12\u6708  5 15:28 \/tmp\/testdb\/\/base\/16384\/16418\n<\/pre>\n
\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u304c\u30bc\u30ed\u3067\u3059\u306d\u3002<\/p>\n
\u9069\u5f53\u306b1\u884cINSERT\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n
\ntest=# INSERT INTO foobar(id, val) VALUES (1, 'abc');\nINSERT 0 1\n<\/pre>\n
\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16418*\n-rw------- 1 postgres postgres 8.0K 12\u6708  5 15:29 \/tmp\/testdb\/\/base\/16384\/16418\n<\/pre>\n
\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u304c8KB\u3068\u306a\u308a\u307e\u3057\u305f\u3002<\/p>\n
\u5148\u307b\u3069\u6295\u5165\u3057\u305fid\u304c1\u306e\u3082\u306e\u3092SELECT\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n
\ntest=# EXPLAIN ANALYZE SELECT * FROM foobar WHERE id = 1;\n                                            QUERY PLAN                                            \n--------------------------------------------------------------------------------------------------\n Seq Scan on foobar  (cost=0.00..25.62 rows=1 width=37) (actual time=0.016..0.019 rows=1 loops=1)\n   Filter: (id = 1)\n Planning Time: 0.084 ms\n Execution Time: 0.043 ms\n(4 rows)\n<\/pre>\n
1\u4ef6\u3057\u304b\u30c7\u30fc\u30bf\u304c\u306a\u3044\u306e\u3067 1ms \u3082\u304b\u304b\u3089\u306a\u3044\u3067\u3059\u306d\u3002<\/p>\n
\u3067\u306f\u30c7\u30fc\u30bf\u3092\u4e00\u6c17\u306b1000\u4e07\u4ef6INSERT\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n
\ntest=# INSERT INTO foobar(id, val) SELECT id,md5(clock_timestamp()::TEXT) AS val FROM generate_series(1,10000000) AS id;\nINSERT 0 10000000\n\ntest=# SELECT COUNT(*) FROM foobar;\n  count\n----------\n 10000001\n(1 row)\n<\/pre>\n
\u6700\u521d\u306bINSERT\u3057\u305f\u30c7\u30fc\u30bf\u3068\u3042\u308f\u305b\u306610000001\u4ef6\u3067\u3059\u3002<\/p>\n
\u30c7\u30fc\u30bf\u306e\u5185\u5bb9\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u611f\u3058\u3067\u3059\u3002<\/p>\n
\ntest=# SELECT * FROM foobar LIMIT 5;\n id |               val\n----+----------------------------------\n  1 | abc\n  1 | d58fda95c19c28d37ea6e7f920775c26\n  2 | 7aee59e7193efcbc9621d8a3687aa522\n  3 | eb69b8be847b4384b2493f8e04b0106b\n  4 | 606173a18a62d2e8208f94e58e5751cd\n(5 rows)\n<\/pre>\n
\u30d5\u30a1\u30a4\u30eb\u3092\u78ba\u8a8d\u3059\u308b\u3068\u4e00\u6c17\u306b\u7d04650MB\u3068\u306a\u308a\u307e\u3057\u305f\u3002<\/p>\n
\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16418*\n-rw------- 1 postgres postgres 652M 12\u6708  5 15:34 \/tmp\/testdb\/\/base\/16384\/16418\n<\/pre>\n
id\u304c1\u306e\u30c7\u30fc\u30bf\u3092SELECT\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n
\ntest=# EXPLAIN ANALYZE SELECT * FROM foobar WHERE id = 1;\n                                                       QUERY PLAN\n-------------------------------------------------------------------------------------------------------------------------\n Gather  (cost=1000.00..138588.01 rows=1 width=37) (actual time=0.285..249.641 rows=2 loops=1)\n   Workers Planned: 2\n   Workers Launched: 2\n   ->  Parallel Seq Scan on foobar  (cost=0.00..137587.91 rows=1 width=37) (actual time=161.653..243.944 rows=1 loops=3)\n         Filter: (id = 1)\n         Rows Removed by Filter: 3333333\n Planning Time: 0.072 ms\n Execution Time: 249.674 ms\n(8 rows)\n<\/pre>\n
\u3055\u3059\u304c\u306b\u7d041000\u4e07\u4ef6\u3082\u30c7\u30fc\u30bf\u304c\u3042\u308b\u306e\u3067\u9045\u3044\u3067\u3059\u3002\u7d04250ms\u304b\u304b\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u305f\u3002
\n\u30d1\u30e9\u30ec\u30eb\u30b7\u30fc\u30b1\u30f3\u30b7\u30e3\u30eb\u30b9\u30ad\u30e3\u30f3\u304c\u5b9f\u88c5\u3055\u308c\u3066\u3044\u306a\u304b\u3063\u305f\u6642\u4ee3\u3060\u3068\u3082\u3063\u3068\u6c17\u304c\u9060\u304f\u306a\u308b\u307b\u3069\u9045\u304b\u3063\u305f\u3053\u3068\u3067\u3057\u3087\u3046\u3002\uff0f(\u30c4)\uff3c<\/p>\n
\u3053\u3053\u304b\u3089\u304c\u4eca\u56de\u306e\u672c\u984c\u3067\u3059\u3002
\n\u6295\u5165\u3057\u305f\u30c7\u30fc\u30bf\u3092id\u304c10000000\u306e\u3082\u306e1\u4ef6\u3060\u3051\u3092\u6b8b\u3057\u3066\u524a\u9664\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n
\ntest=# DELETE FROM foobar WHERE id <= 9999999;\nDELETE 10000000\ntest=# SELECT COUNT(*) FROM foobar;\n count\n-------\n     1\n(1 row)\n<\/pre>\n
\u30c7\u30fc\u30bf\u304c1\u4ef6\u3060\u3051\u306b\u306a\u308a\u307e\u3057\u305f\u3002\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u3092\u78ba\u8a8d\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n
\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16418*\n-rw------- 1 postgres postgres 652M 12\u6708  5 15:42 \/tmp\/testdb\/\/base\/16384\/16418\n<\/pre>\n
\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u304c\u5c0f\u3055\u304f\u306a\u308b\u3053\u3068\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u304b\u306a\u3057\u3044\u3067\u3059\u306d\u3002<\/p>\n
id\u304c1\u306e\u30c7\u30fc\u30bf\u3092SELECT\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n
\ntest=# EXPLAIN ANALYZE SELECT * FROM foobar WHERE id = 1;\n                                                        QUERY PLAN\n---------------------------------------------------------------------------------------------------------------------------\n Gather  (cost=1000.00..144747.67 rows=52917 width=36) (actual time=101.558..102.279 rows=0 loops=1)\n   Workers Planned: 2\n   Workers Launched: 2\n   ->  Parallel Seq Scan on foobar  (cost=0.00..138455.97 rows=22049 width=36) (actual time=98.330..98.331 rows=0 loops=3)\n         Filter: (id = 1)\n         Rows Removed by Filter: 0\n Planning Time: 0.070 ms\n Execution Time: 102.305 ms\n(8 rows)\n<\/pre>\n
\u5148\u307b\u3069\u3088\u308a\u3082\u304b\u306a\u308a\u30de\u30b7\u3067\u306f\u3042\u308a\u307e\u3059\u304c\u3001\u6700\u521d\u306b1\u4ef6\u3060\u3051INSERT\u3057\u305f\u3068\u304d\u306b\u6bd4\u3079\u308b\u3068\u304b\u306a\u308a\u9045\u3044\u3067\u3059\u306d\u3002<\/p>\n
\u3053\u3053\u307e\u3067\u3067DELETE\u3092\u3057\u3066\u3082\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u304c\u5c0f\u3055\u304f\u306a\u308b\u3053\u3068\u306f\u306a\u304f\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3082\u4f4e\u4e0b\u3059\u308b\u3053\u3068\u3092\u78ba\u8a8d\u3067\u304d\u307e\u3057\u305f\u3002<\/p>\n
\u3082\u3046\u4e00\u5ea61000\u4e07\u4ef6\u306e\u30c7\u30fc\u30bf\u3092\u6295\u5165\u3057\u307e\u3059\u3002<\/p>\n
\ntest=# INSERT INTO foobar(id, val) SELECT id,md5(clock_timestamp()::TEXT) AS val FROM generate_series(1,10000000) AS id;\nINSERT 0 10000000\ntest=# select count(*) from foobar;\n  count\n----------\n 10000001\n(1 row)\n<\/pre>\n
\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u3092\u78ba\u8a8d\u3057\u3066\u307f\u307e\u3059\u3002<\/p>\n
\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16418*\n-rw------- 1 postgres postgres 1.0G 12\u6708  5 15:46 \/tmp\/testdb\/\/base\/16384\/16418\n-rw------- 1 postgres postgres 279M 12\u6708  5 15:47 \/tmp\/testdb\/\/base\/16384\/16418.1\n<\/pre>\n
1279MB\u3068\u306a\u308a\u3001\u7d042\u500d\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002
\n\uff08PostgreSQL\u306f\u30c7\u30d5\u30a9\u30eb\u30c8\u8a2d\u5b9a\u30671GB\u6bce\u306b\u30d5\u30a1\u30a4\u30eb\u3092\u5206\u5272\u3057\u3066\u7ba1\u7406\u3057\u307e\u3059\u3002\uff09
\nVACUUM\u3067\u4e0d\u8981\u9818\u57df\u3092\u56de\u53ce\u3057\u3066\u3044\u306a\u304b\u3063\u305f\u305f\u3081\u3001\u3059\u3079\u3066\u65b0\u898f\u306b\u8ffd\u8a18\u3055\u308c\u3066\u3057\u307e\u3063\u305f\u3088\u3046\u3067\u3059\u3002<\/p>\n
SELECT\u6027\u80fd\u3092\u307f\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u5148\u307b\u3069\u7d041000\u4e07\u4ef6\u306e\u30c7\u30fc\u30bf\u304c\u3042\u308b\u3068\u304d\u306f\u7d04 250ms \u3067\u3057\u305f\u3002
\n\u4eca\u56de\u306f\u3002\u3002\u3002<\/p>\n
\ntest=# EXPLAIN ANALYZE SELECT * FROM foobar WHERE id = 1;\n                                                         QUERY PLAN\n-----------------------------------------------------------------------------------------------------------------------------\n Gather  (cost=1000.00..288493.68 rows=105834 width=36) (actual time=95.332..420.700 rows=1 loops=1)\n   Workers Planned: 2\n   Workers Launched: 2\n   ->  Parallel Seq Scan on foobar  (cost=0.00..276910.28 rows=44098 width=36) (actual time=305.777..412.998 rows=0 loops=3)\n         Filter: (id = 1)\n         Rows Removed by Filter: 3333333\n Planning Time: 0.071 ms\n Execution Time: 420.737 ms\n(8 rows)\n<\/pre>\n
\u7d04420ms\u3068\u306a\u308a\u3001\u3055\u3089\u306b\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u4f4e\u4e0b\u3057\u3066\u3057\u307e\u3044\u307e\u3057\u305f\u3002<\/p>\n
\u518d\u5ea6\u3001id\u304c10000000\u4ee5\u5916\u306e\u3082\u306e\u3092\u524a\u9664\u3057\u307e\u3059\u3002<\/p>\n
\ntest=# DELETE FROM foobar WHERE id <= 9999999;\nDELETE 9999999\ntest=# select count(*) from foobar;\n count\n-------\n     2\n(1 row)\n<\/pre>\n
\u6b8b\u3063\u3066\u3044\u308b\u30c7\u30fc\u30bf\u306f2\u4ef6\u3060\u3051\u3067\u3059\u3002SELECT\u6027\u80fd\u306f\u3069\u3046\u3067\u3057\u3087\u3046\u304b\u3002<\/p>\n
\ntest=# EXPLAIN ANALYZE SELECT * FROM foobar WHERE id = 1;\n                                                         QUERY PLAN\n-----------------------------------------------------------------------------------------------------------------------------\n Gather  (cost=1000.00..288493.68 rows=105834 width=36) (actual time=191.770..194.099 rows=0 loops=1)\n   Workers Planned: 2\n   Workers Launched: 2\n   ->  Parallel Seq Scan on foobar  (cost=0.00..276910.28 rows=44098 width=36) (actual time=188.356..188.357 rows=0 loops=3)\n         Filter: (id = 1)\n         Rows Removed by Filter: 1\n Planning Time: 0.071 ms\n Execution Time: 194.127 ms\n(8 rows)\n<\/pre>\n
\u30c7\u30fc\u30bf\u304c2\u4ef6\u3057\u304b\u306a\u3044\u306b\u3082\u304b\u304b\u308f\u3089\u305a\u7d04200ms\u3082\u304b\u304b\u3063\u3066\u3057\u307e\u3063\u3066\u3044\u307e\u3059\u3002\u3053\u308c\u306f\u3072\u3069\u3044\u3002<\/p>\n
VACUUM\u306e\u52b9\u679c\u3092\u8a66\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002
\n\u3053\u308c\u307e\u3067\u306bDELETE\u3057\u305f\u7d042000\u4e07\u4ef6\u306e\u4e0d\u8981\u30c7\u30fc\u30bf\u306e\u9818\u57df\u3092\u518d\u5229\u7528\u53ef\u80fd\u306b\u3057\u307e\u3059\u3002<\/p>\n
\ntest=# VACUUM foobar;\nVACUUM\n<\/pre>\n
\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u3092\u78ba\u8a8d\u3057\u307e\u3059\u3002<\/p>\n
\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16418*\n-rw------- 1 postgres postgres 1.0G 12\u6708  5 16:09 \/tmp\/testdb\/\/base\/16384\/16418\n-rw------- 1 postgres postgres 279M 12\u6708  5 16:10 \/tmp\/testdb\/\/base\/16384\/16418.1\n<\/pre>\n
\u518d\u5229\u7528\u53ef\u80fd\u306b\u3059\u308b\u3060\u3051\u306a\u306e\u3067\u3001\u5909\u5316\u306f\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n
\u3082\u3046\u4e00\u5ea61000\u4e07\u4ef6\u306e\u30c7\u30fc\u30bf\u3092\u6295\u5165\u3057\u307e\u3059\u3002<\/p>\n
\ntest=# INSERT INTO foobar(id, val) SELECT id,md5(clock_timestamp()::TEXT) AS val FROM generate_series(1,10000000) AS id;\nINSERT 0 10000000\n<\/pre>\n
\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u3092\u78ba\u8a8d\u3057\u307e\u3059\u3002<\/p>\n
\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16418*\n-rw------- 1 postgres postgres 1.0G 12\u6708  5 16:13 \/tmp\/testdb\/\/base\/16384\/16418\n-rw------- 1 postgres postgres 279M 12\u6708  5 16:13 \/tmp\/testdb\/\/base\/16384\/16418.1\n<\/pre>\n
\u518d\u5229\u7528\u53ef\u80fd\u306a\u9818\u57df\u306b1000\u4e07\u4ef6\u306e\u30c7\u30fc\u30bf\u304c\u683c\u7d0d\u3055\u308c\u305f\u306e\u3067\u5909\u5316\u306f\u3042\u308a\u307e\u305b\u3093\u3002
\n\u307e\u3060\u518d\u5229\u7528\u53ef\u80fd\u306a\u9818\u57df\u304c\u6b8b\u3063\u3066\u3044\u308b\u306f\u305a\u306a\u306e\u3067\u3001\u3055\u3089\u306b1000\u4e07\u4ef6\u884c\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n
\ntest=# INSERT INTO foobar(id, val) SELECT id,md5(clock_timestamp()::TEXT) AS val FROM generate_series(1,10000000) AS id;\nINSERT 0 10000000\n<\/pre>\n
\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u3092\u78ba\u8a8d\u3057\u307e\u3059\u3002<\/p>\n
\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16418*\n-rw------- 1 postgres postgres 1.0G 12\u6708 13 13:00 \/tmp\/testdb\/base\/16384\/16418\n-rw------- 1 postgres postgres 279M 12\u6708 13 13:01 \/tmp\/testdb\/base\/16384\/16418.1\n<\/pre>\n
\u30b5\u30a4\u30ba\u306f\u5909\u308f\u3063\u3066\u3044\u307e\u305b\u3093\u3002\u518d\u5229\u7528\u53ef\u80fd\u306a\u9818\u57df\u306b\u53ce\u307e\u308a\u304d\u3063\u305f\u3088\u3046\u3067\u3059\u3002<\/p>\n
VACUUM\u306e\u52b9\u679c\u304c\u51fa\u3066\u3044\u307e\u3059\u306d\u3002
\n\u5b9a\u671f\u7684\u306bVACUUM\u3092\u5b9f\u884c\u3057\u3066\u3044\u308c\u3070\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u306e\u80a5\u5927\u5316\u3092\u6291\u5236\u3067\u304d\u308b\u3053\u3068\u3092\u78ba\u8a8d\u3067\u304d\u307e\u3057\u305f\u3002<\/p>\n
\u3057\u304b\u3057\u3001VACUUM\u3067\u306f\u4e00\u5ea6\u80a5\u5927\u5316\u3057\u3066\u3057\u307e\u3063\u305f\u30c6\u30fc\u30d6\u30eb\u3092\u5c0f\u3055\u304f\u3059\u308b\u3053\u3068\u306f\u3067\u304d\u307e\u305b\u3093\u3057\u3001\u4f4e\u4e0b\u3057\u3066\u3057\u307e\u3063\u305f\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3082\u6539\u5584\u3057\u307e\u305b\u3093\u3002\u3042\u304f\u307e\u3067\u3082\u6291\u5236\u306b\u3057\u304b\u306a\u3089\u306a\u3044\u306e\u3067\u3059\u3002
\n\u3053\u3053\u3067 VACUUM FULL \u306e\u51fa\u756a\u3067\u3059\u3002<\/p>\n
\u5b9f\u969b\u306b\u8a66\u3057\u3066\u307f\u308b\uff08VACUUM FULL\uff09<\/h2>\n
\u3082\u3046\u4e00\u5ea6id\u304c10000000\u306e\u3082\u306e\u3092\u6b8b\u3057\u3066\u524a\u9664\u3057\u307e\u3059\u3002<\/p>\n
\ntest=# DELETE FROM foobar WHERE id <= 9999999;\nDELETE 19999998\ntest=# SELECT COUNT(*) FROM foobar;\n count\n-------\n     4\n(1 row)\n<\/pre>\n
\u6b8b\u3063\u305f\u30c7\u30fc\u30bf\u306f4\u4ef6\u306e\u307f\u3067\u3059\u3002
\nVACUUM\u3092\u3057\u3066\u307f\u307e\u3059\u304c\u3001\u5f53\u7136\u3001\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u306f\u5909\u308f\u308a\u307e\u305b\u3093\u3002<\/p>\n
\ntest=# vacuum foobar ;\nVACUUM\n\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16418*\n-rw------- 1 postgres postgres 1.0G 12\u6708 13 13:10 \/tmp\/testdb\/base\/16384\/16418\n-rw------- 1 postgres postgres 279M 12\u6708 13 13:10 \/tmp\/testdb\/base\/16384\/16418.1\n<\/pre>\n
\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3082\u60aa\u3044\u307e\u307e\u3067\u3059\u3002<\/p>\n
\ntest=# EXPLAIN ANALYZE SELECT * FROM foobar WHERE id = 1;\n                                                QUERY PLAN\n----------------------------------------------------------------------------------------------------------\n Seq Scan on foobar  (cost=0.00..166667.10 rows=1 width=36) (actual time=349.559..349.559 rows=0 loops=1)\n   Filter: (id = 1)\n   Rows Removed by Filter: 8\n Planning Time: 0.067 ms\n Execution Time: 349.585 ms\n(5 rows)\n<\/pre>\n
\u30c7\u30fc\u30bf4\u4ef6\u306e\u307f\u3067\u7d04350ms\u3002\u3002\u3002<\/p>\n
\u305d\u308c\u3067\u306f\u3044\u3088\u3044\u3088VACUUM FULL\u3092\u5b9f\u884c\u3057\u307e\u3059\u3002<\/p>\n
\ntest=# VACUUM FULL foobar;\nVACUUM\n<\/pre>\n
VACUUM FULL\u3067\u306f\u65b0\u3057\u3044\u30d5\u30a1\u30a4\u30eb\u306b\u30c7\u30fc\u30bf\u3092\u6574\u7406\u3057\u3066\u5165\u308c\u306a\u304a\u3055\u308c\u308b\u306e\u3067\u3001\u518d\u5ea6\u30d5\u30a1\u30a4\u30eb\u540d\u3092\u78ba\u8a8d\u3057\u307e\u3059\u3002<\/p>\n
\ntest=# SELECT relfilenode,relname FROM pg_class WHERE relname = 'foobar';\n relfilenode | relname\n-------------+---------\n       16424 | foobar\n(1 row)\n<\/pre>\n
\u30d5\u30a1\u30a4\u30eb\u3092\u78ba\u8a8d\u3057\u307e\u3059\u3002<\/p>\n
\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16424*\n-rw------- 1 postgres postgres 8.0K 12\u6708 13 13:14 \/tmp\/testdb\/base\/16384\/16424\n<\/pre>\n
\u30c7\u30fc\u30bf\u304c4\u4ef6\u3057\u304b\u306a\u3044\u306e\u30671\u30d6\u30ed\u30c3\u30af\u306b\u53ce\u307e\u308a\u3001\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u304c8KB\u3068\u306a\u308a\u307e\u3057\u305f\uff01<\/p>\n
\ntest=# EXPLAIN ANALYZE SELECT * FROM foobar WHERE id = 1;\n                                           QUERY PLAN\n-------------------------------------------------------------------------------------------------\n Seq Scan on foobar  (cost=0.00..1.05 rows=1 width=37) (actual time=0.067..0.069 rows=0 loops=1)\n   Filter: (id = 1)\n   Rows Removed by Filter: 4\n Planning Time: 0.130 ms\n Execution Time: 0.094 ms\n(5 rows)\n<\/pre>\n
SELECT\u6027\u80fd\u3082\u5b8c\u5168\u306b\u5fa9\u6d3b\u3067\u3059\uff01<\/p>\n
VACUUM\u306e\u4f8b\u5916\u30b1\u30fc\u30b9<\/h2>\n
VACUUM\u3067\u306f\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u304c\u5c0f\u3055\u304f\u306a\u3089\u306a\u3044\u3053\u3068\u3092\u78ba\u8a8d\u3057\u307e\u3057\u305f\u304c\u3001VACUUM\u3067\u3082\u5c0f\u3055\u304f\u306a\u308b\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002\u305d\u308c\u306f\u3001\u30d5\u30a1\u30a4\u30eb\u672b\u5c3e\u304b\u3089\u9023\u7d9a\u3057\u3066\u4e0d\u8981\u9818\u57df\u304c\u5b58\u5728\u3059\u308b\u5834\u5408\u3067\u3059\u3002\u3053\u306e\u3068\u304d\u3001PostgreSQL\u306f\u30d5\u30a1\u30a4\u30eb\u3092\u5207\u308a\u8a70\u3081\u307e\u3059\u3002
\n\u3053\u308c\u307e\u3067\u306e\u52d5\u4f5c\u78ba\u8a8d\u3067 DELETE FROM foobar WHERE id <= 9999999; \u3068\u3057\u3066\u3044\u305f\u306e\u306f\u305d\u306e\u305f\u3081\u3067\u3059\u3002WHERE\u53e5\u3092 id > 1; \u3068\u3059\u308b\u3068\u30d5\u30a1\u30a4\u30eb\u304c\u5207\u308a\u8a70\u3081\u3089\u308c\u3001\u5c0f\u3055\u304f\u306a\u308a\u307e\u3059\u3002\u78ba\u8a8d\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n
\ntest=# INSERT INTO foobar(id, val) SELECT id,md5(clock_timestamp()::TEXT) as val FROM generate_series(1,10000000) AS id;\nINSERT 0 10000000\n\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16424*\n-rw------- 1 postgres postgres 652M 12\u6708 13 15:45 \/tmp\/testdb\/base\/16384\/16424\n<\/pre>\n
\u4e0a\u306e\u72b6\u614b\u304b\u3089\u3001id\u304c1\u306e\u30c7\u30fc\u30bf\uff08\u30d5\u30a1\u30a4\u30eb\u306e\u5148\u982d\u9818\u57df\u306b\u683c\u7d0d\u3055\u308c\u3066\u3044\u308b\u3068\u60f3\u5b9a\u3055\u308c\u308b\uff09\u306e\u307f\u3092\u6b8b\u3057\u3066\u524a\u9664\u3057\u307e\u3059\u3002<\/p>\n
\ntest=# DELETE FROM foobar WHERE id > 1;\nDELETE 9999999\ntest=# SELECT COUNT(*) FROM foobar;\n count\n-------\n     1\n(1 row)\n<\/pre>\n
VACUUM\u3092\u5b9f\u884c\u3057\u3001\u30d5\u30a1\u30a4\u30eb\u30b5\u30a4\u30ba\u3092\u78ba\u8a8d\u3057\u307e\u3059\u3002<\/p>\n
\ntest=# VACUUM foobar;\nVACUUM\n\n[postgres@testdb tmp]$ ls -lh $PGDATA\/base\/16384\/16424*\n-rw------- 1 postgres postgres 8.0K 12\u6708 13 15:47 \/tmp\/testdb\/base\/16384\/16424\n<\/pre>\n
\u5148\u982d\u9818\u57df\u306e\u307f\u3092\u6b8b\u3057\u3066\u3059\u3079\u3066\u6d88\u3048\u3066\u3057\u307e\u3044\u307e\u3057\u305f\u306d\u3002<\/p>\n
\u203b\u3053\u306e\u6319\u52d5\u306f\u516c\u5f0f\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u306b\u8a18\u8f09\u304c\u306a\u3044\u305f\u3081\u3001\u5909\u66f4\u3055\u308c\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n
\u6700\u5f8c\u306b<\/h2>\n
VACUUM FULL\u306f\u30c6\u30fc\u30d6\u30eb\u306b\u6392\u4ed6\u30ed\u30c3\u30af\u3092\u5fc5\u8981\u3068\u3059\u308b\u3046\u3048\u3001\u51e6\u7406\u306b\u975e\u5e38\u306b\u9577\u3044\u6642\u9593\u3092\u8981\u3057\u307e\u3059\u3002\u305d\u306e\u305f\u3081\u3001VACUUM FULL\u306e\u5b9f\u884c\u304c\u30b5\u30fc\u30d3\u30b9\u969c\u5bb3\u306b\u3064\u306a\u304c\u308b\u3053\u3068\u3082\u3042\u308a\u3048\u307e\u3059\u3002
\nVACUUM FULL\u304c\u5fc5\u8981\u3068\u306a\u3089\u306a\u3044\u3088\u3046\u3001\u666e\u6bb5\u304b\u3089\u9069\u5207\u306bVACUUM\u304c\u5b9f\u884c\u3055\u308c\u308b\u3088\u3046\u306bAUTO VACUUM\u306e\u30d1\u30e9\u30e1\u30fc\u30bf\u8abf\u6574\u3084\u3001\u5404\u30c6\u30fc\u30d6\u30eb\u306eVACUUM\u5b9f\u884c\u72b6\u6cc1\u306e\u76e3\u8996\u304c\u5927\u5207\u3067\u3059\u3002<\/p>\n
\u5e74\u672b\u306b\u5927\u6383\u9664\u3057\u306a\u304f\u3066\u3044\u3044\u3088\u3046\u306b\u666e\u6bb5\u304b\u3089\u3053\u307e\u3081\u306b\u6383\u9664\u3059\u308b\u3053\u3068\u304c\u5927\u5207\u3067\u3059\u306do(\u30c4)9<\/p>\n","protected":false},"excerpt":{"rendered":"
\u3053\u308c\u306f TECHSCORE Advent Calendar 2018 \u306e18\u65e5\u76ee\u306e\u8a18\u4e8b\u3067\u3059\u3002<\/p>\n
\u4eca\u56de\u306fPostgreSQL\u3092\u904b\u7528\u3059\u308b\u4e0a\u3067\u7d76\u5bfe\u306b\u7121\u8996\u3067\u304d\u306a\u3044\u300cVACUUM\u300d\u306b\u3064\u3044\u3066\u3001\u305d\u306e\u6a5f\u80fd\u3068\u5f79\u5272\u3092\u78ba\u8a8d\u3057\u3066\u3044\u304d\u305f\u3044\u3068\u601d\u3044\u307e\u3059\u3002
\u7d9a\u304d\u3092\u8aad\u3080...<\/a><\/p>\n","protected":false},"author":16,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[308,62,18],"tags":[141],"_links":{"self":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts\/18056"}],"collection":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/users\/16"}],"replies":[{"embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/comments?post=18056"}],"version-history":[{"count":41,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts\/18056\/revisions"}],"predecessor-version":[{"id":21295,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts\/18056\/revisions\/21295"}],"wp:attachment":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/media?parent=18056"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/categories?post=18056"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/tags?post=18056"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}