{"id":28670,"date":"2023-10-19T09:43:50","date_gmt":"2023-10-19T07:43:50","guid":{"rendered":"https:\/\/www.dbi-services.com\/blog\/?p=28670"},"modified":"2023-10-19T09:43:52","modified_gmt":"2023-10-19T07:43:52","slug":"what-is-the-difference-between-session_user-and-current_user-in-postgresql","status":"publish","type":"post","link":"https:\/\/www.dbi-services.com\/blog\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/","title":{"rendered":"What is the difference between session_user and current_user in PostgreSQL?"},"content":{"rendered":"\n<p>When you want to know the currently connected user in PostgreSQL for your session there are two system information functions which seem to do the same thing. There is &#8220;session_user&#8221; and there is &#8220;current_user&#8221;. So what is the difference between those or is there no difference at all?<\/p>\n\n\n\n<p>Looking at my users in PostgreSQL all I have right now is the &#8220;postgres&#8221; superuser:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; title: ; notranslate\" title=\"\">\npostgres=# \\du\n                             List of roles\n Role name |                         Attributes                         \n-----------+------------------------------------------------------------\n postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS\n<\/pre><\/div>\n\n\n<p>Both system information functions return the same result:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; title: ; notranslate\" title=\"\">\npostgres=# select current_user;\n current_user \n--------------\n postgres\n(1 row)\n\npostgres=# select session_user;\n session_user \n--------------\n postgres\n(1 row)\n<\/pre><\/div>\n\n\n<p>Let&#8217;s create a new login role:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; title: ; notranslate\" title=\"\">\npostgres=# create user a with login password &#039;a&#039;;\nCREATE ROLE\npostgres=# \\du\n                             List of roles\n Role name |                         Attributes                         \n-----------+------------------------------------------------------------\n a         | \n postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS\n<\/pre><\/div>\n\n\n<p>What do those functions return when we connect with the new user?<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; title: ; notranslate\" title=\"\">\npostgres=# \\c postgres a\nYou are now connected to database &quot;postgres&quot; as user &quot;a&quot;.\npostgres=&gt; select current_user;\n current_user \n--------------\n a\n(1 row)\n\npostgres=&gt; select session_user;\n session_user \n--------------\n a\n(1 row)\n<\/pre><\/div>\n\n\n<p>Same story as above,  both return the same result. Things get different if you use &#8220;<a href=\"https:\/\/www.postgresql.org\/docs\/current\/sql-set-role.html\" target=\"_blank\" rel=\"noreferrer noopener\">set role<\/a>&#8220;:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; title: ; notranslate\" title=\"\">\npostgres=# \\c postgres postgres\nYou are now connected to database &quot;postgres&quot; as user &quot;postgres&quot;.\npostgres=# set role a;\nSET\npostgres=&gt; select current_user,session_user;\n current_user | session_user \n--------------+--------------\n a            | postgres\n(1 row)\n<\/pre><\/div>\n\n\n<p>The session user is still &#8220;postgres&#8221;, but the current user now is &#8220;a&#8221;. This also means, that permission checks are now done for user &#8220;a&#8221; and not for &#8220;postgres&#8221; anymore:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; title: ; notranslate\" title=\"\">\npostgres=&gt; create table t(a int);\nERROR:  permission denied for schema public\nLINE 1: create table t(a int);\n                     ^\npostgres=&gt; create schema a;\nERROR:  permission denied for database postgres\npostgres=&gt; \n<\/pre><\/div>\n\n\n<p>Going back to the initial state can be done with &#8220;set role none&#8221;:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; title: ; notranslate\" title=\"\">\npostgres=&gt; set role none;\nSET\npostgres=# select current_user,session_user;\n current_user | session_user \n--------------+--------------\n postgres     | postgres\n(1 row)\n<\/pre><\/div>\n\n\n<p>There is also &#8220;<a href=\"https:\/\/www.postgresql.org\/docs\/current\/sql-set-session-authorization.html\">set session authorization<\/a>&#8220;, which behave slightly different:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; title: ; notranslate\" title=\"\">\npostgres=# set session authorization a;\nSET\npostgres=&gt; select current_user, session_user;\n current_user | session_user \n--------------+--------------\n a            | a\n(1 row)\n\npostgres=&gt; \n<\/pre><\/div>\n\n\n<p>The current user might also change in security definer functions, but the session user can&#8217;t. The current user is the one which is relevant for permission checking.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>When you want to know the currently connected user in PostgreSQL for your session there are two system information functions which seem to do the same thing. There is &#8220;session_user&#8221; and there is &#8220;current_user&#8221;. So what is the difference between those or is there no difference at all? Looking at my users in PostgreSQL all [&hellip;]<\/p>\n","protected":false},"author":29,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[229,198],"tags":[77],"type_dbi":[],"class_list":["post-28670","post","type-post","status-publish","format-standard","hentry","category-database-administration-monitoring","category-database-management","tag-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>What is the difference between session_user and current_user in PostgreSQL? - 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\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"What is the difference between session_user and current_user in PostgreSQL?\" \/>\n<meta property=\"og:description\" content=\"When you want to know the currently connected user in PostgreSQL for your session there are two system information functions which seem to do the same thing. 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Looking at my users in PostgreSQL all [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.dbi-services.com\/blog\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/\" \/>\n<meta property=\"og:site_name\" content=\"dbi Blog\" \/>\n<meta property=\"article:published_time\" content=\"2023-10-19T07:43:50+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2023-10-19T07:43:52+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=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/\"},\"author\":{\"name\":\"Daniel Westermann\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/#\/schema\/person\/8d08e9bd996a89bd75c0286cbabf3c66\"},\"headline\":\"What is the difference between session_user and current_user in PostgreSQL?\",\"datePublished\":\"2023-10-19T07:43:50+00:00\",\"dateModified\":\"2023-10-19T07:43:52+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/\"},\"wordCount\":202,\"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\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/\",\"url\":\"https:\/\/www.dbi-services.com\/blog\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/\",\"name\":\"What is the difference between session_user and current_user in PostgreSQL? - dbi Blog\",\"isPartOf\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/#website\"},\"datePublished\":\"2023-10-19T07:43:50+00:00\",\"dateModified\":\"2023-10-19T07:43:52+00:00\",\"author\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/#\/schema\/person\/8d08e9bd996a89bd75c0286cbabf3c66\"},\"breadcrumb\":{\"@id\":\"https:\/\/www.dbi-services.com\/blog\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.dbi-services.com\/blog\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.dbi-services.com\/blog\/what-is-the-difference-between-session_user-and-current_user-in-postgresql\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Accueil\",\"item\":\"https:\/\/www.dbi-services.com\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"What is the difference between session_user and current_user in PostgreSQL?\"}]},{\"@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). 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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). 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