Preset Options

• 1: block_size
• 2: data_checksums
• 3: data_directory_mode
• 4: debug_assertions
• 5: debug_exec_backend
• 6: effective_wal_level
• 7: huge_pages_status
• 8: in_hot_standby
• 9: integer_datetimes
• 10: lc_collate
• 11: lc_ctype
• 12: max_function_args
• 13: max_identifier_length
• 14: max_index_keys
• 15: num_os_semaphores
• 16: segment_size
• 17: server_encoding
• 18: server_version
• 19: server_version_num
• 20: shared_memory_size
• 21: shared_memory_size_in_huge_pages
• 22: ssl_library
• 23: wal_block_size
• 24: wal_segment_size

1 - block_size

Identity

Lifecycle

Default history

How it works

Shows the size of a disk block. It is read-only and cannot be changed with SET or configuration-file edits.

It reflects BLCKSZ, normally 8 KiB, chosen when PostgreSQL was built; all heap and index page layouts depend on it.

Interpret it with wal_block_size, wal_segment_size, segment_size. Applications and operations tooling may read block_size for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only block_size with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

wal_block_size · wal_segment_size · segment_size · data_checksums · server_version_num · max_function_args

References

• PostgreSQL 19 Beta 3 — block_size
• PostgreSQL 19 release notes
• Machine-readable GUC export

2 - data_checksums

Identity

Lifecycle

Default history

How it works

Reports the cluster-wide data-checksum state stored in the control file. It is internal/read-only in SQL and cannot be changed with SET.

Checksums are chosen by initdb or changed later with the server stopped by pg_checksums. PostgreSQL verifies page checksums when reading from storage and computes them when writing pages.

A checksum detects a torn or corrupted page; it does not repair it or prove that WAL, backups, memory, and every storage layer are healthy. Changes require an offline procedure, capacity for a full-cluster scan, and a verified backup.

Tuning advice

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.

Common pitfalls

• Trying to change the read-only report with SET or ALTER SYSTEM.
• Running pg_checksums while the server is not cleanly shut down.
• Treating a checksum failure as repairable by ignoring the error.
• Assuming checksums validate WAL records, logical correctness, or backups by themselves.
• Enabling checksums without monitoring checksum failures and storage health.

Related parameters

ignore_checksum_failure · zero_damaged_pages · wal_log_hints · full_page_writes · data_directory · block_size

References

• PostgreSQL 19 Beta 3 — data_checksums
• PostgreSQL 19 release notes
• Machine-readable GUC export

3 - data_directory_mode

Identity

Lifecycle

Default history

How it works

Shows the mode of the data directory. It is read-only and cannot be changed with SET or configuration-file edits.

It reports the effective Unix permission mode of the data directory, commonly 0700 or group-readable 0750, in decimal pg_settings representation.

Interpret it with block_size, data_checksums, debug_assertions. Applications and operations tooling may read data_directory_mode for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only data_directory_mode with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

block_size · data_checksums · debug_assertions · huge_pages_status · in_hot_standby · integer_datetimes

References

• PostgreSQL 19 Beta 3 — data_directory_mode
• PostgreSQL 19 release notes
• Machine-readable GUC export

4 - debug_assertions

Identity

Lifecycle

Default history

How it works

Shows whether the running server has assertion checks enabled. It is read-only and cannot be changed with SET or configuration-file edits.

It reflects whether the server binary was built with assertion checks, a developer diagnostic that adds overhead and may abort on violated invariants.

Interpret it with server_version, server_version_num, server_encoding. Applications and operations tooling may read debug_assertions for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only debug_assertions with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

server_version · server_version_num · server_encoding · ssl_library · integer_datetimes · block_size

References

• PostgreSQL 19 Beta 3 — debug_assertions
• PostgreSQL 19 release notes
• Machine-readable GUC export

5 - debug_exec_backend

Identity

Lifecycle

Default history

How it works

PostgreSQL describes debug_exec_backend as follows: “Shows whether the running server is built with EXEC_BACKEND enabled.” It is read-only state reported by PostgreSQL, not an operator-controlled tuning knob. The atlas measures it in PG19 Beta 3; boot_val is the compiled or initialized baseline, not proof of a running cluster’s effective setting.

EXEC_BACKEND creates new backends by executing a fresh server process instead of relying only on forked address-space inheritance. The reported value is determined by platform or build flags—normally true on Windows—and is useful to explain parameter propagation and platform-specific startup behavior.

Read it together with debug_assertions, server_version, server_version_num, dynamic_shared_memory_type. Check SHOW and pg_settings on the target server, verify the source and pending_restart fields, and compare workload, logs, and resource metrics before and after any change.

Tuning advice

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.

Common pitfalls

• Treating the measured boot_val for debug_exec_backend as proof of the effective value on an initialized or managed cluster.
• Applying a change as though it were immediate while pg_settings reports internal context.
• Changing this setting in isolation without checking the linked limits, observability, and rollback path.
• Depending on beta behavior in production without retesting the PostgreSQL 19 final release.

Related parameters

debug_assertions · server_version · server_version_num · dynamic_shared_memory_type

References

• PostgreSQL 19 Beta 3 — debug_exec_backend
• PostgreSQL 19 release notes
• Machine-readable GUC export

6 - effective_wal_level

Identity

Lifecycle

Default history

How it works

PostgreSQL describes effective_wal_level as follows: “Shows effective WAL level.” It is read-only state reported by PostgreSQL, not an operator-controlled tuning knob. The atlas measures it in PG19 Beta 3; boot_val is the compiled or initialized baseline, not proof of a running cluster’s effective setting.

Unlike configured wal_level, this read-only value reports the operational logging level. PostgreSQL 19 can maintain logical-equivalent WAL when logical slots require it even if wal_level is replica, and a standby inherits the effective value from the most upstream server in its replication chain.

Read it together with wal_level, max_replication_slots, max_wal_senders, track_commit_timestamp. Check SHOW and pg_settings on the target server, verify the source and pending_restart fields, and compare workload, logs, and resource metrics before and after any change.

Tuning advice

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.

Common pitfalls

• Treating the measured boot_val for effective_wal_level as proof of the effective value on an initialized or managed cluster.
• Applying a change as though it were immediate while pg_settings reports internal context.
• Changing this setting in isolation without checking the linked limits, observability, and rollback path.
• Depending on beta behavior in production without retesting the PostgreSQL 19 final release.

Related parameters

wal_level · max_replication_slots · max_wal_senders · track_commit_timestamp

References

• PostgreSQL 19 Beta 3 — effective_wal_level
• PostgreSQL 19 release notes
• Machine-readable GUC export

7 - huge_pages_status

Identity

Lifecycle

Default history

How it works

Reports whether the main shared-memory area actually uses explicit huge pages. It is an internal, read-only startup result with values off, on, or unknown.

The result is derived after applying huge_pages and attempting startup allocation against operating-system support and the available huge-page pool. It is not fixed by the PostgreSQL binary or initdb.

Use shared_memory_size_in_huge_pages to estimate the required pool and compare huge_pages_status with the requested huge_pages policy after every restart. Transparent Huge Pages are a separate operating-system mechanism.

Tuning advice

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.

Common pitfalls

• Trying to SET a read-only startup result.
• Confusing huge_pages_status with the configured huge_pages request.
• Ignoring a too-small operating-system huge-page pool or startup allocation failure.
• Confusing explicit PostgreSQL huge pages with Transparent Huge Pages.
• Assuming a status from one node applies to failover nodes with different OS configuration.

Related parameters

huge_pages · shared_memory_size_in_huge_pages · shared_memory_size · shared_buffers · min_dynamic_shared_memory · dynamic_shared_memory_type

References

• PostgreSQL 19 Beta 3 — huge_pages_status
• PostgreSQL 19 release notes
• Machine-readable GUC export

8 - in_hot_standby

Identity

Lifecycle

Default history

How it works

Shows whether hot standby is currently active. It is read-only and cannot be changed with SET or configuration-file edits.

It changes as recovery enters or leaves hot-standby operation and is intended for feature detection by SQL code.

Interpret it with hot_standby, max_standby_streaming_delay, hot_standby_feedback. Applications and operations tooling may read in_hot_standby for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only in_hot_standby with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

hot_standby · max_standby_streaming_delay · hot_standby_feedback · primary_conninfo · block_size · data_checksums

References

• PostgreSQL 19 Beta 3 — in_hot_standby
• PostgreSQL 19 release notes
• Machine-readable GUC export

9 - integer_datetimes

Identity

Lifecycle

Default history

How it works

Shows whether datetimes are integer based. It is read-only and cannot be changed with SET or configuration-file edits.

It reports the server’s datetime representation. All measured PG9.0–19 Beta 3 builds use integer datetimes; applications should treat it as compatibility metadata.

Interpret it with server_version, server_version_num, server_encoding. Applications and operations tooling may read integer_datetimes for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only integer_datetimes with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

server_version · server_version_num · server_encoding · ssl_library · debug_assertions · block_size

References

• PostgreSQL 19 Beta 3 — integer_datetimes
• PostgreSQL 19 release notes
• Machine-readable GUC export

10 - lc_collate

Identity

Lifecycle

Default history

How it works

Reported the current database’s collation locale through PG15. It was an internal read-only value, not a configurable GUC, and PostgreSQL 16 removed it from pg_settings.

The collation locale is selected when a database is created and can differ between databases in one cluster. It affects ordering and comparison semantics; changing the server configuration cannot rewrite existing indexes or database locale metadata.

On PG16 and later, monitoring and applications should read the current database row in pg_database and its locale-provider-specific metadata, and use pg_collation for individual collation objects. Test collation-version changes separately from this removed reporter.

Tuning advice

Pigsty

Values use the fixed 8-vCPU, 32-GiB, 100-GiB SSD fixture and render the current Pigsty templates for PG15; this does not assert current Pigsty support for that historical or beta release.

Common pitfalls

• Trying to remove or set lc_collate in configuration even though it was always internal/read-only.
• Assuming one cluster-wide value applies to every database.
• Changing operating-system or ICU locale data without checking collation versions and rebuilding affected indexes.
• Comparing text behavior across providers using only a locale name.

Related parameters

lc_ctype · server_encoding · client_encoding · icu_validation_level · default_text_search_config · server_version_num

References

• PostgreSQL 15 — lc_collate
• Machine-readable GUC export

11 - lc_ctype

Identity

Lifecycle

Default history

How it works

Reported the current database’s character-classification and case-conversion locale through PG15. It was internal/read-only and PostgreSQL 16 removed it from pg_settings.

The locale is fixed when a database is created and can differ by database. It affects locale-aware character classes and case conversion, but is not a session switch and cannot be changed with ALTER SYSTEM.

On PG16 and later, migrate SHOW/current_setting consumers to pg_database locale-provider metadata and inspect pg_collation for object-level behavior. Application tests should cover case conversion and pattern/character-class assumptions.

Tuning advice

Pigsty

Values use the fixed 8-vCPU, 32-GiB, 100-GiB SSD fixture and render the current Pigsty templates for PG15; this does not assert current Pigsty support for that historical or beta release.

Common pitfalls

• Trying to configure a value that was always internal/read-only.
• Assuming character classification is identical across databases or locale providers.
• Changing locale libraries without testing expression indexes and case-conversion results.
• Migrating only monitoring text while leaving applications dependent on SHOW lc_ctype.

Related parameters

lc_collate · server_encoding · client_encoding · icu_validation_level · default_text_search_config · server_version_num

References

• PostgreSQL 15 — lc_ctype
• Machine-readable GUC export

12 - max_function_args

Identity

Lifecycle

Default history

How it works

Shows the maximum number of function arguments. It is read-only and cannot be changed with SET or configuration-file edits.

It exposes the FUNC_MAX_ARGS build constant; changing it requires a compatible custom build, not a configuration edit.

Interpret it with max_identifier_length, max_index_keys, block_size. Applications and operations tooling may read max_function_args for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only max_function_args with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

max_identifier_length · max_index_keys · block_size · server_version_num · data_checksums · data_directory_mode

References

• PostgreSQL 19 Beta 3 — max_function_args
• PostgreSQL 19 release notes
• Machine-readable GUC export

13 - max_identifier_length

Identity

Lifecycle

Default history

How it works

Shows the maximum identifier length. It is read-only and cannot be changed with SET or configuration-file edits.

It exposes NAMEDATALEN minus one; longer unquoted or quoted identifiers are truncated when objects are created.

Interpret it with max_function_args, max_index_keys, block_size. Applications and operations tooling may read max_identifier_length for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only max_identifier_length with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

max_function_args · max_index_keys · block_size · server_version_num · data_checksums · data_directory_mode

References

• PostgreSQL 19 Beta 3 — max_identifier_length
• PostgreSQL 19 release notes
• Machine-readable GUC export

14 - max_index_keys

Identity

Lifecycle

Default history

How it works

Shows the maximum number of index keys. It is read-only and cannot be changed with SET or configuration-file edits.

It exposes the INDEX_MAX_KEYS build limit on index attributes, including key and INCLUDE columns where applicable.

Interpret it with max_function_args, max_identifier_length, block_size. Applications and operations tooling may read max_index_keys for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only max_index_keys with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

max_function_args · max_identifier_length · block_size · server_version_num · data_checksums · data_directory_mode

References

• PostgreSQL 19 Beta 3 — max_index_keys
• PostgreSQL 19 release notes
• Machine-readable GUC export

15 - num_os_semaphores

Identity

Lifecycle

Default history

How it works

Shows the number of semaphores required for the server. It is read-only and cannot be changed with SET or configuration-file edits.

It is computed from the startup process and connection configuration so administrators can plan System V semaphore capacity.

Interpret it with shared_memory_size, shared_memory_size_in_huge_pages, huge_pages. Applications and operations tooling may read num_os_semaphores for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only num_os_semaphores with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

shared_memory_size · shared_memory_size_in_huge_pages · huge_pages · huge_pages_status · max_connections · block_size

References

• PostgreSQL 19 Beta 3 — num_os_semaphores
• PostgreSQL 19 release notes
• Machine-readable GUC export

16 - segment_size

Identity

Lifecycle

Default history

How it works

Shows the number of pages per disk file. It is read-only and cannot be changed with SET or configuration-file edits.

It reports the number of database pages per relation segment; together with block_size it determines the file-segmentation boundary.

Interpret it with block_size, wal_block_size, wal_segment_size. Applications and operations tooling may read segment_size for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only segment_size with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

block_size · wal_block_size · wal_segment_size · data_checksums · server_version_num · data_directory_mode

References

• PostgreSQL 19 Beta 3 — segment_size
• PostgreSQL 19 release notes
• Machine-readable GUC export

17 - server_encoding

Identity

Lifecycle

Default history

How it works

Shows the server (database) character set encoding. It is read-only and cannot be changed with SET or configuration-file edits.

It reports the current database encoding. Encoding is selected at database creation and can differ between databases in a cluster.

Interpret it with lc_collate, lc_ctype, client_encoding. Applications and operations tooling may read server_encoding for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only server_encoding with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

lc_collate · lc_ctype · client_encoding · default_text_search_config · icu_validation_level · server_version

References

• PostgreSQL 19 Beta 3 — server_encoding
• PostgreSQL 19 release notes
• Machine-readable GUC export

18 - server_version

Identity

Lifecycle

Default history

How it works

Shows the server version. It is read-only and cannot be changed with SET or configuration-file edits.

It is the human-readable server build/version string and may include vendor packaging text; it is not safe for numeric ordering.

Interpret it with server_version_num, server_encoding, ssl_library. Applications and operations tooling may read server_version for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only server_version with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

server_version_num · server_encoding · ssl_library · integer_datetimes · debug_assertions · block_size

References

• PostgreSQL 19 Beta 3 — server_version
• PostgreSQL 19 release notes
• Machine-readable GUC export

19 - server_version_num

Identity

Lifecycle

Default history

How it works

Reports the running server binary’s version as an integer. It is internal/read-only and is determined by the binary, not by initdb or database creation.

For the measured PG9.0–19 Beta 3 releases, the integer encodes the major version and minor update so software can make numeric feature/version comparisons without parsing vendor text from server_version.

Use it for compatibility gating only when server-side feature discovery is unavailable. Extensions and clients must still account for vendor backports that do not change the upstream version number.

Tuning advice

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.

Common pitfalls

• Comparing the integer as a string.
• Trying to change it with configuration or by recreating a database.
• Assuming the number captures vendor backports and downstream patches.
• Using a client-library version as a substitute for the connected server version.

Related parameters

server_version · server_encoding · integer_datetimes · ssl_library · max_identifier_length · block_size

References

• PostgreSQL 19 Beta 3 — server_version_num
• PostgreSQL 19 release notes
• Machine-readable GUC export

20 - shared_memory_size

Identity

Lifecycle

Default history

How it works

Shows the size of the server’s main shared memory area (rounded up to the nearest MB). It is read-only and cannot be changed with SET or configuration-file edits.

It reports the rounded size of PostgreSQL’s main shared-memory segment after startup sizing.

Interpret it with shared_memory_size_in_huge_pages, huge_pages, huge_pages_status. Applications and operations tooling may read shared_memory_size for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only shared_memory_size with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

shared_memory_size_in_huge_pages · huge_pages · huge_pages_status · num_os_semaphores · max_connections · block_size

References

• PostgreSQL 19 Beta 3 — shared_memory_size
• PostgreSQL 19 release notes
• Machine-readable GUC export

21 - shared_memory_size_in_huge_pages

Identity

Lifecycle

Default history

How it works

Shows the number of huge pages needed for the main shared memory area. It is read-only and cannot be changed with SET or configuration-file edits.

It estimates how many huge pages the main shared-memory segment needs and returns -1 when the platform cannot provide the estimate.

Interpret it with shared_memory_size, huge_pages, huge_pages_status. Applications and operations tooling may read shared_memory_size_in_huge_pages for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only shared_memory_size_in_huge_pages with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

shared_memory_size · huge_pages · huge_pages_status · num_os_semaphores · max_connections · block_size

References

• PostgreSQL 19 Beta 3 — shared_memory_size_in_huge_pages
• PostgreSQL 19 release notes
• Machine-readable GUC export

22 - ssl_library

Identity

Lifecycle

Default history

How it works

Shows the name of the SSL library. It is read-only and cannot be changed with SET or configuration-file edits.

It reports the SSL implementation linked into the server, which helps diagnose provider-specific TLS behavior.

Interpret it with server_version, server_version_num, server_encoding. Applications and operations tooling may read ssl_library for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only ssl_library with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

server_version · server_version_num · server_encoding · integer_datetimes · debug_assertions · block_size

References

• PostgreSQL 19 Beta 3 — ssl_library
• PostgreSQL 19 release notes
• Machine-readable GUC export

23 - wal_block_size

Identity

Lifecycle

Default history

How it works

Shows the block size in the write ahead log. It is read-only and cannot be changed with SET or configuration-file edits.

It reflects XLOG_BLCKSZ, normally 8 KiB, chosen at build time and used for WAL I/O buffers.

Interpret it with block_size, wal_segment_size, segment_size. Applications and operations tooling may read wal_block_size for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only wal_block_size with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

block_size · wal_segment_size · segment_size · data_checksums · server_version_num · data_directory_mode

References

• PostgreSQL 19 Beta 3 — wal_block_size
• PostgreSQL 19 release notes
• Machine-readable GUC export

24 - wal_segment_size

Identity

Lifecycle

Default history

How it works

Shows the size of write ahead log segments. It is read-only and cannot be changed with SET or configuration-file edits.

It reports the WAL segment size. PostgreSQL 11 and later choose it at initdb time; older clusters normally inherit the build-time value.

Interpret it with min_wal_size, max_wal_size, wal_keep_size. Applications and operations tooling may read wal_segment_size for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Tuning advice

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.

Common pitfalls

• Trying to change read-only wal_segment_size with SET or a configuration file.
• Assuming every cluster, database, or vendor build reports the same value.
• Ignoring the value in file-format or feature-compatibility checks.
• Treating reported metadata as a performance target instead of an environment fact.

Related parameters

min_wal_size · max_wal_size · wal_keep_size · checkpoint_timeout · checkpoint_completion_target · wal_keep_segments

References

• PostgreSQL 19 Beta 3 — wal_segment_size
• PostgreSQL 19 release notes
• Machine-readable GUC export