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Use bump context for TID bitmaps stored by vacuum 

Vacuum does not pfree individual entries, and only frees the entire
storage space when finished with it. This allows using a bump context,
eliminating the chunk header in each leaf allocation. Most leaf
allocations will be 16 to 32 bytes, so that's a significant savings.
TidStoreCreateLocal gets a boolean parameter to indicate that the
created store is insert-only.

This requires a separate tree context for iteration, since we free
the iteration state after iteration completes.

Discussion: https://postgr.es/m/CANWCAZac%3DpBePg3rhX8nXkUuaLoiAJJLtmnCfZsPEAS4EtJ%3Dkg%40mail.gmail.com
Discussion: https://postgr.es/m/CANWCAZZQFfxvzO8yZHFWtQV+Z2gAMv1ku16Vu7KWmb5kZQyd1w@mail.gmail.com
This commit is contained in:
John Naylor 2024-04-07 12:27:34 +07:00
parent bb766cde63
commit 8a1b31e6e5
5 changed files with 28 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
src/backend/access/common/tidstore.c
View File

@ -120,7 +120,7 @@ static void tidstore_iter_extract_tids(TidStoreIter *iter, BlockNumber blkno,
* by TidStoreMemoryUsage().
*/
TidStore *
TidStoreCreateLocal(size_t max_bytes)
TidStoreCreateLocal(size_t max_bytes, bool insert_only)
{
TidStore *ts;
size_t initBlockSize = ALLOCSET_DEFAULT_INITSIZE;
@ -138,11 +138,22 @@ TidStoreCreateLocal(size_t max_bytes)
maxBlockSize = ALLOCSET_DEFAULT_INITSIZE;
/* Create a memory context for the TID storage */
ts->rt_context = AllocSetContextCreate(CurrentMemoryContext,
if (insert_only)
{
ts->rt_context = BumpContextCreate(CurrentMemoryContext,
"TID storage",
minContextSize,
initBlockSize,
maxBlockSize);
}
else
{
ts->rt_context = AllocSetContextCreate(CurrentMemoryContext,
"TID storage",
minContextSize,
initBlockSize,
maxBlockSize);
}
ts->tree.local = local_ts_create(ts->rt_context);

4
src/backend/access/heap/vacuumlazy.c
View File

@ -2874,7 +2874,7 @@ dead_items_alloc(LVRelState *vacrel, int nworkers)
dead_items_info->num_items = 0;
vacrel->dead_items_info = dead_items_info;
vacrel->dead_items = TidStoreCreateLocal(dead_items_info->max_bytes);
vacrel->dead_items = TidStoreCreateLocal(dead_items_info->max_bytes, true);
}
/*
@ -2910,7 +2910,7 @@ dead_items_reset(LVRelState *vacrel)
/* Recreate the tidstore with the same max_bytes limitation */
TidStoreDestroy(dead_items);
vacrel->dead_items = TidStoreCreateLocal(vacrel->dead_items_info->max_bytes);
vacrel->dead_items = TidStoreCreateLocal(vacrel->dead_items_info->max_bytes, true);
/* Reset the counter */
vacrel->dead_items_info->num_items = 0;

2
src/include/access/tidstore.h
View File

@ -29,7 +29,7 @@ typedef struct TidStoreIterResult
OffsetNumber *offsets;
} TidStoreIterResult;
extern TidStore *TidStoreCreateLocal(size_t max_bytes);
extern TidStore *TidStoreCreateLocal(size_t max_bytes, bool insert_only);
extern TidStore *TidStoreCreateShared(size_t max_bytes, int tranche_id);
extern TidStore *TidStoreAttach(dsa_handle area_handle, dsa_pointer handle);
extern void TidStoreDetach(TidStore *ts);

11
src/include/lib/radixtree.h
View File

@ -691,6 +691,7 @@ struct RT_RADIX_TREE
/* leaf_context is used only for single-value leaves */
MemoryContextData *leaf_context;
#endif
MemoryContextData *iter_context;
};
/*
@ -1796,6 +1797,14 @@ RT_CREATE(MemoryContext ctx)
tree = (RT_RADIX_TREE *) palloc0(sizeof(RT_RADIX_TREE));
tree->context = ctx;
/*
* Separate context for iteration in case the tree context doesn't support
* pfree
*/
tree->iter_context = AllocSetContextCreate(ctx,
RT_STR(RT_PREFIX) "radix_tree iter context",
ALLOCSET_SMALL_SIZES);
#ifdef RT_SHMEM
tree->dsa = dsa;
dp = dsa_allocate0(dsa, sizeof(RT_RADIX_TREE_CONTROL));
@ -2038,7 +2047,7 @@ RT_BEGIN_ITERATE(RT_RADIX_TREE * tree)
RT_ITER *iter;
RT_CHILD_PTR root;
iter = (RT_ITER *) MemoryContextAllocZero(tree->context,
iter = (RT_ITER *) MemoryContextAllocZero(tree->iter_context,
sizeof(RT_ITER));
iter->tree = tree;

3
src/test/modules/test_tidstore/test_tidstore.c
View File

@ -116,7 +116,8 @@ test_create(PG_FUNCTION_ARGS)
dsa_pin_mapping(TidStoreGetDSA(tidstore));
}
else
tidstore = TidStoreCreateLocal(tidstore_max_size);
/* VACUUM uses insert only, so we test the other option. */
tidstore = TidStoreCreateLocal(tidstore_max_size, false);
tidstore_empty_size = TidStoreMemoryUsage(tidstore);