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From: jgk@panix.com (Joe keane)
Newsgroups: comp.programming,comp.lang.c
Subject: double hashing
Date: Mon, 2 Apr 2012 19:49:06 +0000 (UTC)
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Xref: csiph.com comp.programming:1396 comp.lang.c:19223

question

We some have 'docs' that can be 'contracted' or 'expanded'.

They sometimes change from contracted to expanded and vice versa.

They each have a 'key' that's unique [and doesn't change when they
change state].

struct condocinfo { ... };
struct expdocinfo { ... };

The info for an expanded doc is a superset of the info for a contracted doc.
[e.g., pointers to more structures].

Lookup by key.

Scheme 1

We keep a hash table for all docs that contains the info for contracted
docs.  We keep a hash table for only expanded docs that contains the
info for expanded docs that's not in the first one.

Scheme 2

We keep a hash table for only contracted docs that contains the info for
contracted docs.  We keep a hash table for only expanded docs that
contains the info for expanded docs.

Time?  Space?

[it's for an old project so it's academic]