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[PATCH v52 04/10] Fix a few problems in index build progress reporting. 385+ messages / 2 participants [nested] [flat]
* [PATCH v52 04/10] Fix a few problems in index build progress reporting. @ 2026-03-27 15:50 Álvaro Herrera <alvherre@kurilemu.de> 0 siblings, 0 replies; 385+ messages in thread From: Álvaro Herrera @ 2026-03-27 15:50 UTC (permalink / raw) First, index_build() should not update the progress when being driven by REPACK, because the progress reporting infractructure cannot handle status of two commands at the same time. So far, REPACK with the CONCURRENTLY option neglected this problem altogether, but even the existing REPACK wasn't consistent enough: even if the 'progress' variable in repack_index() was false, it didn't pass the value to index_build(). Second, REPACK (CONCURRENTLY) should not set PROGRESS_REPACK_PHASE to PROGRESS_REPACK_PHASE_FINAL_CLEANUP in rebuild_relation() because it calls finish_heap_swap() anyway (via rebuild_relation_finish_concurrent()), which does the same thing. --- src/backend/bootstrap/bootstrap.c | 2 +- src/backend/catalog/heap.c | 3 ++- src/backend/catalog/index.c | 22 ++++++++++++++++++---- src/backend/catalog/toasting.c | 3 ++- src/backend/commands/indexcmds.c | 1 + src/include/catalog/index.h | 4 +++- 6 files changed, 27 insertions(+), 8 deletions(-) diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c index 38ef683d4c7..60fb7051830 100644 --- a/src/backend/bootstrap/bootstrap.c +++ b/src/backend/bootstrap/bootstrap.c @@ -1183,7 +1183,7 @@ build_indices(void) heap = table_open(ILHead->il_heap, NoLock); ind = index_open(ILHead->il_ind, NoLock); - index_build(heap, ind, ILHead->il_info, false, false); + index_build(heap, ind, ILHead->il_info, false, false, false); index_close(ind, NoLock); table_close(heap, NoLock); diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c index 5748aa9a1a9..ae6b7cda3dd 100644 --- a/src/backend/catalog/heap.c +++ b/src/backend/catalog/heap.c @@ -3570,7 +3570,8 @@ RelationTruncateIndexes(Relation heapRelation) /* Initialize the index and rebuild */ /* Note: we do not need to re-establish pkey setting */ - index_build(heapRelation, currentIndex, indexInfo, true, false); + index_build(heapRelation, currentIndex, indexInfo, true, false, + true); /* We're done with this index */ index_close(currentIndex, NoLock); diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index e418d67e8e4..4b8ed2c7660 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -715,6 +715,9 @@ UpdateIndexRelation(Oid indexoid, * already exists. * INDEX_CREATE_PARTITIONED: * create a partitioned index (table must be partitioned) + * INDEX_CREATE_REPORT_PROGRESS: + * update the backend's progress information during index build. + * constr_flags: flags passed to index_constraint_create * (only if INDEX_CREATE_ADD_CONSTRAINT is set) * allow_system_table_mods: allow table to be a system catalog @@ -760,6 +763,7 @@ index_create(Relation heapRelation, bool invalid = (flags & INDEX_CREATE_INVALID) != 0; bool concurrent = (flags & INDEX_CREATE_CONCURRENT) != 0; bool partitioned = (flags & INDEX_CREATE_PARTITIONED) != 0; + bool progress = (flags & INDEX_CREATE_REPORT_PROGRESS) != 0; char relkind; TransactionId relfrozenxid; MultiXactId relminmxid; @@ -1276,7 +1280,8 @@ index_create(Relation heapRelation, } else { - index_build(heapRelation, indexRelation, indexInfo, false, true); + index_build(heapRelation, indexRelation, indexInfo, false, true, + progress); } /* @@ -1448,6 +1453,12 @@ index_create_copy(Relation heapRelation, bool concurrently, stattargets[i].isnull = isnull; } + /* + * Note: The current callers do not need INDEX_CREATE_REPORT_PROGRESS. If + * 'concurrently' is true, there is no build at all. Otherwise the index + * build is a sub-command of REPACK. The current infrastructure does not + * allow two commands to report their progress at the same time. + */ if (concurrently) flags = INDEX_CREATE_SKIP_BUILD | INDEX_CREATE_CONCURRENT; @@ -1538,7 +1549,7 @@ index_concurrently_build(Oid heapRelationId, indexInfo->ii_BrokenHotChain = false; /* Now build the index */ - index_build(heapRel, indexRelation, indexInfo, false, true); + index_build(heapRel, indexRelation, indexInfo, false, true, true); /* Roll back any GUC changes executed by index functions */ AtEOXact_GUC(false, save_nestlevel); @@ -3009,6 +3020,7 @@ index_update_stats(Relation rel, * * isreindex indicates we are recreating a previously-existing index. * parallel indicates if parallelism may be useful. + * progress indicates if the backend should update its progress info. * * Note: before Postgres 8.2, the passed-in heap and index Relations * were automatically closed by this routine. This is no longer the case. @@ -3019,7 +3031,8 @@ index_build(Relation heapRelation, Relation indexRelation, IndexInfo *indexInfo, bool isreindex, - bool parallel) + bool parallel, + bool progress) { IndexBuildResult *stats; Oid save_userid; @@ -3070,6 +3083,7 @@ index_build(Relation heapRelation, RestrictSearchPath(); /* Set up initial progress report status */ + if (progress) { const int progress_index[] = { PROGRESS_CREATEIDX_PHASE, @@ -3827,7 +3841,7 @@ reindex_index(const ReindexStmt *stmt, Oid indexId, /* Initialize the index and rebuild */ /* Note: we do not need to re-establish pkey setting */ - index_build(heapRelation, iRel, indexInfo, true, true); + index_build(heapRelation, iRel, indexInfo, true, true, progress); /* Re-allow use of target index */ ResetReindexProcessing(); diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c index 4aa52a4bd25..51b27a8c71c 100644 --- a/src/backend/catalog/toasting.c +++ b/src/backend/catalog/toasting.c @@ -332,7 +332,8 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid, BTREE_AM_OID, rel->rd_rel->reltablespace, collationIds, opclassIds, NULL, coloptions, NULL, (Datum) 0, - INDEX_CREATE_IS_PRIMARY, 0, true, true, NULL); + INDEX_CREATE_IS_PRIMARY | INDEX_CREATE_REPORT_PROGRESS, 0, + true, true, NULL); table_close(toast_rel, NoLock); diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c index cba379810c7..932924c13e0 100644 --- a/src/backend/commands/indexcmds.c +++ b/src/backend/commands/indexcmds.c @@ -1231,6 +1231,7 @@ DefineIndex(ParseState *pstate, flags |= INDEX_CREATE_PARTITIONED; if (stmt->primary) flags |= INDEX_CREATE_IS_PRIMARY; + flags |= INDEX_CREATE_REPORT_PROGRESS; /* * If the table is partitioned, and recursion was declined but partitions diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h index ed9e4c37d27..7ebe4f0bd87 100644 --- a/src/include/catalog/index.h +++ b/src/include/catalog/index.h @@ -71,6 +71,7 @@ extern void index_check_primary_key(Relation heapRel, #define INDEX_CREATE_IF_NOT_EXISTS (1 << 4) #define INDEX_CREATE_PARTITIONED (1 << 5) #define INDEX_CREATE_INVALID (1 << 6) +#define INDEX_CREATE_REPORT_PROGRESS (1 << 7) extern Oid index_create(Relation heapRelation, const char *indexRelationName, @@ -148,7 +149,8 @@ extern void index_build(Relation heapRelation, Relation indexRelation, IndexInfo *indexInfo, bool isreindex, - bool parallel); + bool parallel, + bool progress); extern void validate_index(Oid heapId, Oid indexId, Snapshot snapshot); -- 2.47.3 --gp2pyozrd5pweboh Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v52-0005-invert-meaning-of-index_create-flag-bit.patch" ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick zstd here. Users can still make the informed choice and switch to lz4 if their workload works better there, but zstd is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of zstd, lz4, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..9bfe0443848 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>) + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>zstd</literal>, + <literal>lz4</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..9d178fb09c1 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, zstd, lz4, or pglz (on = zstd if + # available, else lz4 if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..9259b3461c7 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer zstd when compiled in; otherwise use lz4 if available, falling back + * to pglz. + */ +#ifdef USE_ZSTD +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#elif defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --CjtMoaqLlMP6LcXJ-- ^ permalink raw reply [nested|flat] 385+ messages in thread
* [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz @ 2026-07-31 12:24 Christoph Berg <myon@debian.org> 0 siblings, 0 replies; 385+ messages in thread From: Christoph Berg @ 2026-07-31 12:24 UTC (permalink / raw) Previously, wal_compression=on was an alias for pglz, with the idea that users could make an informed choice to pick a better option. But in practice, users either don't want to make that choice (they just want WAL compression), can't really pick the best option (they are setting the default in an environment where someone else is running the workload), or simply don't know that there are other options (previously, "on" was the only choice available). In all these cases, mapping "on" to something that isn't pglz is better. It is strictly slower and does not compress better. We pick lz4 here. Users can still make the informed choice and switch to zstd if their workload works better there, but lz4 is still better than pglz in that case. Like for the default TOAST compression, the actual default "on" value depends on if PostgreSQL was compiled with the compression algorithms. The first of lz4, zstd, pglz is picked. (Only the latter is always available, but practically, builds will have at least one of the better algorithms.) --- doc/src/sgml/config.sgml | 12 ++++++------ src/backend/utils/misc/guc_tables.c | 8 ++++---- src/backend/utils/misc/postgresql.conf.sample | 3 ++- src/include/access/xlog.h | 13 +++++++++++++ 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index aa7b1bd75d2..39ec64a611a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -3667,12 +3667,12 @@ include_dir 'conf.d' <xref linkend="guc-full-page-writes"/> is on, during a base backup, etc.). A compressed page image will be decompressed during WAL replay. - The supported methods are <literal>pglz</literal>, - <literal>lz4</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-lz4</option>) and - <literal>zstd</literal> (if <productname>PostgreSQL</productname> - was compiled with <option>--with-zstd</option>). - The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>. + The supported methods are <literal>off</literal>, <literal>on</literal>, + <literal>lz4</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-lz4</option>), + <literal>zstd</literal> (if <productname>PostgreSQL</productname> was compiled with <option>--with-zstd</option>), and + <literal>pglz</literal>. + The value <literal>on</literal> selects the first of <literal>lz4</literal>, + <literal>zstd</literal>, <literal>pglz</literal> that is available. The default value is <literal>off</literal>. Only superusers and users with the appropriate <literal>SET</literal> privilege can change this setting. diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 1ec460b6a82..e0b21053287 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -484,13 +484,13 @@ static const struct config_enum_entry wal_compression_options[] = { #ifdef USE_ZSTD {"zstd", WAL_COMPRESSION_ZSTD, false}, #endif - {"on", WAL_COMPRESSION_PGLZ, false}, + {"on", DEFAULT_WAL_COMPRESSION, false}, {"off", WAL_COMPRESSION_NONE, false}, - {"true", WAL_COMPRESSION_PGLZ, true}, + {"true", DEFAULT_WAL_COMPRESSION, true}, {"false", WAL_COMPRESSION_NONE, true}, - {"yes", WAL_COMPRESSION_PGLZ, true}, + {"yes", DEFAULT_WAL_COMPRESSION, true}, {"no", WAL_COMPRESSION_NONE, true}, - {"1", WAL_COMPRESSION_PGLZ, true}, + {"1", DEFAULT_WAL_COMPRESSION, true}, {"0", WAL_COMPRESSION_NONE, true}, {NULL, 0, false} }; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 7958653077b..ff108e3d3a5 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -262,7 +262,8 @@ #wal_log_hints = off # also do full page writes of non-critical updates # (change requires restart) #wal_compression = off # enables compression of full-page writes; - # off, pglz (or "on"), lz4, or zstd + # off, on, lz4, zstd, or pglz (on = lz4 if + # available, else zstd if available, else pglz) #wal_init_zero = on # zero-fill new WAL files #wal_recycle = on # recycle WAL files #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 4dd98624204..8daf24d93cf 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -87,6 +87,19 @@ typedef enum WalCompression WAL_COMPRESSION_ZSTD, } WalCompression; +/* + * Choose an appropriate default WAL compression method for wal_compression=on. + * Prefer lz4 when compiled in; otherwise use zstd if available, falling back + * to pglz. + */ +#if defined(USE_LZ4) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_LZ4 +#elif defined(USE_ZSTD) +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_ZSTD +#else +#define DEFAULT_WAL_COMPRESSION WAL_COMPRESSION_PGLZ +#endif + /* Recovery states */ typedef enum RecoveryState { -- 2.53.0 --vDkUrtfZPOyy795V-- ^ permalink raw reply [nested|flat] 385+ messages in thread
end of thread, other threads:[~2026-07-31 12:24 UTC | newest] Thread overview: 385+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2026-03-27 15:50 [PATCH v52 04/10] Fix a few problems in index build progress reporting. Álvaro Herrera <alvherre@kurilemu.de> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v3] Change wal_compression=on to the first of zstd, lz4, pglz Christoph Berg <myon@debian.org> 2026-07-31 12:24 [PATCH v4] Change wal_compression=on to the first of lz4, zstd, pglz Christoph Berg <myon@debian.org>
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