Re: Hash support for grouping sets

From: Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>
To: Mark Dilger <hornschnorter(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Hash support for grouping sets
Date: 2017-03-15 21:51:55
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Another small update to the patch, this time to eliminate any
possibility of integer overflow when handling extremely large estimated

Key change:

- k_weights[i] = (int) floor(sz / scale);
+ /*
+ * If sz is enormous, but work_mem (and hence scale) is
+ * small, avoid integer overflow here.
+ */
+ k_weights[i] = (int) Min(floor(sz / scale),
+ k_capacity + 1.0);

Andrew (irc:RhodiumToad)

Attachment Content-Type Size
gshash25.patch text/x-patch 149.5 KB

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