Re: JDBC slow performance on resultSet iteration?

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
>>>>> >
>>>>> >
>>>>>
>>>>>
>>>>>
>>>>> --
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>>>>>
>>>>
>>>>
>>>
>>>
>>
>