This makes a lot of sense now - I haven't read up on the C interface and
assumed that "step" was a JDBC thing. Thanks for clearing that up.
George.
On 09/26/2009 01:01 AM, Pavel Ivanov wrote:
>> Does anyone know why this method might be so expensive?
>>
> Because it's main method to execute your queries.
> I believe I can safely assume that org.sqlite.NativeDB.step maps
> directly to C call sqlite3_step() and it's the only function where
> query is executed. It doesn't just iterate through resultset it
> obtains this resultset it too.
>
> Pavel
>
> On Thu, Sep 24, 2009 at 11:24 PM, George Bills<gbi...@funnelback.com> wrote:
>
>> Hi everyone - this might be a general JDBC question rather than an
>> SQLite specific question, but I'm not sure.
>>
>> I've got an app that's writing to an SQLite database using the latest
>> SQLite JDBC driver ("v056, based on SQLite 3.6.14.2") from
>> http://www.zentus.com/sqlitejdbc/.
>>
>> I've done some basic profiling using hprof, and initially things are
>> fine. But then my tables get quite large (e.g. 26 million / 7 million /
>> 6 million rows), and after this point, I find that a huge amount of my
>> apps time is being spent in "org.sqlite.NativeDB.step".
>>
>> Does anyone know why this method might be so expensive? I probably need
>> to dig deeper with my profiling and find out exactly which methods are
>> calling the expensive "step"s, but I'm fairly new to working with JDBC
>> and any hints or suggestions would be helpful.
>>
>> During the applications run, I'll be running a certain amount of selects
>> and inserts, but in all cases, I'll be selecting or inserting 1 row at a
>> time, so I wouldn't expect that iterating over my ResultSet (I assume
>> this is what org.sqlite.NativeDB.step is doing) would be very expensive.
>>
>> The code that does the selection of a row, given an SQL string and an
>> array of string parameters is like:
>>
>> selectStatement = databaseConnection.prepareStatement(SQL);
>> setStatementParameters(selectStatement, parameters);
>> resultSet = selectStatement.executeQuery();
>> singleResult = parseResultForSingleElement(resultSet,
>> columnName);
>>
>> The code that does the insertion of a row, given an SQL string and an
>> array of string parameters is like:
>>
>> insertStatement = databaseConnection.prepareStatement(SQL);
>> setStatementParameters(insertStatement, parameters);
>> insertStatement.executeUpdate();
>> resultSet = insertStatement.getGeneratedKeys();
>> autoincrementPK = parseResultForSingleElement(resultSet, null);
>>
>> parseResultForSingleElement is like:
>>
>> if (numColumns == 1&& res.next()) {
>> E val;
>> if (columnName != null) {
>> val = (E) res.getObject(columnName);
>> } else {
>> val = (E) res.getObject(1);
>> }
>> if (res.wasNull()) {
>> ret = new SQLVal<E>(ResultStatus.RESULT_WAS_NULL);
>> } else {
>> ret = new SQLVal<E>(val);
>> }
>> }
>>
>> Thanks for any help.
>> George.
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>>
>>
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