2009/3/6 Thomas Mueller <[email protected]>
>
> Hi,
>
> I'm sorry I don't understand why getLastSetBit can take much time...
> Could you describe your use case please? What database version do you
> use? If you use version 1.0.x, could you try if upgrading to 1.1.x
> solves the problem?
>
Ok, now I've tested it out with 1.1.108. Off the bat it appears to be
a lot faster than 1.0 at inserting records (almost a factor 2 (and a
factor 3 faster than PostgresQL)), but over time I see severe
performance degradation in the inserts (as I also do with 1.0).
Unfortunately I am having a hard time setting up the profiler today as
the network seems to be mad at me or something...
Also I have yet to test this with my patch enabled (I will only do
this if profiling the app turns up BitField.getLastSetBit() again).
Here's a bit of metadata on my setup: My record corpus right now is
about 3M records (but when I hit production it'll be more like 10M).
Inserts are flying until I reach about 1M at which it slowly decreases
to about half speed (which is still faster than fx PostgresQL :-) on
the same data). Then somewhere around 3M the INSERT rate slows to a
halt at about ½ record/sec.
My DB looks like this:
/* RECORDS TABLE (this is where it where everything happens) */
CREATE TABLE summa_records (id VARCHAR(255) PRIMARY KEY,
base VARCHAR(31),
deleted INTEGER,
indexable INTEGER,
hasRelations INTEGER,
data BYTEA,
ctime BIGINT,
mtime BIGINT,
meta BYTEA);
CREATE UNIQUE INDEX i ON summa_records(id);
CREATE UNIQUE INDEX mb ON summa_records(mtime,base);
And then we have a second table 'summa_relations' we use to store some
relations in. I have tweaked my configs so that we don't do any
INSERTs in this table in my tests, only one SELECT after each INSERT
so I doubt it is important, but in any case:
/* RELATIONS TABLE */
CREATE TABLE summa_relations (parentId VARCHAR(255),
childId
VARCHAR(255) );
CREATE UNIQUE INDEX pc ON summa_relations(parentId,childId);
CREATE INDEX c ON summa_relations(childId);
--
Cheers,
Mikkel Kamstrup Erlandsen,
State and University Library of Denmark
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