fix initialization of pgspHashKey structure #40
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SeleznevPavel
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@rjuju can i ask you to do a review? |
rjuju
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Jan 17, 2025
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| Assert(plan != NULL && queryId != PGSP_NO_QUERYID); | ||
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| memset(&key, 0, sizeof(pgspHashKey)); |
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This should be ifdef'd for pg11+ as until pg10 it was still a uint32, since the rest of the code correctly handle the version change.
| if (plan_storage == PLAN_STORAGE_SHMEM) | ||
| memcpy(SHMEM_PLAN_PTR(entry), shorten_plan, plan_len + 1); | ||
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nit: you could just remove this line as there is another newline just after.
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The size of the key used in the hash table is sizeof(pgspHashKey) = 24.
The hash is calculated for 24 bytes, but the key consists of Oid + Oid + queryid_t + uint32 = 4 + 4 + 8 + 4 = 20 bytes. Memory in pgsp_store is allocated on the stack, uninitialized and filled for 20 bytes, respectively, garbage remains in the remaining 4 bytes.
This leads to the fact that different hashes were obtained from the same key, so there was no query aggregation - each time a new entry was added to the hash table.