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Allow table AM to store complex data structures in rd_amcache

author Alexander Korotkov <akorotkov@postgresql.org>

2024年3月21日 21:00:34 +0000 (23:00 +0200)

committer Alexander Korotkov <akorotkov@postgresql.org>

2024年3月21日 21:00:34 +0000 (23:00 +0200)

The new table AM method free_rd_amcache is responsible for freeing all the
memory related to rd_amcache and setting free_rd_amcache to NULL. If the new
method is not specified, we still assume rd_amcache to be a single chunk of
memory, which could be just pfree'd.

Discussion: https://postgr.es/m/CAPpHfdurb9ycV8udYqM%3Do0sPS66PJ4RCBM1g-bBpvzUfogY0EA%40mail.gmail.com
Reviewed-by: Matthias van de Meent, Mark Dilger, Pavel Borisov
Reviewed-by: Nikita Malakhov, Japin Li

src/backend/access/heap/heapam_handler.c patch | blob | blame | history

src/backend/utils/cache/relcache.c patch | blob | blame | history

src/include/access/tableam.h patch | blob | blame | history

src/include/utils/rel.h patch | blob | blame | history

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c

index 680a50bf8b161bb37576efad4b962631a6d73f0e..4dd1341f606cb371ee6687f5098459017b9d08f5 100644 (file)

--- a/src/backend/access/heap/heapam_handler.c

+++ b/src/backend/access/heap/heapam_handler.c

@@ -2582,6 +2582,7 @@ static const TableAmRoutine heapam_methods = {

.index_build_range_scan = heapam_index_build_range_scan,

.index_validate_scan = heapam_index_validate_scan,

+ .free_rd_amcache = NULL,

.relation_size = table_block_relation_size,

.relation_needs_toast_table = heapam_relation_needs_toast_table,

.relation_toast_am = heapam_relation_toast_am,

diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c

index 2cd19d603fba7ce941e41f15d2fe231f62eca879..dcd18e462686c1581dcec4bb80ad9430420e502d 100644 (file)

--- a/src/backend/utils/cache/relcache.c

+++ b/src/backend/utils/cache/relcache.c

@@ -2262,9 +2262,7 @@ RelationReloadIndexInfo(Relation relation)

RelationCloseSmgr(relation);

/* Must free any AM cached data upon relcache flush */

- if (relation->rd_amcache)

- pfree(relation->rd_amcache);

- relation->rd_amcache = NULL;

+ table_free_rd_amcache(relation);

* If it's a shared index, we might be called before backend startup has

@@ -2484,8 +2482,7 @@ RelationDestroyRelation(Relation relation, bool remember_tupdesc)

pfree(relation->rd_options);

if (relation->rd_indextuple)

pfree(relation->rd_indextuple);

- if (relation->rd_amcache)

- pfree(relation->rd_amcache);

+ table_free_rd_amcache(relation);

if (relation->rd_fdwroutine)

pfree(relation->rd_fdwroutine);

if (relation->rd_indexcxt)

@@ -2547,9 +2544,7 @@ RelationClearRelation(Relation relation, bool rebuild)

RelationCloseSmgr(relation);

/* Free AM cached data, if any */

- if (relation->rd_amcache)

- pfree(relation->rd_amcache);

- relation->rd_amcache = NULL;

+ table_free_rd_amcache(relation);

* Treat nailed-in system relations separately, they always need to be

diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h

index 8249b37bbf16266a4918a8787005395ce63beb2e..fd474b74883c6dcbc43daf0a4ef45af0176f0fe3 100644 (file)

--- a/src/include/access/tableam.h

+++ b/src/include/access/tableam.h

@@ -708,6 +708,14 @@ typedef struct TableAmRoutine

* ------------------------------------------------------------------------

+ /*

+ * This callback frees relation private cache data stored in rd_amcache.

+ * After the call all memory related to rd_amcache must be freed,

+ * rd_amcache must be set to NULL. If this callback is not provided,

+ * rd_amcache is assumed to point to a single memory chunk.

+ */

+ void (*free_rd_amcache) (Relation rel);

* See table_relation_size().

@@ -1847,6 +1855,32 @@ table_index_validate_scan(Relation table_rel,

* ----------------------------------------------------------------------------

+/*

+ * Frees relation private cache data stored in rd_amcache. Uses

+ * free_rd_amcache method if provided. Assumes rd_amcache to point to single

+ * memory chunk otherwise.

+ */

+static inline void

+table_free_rd_amcache(Relation rel)

+ if (rel->rd_tableam && rel->rd_tableam->free_rd_amcache)

+ {

+ rel->rd_tableam->free_rd_amcache(rel);

+ /*

+ * We are assuming free_rd_amcache() did clear the cache and left NULL

+ * in rd_amcache.

+ */

+ Assert(rel->rd_amcache == NULL);

+ }

+ else

+ {

+ if (rel->rd_amcache)

+ pfree(rel->rd_amcache);

+ rel->rd_amcache = NULL;

+ }

* Return the current size of `rel` in bytes. If `forkNumber` is

* InvalidForkNumber, return the relation's overall size, otherwise the size

diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h

index 87002049538a8990aa64a9814a4e3a88dd350eea..f25f769af2b2a0a7352dc957692d4a07874d59ba 100644 (file)

--- a/src/include/utils/rel.h

+++ b/src/include/utils/rel.h

@@ -221,10 +221,12 @@ typedef struct RelationData

* rd_amcache is available for index and table AMs to cache private data

* about the relation. This must be just a cache since it may get reset

* at any time (in particular, it will get reset by a relcache inval

- * message for the relation). If used, it must point to a single memory

- * chunk palloc'd in CacheMemoryContext, or in rd_indexcxt for an index

- * relation. A relcache reset will include freeing that chunk and setting

- * rd_amcache = NULL.

+ * message for the relation). If used for table AM it must point to a

+ * single memory chunk palloc'd in CacheMemoryContext, or more complex

+ * data structure in that memory context to be freed by free_rd_amcache

+ * method. If used for index AM it must point to a single memory chunk

+ * palloc'd in rd_indexcxt memory context. A relcache reset will include

+ * freeing that chunk and setting rd_amcache = NULL.

void *rd_amcache; /* available for use by index/table AM */

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