{"id":6059,"date":"2026-08-06T07:00:00","date_gmt":"2026-08-06T04:00:00","guid":{"rendered":"https:\/\/www.dataplatform.gr\/?p=6059"},"modified":"2026-08-07T02:02:50","modified_gmt":"2026-08-06T23:02:50","slug":"ti-ta-wal-sti-postgresql-pos-ta-rythmizoym","status":"publish","type":"post","link":"https:\/\/www.dataplatform.gr\/en\/%cf%84%ce%b9-%ce%b5%ce%af%ce%bd%ce%b1%ce%b9-%cf-%84%ce%b1-wal-%cf%83%cf%84%ce%b7-postgresql-%ce%ba%ceb-1%ce%b9-%cf%80%cf%8e%cf%82-%cf%84%ce%b1-%cf%81-cf%85%ce%b8%ce%bc%ce%af%ce%b6%ce%bf%cf%85%ce%bc\/","title":{"rendered":"What are WALs in PostgreSQL and how do we configure them?"},"content":{"rendered":"<p class=\"wp-block-paragraph\">\u03a3\u03b5 \u03b1\u03c5\u03c4\u03cc \u03c4\u03bf \u03ac\u03c1\u03b8\u03c1\u03bf \u03b8\u03b1 \u03b4\u03bf\u03cd\u03bc\u03b5 \u03c4\u03bf\u03bd \u03bc\u03b7\u03c7\u03b1\u03bd\u03b9\u03c3\u03bc\u03cc \u03c0\u03bf\u03c5 \u03c3\u03c5\u03bd\u03b4\u03ad\u03b5\u03b9 \u03c4\u03b7 \u03bc\u03bd\u03ae\u03bc\u03b7 \u03bc\u03b5 \u03c4\u03bf\u03bd \u03b4\u03af\u03c3\u03ba\u03bf \u03ba\u03b1\u03b9 \u03b5\u03be\u03b1\u03c3\u03c6\u03b1\u03bb\u03af\u03b6\u03b5\u03b9 \u03cc\u03c4\u03b9 \u03b4\u03b5\u03bd \u03b8\u03b1 \u03c7\u03ac\u03c3\u03bf\u03c5\u03bc\u03b5 \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03b1 \u03b1\u03bd \u03c0\u03ad\u03c3\u03b5\u03b9 \u03b7 \u03b2\u03ac\u03c3\u03b7 \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03c9\u03bd (\u03c0.\u03c7. \u03b1\u03c0\u03bf \u03c1\u03b5\u03cd\u03bc\u03b1): \u03c4\u03b1 <strong>Write-Ahead Logs (WAL)<\/strong> and <strong>Checkpoints<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u038c\u03c4\u03b1\u03bd \u03b5\u03ba\u03c4\u03b5\u03bb\u03bf\u03cd\u03bc\u03b5 \u03ad\u03bd\u03b1 <code>INSERT<\/code>, <code>UPDATE<\/code> the <code>DELETE<\/code>, \u03b7 \u03b1\u03bb\u03bb\u03b1\u03b3\u03ae \u03b3\u03af\u03bd\u03b5\u03c4\u03b1\u03b9 \u03b1\u03c1\u03c7\u03b9\u03ba\u03ac \u03c3\u03c4\u03b7 \u03bc\u03bd\u03ae\u03bc\u03b7 (<code>shared_buffer<\/code>) \u03ba\u03b1\u03b9 \u03b1\u03bc\u03ad\u03c3\u03c9\u03c2 \u03bc\u03b5\u03c4\u03ac <strong>\u03ba\u03b1\u03c4\u03b1\u03b3\u03c1\u03ac\u03c6\u03b5\u03c4\u03b1\u03b9 \u03c3\u03c4\u03bf WAL file<\/strong> \u03c3\u03c4\u03bf \u03b4\u03af\u03c3\u03ba\u03bf, \u03ce\u03c3\u03c4\u03b5 \u03bd\u03b1 \u03b5\u03c0\u03b9\u03b2\u03b5\u03b2\u03b1\u03b9\u03c9\u03b8\u03b5\u03af \u03cc\u03c4\u03b9 \u03b7 \u03c3\u03c5\u03bd\u03b1\u03bb\u03bb\u03b1\u03b3\u03ae \u03bf\u03bb\u03bf\u03ba\u03bb\u03b7\u03c1\u03ce\u03b8\u03b7\u03ba\u03b5. \u0391\u03bd \u03bf server \u03ba\u03c1\u03b1\u03c3\u03ac\u03c1\u03b5\u03b9, \u03b7 PostgreSQL \u03c3\u03c4\u03b7\u03bd \u03b5\u03c0\u03b1\u03bd\u03b5\u03ba\u03ba\u03af\u03bd\u03b7\u03c3\u03b7 \u03b4\u03b9\u03b1\u03b2\u03ac\u03b6\u03b5\u03b9 \u03c4\u03b1 WAL files \u03ba\u03b1\u03b9 \u03be\u03b1\u03bd\u03b1\u03c0\u03b5\u03c1\u03bd\u03ac\u03b5\u03b9 \u03cc\u03c3\u03b5\u03c2 \u03b1\u03bb\u03bb\u03b1\u03b3\u03ad\u03c2 \u03b4\u03b5\u03bd \u03b5\u03af\u03c7\u03b1\u03bd \u03c0\u03c1\u03bf\u03bb\u03ac\u03b2\u03b5\u03b9 \u03bd\u03b1 \u03b3\u03c1\u03b1\u03c6\u03c4\u03bf\u03cd\u03bd \u03bc\u03cc\u03bd\u03b9\u03bc\u03b1 \u03c3\u03c4\u03bf\u03c5\u03c2 \u03c0\u03af\u03bd\u03b1\u03ba\u03b5\u03c2.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0393\u03b9\u03b1 \u03cc\u03c3\u03bf\u03c5\u03c2 \u03c0\u03c1\u03bf\u03ad\u03c1\u03c7\u03bf\u03bd\u03c4\u03b1\u03b9 \u03b1\u03c0\u03cc Oracle, \u03c4\u03b1 WAL files \u03b5\u03af\u03bd\u03b1\u03b9 \u03c4\u03bf \u03b1\u03bd\u03c4\u03af\u03c3\u03c4\u03bf\u03b9\u03c7\u03bf \u03c4\u03c9\u03bd <strong>Redo Logs<\/strong>, \u03b5\u03bd\u03ce \u03c3\u03c4\u03bf\u03bd SQL Server \u03b5\u03af\u03bd\u03b1\u03b9 \u03c4\u03bf <strong>Transaction Log<\/strong>. \u03a3\u03c4\u03b7\u03bd PostgreSQL \u03b2\u03c1\u03b9\u03c3\u03ba\u03bf\u03bd\u03c4\u03b1\u03b9 \u03c3\u03c4\u03bf\u03bd \u03c6\u03ac\u03ba\u03b5\u03bb\u03bf <code>pg_wal<\/code> \u03c9\u03c2 \u03b1\u03c1\u03c7\u03b5\u03af\u03b1 \u03c4\u03c9\u03bd 16MB.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u03a4\u03b9 \u03b5\u03af\u03bd\u03b1\u03b9 \u03c4\u03bf Checkpoint;<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u0394\u03b5\u03bd \u03bc\u03c0\u03bf\u03c1\u03bf\u03cd\u03bc\u03b5 \u03bd\u03b1 \u03ba\u03c1\u03b1\u03c4\u03ac\u03bc\u03b5 \u03c4\u03b9\u03c2 \u03b1\u03bb\u03bb\u03b1\u03b3\u03ad\u03c2 \u03bc\u03cc\u03bd\u03bf \u03c3\u03c4\u03b7 \u03bc\u03bd\u03ae\u03bc\u03b7, \u03b3\u03b9\u03b1\u03c4\u03af \u03b1\u03bd \u03ad\u03c0\u03b5\u03c6\u03c4\u03b5 \u03c4\u03bf \u03c1\u03b5\u03cd\u03bc\u03b1, \u03b7 \u03b5\u03c0\u03b1\u03bd\u03b5\u03ba\u03ba\u03af\u03bd\u03b7\u03c3\u03b7 \u03b8\u03b1 \u03ad\u03c0\u03b1\u03b9\u03c1\u03bd\u03b5 \u03ce\u03c1\u03b5\u03c2 \u03b4\u03b9\u03b1\u03b2\u03ac\u03b6\u03bf\u03bd\u03c4\u03b1\u03c2 WAL files \u03b7\u03bc\u03b5\u03c1\u03ce\u03bd. \u03a4\u03bf <strong>Checkpoint<\/strong> \u03b5\u03af\u03bd\u03b1\u03b9 \u03b7 \u03b4\u03b9\u03b1\u03b4\u03b9\u03ba\u03b1\u03c3\u03af\u03b1 \u03ba\u03b1\u03c4\u03ac \u03c4\u03b7\u03bd \u03bf\u03c0\u03bf\u03af\u03b1 \u03b7 PostgreSQL \u03c0\u03b1\u03af\u03c1\u03bd\u03b5\u03b9 \u03cc\u03bb\u03b5\u03c2 \u03c4\u03b9\u03c2 \u03b1\u03bb\u03bb\u03b1\u03b3\u03ad\u03c2 \u03b1\u03c0\u03cc \u03c4\u03b7 \u03bc\u03bd\u03ae\u03bc\u03b7 \u03ba\u03b1\u03b9 \u03c4\u03b9\u03c2 \u03b3\u03c1\u03ac\u03c6\u03b5\u03b9 \u03c6\u03c5\u03c3\u03b9\u03ba\u03ac \u03c3\u03c4\u03bf\u03c5\u03c2 \u03c0\u03af\u03bd\u03b1\u03ba\u03b5\u03c2 \u03c3\u03c4\u03bf \u03b4\u03af\u03c3\u03ba\u03bf. \u039c\u03cc\u03bb\u03b9\u03c2 \u03c4\u03b5\u03bb\u03b5\u03b9\u03ce\u03c3\u03b5\u03b9, \u03c4\u03b1 \u03c0\u03b1\u03bb\u03b9\u03ac WAL files \u03c0\u03bf\u03c5 \u03b4\u03b5\u03bd \u03c7\u03c1\u03b5\u03b9\u03ac\u03b6\u03bf\u03bd\u03c4\u03b1\u03b9 \u03ac\u03bb\u03bb\u03bf \u03b4\u03b9\u03b1\u03b3\u03c1\u03ac\u03c6\u03bf\u03bd\u03c4\u03b1\u03b9.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0391\u03bd \u03c4\u03bf checkpoint \u03b3\u03c1\u03ac\u03c8\u03b5\u03b9 \u03c0\u03bf\u03bb\u03cd \u03cc\u03b3\u03ba\u03bf \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03c9\u03bd \u03b1\u03c0\u03cc\u03c4\u03bf\u03bc\u03b1, \u03bf \u03b4\u03af\u03c3\u03ba\u03bf\u03c2 \u03c6\u03c4\u03ac\u03bd\u03b5\u03b9 \u03c3\u03c4\u03bf 100% \u03ba\u03b1\u03b9 \u03b7 \u03b2\u03ac\u03c3\u03b7 \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03c9\u03bd \u03ba\u03bf\u03bb\u03bb\u03ac\u03b5\u03b9. \u0393\u03b9&#8217; \u03b1\u03c5\u03c4\u03cc \u03c7\u03c1\u03b5\u03b9\u03ac\u03b6\u03b5\u03c4\u03b1\u03b9 \u03c3\u03c9\u03c3\u03c4\u03cc tuning.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u03a0\u03ce\u03c2 \u03c4\u03b1 \u03c1\u03c5\u03b8\u03bc\u03af\u03b6\u03bf\u03c5\u03bc\u03b5 \u03c3\u03c4\u03bf service \u03c4\u03b7\u03c2 PostgreSQL<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u039f\u03b9 \u03c0\u03c1\u03bf\u03b5\u03c0\u03b9\u03bb\u03b5\u03b3\u03bc\u03ad\u03bd\u03b5\u03c2 \u03c1\u03c5\u03b8\u03bc\u03af\u03c3\u03b5\u03b9\u03c2 \u03c4\u03b7\u03c2 PostgreSQL \u03b5\u03af\u03bd\u03b1\u03b9 \u03c0\u03bf\u03bb\u03cd \u03c7\u03b1\u03bc\u03b7\u03bb\u03ad\u03c2, \u03c3\u03b5 \u03c0\u03b1\u03c1\u03b1\u03b3\u03c9\u03b3\u03b9\u03ba\u03ad\u03c2 \u03b2\u03ac\u03c3\u03b5\u03b9\u03c2 \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03c9\u03bd \u03c0\u03c1\u03bf\u03c3\u03b1\u03c1\u03bc\u03cc\u03b6\u03bf\u03c5\u03bc\u03b5 \u03c4\u03b9\u03c2 \u03b2\u03b1\u03c3\u03b9\u03ba\u03ad\u03c2 \u03c0\u03b1\u03c1\u03b1\u03bc\u03ad\u03c4\u03c1\u03bf\u03c5\u03c2 \u03c3\u03c4\u03bf <code>postgresql.conf<\/code>, \u03bf\u03b9 \u03bf\u03c0\u03bf\u03af\u03b5\u03c2 \u03b5\u03b9\u03bd\u03b1\u03b9 \u03b4\u03c5\u03bd\u03b1\u03bc\u03b9\u03ba\u03ad\u03c2 \u03b4\u03b5\u03bd \u03c7\u03c1\u03b5\u03b9\u03ac\u03b6\u03b5\u03c4\u03b1\u03b9 \u03bd\u03b1 \u03c0\u03ad\u03c3\u03b5\u03b9 \u03c4\u03bf service \u03b1\u03c0\u03bb\u03ac reload \u03bc\u03ad\u03c3\u03c9 SQL (<code>SELECT pg_reload_conf();<\/code>):<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">max_wal_size<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u039f\u03c1\u03af\u03b6\u03b5\u03b9 \u03c0\u03cc\u03c3\u03bf\u03c2 \u03cc\u03b3\u03ba\u03bf\u03c2 WAL \u03b5\u03c0\u03b9\u03c4\u03c1\u03ad\u03c0\u03b5\u03c4\u03b1\u03b9 \u03bd\u03b1 \u03bc\u03b1\u03b6\u03b5\u03c5\u03c4\u03b5\u03af \u03c0\u03c1\u03b9\u03bd \u03b7 \u03b2\u03ac\u03c3\u03b7 \u03b1\u03bd\u03b1\u03b3\u03ba\u03b1\u03c3\u03c4\u03b5\u03af \u03bd\u03b1 \u03ba\u03ac\u03bd\u03b5\u03b9 Checkpoint. \u03a4\u03bf 1GB (default) \u03b5\u03af\u03bd\u03b1\u03b9 \u03c0\u03bf\u03bb\u03cd \u03bc\u03b9\u03ba\u03c1\u03cc \u03ba\u03b1\u03b9 \u03b1\u03bd\u03b1\u03b3\u03ba\u03ac\u03b6\u03b5\u03b9 \u03c4\u03b7 \u03b2\u03ac\u03c3\u03b7 \u03bd\u03b1 \u03ba\u03ac\u03bd\u03b5\u03b9 \u03c3\u03c5\u03bd\u03b5\u03c7\u03ce\u03c2 checkpoints. \u03a3\u03b5 \u03c0\u03b1\u03c1\u03b1\u03b3\u03c9\u03b3\u03b9\u03ba\u03ac \u03c3\u03c5\u03c3\u03c4\u03ae\u03bc\u03b1\u03c4\u03b1 \u03c4\u03bf \u03b1\u03bd\u03b5\u03b2\u03ac\u03b6\u03bf\u03c5\u03bc\u03b5 \u03c3\u03b5 <strong>16GB<\/strong> \u03c0\u03bf\u03c5 \u03b5\u03b9\u03bd\u03b1\u03b9 \u03c4\u03bf standard, \u03c3\u03b5 \u03c0\u03bf\u03bb\u03cd \u03b2\u03ac\u03c3\u03b5\u03b9\u03c2 \u03bc\u03b5 \u03c7\u03b9\u03bb\u03b9\u03ac\u03b4\u03b5\u03c2 \u03b5\u03b3\u03b3\u03c1\u03b1\u03c6\u03ad\u03c2 \u03bc\u03c0\u03bf\u03c1\u03b5\u03af \u03bd\u03b1 \u03c7\u03c1\u03b5\u03b9\u03b1\u03c3\u03c4\u03b5\u03af \u03bd\u03b1 \u03c4\u03bf \u03c0\u03b1\u03bc\u03b5 32GB \u03ae \u03b1\u03ba\u03cc\u03bc\u03b1 \u03ba\u03b1\u03b9 64GB.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">checkpoint_timeout<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u039f\u03c1\u03af\u03b6\u03b5\u03b9 \u03c4\u03bf\u03bd \u03bc\u03ad\u03b3\u03b9\u03c3\u03c4\u03bf \u03c7\u03c1\u03cc\u03bd\u03bf \u03b1\u03bd\u03ac\u03bc\u03b5\u03c3\u03b1 \u03c3\u03b5 \u03b4\u03cd\u03bf checkpoints. \u03a4\u03b1 5 \u03bb\u03b5\u03c0\u03c4\u03ac (default) \u03b5\u03af\u03bd\u03b1\u03b9 \u03c0\u03bf\u03bb\u03cd \u03c3\u03c5\u03c7\u03bd\u03cc \u03b4\u03b9\u03ac\u03c3\u03c4\u03b7\u03bc\u03b1, \u03bf\u03c0\u03cc\u03c4\u03b5 \u03c4\u03bf \u03b1\u03bd\u03b5\u03b2\u03ac\u03b6\u03bf\u03c5\u03bc\u03b5 \u03c3\u03b5 <strong>15m<\/strong> \u03b3\u03b9\u03b1 \u03bd\u03b1 \u03b1\u03c1\u03b1\u03b9\u03ce\u03c3\u03bf\u03c5\u03bc\u03b5 \u03c4\u03b9\u03c2 \u03b5\u03b3\u03b3\u03c1\u03b1\u03c6\u03ad\u03c2 \u03c3\u03c4\u03bf \u03b4\u03af\u03c3\u03ba\u03bf.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">checkpoint_completion_target<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u039f\u03c1\u03af\u03b6\u03b5\u03b9 \u03c3\u03b5 \u03c0\u03cc\u03c3\u03bf \u03c0\u03bf\u03c3\u03bf\u03c3\u03c4\u03cc \u03c4\u03bf\u03c5 \u03c7\u03c1\u03cc\u03bd\u03bf\u03c5 <code>checkpoint_timeout<\/code> \u03c0\u03c1\u03ad\u03c0\u03b5\u03b9 \u03bd\u03b1 \u03b1\u03c0\u03bb\u03c9\u03b8\u03b5\u03af \u03b7 \u03b5\u03b3\u03b3\u03c1\u03b1\u03c6\u03ae \u03c4\u03c9\u03bd \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03c9\u03bd. \u039c\u03b5 \u03c4\u03b9\u03bc\u03ae 0.9 \u03ba\u03b1\u03b9 <code>checkpoint_timeout <\/code>15, \u03b7 PostgreSQL \u03b3\u03c1\u03ac\u03c6\u03b5\u03b9 \u03c3\u03c4\u03b1\u03b4\u03b9\u03b1\u03ba\u03ac \u03c4\u03b1 \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03b1 \u03bc\u03ad\u03c3\u03b1 \u03c3\u03b5 13.5 \u03bb\u03b5\u03c0\u03c4\u03ac. \u0391\u03c5\u03c4\u03cc \u03b1\u03c0\u03bb\u03ce\u03bd\u03b5\u03b9 \u03c4\u03b7\u03bd \u03b5\u03b3\u03c1\u03b1\u03c6\u03ae \u03ba\u03b1\u03b9 \u03b5\u03be\u03b1\u03c6\u03b1\u03bd\u03af\u03b6\u03b5\u03b9 \u03c4\u03b1 \u03ba\u03bf\u03bb\u03bb\u03ae\u03bc\u03b1\u03c4\u03b1. \u03a3\u03c4\u03b9\u03c2 \u03bd\u03ad\u03b5\u03c2 \u03b5\u03ba\u03b4\u03cc\u03c3\u03b5\u03b9\u03c2 \u03b5\u03af\u03bd\u03b1\u03b9 \u03ae\u03b4\u03b7 0.9 \u03ba\u03b1\u03b9 \u03c4\u03bf \u03b1\u03c6\u03ae\u03bd\u03bf\u03c5\u03bc\u03b5 \u03b5\u03ba\u03b5\u03af.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Example:<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\" data-no-translation=\"\" data-no-auto-translation=\"\">vi $PGDATA\/postgresql.conf<\/pre>\n\n\n\n<pre class=\"wp-block-code\" data-no-translation=\"\" data-no-auto-translation=\"\"><code>checkpoint_timeout = 15m \nmax_wal_size = 16GB \nmin_wal_size = 2GB \ncheckpoint_completion_target = 0.9<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u03a0\u03ce\u03c2 \u03b2\u03bb\u03ad\u03c0\u03bf\u03c5\u03bc\u03b5 \u03b1\u03bd \u03c7\u03c1\u03b5\u03b9\u03ac\u03b6\u03b5\u03c4\u03b1\u03b9 tuning<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u0393\u03b9\u03b1 \u03bd\u03b1 \u03b4\u03bf\u03cd\u03bc\u03b5 \u03b1\u03bd \u03c4\u03b1 checkpoints \u03b3\u03af\u03bd\u03bf\u03bd\u03c4\u03b1\u03b9 \u03c3\u03c4\u03b7\u03bd \u03ce\u03c1\u03b1 \u03c4\u03bf\u03c5\u03c2 \u03ae \u03b1\u03bd \u03b5\u03be\u03b1\u03bd\u03b1\u03b3\u03ba\u03ac\u03b6\u03bf\u03bd\u03c4\u03b1\u03b9 \u03b5\u03c0\u03b5\u03b9\u03b4\u03ae \u03b3\u03b5\u03bc\u03af\u03b6\u03b5\u03b9 \u03c4\u03bf <code>max_wal_size<\/code>, \u03c4\u03c1\u03ad\u03c7\u03bf\u03c5\u03bc\u03b5 \u03c4\u03bf \u03c0\u03b1\u03c1\u03b1\u03ba\u03ac\u03c4\u03c9 query:<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\" data-no-translation=\"\" data-no-auto-translation=\"\">SELECT \n    checkpoints_timed,\n    checkpoints_req,\n    checkpoint_write_time,\n    checkpoint_sync_time,\n    ROUND(100.0 * checkpoints_req \/ NULLIF(checkpoints_timed + checkpoints_req, 0), 2) AS forced_checkpoint_pct\nFROM pg_stat_bgwriter;<\/pre>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"758\" height=\"401\" src=\"https:\/\/www.dataplatform.gr\/wp-content\/uploads\/2026\/07\/pgwa-01.png\" alt=\"\" class=\"wp-image-6060\" srcset=\"https:\/\/www.dataplatform.gr\/wp-content\/uploads\/2026\/07\/pgwa-01.png 758w, https:\/\/www.dataplatform.gr\/wp-content\/uploads\/2026\/07\/pgwa-01-300x159.png 300w, https:\/\/www.dataplatform.gr\/wp-content\/uploads\/2026\/07\/pgwa-01-18x10.png 18w\" sizes=\"auto, (max-width: 758px) 100vw, 758px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\u03a3\u03c4\u03b1 \u03b1\u03c0\u03bf\u03c4\u03b5\u03bb\u03ad\u03c3\u03bc\u03b1\u03c4\u03b1, \u03c4\u03bf <code>checkpoints_timed<\/code> \u03b4\u03b5\u03af\u03c7\u03bd\u03b5\u03b9 \u03c4\u03b1 checkpoints \u03c0\u03bf\u03c5 \u03ad\u03b3\u03b9\u03bd\u03b1\u03bd \u03ba\u03b1\u03bd\u03bf\u03bd\u03b9\u03ba\u03ac \u03b2\u03ac\u03c3\u03b5\u03b9 \u03c7\u03c1\u03cc\u03bd\u03bf\u03c5, \u03b5\u03bd\u03ce \u03c4\u03bf <code>checkpoints_req<\/code> \u03b4\u03b5\u03af\u03c7\u03bd\u03b5\u03b9 \u03c4\u03b1 \u03b1\u03bd\u03b1\u03b3\u03ba\u03b1\u03c3\u03c4\u03b9\u03ba\u03ac \u03b5\u03c0\u03b5\u03b9\u03b4\u03ae \u03b3\u03b5\u03bc\u03af\u03c3\u03b1\u03bc\u03b5 \u03c4\u03bf <code>max_wal_size<\/code>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u03a3\u03c4\u03cc\u03c7\u03bf\u03c2 \u03bc\u03b1\u03c2 \u03b5\u03af\u03bd\u03b1\u03b9 \u03c4\u03bf \u03c0\u03bf\u03c3\u03bf\u03c3\u03c4\u03cc <strong><code>forced_checkpoint_pct<\/code> \u03bd\u03b1 \u03b5\u03af\u03bd\u03b1\u03b9 \u03ba\u03ac\u03c4\u03c9 \u03b1\u03c0\u03cc 10%<\/strong>. \u0391\u03bd \u03b2\u03bb\u03ad\u03c0\u03b5\u03c4\u03b5 \u03bc\u03b5\u03b3\u03b1\u03bb\u03cd\u03c4\u03b5\u03c1\u03bf \u03c0\u03bf\u03c3\u03bf\u03c3\u03c4\u03cc, \u03c3\u03b7\u03bc\u03b1\u03af\u03bd\u03b5\u03b9 \u03cc\u03c4\u03b9 \u03b7 \u03b2\u03ac\u03c3\u03b7 \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03c9\u03bd \u03c0\u03b1\u03c1\u03ac\u03b3\u03b5\u03b9 WAL \u03c0\u03bf\u03bb\u03cd \u03b3\u03c1\u03ae\u03b3\u03bf\u03c1\u03b1 \u03ba\u03b1\u03b9 \u03c0\u03c1\u03ad\u03c0\u03b5\u03b9 \u03bd\u03b1 \u03b1\u03c5\u03be\u03ae\u03c3\u03b5\u03c4\u03b5 \u03c4\u03bf <code>max_wal_size<\/code>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Sources:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.postgresql.org\/docs\/current\/\" data-type=\"link\" data-id=\"https:\/\/www.postgresql.org\/docs\/current\/\">PostgreSQL 18.4 Documentation<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>","protected":false},"excerpt":{"rendered":"<p>\u03a3\u03b5 \u03b1\u03c5\u03c4\u03cc \u03c4\u03bf \u03ac\u03c1\u03b8\u03c1\u03bf \u03b8\u03b1 \u03b4\u03bf\u03cd\u03bc\u03b5 \u03c4\u03bf\u03bd \u03bc\u03b7\u03c7\u03b1\u03bd\u03b9\u03c3\u03bc\u03cc \u03c0\u03bf\u03c5 \u03c3\u03c5\u03bd\u03b4\u03ad\u03b5\u03b9 \u03c4\u03b7 \u03bc\u03bd\u03ae\u03bc\u03b7 \u03bc\u03b5 \u03c4\u03bf\u03bd \u03b4\u03af\u03c3\u03ba\u03bf \u03ba\u03b1\u03b9 \u03b5\u03be\u03b1\u03c3\u03c6\u03b1\u03bb\u03af\u03b6\u03b5\u03b9 \u03cc\u03c4\u03b9 \u03b4\u03b5\u03bd \u03b8\u03b1 \u03c7\u03ac\u03c3\u03bf\u03c5\u03bc\u03b5 \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03b1 \u03b1\u03bd \u03c0\u03ad\u03c3\u03b5\u03b9 \u03b7 \u03b2\u03ac\u03c3\u03b7 \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03c9\u03bd (\u03c0.\u03c7. \u03b1\u03c0\u03bf \u03c1\u03b5\u03cd\u03bc\u03b1): \u03c4\u03b1 Write-Ahead Logs (WAL) \u03ba\u03b1\u03b9 \u03c4\u03b1 Checkpoints. \u038c\u03c4\u03b1\u03bd \u03b5\u03ba\u03c4\u03b5\u03bb\u03bf\u03cd\u03bc\u03b5 \u03ad\u03bd\u03b1 INSERT, UPDATE \u03ae DELETE, \u03b7 \u03b1\u03bb\u03bb\u03b1\u03b3\u03ae \u03b3\u03af\u03bd\u03b5\u03c4\u03b1\u03b9 \u03b1\u03c1\u03c7\u03b9\u03ba\u03ac \u03c3\u03c4\u03b7 \u03bc\u03bd\u03ae\u03bc\u03b7 (shared_buffer) \u03ba\u03b1\u03b9 \u03b1\u03bc\u03ad\u03c3\u03c9\u03c2 \u03bc\u03b5\u03c4\u03ac \u03ba\u03b1\u03c4\u03b1\u03b3\u03c1\u03ac\u03c6\u03b5\u03c4\u03b1\u03b9 [&hellip;]<\/p>","protected":false},"author":1,"featured_media":2376,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11,123],"tags":[29,48,124,30],"class_list":["post-6059","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-databases","category-postgresql","tag-databases","tag-performance_tuning","tag-postgresql","tag-rdbms"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.0 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>\u03a4\u03b9 \u03b5\u03af\u03bd\u03b1\u03b9 \u03c4\u03b1 WAL \u03c3\u03c4\u03b7 PostgreSQL \u03ba\u03b1\u03b9 \u03c0\u03ce\u03c2 \u03c4\u03b1 \u03c1\u03c5\u03b8\u03bc\u03af\u03b6\u03bf\u03c5\u03bc\u03b5 - DataPlatform.gr<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" 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\u03b4\u03af\u03c3\u03ba\u03bf \u03ba\u03b1\u03b9 \u03b5\u03be\u03b1\u03c3\u03c6\u03b1\u03bb\u03af\u03b6\u03b5\u03b9 \u03cc\u03c4\u03b9 \u03b4\u03b5\u03bd \u03b8\u03b1 \u03c7\u03ac\u03c3\u03bf\u03c5\u03bc\u03b5 \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03b1 \u03b1\u03bd \u03c0\u03ad\u03c3\u03b5\u03b9 \u03b7 \u03b2\u03ac\u03c3\u03b7 \u03b4\u03b5\u03b4\u03bf\u03bc\u03ad\u03bd\u03c9\u03bd (\u03c0.\u03c7. \u03b1\u03c0\u03bf \u03c1\u03b5\u03cd\u03bc\u03b1): \u03c4\u03b1 Write-Ahead Logs (WAL) \u03ba\u03b1\u03b9 \u03c4\u03b1 Checkpoints. \u038c\u03c4\u03b1\u03bd \u03b5\u03ba\u03c4\u03b5\u03bb\u03bf\u03cd\u03bc\u03b5 \u03ad\u03bd\u03b1 INSERT, UPDATE \u03ae DELETE, \u03b7 \u03b1\u03bb\u03bb\u03b1\u03b3\u03ae \u03b3\u03af\u03bd\u03b5\u03c4\u03b1\u03b9 \u03b1\u03c1\u03c7\u03b9\u03ba\u03ac \u03c3\u03c4\u03b7 \u03bc\u03bd\u03ae\u03bc\u03b7 (shared_buffer) \u03ba\u03b1\u03b9 \u03b1\u03bc\u03ad\u03c3\u03c9\u03c2 \u03bc\u03b5\u03c4\u03ac 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