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Allow table AM to store complex data structures in rd_amcache 

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
This commit is contained in:
Alexander Korotkov 2024-03-21 23:00:34 +02:00
parent 57184c3b5d
commit 02eb07ea89
4 changed files with 44 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
src/backend/access/heap/heapam_handler.c
View File

@ -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,

11
src/backend/utils/cache/relcache.c vendored
View File

@ -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

34
src/include/access/tableam.h
View File

@ -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

10
src/include/utils/rel.h
View File

@ -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 */