# krb_caseins_users

> krb_caseins_users is the PostgreSQL setting that defines whether Kerberos and GSSAPI user names should be treated as case-insensitive.
---

> [!NOTE]
> **Fact — official short description:** “Sets whether Kerberos and GSSAPI user names should be treated as case-insensitive.”

## Identity {#identity}

| Field | Value | Meaning |
| --- | --- | --- |
| Type | `bool` | Upstream pg_settings type |
| Context | `sighup` | Takes effect after configuration reload |
| Unit | — | Raw unit |
| Range | — | Raw limits in the last observed version |
| Enum values | — | — for non-enum types |
| Category | Connections and Authentication / Authentication | Upstream classification |
| Latest boot value | `off` | off |
{.fields meta="-"}

## Lifecycle {#lifecycle}

| Fact | Value |
| --- | --- |
| First observed | PG9.0 (research boundary) |
| Present in | PG9.0–19 Beta 3 |
| Removed in | No |
| Introduction commit | Not asserted: predates the PG9.0 research boundary |
| Commit date | — |
| Discussion | — |

## Default history {#default-history}

| Versions | Raw `boot_val` | Unit | Human value |
| --- | --- | --- | --- |
| PG9.0–19 Beta 3 | `off` | — | off |
{.full-width caption="Measured PG9.0–19 Beta 3 boot defaults"}

## How it works {#mechanism}

krb_caseins_users sets whether Kerberos and GSSAPI user names should be treated as case-insensitive. It affects comparison of authenticated Kerberos/GSS names with database role names; case folding can merge identities that an existing mapping treated as distinct.

krb_caseins_users is a SIGHUP-context setting: a configuration reload activates the new server value without a restart; subsequent operations that consult it use the refreshed value.

The final authentication path combines this setting with pg_hba.conf, role attributes, credential material, client capabilities, and sometimes operating-system identity services.

## Tuning advice {#tuning-advice}

> [!TIP]
> **Advice.** These are workload-specific starting points and must be validated with measurements.

| Workload | Guidance |
| --- | --- |
| OLTP | Set krb_caseins_users from the authentication architecture and security policy, not workload throughput. Test every driver, identity mapping, failover path, and credential-rotation procedure. |
| OLAP | Apply the same security baseline to analytical access; isolate any legacy client exception to a dedicated role and a dated migration plan. |
| Small nodes | Prefer the current secure default for krb_caseins_users. Avoid weakening authentication to save marginal CPU on a small node; reduce connection churn with pooling instead. |
{.full-width}

## Pigsty {#pigsty}

Values use the fixed 8-vCPU, 32-GiB, 100-GiB SSD fixture and render the current Pigsty templates for PG19 Beta 3; this does not assert current Pigsty support for that historical or beta release.

| Template | Effective value | Versus upstream boot | Source expression |
| --- | --- | --- | --- |
| OLTP | Unmodified | — | — |
| OLAP | Unmodified | — | — |
| CRIT | Unmodified | — | — |
| TINY | Unmodified | — | — |
{.full-width}

> [!CAUTION]
> **Advice — pending human review.** Fact from the current Pigsty template projection: OLTP: PG9.0–19 Beta 3 unmodified; OLAP: PG9.0–19 Beta 3 unmodified; CRIT: PG9.0–19 Beta 3 unmodified; TINY: PG9.0–19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

## Common pitfalls {#common-pitfalls}

- Editing krb_caseins_users without reloading configuration and verifying the effective value and subsequent behavior.
- Changing one authentication setting without testing pg_hba.conf ordering, existing secrets, mappings, and every client library.
- Weakening identity policy to solve connection churn or CPU cost that should be addressed with pooling and capacity planning.
- Changing krb_caseins_users globally without a rollback plan and a client or operational compatibility test.

## Related parameters {#related-parameters}

[`password_encryption`](/parameters/password-encryption/) · [`scram_iterations`](/parameters/scram-iterations/) · [`md5_password_warnings`](/parameters/md5-password-warnings/) · [`authentication_timeout`](/parameters/authentication-timeout/) · [`oauth_validator_libraries`](/parameters/oauth-validator-libraries/) · [`krb_server_keyfile`](/parameters/krb-server-keyfile/)

## References {#references}

- [PostgreSQL 19 Beta 3 — krb_caseins_users](https://www.postgresql.org/docs/19/runtime-config-connection.html#GUC-KRB-CASEINS-USERS)
- [PostgreSQL 19 release notes](https://www.postgresql.org/docs/19/release-19.html)
- [Machine-readable GUC export](/data/guc.jsonl)