Accommodate very large dshash tables.

If a dshash table grows very large (e.g., the dshash table for
cumulative statistics when there are millions of tables), resizing
it may fail with an error like:

	ERROR: invalid DSA memory alloc request size 1073741824

To fix, permit dshash resizing to allocate more than 1 GB by
providing the DSA_ALLOC_HUGE flag.

Reported-by: Andreas Scherbaum
Author: Matthias van de Meent
Reviewed-by: Cédric Villemain, Michael Paquier, Andres Freund
Discussion: https://postgr.es/m/80a12d59-0d5e-4c54-866c-e69cd6536471%40pgug.de
Backpatch-through: 13

diff --git a/src/backend/lib/dshash.c b/src/backend/lib/dshash.c
index 93a9e21ddd209a3a1e50d51d70f58c60004f7fa8..06deb610245e295feda066a0654413afb499fdaa 100644 (file)
--- a/src/backend/lib/dshash.c
+++ b/src/backend/lib/dshash.c
@@ -887,8 +887,10 @@ resize(dshash_table *hash_table, size_t new_size_log2)
    Assert(new_size_log2 == hash_table->control->size_log2 + 1);
 
    /* Allocate the space for the new table. */
-   new_buckets_shared = dsa_allocate0(hash_table->area,
-                                      sizeof(dsa_pointer) * new_size);
+   new_buckets_shared =
+       dsa_allocate_extended(hash_table->area,
+                             sizeof(dsa_pointer) * new_size,
+                             DSA_ALLOC_HUGE | DSA_ALLOC_ZERO);
    new_buckets = dsa_get_address(hash_table->area, new_buckets_shared);
 
    /*