{"id":4395,"date":"2025-07-14T16:12:36","date_gmt":"2025-07-14T16:12:36","guid":{"rendered":"https:\/\/nenadnoveljic.com\/blog\/?p=4395"},"modified":"2025-07-14T16:14:37","modified_gmt":"2025-07-14T16:14:37","slug":"collecting-table-privileges-in-postgresql","status":"publish","type":"post","link":"https:\/\/nenadnoveljic.com\/blog\/collecting-table-privileges-in-postgresql\/","title":{"rendered":"Collecting table privileges in PostgreSQL"},"content":{"rendered":"

information_schema.table_privileges<\/h1>\n

In PostgreSQL, viewing information_schema.table_privileges<\/code> only shows privileges granted to or by the current role. This is by design and is documented in the information_schema.table_privileges<\/a> reference.<\/p>\n

\npostgres=# set role admin_user;\nSET\n\npostgres=# create user u;\nCREATE ROLE\n\npostgres=# create table t (n integer);\nCREATE TABLE\n\npostgres=# grant select on t to u;\nGRANT\n\npostgres=# select * from information_schema.table_privileges \n           where table_name = 't' and grantee = 'u';\n grantor     | grantee | table_catalog | table_schema | table_name | privilege_type | is_grantable | with_hierarchy \n-------------+---------+---------------+--------------+------------+----------------+--------------+----------------\n admin_user | u     | postgres      | public       | t          | SELECT         | NO           | YES\n<\/code><\/pre>\n
However, when executed under a low-privileged user, the query returns no rows:<\/p>\n
\npostgres=# create user monitoring;\nCREATE ROLE\n\npostgres=# set role monitoring;\nSET\n\npostgres=> select * from information_schema.table_privileges \n            where table_name = 't' and grantee = 'u';\n(0 rows)\n<\/code><\/pre>\n
This behavior is similar to Oracle\u2019s ALL_TAB_PRIVS<\/a>, which only shows privileges related to the current user. For full visibility, we want behavior like Oracle\u2019s DBA_TAB_PRIVS<\/a>.<\/p>\n
To do this in PostgreSQL, we must solve two issues:<\/p>\n
    \n
  1. The non-privileged user must be granted SELECT<\/code> access on safe columns from pg_authid<\/code>.<\/li>\n
  2. We must bypass the current-user-only filter used by information_schema.table_privileges<\/code>.<\/li>\n<\/ol>\n
    pg_authid access<\/h1>\n
    pg_authid<\/code> contains sensitive information (like password hashes), so we limit access to just the necessary columns:<\/p>\n
    \nGRANT SELECT(oid, rolname) ON pg_authid TO monitoring;\n<\/code><\/pre>\n
    Remove current user filter<\/h1>\n
    The default filter in the view definition limits results to grants involving the current user or PUBLIC. This can be seen in the PostgreSQL source code<\/a>:\n<\/p>\n
    \nAND (pg_has_role(u_grantor.oid, 'USAGE')\n     OR pg_has_role(grantee.oid, 'USAGE')\n     OR grantee.rolname = 'PUBLIC');\n<\/code><\/pre>\n
    Final SELECT<\/h1>\n
    This query returns all privileges granted on tables in the cluster, regardless of the current role:<\/p>\n
    \nSELECT CAST(u_grantor.rolname AS text) AS grantor,\n       CAST(grantee.rolname AS text) AS grantee,\n       CAST(current_database() AS text) AS table_catalog,\n       CAST(nc.nspname AS text) AS table_schema,\n       CAST(c.relname AS text) AS table_name,\n       CAST(c.prtype AS text) AS privilege_type,\n       CAST(CASE WHEN pg_has_role(grantee.oid, c.relowner, 'USAGE') OR c.grantable\n                 THEN 'YES' ELSE 'NO' END AS text) AS is_grantable,\n       CAST(CASE WHEN c.prtype = 'SELECT' THEN 'YES' ELSE 'NO' END AS text) AS with_hierarchy\nFROM (\n      SELECT oid, relname, relnamespace, relkind, relowner,\n             (aclexplode(coalesce(relacl, acldefault('r', relowner)))).*\n      FROM pg_class\n     ) AS c (oid, relname, relnamespace, relkind, relowner, grantor, grantee, prtype, grantable),\n     pg_namespace nc,\n     pg_authid u_grantor,\n     (\n       SELECT oid, rolname FROM pg_authid\n       UNION ALL\n       SELECT 0::oid, 'PUBLIC'\n     ) AS grantee (oid, rolname)\nWHERE c.relnamespace = nc.oid\n      AND c.relkind IN ('r', 'v', 'f', 'p')\n      AND c.grantee = grantee.oid\n      AND c.grantor = u_grantor.oid\n      AND c.prtype IN ('INSERT', 'SELECT', 'UPDATE', 'DELETE', 'TRUNCATE', 'REFERENCES', 'TRIGGER');\n<\/code><\/pre>\n
    When executed by the low-privileged monitoring<\/code> role, this query returns:<\/p>\n
    \n grantor   | grantee | table_catalog | table_schema | table_name | privilege_type | is_grantable | with_hierarchy \n-----------+---------+---------------+--------------+------------+----------------+--------------+----------------\n admin_user | u       | postgres      | public       | t          | SELECT         | NO           | YES\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
    Collecting privileges under a low-privileged user Continue Reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"footnotes":""},"categories":[60],"tags":[],"class_list":["post-4395","post","type-post","status-publish","format-standard","hentry","category-postgresql"],"yoast_head":"\nCollecting table privileges in PostgreSQL - All-round Database Topics<\/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:\/\/nenadnoveljic.com\/blog\/collecting-table-privileges-in-postgresql\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Collecting table privileges in PostgreSQL - All-round Database Topics\" \/>\n<meta property=\"og:description\" content=\"Collecting privileges under a low-privileged user Continue Reading →\" \/>\n<meta property=\"og:url\" content=\"https:\/\/nenadnoveljic.com\/blog\/collecting-table-privileges-in-postgresql\/\" \/>\n<meta property=\"og:site_name\" content=\"All-round Database Topics\" \/>\n<meta property=\"article:published_time\" content=\"2025-07-14T16:12:36+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-07-14T16:14:37+00:00\" \/>\n<meta name=\"author\" content=\"Nenad Noveljic\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@NenadNoveljic\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Nenad Noveljic\" \/>\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:\\\/\\\/nenadnoveljic.com\\\/blog\\\/collecting-table-privileges-in-postgresql\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/nenadnoveljic.com\\\/blog\\\/collecting-table-privileges-in-postgresql\\\/\"},\"author\":{\"name\":\"Nenad Noveljic\",\"@id\":\"https:\\\/\\\/nenadnoveljic.com\\\/blog\\\/#\\\/schema\\\/person\\\/51458d9dd86dbbdd19f5add451d44efa\"},\"headline\":\"Collecting table privileges in PostgreSQL\",\"datePublished\":\"2025-07-14T16:12:36+00:00\",\"dateModified\":\"2025-07-14T16:14:37+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/nenadnoveljic.com\\\/blog\\\/collecting-table-privileges-in-postgresql\\\/\"},\"wordCount\":183,\"commentCount\":0,\"articleSection\":[\"PostgreSQL\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\\\/\\\/nenadnoveljic.com\\\/blog\\\/collecting-table-privileges-in-postgresql\\\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/nenadnoveljic.com\\\/blog\\\/collecting-table-privileges-in-postgresql\\\/\",\"url\":\"https:\\\/\\\/nenadnoveljic.com\\\/blog\\\/collecting-table-privileges-in-postgresql\\\/\",\"name\":\"Collecting table privileges in PostgreSQL - 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