# backslash_quote

> backslash_quote — Sets whether "\'" is allowed in string literals. Observed in PG9.0–19 Beta 3; its last measured boot default is safe_encoding in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.
---

> [!NOTE]
> **Fact — official short description:** “Sets whether "\'" is allowed in string literals.”

## Identity {#identity}

| Field | Value | Meaning |
| --- | --- | --- |
| Type | `enum` | Upstream pg_settings type |
| Context | `user` | Settable by an ordinary user |
| Unit | — | Raw unit |
| Range | — | Raw limits in the last observed version |
| Enum values | `safe_encoding`, `on`, `off` | — for non-enum types |
| Category | Version and Platform Compatibility / Previous PostgreSQL Versions | Upstream classification |
| Latest boot value | `safe_encoding` | safe_encoding |
{.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 | `safe_encoding` | — | safe_encoding |
{.full-width caption="Measured PG9.0–19 Beta 3 boot defaults"}

## How it works {#mechanism}

Sets whether "\'" is allowed in string literals. It can be changed at session scope, so different sessions may observe different behavior.

The safe_encoding mode accepts \' only when the client encoding cannot contain a backslash byte inside a multibyte character. This defense belongs to old string-literal syntax; E'...' is the explicit escape-string form and standard_conforming_strings governs ordinary strings.

Monitor and change backslash_quote together with array_nulls, escape_string_warning, standard_conforming_strings. Validate on the relevant server role and real workload, then use its user context to choose session change, reload, or restart; a historical boot default is not the current effective value.

## Tuning advice {#tuning-advice}

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

| Workload | Guidance |
| --- | --- |
| OLTP | Keep the modern default and repair legacy clients/SQL that depend on backslash_quote. Test migration at session scope first; do not make a compatibility switch permanent cluster policy. |
| OLAP | Regression-test ETL, generated SQL, and old drivers, where parsing/quoting assumptions hide. Performance is rarely a reason to change this switch. |
| Small nodes | Keep the default without a legacy requirement. If temporarily enabled, record owner, affected connections, and a removal date. |
{.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}

- Keeping a compatibility switch permanently instead of fixing the client.
- Testing in one session and deploying globally to unrelated applications.
- Confusing parsing compatibility with data or security compatibility.
- Forgetting to remove an override after the upgrade migration is complete.

## Related parameters {#related-parameters}

[`array_nulls`](/parameters/array-nulls/) · [`escape_string_warning`](/parameters/escape-string-warning/) · [`standard_conforming_strings`](/parameters/standard-conforming-strings/) · [`transform_null_equals`](/parameters/transform-null-equals/) · [`quote_all_identifiers`](/parameters/quote-all-identifiers/) · [`default_with_oids`](/parameters/default-with-oids/)

## References {#references}

- [PostgreSQL 19 Beta 3 — backslash_quote](https://www.postgresql.org/docs/19/runtime-config-compatible.html#GUC-BACKSLASH-QUOTE)
- [PostgreSQL 19 release notes](https://www.postgresql.org/docs/19/release-19.html)
- [Machine-readable GUC export](/data/guc.jsonl)