From b1c9b9ef216cffe6a8cf3038c1999d625285a4c5 Mon Sep 17 00:00:00 2001 From: David Geier Date: Thu, 3 Sep 2026 09:55:16 +0200 Subject: [PATCH v1 3/8] Packing RelationData --- src/include/utils/rel_internal.h | 88 ++++++++++++++++++-------------- 1 file changed, 49 insertions(+), 39 deletions(-) diff --git a/src/include/utils/rel_internal.h b/src/include/utils/rel_internal.h index 0f2bdaba808..1a73fcbce42 100644 --- a/src/include/utils/rel_internal.h +++ b/src/include/utils/rel_internal.h @@ -38,18 +38,22 @@ typedef LockInfoData *LockInfo; * Here are the contents of a relation cache entry. */ +/* + * Field order within RelationData (and within each branch of the union + * further down) is chosen to minimize struct padding: pointer-sized + * (8-byte) fields are grouped first, followed by 4-byte fields, followed + * by 1-byte bool fields. Don't reorder fields without re-checking that + * this packing is preserved. + */ typedef struct RelationData { - RelFileLocator rd_locator; /* relation physical identifier */ SMgrRelation rd_smgr; /* cached file handle, or NULL */ + Form_pg_class rd_rel; /* RELATION tuple */ + TupleDesc rd_att; /* tuple descriptor */ + + RelFileLocator rd_locator; /* relation physical identifier */ int rd_refcnt; /* reference count */ ProcNumber rd_backend; /* owning backend's proc number, if temp rel */ - bool rd_islocaltemp; /* rel is a temp rel of this session */ - bool rd_isnailed; /* rel is nailed in cache */ - bool rd_isvalid; /* relcache entry is valid */ - bool rd_indexvalid; /* is rd_indexlist valid? (also rd_pkindex and - * rd_replidindex) */ - bool rd_statvalid; /* is rd_statlist valid? */ /*---------- * rd_createSubid is the ID of the highest subtransaction the rel has @@ -94,11 +98,20 @@ typedef struct RelationData * any value */ SubTransactionId rd_droppedSubid; /* dropped with another Subid set */ - Form_pg_class rd_rel; /* RELATION tuple */ - TupleDesc rd_att; /* tuple descriptor */ Oid rd_id; /* relation's object id */ LockInfoData rd_lockInfo; /* lock mgr's info for locking relation */ + bool rd_islocaltemp; /* rel is a temp rel of this session */ + bool rd_isnailed; /* rel is nailed in cache */ + bool rd_isvalid; /* relcache entry is valid */ + bool rd_indexvalid; /* is rd_indexlist valid? (also rd_pkindex and + * rd_replidindex) */ + bool rd_statvalid; /* is rd_statlist valid? */ + bool rd_ispkdeferrable; /* is rd_pkindex a deferrable PK? */ + bool rd_attrsvalid; /* are bitmaps of attrs valid? (see + * RelationGetIndexAttrBitmap) */ + bool pgstat_enabled; /* should relation stats be counted */ + /* * The following two blocks of fields are mutually exclusive: a * relation is never both an index and a non-index (table-like) @@ -127,7 +140,6 @@ typedef struct RelationData /* data managed by RelationGetFKeyList: */ List *rd_fkeylist; /* list of ForeignKeyCacheInfo (see below) */ - bool rd_fkeyvalid; /* true if list has been computed */ /* data managed by RelationGetPartitionKey: */ PartitionKey rd_partkey; /* partition key, or NULL */ @@ -141,18 +153,8 @@ typedef struct RelationData PartitionDesc rd_partdesc_nodetached; /* partdesc w/o detached parts */ MemoryContext rd_pddcxt; /* for rd_partdesc_nodetached, if any */ - /* - * pg_inherits.xmin of the partition that was excluded in - * rd_partdesc_nodetached. This informs a future user of that partdesc: - * if this value is not in progress for the active snapshot, then the - * partdesc can be used, otherwise they have to build a new one. (This - * matches what find_inheritance_children_extended would do). - */ - TransactionId rd_partdesc_nodetached_xmin; - /* data managed by RelationGetPartitionQual: */ List *rd_partcheck; /* partition CHECK quals */ - bool rd_partcheckvalid; /* true if list has been computed */ MemoryContext rd_partcheckcxt; /* private cxt for rd_partcheck, if any */ /* data managed by RelationGetIndexAttrBitmap: */ @@ -173,6 +175,18 @@ typedef struct RelationData */ /* use "struct" here to avoid needing to include fdwapi.h: */ struct FdwRoutine *rd_fdwroutine; /* cached function pointers, or NULL */ + + /* + * pg_inherits.xmin of the partition that was excluded in + * rd_partdesc_nodetached. This informs a future user of that partdesc: + * if this value is not in progress for the active snapshot, then the + * partdesc can be used, otherwise they have to build a new one. (This + * matches what find_inheritance_children_extended would do). + */ + TransactionId rd_partdesc_nodetached_xmin; + + bool rd_fkeyvalid; /* true if rd_fkeylist has been computed */ + bool rd_partcheckvalid; /* true if rd_partcheck has been computed */ }; /* fields used only for an index relation */ @@ -210,16 +224,10 @@ typedef struct RelationData /* data managed by RelationGetIndexList: */ List *rd_indexlist; /* list of OIDs of indexes on relation */ - Oid rd_pkindex; /* OID of (deferrable?) primary key, if any */ - bool rd_ispkdeferrable; /* is rd_pkindex a deferrable PK? */ - Oid rd_replidindex; /* OID of replica identity index, if any */ /* data managed by RelationGetStatExtList: */ List *rd_statlist; /* list of OIDs of extended stats */ - /* data managed by RelationGetIndexAttrBitmap: */ - bool rd_attrsvalid; /* are bitmaps of attrs valid? */ - /* * rd_options is set whenever rd_rel is loaded into the relcache entry. * Note that you can NOT look into rd_rel for this data. NULL means "use @@ -227,15 +235,6 @@ typedef struct RelationData */ bytea *rd_options; /* parsed pg_class.reloptions */ - /* - * Oid of the handler for this relation. For an index this is a function - * returning IndexAmRoutine, for table like relations a function returning - * TableAmRoutine. This is stored separately from rd_indam, rd_tableam as - * its lookup requires syscache access, but during relcache bootstrap we - * need to be able to initialize rd_tableam without syscache lookups. - */ - Oid rd_amhandler; /* OID of index AM's handler function */ - /* * Table access method. */ @@ -252,6 +251,21 @@ typedef struct RelationData */ void *rd_amcache; /* available for use by index/table AM */ + /* use "struct" here to avoid needing to include pgstat.h: */ + struct PgStat_RelationStatus *pgstat_info; /* statistics collection area */ + + Oid rd_pkindex; /* OID of (deferrable?) primary key, if any */ + Oid rd_replidindex; /* OID of replica identity index, if any */ + + /* + * Oid of the handler for this relation. For an index this is a function + * returning IndexAmRoutine, for table like relations a function returning + * TableAmRoutine. This is stored separately from rd_indam, rd_tableam as + * its lookup requires syscache access, but during relcache bootstrap we + * need to be able to initialize rd_tableam without syscache lookups. + */ + Oid rd_amhandler; /* OID of index AM's handler function */ + /* * Hack for CLUSTER, rewriting ALTER TABLE, etc: when writing a new * version of a table, we need to make any toast pointers inserted into it @@ -262,10 +276,6 @@ typedef struct RelationData * causes toast_save_datum() to try to preserve toast value OIDs. */ Oid rd_toastoid; /* Real TOAST table's OID, or InvalidOid */ - - bool pgstat_enabled; /* should relation stats be counted */ - /* use "struct" here to avoid needing to include pgstat.h: */ - struct PgStat_RelationStatus *pgstat_info; /* statistics collection area */ } RelationData; #endif /* REL_INTERNAL_H */ -- 2.51.0