Re: JDBC slow performance on resultSet iteration?

I believe it, or some version of it, is.

On Nov 5, 2013, at 11:50 AM, Edson Richter <edsonrichter(at)hotmail(dot)com> wrote:

> Em 05/11/2013 16:45, Kevin Wooten escreveu:
>> Well yes and no. The driver may be transferring your data in binary already but we should work out if that is actually true. I believe that option "-Dorg.postgresql.forcebinary=boolean” still works and forces an Extended Query which will allow binary transfers.
>>
>> Try running with that option and see if it changes the timings.
>>
>> On Nov 5, 2013, at 11:27 AM, Rui Pedro Leal <rui(dot)pedro(dot)leal(at)gmail(dot)com> wrote:
>>
>>> Hello Kevin,
>>>
>>> That's exactly my immediate (and hopefully wrong) conclusion: the getXXX calls are really costly!
>>>
>>> So, you are proposing using the binary protocol. I've never known the existence of that. Is this it: http://wiki.postgresql.org/wiki/JDBC-BinaryTransfer ?
>>>
>>> Thanks.
>>>
>>> [] Rui Pedro Leal
>>> [] rui(dot)pedro(dot)leal(at)gmail(dot)com
>>>
>>> On 2013/11/05, at 18:14, Kevin Wooten wrote:
>>>
>>>> Well I can speak from experience…
>>>>
>>>> When I was comparing the performance of my implementation with pgjdbc I was very disheartened at the beginning as pgjdbc was seemingly much faster. It was only after I switched the test to take into account the getXXX calls that the true cost of using the driver was discovered. If you just execute a query and ignore the results pgjdbc is essentially just receiving a stream of text. It ignores all of the work of turning that text into Java objects/primitives.
>>>>
>>>> My implementation uses binary protocol for this reason and that removes a lot of the overhead that pgjdbc has. If pgAdmin is using the binary protocol as well this could very well be the difference that is being seen, because it is a significant amount of time.
>>>>
>>>> On Nov 5, 2013, at 11:03 AM, Dave Cramer <pg(at)fastcrypt(dot)com> wrote:
>>>>
>>>>> I do not know, the best way to figure this out is to use explain analyze in pg_admin.
>>>>>
>>>>> What I am debating is the java code is using a cursor. pgAdmin is not.
>>>>>
>>>>> Try it without setFetchSize()
>>>>>
>>>>> Dave Cramer
>>>>>
>>>>> dave.cramer(at)credativ(dot)ca
>>>>> http://www.credativ.ca
>>>>>
>>>>>
>>>>> On Tue, Nov 5, 2013 at 1:00 PM, Rui Pedro Leal <rui(dot)pedro(dot)leal(at)gmail(dot)com> wrote:
>>>>> Dave,
>>>>>
>>>>> I understand what you are saying, but i must get the results, right? :)
>>>>>
>>>>> I think in pgAdmin the total query time, presented by the query execution windows, is also considering the rendering / presenting of the query results, so this is comparable ... right?
>>>>>
>>>>> [] Rui Pedro Leal
>>>>> [] rui(dot)pedro(dot)leal(at)gmail(dot)com
>>>>>
>>>>> On 2013/11/05, at 17:34, Dave Cramer wrote:
>>>>>
>>>>>> Rui Leal,
>>>>>>
>>>>>> You shouldn't see that much of a penatly, but I question how you are measuring it. Since you are timing the loop which is using cursors.
>>>>>>
>>>>>> Just run a simple query and time it without iterating through the result set. That would be equivalent
>>>>>>
>>>>>> Dave Cramer
>>>>>>
>>>>>> dave.cramer(at)credativ(dot)ca
>>>>>> http://www.credativ.ca
>>>>>>
>>>>>>
>>>>>> On Tue, Nov 5, 2013 at 12:16 PM, Rui Pedro Leal <rui(dot)pedro(dot)leal(at)gmail(dot)com> wrote:
>>>>>> Hello Dave, thanks for the quick reply.
>>>>>>
>>>>>> I'm just executing the same query on pgAdmin query interface. Just a way to measure performance of the query + getting results vs the JDBC way.
>>>>>>
>>>>>> I'm using fetchsize in order to get some faster results when iterating the resultSet. I've tried not to use fetchSize/cursor but the performance is naturally slower (and worser than the simple pgAdmin query).
>>>>>>
>>>>>> What i'm asking is .. is this performance penalty i'm getting using postgres JDBC normal and within what's expected? I'm i doing something wrong? Can i do it in any other way?
>>>>>>
>>>>>> Regards,
>>>>>>
>>>>>> Rui Leal
>>>>>>
>>>>>> [] Rui Pedro Leal
>>>>>> [] rui(dot)pedro(dot)leal(at)gmail(dot)com
>>>>>>
>>>>>>
>>>>>> On 2013/11/05, at 16:43, Dave Cramer wrote:
>>>>>>
>>>>>>> How can you measure the same query in pgAdmin ? JDBC will use a cursor when you set the fetchsize.
>>>>>>>
>>>>>>> Dave Cramer
>>>>>>>
>>>>>>> dave.cramer(at)credativ(dot)ca
>>>>>>> http://www.credativ.ca
>>>>>>>
>>>>>>>
>>>>>>> On Tue, Nov 5, 2013 at 11:12 AM, Rui Pedro Leal <rui(dot)pedro(dot)leal(at)gmail(dot)com> wrote:
>>>>>>> Just an quick info update: i'm using the postgresql-9.2-1003-jdbc4 driver
>>>>>>>
>>>>>>> On 2013/11/05, at 16:09, Rui Pedro Leal wrote:
>>>>>>>
>>>>>>> > Hello everyone,
>>>>>>> >
>>>>>>> > I'm having slow JDBC performance on iterating a resultSet obtained from a somewhat simple query.
>>>>>>> >
>>>>>>> > The query, although using PostGIS functions, is pretty straight forward:
>>>>>>> >
>>>>>>> > SELECT _id, _spatial_type, ST_AsBinary(_geometry), _attribute, _count, _references, countpersons, countfatals, countdrunks, density
>>>>>>> > FROM accidents_5
>>>>>>> > WHERE (_geometry && ST_MakeEnvelope(-126.60644531250001,26.43122806450644,-63.369140625,52.96187505907603, 4326) )
>>>>>>> > ORDER BY _pk_id
>>>>>>> >
>>>>>>> > The results are the following:
>>>>>>> > - Executing the query directly from pgAdmin: ~2807ms
>>>>>>> > - Executing from JVM + JDBC: 4184ms
>>>>>>> >
>>>>>>> > The code i'm executing is pretty much standard:
>>>>>>> >
>>>>>>> > -------------------- code --------------------
>>>>>>> >
>>>>>>> > public static void main(final String[] args) throws Exception {
>>>>>>> >
>>>>>>> > String sql = "SELECT _id, _spatial_type, ST_AsBinary(_geometry), _attribute, _count, _references, countpersons, countfatals, countdrunks, density";
>>>>>>> > sql += " FROM accidents_5";
>>>>>>> > sql += " WHERE (_geometry && ST_MakeEnvelope(-126.60644531250001,26.43122806450644,-63.369140625,52.96187505907603, 4326) )";
>>>>>>> > sql += " ORDER BY _pk_id";
>>>>>>> >
>>>>>>> > System.out.println(sql);
>>>>>>> >
>>>>>>> > Long time = System.currentTimeMillis();
>>>>>>> > try {
>>>>>>> > Connection connection = DataStoreInfo.getDataStores().get(0);
>>>>>>> > connection.setAutoCommit(false);
>>>>>>> >
>>>>>>> > System.out.println("[QUERY " + Thread.currentThread().getId()
>>>>>>> > + "] - connection in "
>>>>>>> > + (System.currentTimeMillis() - time) + "ms.");
>>>>>>> >
>>>>>>> > Statement st = connection.createStatement(
>>>>>>> > ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY,
>>>>>>> > ResultSet.CLOSE_CURSORS_AT_COMMIT);
>>>>>>> > st.setFetchSize(250);
>>>>>>> >
>>>>>>> > System.out.println("[QUERY " + Thread.currentThread().getId()
>>>>>>> > + "] - statement in " + (System.currentTimeMillis() - time)
>>>>>>> > + "ms.");
>>>>>>> >
>>>>>>> > ResultSet resultSet = st.executeQuery(sql);
>>>>>>> >
>>>>>>> > System.out.println("[QUERY " + Thread.currentThread().getId()
>>>>>>> > + "] - done in " + (System.currentTimeMillis() - time)
>>>>>>> > + "ms.");
>>>>>>> >
>>>>>>> > GeometryFactory geofact = new GeometryFactory(new PrecisionModel(),4326);
>>>>>>> > WKBReader wkbReader = new WKBReader(geofact);
>>>>>>> >
>>>>>>> > String id;
>>>>>>> > String spatialType;
>>>>>>> > Geometry geometry;
>>>>>>> > String attribute;
>>>>>>> > Long count;
>>>>>>> > String reference;
>>>>>>> > Map<String, Double> properties;
>>>>>>> > String granularSynthString = "GranularSynthesis";
>>>>>>> >
>>>>>>> > while (resultSet.next()) {
>>>>>>> > id = resultSet.getString(1);
>>>>>>> > spatialType = resultSet.getString(2);
>>>>>>> >
>>>>>>> > // geometry = wkbReader.read(resultSet.getBytes(3)); // ignored the WKBReader and the results are about the same.
>>>>>>> > attribute = resultSet.getString(4);
>>>>>>> > count = resultSet.getLong(5);
>>>>>>> > reference = resultSet.getString(6);
>>>>>>> >
>>>>>>> > properties = new HashMap<String, Double>();
>>>>>>> > Double aux = resultSet.getDouble(7);
>>>>>>> > properties.put("countpersons", aux);
>>>>>>> > aux = resultSet.getDouble(8);
>>>>>>> > properties.put("countfatals", aux);
>>>>>>> > aux = resultSet.getDouble(9);
>>>>>>> > properties.put("countdrunks", aux);
>>>>>>> > aux = resultSet.getDouble(10);
>>>>>>> > properties.put("density", aux);
>>>>>>> > }
>>>>>>> >
>>>>>>> > System.out.println("[QUERY " + Thread.currentThread().getId()
>>>>>>> > + "] - done & iterated in "
>>>>>>> > + (System.currentTimeMillis() - time) + "ms.");
>>>>>>> >
>>>>>>> > resultSet.close();
>>>>>>> > st.close();
>>>>>>> > connection.commit();
>>>>>>> > connection.close();
>>>>>>> > } catch (SQLException exception) {
>>>>>>> > exception.printStackTrace();
>>>>>>> > // } catch (ParseException exception) { // ignored from WKBreader
>>>>>>> > // exception.printStackTrace();
>>>>>>> > }
>>>>>>> >
>>>>>>> > System.out.println("[End " + Thread.currentThread().getId()
>>>>>>> > + "] - done in " + (System.currentTimeMillis() - time) + "ms.");
>>>>>>> > }
>>>>>>> >
>>>>>>> > -------------------- end code --------------------
>>>>>>> >
>>>>>>> > Although i'm executing this on slow MacbookPro (2.6 core duo, 2Gbs RAM but SSD) and have a 9.1.2 postgres, i've also tested this on a recent retina MBP and the ratio between pgAdmin and JDBC execution is similar.
>>>>>>> >
>>>>>>> > Is this expected? Can someone point if i'm doing something terrible wrong?
>>>>>>> >
>>>>>>> > I'm not concerned about the query performance per-se (i know it CAN be optimized), but the differences just using JDBC and iterating the resultSet are really annoying.
>>>>>>> >
>>>>>>> > Thanks in advance for any help.
>>>>>>> >
>>>>>>> > Kind regards,
>>>>>>> >
>>>>>>> > Rui Leal
>>>>>>> >
>>>>>>> >
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Sent via pgsql-jdbc mailing list (pgsql-jdbc(at)postgresql(dot)org)
>>>>>>> To make changes to your subscription:
>>>>>>> http://www.postgresql.org/mailpref/pgsql-jdbc
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
> Does this patches already integrated into main stream driver source code?
>
> Edson