{"id":36528,"date":"2025-01-08T12:58:39","date_gmt":"2025-01-08T11:58:39","guid":{"rendered":"https:\/\/www.dbi-services.com\/blog\/?p=36528"},"modified":"2025-01-08T12:58:39","modified_gmt":"2025-01-08T11:58:39","slug":"postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly","status":"publish","type":"post","link":"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/","title":{"rendered":"PostgreSQL 18: Change the maximum number of  autovacuum workers on the fly"},"content":{"rendered":"\n<p>For PostgreSQL it is critical, that autovacuum is able to keep up with the changes to the instance. One of the parameters you can adapt for this is <a href=\"https:\/\/www.postgresql.org\/docs\/17\/runtime-config-autovacuum.html#GUC-AUTOVACUUM-MAX-WORKERS\" target=\"_blank\" rel=\"noreferrer noopener\">autovacuum_max_workers<\/a>. This parameter controls how many worker process can be started in parallel by the autovacuum launcher process. By default, this is set to 3, which means that a maximum of three worker processes can run in parallel to do the work. While you can increase this parameter easily, it requires a restart of instance to become active. Starting with PostgreSQL 18 (scheduled to be released later this year), you&#8217;ll be able to change this on the fly.<\/p>\n\n\n\n<p>The default configuration for PostgreSQL 18 is still three worker processes:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; highlight: [1,7]; title: ; notranslate\" title=\"\">\npostgres=# select version();\n                                version                                 \n------------------------------------------------------------------------\n PostgreSQL 18devel on x86_64-freebsd, compiled by clang-18.1.6, 64-bit\n(1 row)\n\npostgres=# show autovacuum_max_workers ;\n autovacuum_max_workers \n------------------------\n 3\n(1 row)\n<\/pre><\/div>\n\n\n<p>But now, you can increase that on the fly without restarting the instance (sighup means reload):<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; title: ; notranslate\" title=\"\">\npostgres=# select context from pg_settings where name = &#039;autovacuum_max_workers&#039;;\n context \n---------\n sighup\n(1 row)\n\npostgres=# \n<\/pre><\/div>\n\n\n<p>On a PostgreSQL 17 (and before) instance, it looks like this (postmaster means restart):<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; highlight: [1,3]; title: ; notranslate\" title=\"\">\npostgres=# select version();\n                                                                                           version                                                                                            \n----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------\n PostgreSQL 17.2 on x86_64-unknown-freebsd14.2, compiled by FreeBSD clang version 18.1.6 , 64-bit\n(1 row)\n\npostgres=# select context from pg_settings where name = &#039;autovacuum_max_workers&#039;;\n  context   \n------------\n postmaster\n(1 row)\n<\/pre><\/div>\n\n\n<p>So, lets assume we have an instance where a lot of stuff is going on and we want to increase the worker processes to 32 on a PostgreSQL 18 instance:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; highlight: [1,3,9]; title: ; notranslate\" title=\"\">\npostgres=# alter system set autovacuum_max_workers = 32;\nALTER SYSTEM\npostgres=# select pg_reload_conf();\n pg_reload_conf \n----------------\n t\n(1 row)\n\npostgres=# show autovacuum_max_workers ;\n autovacuum_max_workers \n------------------------\n 32\n(1 row)\n<\/pre><\/div>\n\n\n<p>That seems to have worked, but if you take a look at the PostgreSQL log file you&#8217;ll notice this:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\n2025-01-08 11:48:59.504 CET - 1 - 4411 - &#x5B;local] - postgres@postgres - 0LOG:  statement: alter system set autovacuum_max_workers = 32;\n2025-01-08 11:49:05.210 CET - 8 - 4174 -  - @ - 0LOG:  received SIGHUP, reloading configuration files\n2025-01-08 11:49:05.212 CET - 9 - 4174 -  - @ - 0LOG:  parameter &quot;autovacuum_max_workers&quot; changed to &quot;32&quot;\n2025-01-08 11:49:05.221 CET - 1 - 4180 -  - @ - 0WARNING:  &quot;autovacuum_max_workers&quot; (32) should be less than or equal to &quot;autovacuum_worker_slots&quot; (16)\n<\/pre><\/div>\n\n\n<p>This means there still is a limit, which is defined by &#8220;<a href=\"https:\/\/www.postgresql.org\/docs\/devel\/runtime-config-autovacuum.html#GUC-AUTOVACUUM-WORKER-SLOTS\" target=\"_blank\" rel=\"noreferrer noopener\">autovacuum_worker_slots<\/a>&#8220;, and the default for this one is 16. For most instances this probably is fine, you can go from the default (3) anywhere up to 16 without restarting the instance. If you think you&#8217;ll need more from time to time, then you also should increase autovacuum_worker_slots, but this does require a restart of the instance.<\/p>\n\n\n\n<p>Here the <a href=\"https:\/\/git.postgresql.org\/gitweb\/?p=postgresql.git;a=commitdiff;h=c758119e5bfb47b38cf957f9a5a37ceae96fa9b3\" target=\"_blank\" rel=\"noreferrer noopener\">link to the commit<\/a>.<\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>For PostgreSQL it is critical, that autovacuum is able to keep up with the changes to the instance. One of the parameters you can adapt for this is autovacuum_max_workers. This parameter controls how many worker process can be started in parallel by the autovacuum launcher process. By default, this is set to 3, which means [&hellip;]<\/p>\n","protected":false},"author":29,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[229,198],"tags":[77],"type_dbi":[2749],"class_list":["post-36528","post","type-post","status-publish","format-standard","hentry","category-database-administration-monitoring","category-database-management","tag-postgresql","type-postgresql"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v27.2 (Yoast SEO v27.2) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>PostgreSQL 18: Change the maximum number of autovacuum workers on the fly - dbi Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"PostgreSQL 18: Change the maximum number of autovacuum workers on the fly\" \/>\n<meta property=\"og:description\" content=\"For PostgreSQL it is critical, that autovacuum is able to keep up with the changes to the instance. One of the parameters you can adapt for this is autovacuum_max_workers. This parameter controls how many worker process can be started in parallel by the autovacuum launcher process. By default, this is set to 3, which means [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/\" \/>\n<meta property=\"og:site_name\" content=\"dbi Blog\" \/>\n<meta property=\"article:published_time\" content=\"2025-01-08T11:58:39+00:00\" \/>\n<meta name=\"author\" content=\"Daniel Westermann\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@westermanndanie\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Daniel Westermann\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/\"},\"author\":{\"name\":\"Daniel Westermann\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/#\/schema\/person\/8d08e9bd996a89bd75c0286cbabf3c66\"},\"headline\":\"PostgreSQL 18: Change the maximum number of autovacuum workers on the fly\",\"datePublished\":\"2025-01-08T11:58:39+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/\"},\"wordCount\":280,\"commentCount\":0,\"keywords\":[\"PostgreSQL\"],\"articleSection\":[\"Database Administration &amp; Monitoring\",\"Database management\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/\",\"url\":\"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/\",\"name\":\"PostgreSQL 18: Change the maximum number of autovacuum workers on the fly - dbi Blog\",\"isPartOf\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/#website\"},\"datePublished\":\"2025-01-08T11:58:39+00:00\",\"author\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/#\/schema\/person\/8d08e9bd996a89bd75c0286cbabf3c66\"},\"breadcrumb\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Accueil\",\"item\":\"https:\/\/www.dbi-services.com\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"PostgreSQL 18: Change the maximum number of autovacuum workers on the fly\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/#website\",\"url\":\"https:\/\/www.dbi-services.com\/blog\/\",\"name\":\"dbi Blog\",\"description\":\"\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.dbi-services.com\/blog\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/#\/schema\/person\/8d08e9bd996a89bd75c0286cbabf3c66\",\"name\":\"Daniel Westermann\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/secure.gravatar.com\/avatar\/31350ceeecb1dd8986339a29bf040d4cd3cd087d410deccd8f55234466d6c317?s=96&d=mm&r=g\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/31350ceeecb1dd8986339a29bf040d4cd3cd087d410deccd8f55234466d6c317?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/31350ceeecb1dd8986339a29bf040d4cd3cd087d410deccd8f55234466d6c317?s=96&d=mm&r=g\",\"caption\":\"Daniel Westermann\"},\"description\":\"Daniel Westermann is Principal Consultant and Technology Leader Open Infrastructure at dbi services. He has more than 15 years of experience in management, engineering and optimization of databases and infrastructures, especially on Oracle and PostgreSQL. Since the beginning of his career, he has specialized in Oracle Technologies and is Oracle Certified Professional 12c and Oracle Certified Expert RAC\/GridInfra. Over time, Daniel has become increasingly interested in open source technologies, becoming \u201cTechnology Leader Open Infrastructure\u201d and PostgreSQL expert. \u00a0Based on community or EnterpriseDB tools, he develops and installs complex high available solutions with PostgreSQL. He is also a certified PostgreSQL Plus 9.0 Professional and a Postgres Advanced Server 9.4 Professional. He is a regular speaker at PostgreSQL conferences in Switzerland and Europe. Today Daniel is also supporting our customers on AWS services such as AWS RDS, database migrations into the cloud, EC2 and automated infrastructure management with AWS SSM (System Manager). He is a certified AWS Solutions Architect Professional. Prior to dbi services, Daniel was Management System Engineer at LC SYSTEMS-Engineering AG in Basel. Before that, he worked as Oracle Developper &amp;\u00a0Project Manager at Delta Energy Solutions AG in Basel (today Powel AG). Daniel holds a diploma in Business Informatics (DHBW, Germany). His branch-related experience mainly covers the pharma industry, the financial sector, energy, lottery and telecommunications.\",\"sameAs\":[\"https:\/\/x.com\/westermanndanie\"],\"url\":\"https:\/\/www.dbi-services.com\/blog\/author\/daniel-westermann\/\"}]}<\/script>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"PostgreSQL 18: Change the maximum number of autovacuum workers on the fly - dbi Blog","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.dbi-services.com\/blog\/postgresql-18-change-the-maximum-number-of-autovacuum-workers-on-the-fly\/","og_locale":"en_US","og_type":"article","og_title":"PostgreSQL 18: Change the maximum number of autovacuum workers on the fly","og_description":"For PostgreSQL it is critical, that autovacuum is able to keep up with the changes to the instance. 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He has more than 15 years of experience in management, engineering and optimization of databases and infrastructures, especially on Oracle and PostgreSQL. Since the beginning of his career, he has specialized in Oracle Technologies and is Oracle Certified Professional 12c and Oracle Certified Expert RAC\/GridInfra. Over time, Daniel has become increasingly interested in open source technologies, becoming \u201cTechnology Leader Open Infrastructure\u201d and PostgreSQL expert. \u00a0Based on community or EnterpriseDB tools, he develops and installs complex high available solutions with PostgreSQL. He is also a certified PostgreSQL Plus 9.0 Professional and a Postgres Advanced Server 9.4 Professional. He is a regular speaker at PostgreSQL conferences in Switzerland and Europe. Today Daniel is also supporting our customers on AWS services such as AWS RDS, database migrations into the cloud, EC2 and automated infrastructure management with AWS SSM (System Manager). He is a certified AWS Solutions Architect Professional. Prior to dbi services, Daniel was Management System Engineer at LC SYSTEMS-Engineering AG in Basel. Before that, he worked as Oracle Developper &amp;\u00a0Project Manager at Delta Energy Solutions AG in Basel (today Powel AG). Daniel holds a diploma in Business Informatics (DHBW, Germany). His branch-related experience mainly covers the pharma industry, the financial sector, energy, lottery and telecommunications.","sameAs":["https:\/\/x.com\/westermanndanie"],"url":"https:\/\/www.dbi-services.com\/blog\/author\/daniel-westermann\/"}]}},"_links":{"self":[{"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/posts\/36528","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/users\/29"}],"replies":[{"embeddable":true,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/comments?post=36528"}],"version-history":[{"count":7,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/posts\/36528\/revisions"}],"predecessor-version":[{"id":36535,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/posts\/36528\/revisions\/36535"}],"wp:attachment":[{"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/media?parent=36528"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/categories?post=36528"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/tags?post=36528"},{"taxonomy":"type","embeddable":true,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/type_dbi?post=36528"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}