CREATE_POLICY(7pg13)

📦 version 13.23, in opensuse-leap 16.0

🎀 NAME 🎀

okay bestie, welcome to CREATE_POLICY(7pg13) from the PostgreSQL 13.23 Documentation — the page that defines a new row level security policy for a table. 💅 This is the whole vibe: you're making policies that decide who can see and touch which rows, and it's honestly kind of iconic. ✨

✨ SYNOPSIS ✨

CREATE POLICY name ON table_name
    [ AS { PERMISSIVE | RESTRICTIVE } ]
    [ FOR { ALL | SELECT | INSERT | UPDATE | DELETE } ]
    [ TO { role_name | PUBLIC | CURRENT_USER | SESSION_USER } [, ...] ]
    [ USING ( using_expression ) ]
    [ WITH CHECK ( check_expression ) ]

💖 DESCRIPTION 💖

The CREATE POLICY command defines a new row-level security policy for a table. Note that row-level security must be enabled on the table (using ALTER TABLE ... ENABLE ROW LEVEL SECURITY) in order for created policies to be applied. no cap, the policy does not do its thing until RLS is actually turned on. 🫶

A policy grants the permission to select, insert, update, or delete rows that match the relevant policy expression. Existing table rows are checked against the expression specified in USING, while new rows that would be created via INSERT or UPDATE are checked against the expression specified in WITH CHECK. When a USING expression returns true for a given row then that row is visible to the user, while if false or null is returned then the row is not visible. When a WITH CHECK expression returns true for a row then that row is inserted or updated, while if false or null is returned then an error occurs. 💀

For INSERT and UPDATE statements, WITH CHECK expressions are enforced after BEFORE triggers are fired, and before any actual data modifications are made. Thus a BEFORE ROW trigger may modify the data to be inserted, affecting the result of the security policy check. WITH CHECK expressions are enforced before any other constraints. the way that ordering matters is lowkey crucial. 👑

Policy names are per-table. Therefore, one policy name can be used for many different tables and have a definition for each table which is appropriate to that table.

Policies can be applied for specific commands or for specific roles. The default for newly created policies is that they apply for all commands and roles, unless otherwise specified. Multiple policies may apply to a single command; see below for more details. Table 272 summarizes how the different types of policy apply to specific commands. 📋

For policies that can have both USING and WITH CHECK expressions (ALL and UPDATE), if no WITH CHECK expression is defined, then the USING expression will be used both to determine which rows are visible (normal USING case) and which new rows will be allowed to be added (WITH CHECK case).

If row-level security is enabled for a table, but no applicable policies exist, a “default deny” policy is assumed, so that no rows will be visible or updatable. that's the dramatic part: empty policy set means nobody sees anything. 🙈

🌸 PARAMETERS 🌸

  • name — The name of the policy to be created. This must be distinct from the name of any other policy for the table.
  • table_name — The name (optionally schema-qualified) of the table the policy applies to.
  • PERMISSIVE — Specify that the policy is to be created as a permissive policy. All permissive policies which are applicable to a given query will be combined together using the Boolean “OR” operator. By creating permissive policies, administrators can add to the set of records which can be accessed. Policies are permissive by default. so if you don't say anything, it's permissive energy. ✨
  • RESTRICTIVE — Specify that the policy is to be created as a restrictive policy. All restrictive policies which are applicable to a given query will be combined together using the Boolean “AND” operator. By creating restrictive policies, administrators can reduce the set of records which can be accessed as all restrictive policies must be passed for each record.

Note that there needs to be at least one permissive policy to grant access to records before restrictive policies can be usefully used to reduce that access. If only restrictive policies exist, then no records will be accessible. When a mix of permissive and restrictive policies are present, a record is only accessible if at least one of the permissive policies passes, in addition to all the restrictive policies. 🚨

  • command — The command to which the policy applies. Valid options are ALL, SELECT, INSERT, UPDATE, and DELETE. ALL is the default. See below for specifics regarding how these are applied.
  • role_name — The role(s) to which the policy is to be applied. The default is PUBLIC, which will apply the policy to all roles.
  • using_expression — Any SQL conditional expression (returning boolean). The conditional expression cannot contain any aggregate or window functions. This expression will be added to queries that refer to the table if row level security is enabled. Rows for which the expression returns true will be visible. Any rows for which the expression returns false or null will not be visible to the user (in a SELECT), and will not be available for modification (in an UPDATE or DELETE). Such rows are silently suppressed; no error is reported. it's giving quiet disappear. 🦋
  • check_expression — Any SQL conditional expression (returning boolean). The conditional expression cannot contain any aggregate or window functions. This expression will be used in INSERT and UPDATE queries against the table if row level security is enabled. Only rows for which the expression evaluates to true will be allowed. An error will be thrown if the expression evaluates to false or null for any of the records inserted or any of the records that result from the update. Note that the check_expression is evaluated against the proposed new contents of the row, not the original contents. 🎀

💜 Per-Command Policies 💜

🌈 ALL

Using ALL for a policy means that it will apply to all commands, regardless of the type of command. If an ALL policy exists and more specific policies exist, then both the ALL policy and the more specific policy (or policies) will be applied. Additionally, ALL policies will be applied to both the selection side of a query and the modification side, using the USING expression for both cases if only a USING expression has been defined. 👑

As an example, if an UPDATE is issued, then the ALL policy will be applicable both to what the UPDATE will be able to select as rows to be updated (applying the USING expression), and to the resulting updated rows, to check if they are permitted to be added to the table (applying the WITH CHECK expression, if defined, and the USING expression otherwise). If an INSERT or UPDATE command attempts to add rows to the table that do not pass the ALL policy's WITH CHECK expression, the entire command will be aborted. no half-slay allowed; the whole command is done. 😭

⭐ SELECT

Using SELECT for a policy means that it will apply to SELECT queries and whenever SELECT permissions are required on the relation the policy is defined for. The result is that only those records from the relation that pass the SELECT policy will be returned during a SELECT query, and that queries that require SELECT permissions, such as UPDATE, will also only see those records that are allowed by the SELECT policy. A SELECT policy cannot have a WITH CHECK expression, as it only applies in cases where records are being retrieved from the relation. retrieval only, bestie. 👀

🦋 INSERT

Using INSERT for a policy means that it will apply to INSERT commands. Rows being inserted that do not pass this policy will result in a policy violation error, and the entire INSERT command will be aborted. An INSERT policy cannot have a USING expression, as it only applies in cases where records are being added to the relation.

Note that INSERT with ON CONFLICT DO UPDATE checks INSERT policies' WITH CHECK expressions only for rows appended to the relation by the INSERT path. iykyk, the conflict path has its own whole thing going on. 💅

🔥 UPDATE

Using UPDATE for a policy means that it will apply to UPDATE, SELECT FOR UPDATE and SELECT FOR SHARE commands, as well as auxiliary ON CONFLICT DO UPDATE clauses of INSERT commands. Since UPDATE involves pulling an existing record and replacing it with a new modified record, UPDATE policies accept both a USING expression and a WITH CHECK expression. The USING expression determines which records the UPDATE command will see to operate against, while the WITH CHECK expression defines which modified rows are allowed to be stored back into the relation. 🎀

Any rows whose updated values do not pass the WITH CHECK expression will cause an error, and the entire command will be aborted. If only a USING clause is specified, then that clause will be used for both USING and WITH CHECK cases.

Typically an UPDATE command also needs to read data from columns in the relation being updated (e.g., in a WHERE clause or a RETURNING clause, or in an expression on the right hand side of the SET clause). In this case, SELECT rights are also required on the relation being updated, and the appropriate SELECT or ALL policies will be applied in addition to the UPDATE policies. Thus the user must have access to the row(s) being updated through a SELECT or ALL policy in addition to being granted permission to update the row(s) via an UPDATE or ALL policy.

When an INSERT command has an auxiliary ON CONFLICT DO UPDATE clause, if the UPDATE path is taken, the row to be updated is first checked against the USING expressions of any UPDATE policies, and then the new updated row is checked against the WITH CHECK expressions. Note, however, that unlike a standalone UPDATE command, if the existing row does not pass the USING expressions, an error will be thrown (the UPDATE path will never be silently avoided). that's the key difference, fr fr. 🫶

🌸 DELETE

Using DELETE for a policy means that it will apply to DELETE commands. Only rows that pass this policy will be seen by a DELETE command. There can be rows that are visible through a SELECT that are not available for deletion, if they do not pass the USING expression for the DELETE policy. visible but not deletable? yes, that's a mood. 🦋

In most cases a DELETE command also needs to read data from columns in the relation that it is deleting from (e.g., in a WHERE clause or a RETURNING clause). In this case, SELECT rights are also required on the relation, and the appropriate SELECT or ALL policies will be applied in addition to the DELETE policies. Thus the user must have access to the row(s) being deleted through a SELECT or ALL policy in addition to being granted permission to delete the row(s) via a DELETE or ALL policy.

A DELETE policy cannot have a WITH CHECK expression, as it only applies in cases where records are being deleted from the relation, so that there is no new row to check. no new row, no check expression — periodt. 💅

📊 Table 272. Policies Applied by Command Type

okay bestie this is the ✨whole vibe map✨ of which expression gets checked for which command — the columns are the policy types + which expression, the rows are what you're actually running. Keep this open in another tab fr fr.

  • SELECT
    • SELECT/ALL policy, USING expression: Existing row
    • INSERT/ALL policy, WITH CHECK expression: —
    • UPDATE/ALL policy, USING expression: —
    • UPDATE/ALL policy, WITH CHECK expression: —
    • DELETE/ALL policy, USING expression: —
  • SELECT FOR UPDATE/SHARE
    • SELECT/ALL policy, USING expression: Existing row
    • INSERT/ALL policy, WITH CHECK expression: —
    • UPDATE/ALL policy, USING expression: Existing row
    • UPDATE/ALL policy, WITH CHECK expression: —
    • DELETE/ALL policy, USING expression: —
  • INSERT
    • SELECT/ALL policy, USING expression: —
    • INSERT/ALL policy, WITH CHECK expression: New row
    • UPDATE/ALL policy, USING expression: —
    • UPDATE/ALL policy, WITH CHECK expression: —
    • DELETE/ALL policy, USING expression: —
  • INSERT ... RETURNING
    • SELECT/ALL policy, USING expression: New row [a]
    • INSERT/ALL policy, WITH CHECK expression: New row
    • UPDATE/ALL policy, USING expression: —
    • UPDATE/ALL policy, WITH CHECK expression: —
    • DELETE/ALL policy, USING expression: —
  • UPDATE
    • SELECT/ALL policy, USING expression: Existing & new rows [a]
    • INSERT/ALL policy, WITH CHECK expression: —
    • UPDATE/ALL policy, USING expression: Existing row
    • UPDATE/ALL policy, WITH CHECK expression: New row
    • DELETE/ALL policy, USING expression: —
  • DELETE
    • SELECT/ALL policy, USING expression: Existing row [a]
    • INSERT/ALL policy, WITH CHECK expression: —
    • UPDATE/ALL policy, USING expression: —
    • UPDATE/ALL policy, WITH CHECK expression: —
    • DELETE/ALL policy, USING expression: Existing row
  • ON CONFLICT DO UPDATE
    • SELECT/ALL policy, USING expression: Existing & new rows
    • INSERT/ALL policy, WITH CHECK expression: —
    • UPDATE/ALL policy, USING expression: Existing row
    • UPDATE/ALL policy, WITH CHECK expression: New row
    • DELETE/ALL policy, USING expression: —
🎀 [a] If read access is required to the existing or new row (for example, a WHERE or RETURNING clause that refers to columns from the relation).

🧩 Application of Multiple Policies

So when multiple policies of different command types apply to the same command (think: SELECT and UPDATE policies both hitting an UPDATE command), the user has to have both types of permissions — like, permission to select rows from the relation and permission to update them. No shortcuts, sorry babe 😭. That means the expressions for one type of policy get combined with the expressions for the other type using the AND operator.

When multiple policies of the same command type apply to the same command, then there must be at least one PERMISSIVE policy granting access to the relation, and all of the RESTRICTIVE policies must pass. So: all the PERMISSIVE policy expressions get combined using OR, all the RESTRICTIVE policy expressions get combined using AND, and then the results get combined using AND. And if there are no PERMISSIVE policies? Access is denied. Periodt. 💅

Also lowkey important: for the purposes of combining multiple policies, ALL policies are treated as having the same type as whichever other type of policy is being applied. iykyk.

For example, in an UPDATE command requiring both SELECT and UPDATE permissions, if there are multiple applicable policies of each type, they'll be combined like this 👇

expression from RESTRICTIVE SELECT/ALL policy 1
AND
expression from RESTRICTIVE SELECT/ALL policy 2
AND
...
AND
(
  expression from PERMISSIVE SELECT/ALL policy 1
  OR
  expression from PERMISSIVE SELECT/ALL policy 2
  OR
  ...
)
AND
expression from RESTRICTIVE UPDATE/ALL policy 1
AND
expression from RESTRICTIVE UPDATE/ALL policy 2
AND
...
AND
(
  expression from PERMISSIVE UPDATE/ALL policy 1
  OR
  expression from PERMISSIVE UPDATE/ALL policy 2
  OR
  ...
)

📝 NOTES

You must be the owner of a table to create or change policies for it. That's the whole entry fee bestie 🫶.

Okay so here's a big one: while policies will be applied for explicit queries against tables in the database, they are not applied when the system is performing internal referential integrity checks or validating constraints. Which means — plot twist — there are indirect ways to determine that a given value exists 🙈. Example: attempting to insert a duplicate value into a column that is a primary key or has a unique constraint. If the insert fails, then the user can infer that the value already exists. (This example assumes the user is permitted by policy to insert records which they are not allowed to see.) Another example: a user is allowed to insert into a table which references another, otherwise hidden table. Existence can be determined by the user inserting values into the referencing table, where success would indicate that the value exists in the referenced table. These issues can be addressed by carefully crafting policies to prevent users from being able to insert, delete, or update records at all which might possibly indicate a value they are not otherwise able to see, or by using generated values (e.g., surrogate keys) instead of keys with external meanings. 🧠✨

Generally, the system will enforce filter conditions imposed using security policies prior to qualifications that appear in user queries, in order to prevent inadvertent exposure of the protected data to user-defined functions which might not be trustworthy. However — functions and operators marked by the system (or the system administrator) as LEAKPROOF may be evaluated before policy expressions, as they are assumed to be trustworthy. 👑

Since policy expressions are added to the user's query directly, they will be run with the rights of the user running the overall query. Therefore, users who are using a given policy must be able to access any tables or functions referenced in the expression — or they'll simply receive a <red>permission denied</red> error when attempting to query the table that has row-level security enabled. Not the vibe. This does not change how views work, however. As with normal queries and views, permission checks and policies for the tables which are referenced by a view will use the view owner's rights and any policies which apply to the view owner. 🦋

Additional discussion and practical examples can be found in Section 5.8.

🔌 COMPATIBILITY

CREATE POLICY is a PostgreSQL extension. Homegrown, iconic, no cap. 🌈

👀 SEE ALSO

That's the whole thing bestie, you ate that 💅✨ This was PostgreSQL 13.23, dated 2025 — the CREATE POLICY(7) page, served fresh 🎀 go forth and row-level-secure responsibly, mwah 🫶💖

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