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Ensure proper alignment of tuples in HashMemoryChunkData buffers

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pg commitid  5dc692f78d3
This commit is contained in:
wuyuechuan
2020-11-28 09:08:55 +08:00
parent 91064e7f9d
commit deec0bb6d6
2 changed files with 23 additions and 21 deletions
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12
src/include/executor/hashjoin.h
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@ -114,7 +114,7 @@ typedef struct HashSkewBucket {
*/
typedef struct HashMemoryChunkData {
int ntuples; /* number of tuples stored in this chunk */
size_t maxlen; /* size of the buffer holding the tuples */
size_t maxlen; /* size of the chunk's tuple buffer */
size_t used; /* number of buffer bytes already used */
/* pointer to the next chunk (linked list) */
@ -122,13 +122,19 @@ typedef struct HashMemoryChunkData {
HashMemoryChunkData* unshared;
HashMemoryChunkData* shared;
} next;
char data[FLEXIBLE_ARRAY_MEMBER]; /* buffer allocated at the end */
/*
* The chunk's tuple buffer starts after the HashMemoryChunkData struct,
* at offset HASH_CHUNK_HEADER_SIZE (which must be maxaligned). Note that
* that offset is not included in "maxlen" or "used".
*/
} HashMemoryChunkData;
typedef struct HashMemoryChunkData* HashMemoryChunk;
#define HASH_CHUNK_SIZE (32 * 1024L)
#define HASH_CHUNK_HEADER_SIZE (offsetof(HashMemoryChunkData, data))
#define HASH_CHUNK_HEADER_SIZE MAXALIGN(sizeof(HashMemoryChunkData))
#define HASH_CHUNK_DATA(hc) (((char *) (hc)) + HASH_CHUNK_HEADER_SIZE)
/* tuples exceeding HASH_CHUNK_THRESHOLD bytes are put in their own chunk */
#define HASH_CHUNK_THRESHOLD (HASH_CHUNK_SIZE / 4)
/*