Alex Hunsaker napsal(a):
On Thu, Sep 4, 2008 at 9:48 PM, Alex Hunsaker <[EMAIL PROTECTED]> wrote:
Ok here are the results:
(data generated from the c program before)
select count(1) from test_hash;
count
-----------
100000011
create index test_hash_num_idx on test_hash using hash (num);
CVS: Time: 698065.180 ms
patch: Time: 565982.099 ms
./pgbench -c 1 -t 100000 -n -f bench.sql
bench.sql
select count(1) from test_hash where num = 110034304728896610;
CVS: tps = 7232.375875 (excluding connections establishing)
patch: tps = 7913.700150 (excluding connections establishing)
EXPLAIN ANALYZE select count(1) from test_hash where num = 110034304728896610;
QUERY
PLAN
------------------------------------------------------------------------------------------------------------------------------------
Aggregate (cost=29.24..29.25 rows=1 width=0) (actual
time=0.066..0.067 rows=1 loops=1)
-> Index Scan using test_hash_num_idx on test_hash
(cost=0.00..29.24 rows=1 width=0) (actual time=0.051..0.054 rows=1
loops=1)
Index Cond: (num = 110034304728896610::bigint)
Total runtime: 0.153 ms
Oddly the index sizes were the same (4096 MB) is that to be expected?
I think yes, because haskey is uint32. You save space only if you use hash for
example on varchar attribute.
Zdenek
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