Magnus Hagander wrote:
>>And the patch that was applied gives the same result.
>>
>>What is more, I am not seeing the reported speedup - in fact
>>I am seeing no speedup worth mentioning.
>>
>>This is on XP-Pro, with default postgres settings. The test
>>sets were somewhat larger than thos Magnus used - basically
>>TPC-H lineitems and orders tables (6m and 1.5m rows respectively).
>>
>>
>
>First, that was Merlin and not me :-)
>
>
My apologies to both of you. Or to at least one of you, anyway. :-)
>Second, it didn't really show any improvement for him either in his
>normal test. But when he re-ran it with just the count(*) test it showed
>improvement. Did you run a count(*) test or some other test?
>
>
>
The tests were
select count(*) from lineitems;
select count(*) from orders;
The table definitions are:
CREATE TABLE orders ( o_orderkey INTEGER NOT NULL, o_custkey INTEGER NOT NULL, o_orderstatus CHAR(1)
NOTNULL, o_totalprice DECIMAL(15,2) NOT NULL, o_orderdate DATE NOT NULL, o_orderpriority CHAR(15) NOT NULL,
--R o_clerk CHAR(15) NOT NULL, -- R o_shippriority INTEGER NOT NULL, o_comment VARCHAR(79) NOT NULL
);
CREATE TABLE lineitem ( l_orderkey INTEGER NOT NULL, l_partkey INTEGER NOT NULL, l_suppkey INTEGER NOT NULL,
l_linenumber INTEGER NOT NULL, l_quantity DECIMAL(15,2) NOT NULL, l_extendedprice DECIMAL(15,2) NOT NULL,
l_discount DECIMAL(15,2) NOT NULL, l_tax DECIMAL(15,2) NOT NULL, l_returnflag CHAR(1) NOT NULL, l_linestatus
CHAR(1) NOT NULL, l_shipdate DATE NOT NULL, l_commitdate DATE NOT NULL, l_receiptdate DATE NOT NULL, l_shipinstruct
CHAR(25)NOT NULL, -- R l_shipmode CHAR(10) NOT NULL, -- R l_comment VARCHAR(44) NOT NULL
);
I could make the whole dataset available, but tarred and zipped it's
about 300Mb. The reason I used this dataset was that I wanted to see a
test that took many seconds, and Merlin's did not - I wanted to see how
any performance gain scaled.
But it looks to me like we need to leave this for 8.2 now anyway, unless
someone can quickly get to the bottom of why it's hanging.
cheers
andrew