# Version and Platform Compatibility

> Complete dossiers for 12 core PostgreSQL settings in Version and Platform Compatibility.
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Dossier URLs remain flat; this category exists only to organize browsing and the sidebar.

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Section pages:

- [allow_alter_system](/parameters/allow-alter-system/): allow_alter_system allows running the ALTER SYSTEM command. It is a sighup setting present in PG17–18; the latest recorded boot default is on.
- [array_nulls](/parameters/array-nulls/): array_nulls — Enables input of NULL elements in arrays. Observed in PG9.0–19 Beta 3; its last measured boot default is on in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.
- [backslash_quote](/parameters/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.
- [default_with_oids](/parameters/default-with-oids/): default_with_oids — Create new tables with OIDs by default. Observed in PG9.0–11; its last measured boot default is off in PG11, with user context. It was removed in PG12.
- [escape_string_warning](/parameters/escape-string-warning/): escape_string_warning — Warn about backslash escapes in ordinary string literals. Observed in PG9.0–18; its last measured boot default is on in PG18, with user context. It was removed in PG19 Beta 3.
- [lo_compat_privileges](/parameters/lo-compat-privileges/): lo_compat_privileges — Enables backward compatibility mode for privilege checks on large objects. Observed in PG9.0–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.
- [operator_precedence_warning](/parameters/operator-precedence-warning/): operator_precedence_warning — Emit a warning for constructs that changed meaning since PostgreSQL 9.4. Observed in PG9.5–13; its last measured boot default is off in PG13, with user context. It was removed in PG14.
- [quote_all_identifiers](/parameters/quote-all-identifiers/): quote_all_identifiers — When generating SQL fragments, quote all identifiers. Observed in PG9.1–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.
- [sql_inheritance](/parameters/sql-inheritance/): sql_inheritance — Causes subtables to be included by default in various commands. Observed in PG9.0–9.6; its last measured boot default is on in PG9.6, with user context. It was removed in PG10.
- [standard_conforming_strings](/parameters/standard-conforming-strings/): standard_conforming_strings — Nonstandard strings are no longer supported; this can only be true. Observed in PG9.0–19 Beta 3; its last measured boot default is on in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.
- [synchronize_seqscans](/parameters/synchronize-seqscans/): synchronize_seqscans — Enables synchronized sequential scans. Observed in PG9.0–19 Beta 3; its last measured boot default is on in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.
- [transform_null_equals](/parameters/transform-null-equals/): transform_null_equals — Treats "expr=NULL" as "expr IS NULL". Observed in PG9.0–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.