That's a question that many Java developers would like the answer to.
Unfortunately, anything better than milliseconds requires JNI, since
the current JVM doesn't officially support anything higher. There are
solutions to this particular problem, but for most people,
milliseconds are sufficient outside of testing. This is because the
likelihood of making two conflicting changes to the same row/column in
the same "session" within the same millisecond is pretty low for
actual users and real scenarios. Tests tend to be a little unrealistic
in the sense that they happen quickly within a short amount of time
and aren't dependent on the timing of people or other systems.
If you are using a "remove and replace" scheme, it could still be a
problem. The way I get around it for now is to use the microsecond
unit of time with a millisecond source (getCurrentMillis()), and
increment it artificially when it would return the same value twice in
a row. It's a hack, but it works for my purposes.
On Sun, Jul 25, 2010 at 12:54 AM, Oleg Tsvinev <oleg.tsvi...@gmail.com> wrote:
> Thank you guys for your help!
> Yes, I am using System.currentTimeMillis() in my CRUD test. Even though I'm
> still using it my tests now run as expected. I do not use cassandra-cli
> anymore.
> @Ran great job on Hector, I wish there was more documentation but I managed.
> @Jonathan, what is the recommended time source? I use batch_mutation to
> insert and update multiple columns atomically. Do I have to use
> the batch_mutation for deletion, too?
> On Sat, Jul 24, 2010 at 2:36 PM, Jonathan Shook <jsh...@gmail.com> wrote:
>>
>> Just to clarify, microseconds may be used, but they provide the same
>> behavior as milliseconds if they aren't using a higher time resolution
>> underneath. In some cases, the microseconds are generated simply as
>> milliseconds * 1000, which doesn't actually fix any sequencing bugs.
>>
>> On Sat, Jul 24, 2010 at 3:46 PM, Ran Tavory <ran...@gmail.com> wrote:
>> > Hi Oleg, I didn't follow up the entire thread, but just to let you know
>> > that
>> > the 0.6.* version of the CLI uses microsec as the time unit for
>> > timestamps.
>> > Hector also uses micros to match that, however, previous versions of
>> > hector
>> > (as well as the CLI) used milliseconds, not micro.
>> > So if you're using hector version 0.6.0-11 or earlier, or by any chance
>> > in
>> > some other ways are mixing milisec in your app (are you using
>> > System.currentTimeMili() somewhere?) then the behavior you're seeing is
>> > expected.
>> >
>> > On Sat, Jul 24, 2010 at 1:06 AM, Jonathan Shook <jsh...@gmail.com>
>> > wrote:
>> >>
>> >> I think you are getting it.
>> >>
>> >> As far as what means what at which level, it's really about using them
>> >> consistently in every case. The [row] key (or [row] key range) is a
>> >> top-level argument for all of the operations, since it is the "key" to
>> >> mapping the set of responsible nodes. The key is the part of the name
>> >> of any column which most affects how the load is apportioned in the
>> >> cluster, so it is used very early in request processing.
>> >>
>> >>
>> >> On Fri, Jul 23, 2010 at 4:22 PM, Peter Minearo
>> >> <peter.mine...@reardencommerce.com> wrote:
>> >> > Consequentially the remove should look like:
>> >> >
>> >> >
>> >> > ColumnPath cp1 = new ColumnPath("Super2");
>> >> > cp1.setSuper_column("Best Western".getBytes());
>> >> >
>> >> > client.remove(KEYSPACE,
>> >> > "hotel",
>> >> > cp1,
>> >> > System.currentTimeMillis(),
>> >> > ConsistencyLevel.ONE);
>> >> >
>> >> > ColumnPath cp2 = new ColumnPath("Super2");
>> >> > cp2.setSuper_column("Econolodge".getBytes());
>> >> >
>> >> > client.remove(KEYSPACE,
>> >> > "hotel",
>> >> > cp2,
>> >> > System.currentTimeMillis(),
>> >> > ConsistencyLevel.ONE);
>> >> >
>> >> >
>> >> > -----Original Message-----
>> >> > From: Peter Minearo [mailto:peter.mine...@reardencommerce.com]
>> >> > Sent: Fri 7/23/2010 2:17 PM
>> >> > To: user@cassandra.apache.org
>> >> > Subject: RE: CRUD test
>> >> >
>> >> > CORRECTION:
>> >> >
>> >> > ColumnPath cp1 = new ColumnPath("Super2");
>> >> > cp1.setSuper_column("Best Western".getBytes());
>> >> > cp1.setColumn("name".getBytes());
>> >> > client.insert(KEYSPACE, "hotel", cp1, "Best Western of
>> >> > SF".getBytes(),
>> >> > System.currentTimeMillis(), ConsistencyLevel.ALL);
>> >> >
>> >> >
>> >> > -----Original Message-----
>> >> > From: Peter Minearo [mailto:peter.mine...@reardencommerce.com]
>> >> > Sent: Friday, July 23, 2010 2:14 PM
>> >> > To: user@cassandra.apache.org
>> >> > Subject: RE: CRUD test
>> >> >
>> >> > Interesting!! Let me rephrase to make sure I understood what is going
>> >> > on:
>> >> >
>> >> > When Inserting data via the "insert" function/method:
>> >> >
>> >> > void insert(string keyspace, string key, ColumnPath column_path,
>> >> > binary
>> >> > value, i64 timestamp, ConsistencyLevel consistency_level)
>> >> >
>> >> > The "key" parameter is the actual Key to the "Row", which contains
>> >> > SuperColumns. The 'ColumnPath' gives the path within the Key.
>> >> >
>> >> >
>> >> >
>> >> > INCORRECT:
>> >> > ColumnPath cp1 = new ColumnPath("Super2");
>> >> > cp1.setSuper_column("hotel".getBytes());
>> >> > cp1.setColumn("Best Western".getBytes()); client.insert(KEYSPACE,
>> >> > "name", cp1, "Best Western of SF".getBytes(),
>> >> > System.currentTimeMillis(),
>> >> > ConsistencyLevel.ALL);
>> >> >
>> >> >
>> >> > CORRECT:
>> >> > ColumnPath cp1 = new ColumnPath("Super2");
>> >> > cp1.setSuper_column("name".getBytes());
>> >> > cp1.setColumn("Best Western".getBytes()); client.insert(KEYSPACE,
>> >> > "hotel", cp1, "Best Western of SF".getBytes(),
>> >> > System.currentTimeMillis(),
>> >> > ConsistencyLevel.ALL);
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >> > -----Original Message-----
>> >> > From: Jonathan Shook [mailto:jsh...@gmail.com]
>> >> > Sent: Friday, July 23, 2010 1:49 PM
>> >> > To: user@cassandra.apache.org
>> >> > Subject: Re: CRUD test
>> >> >
>> >> > Correct.
>> >> >
>> >> > After the initial insert,
>> >> >
>> >> > cassandra> get Keyspace1.Super2['name']
>> >> > => (super_column=hotel,
>> >> > (column=Best Western, value=Best Western of SF,
>> >> > timestamp=1279916772571)
>> >> > (column=Econolodge, value=Econolodge of SF,
>> >> > timestamp=1279916772573)) Returned 1 results.
>> >> >
>> >> > ... and ...
>> >> >
>> >> > cassandra> get Keyspace1.Super2['hotel']
>> >> > Returned 0 results.
>> >> >
>> >> >
>> >> >
>> >> > On Fri, Jul 23, 2010 at 3:41 PM, Peter Minearo
>> >> > <peter.mine...@reardencommerce.com> wrote:
>> >> >> The Model Should look like:
>> >> >>
>> >> >>
>> >> >> Super2 = {
>> >> >> hotel: {
>> >> >> Best Western: {name: "Best Western of SF"}
>> >> >> Econolodge: {name: "Econolodge of SF"}
>> >> >> }
>> >> >> }
>> >> >>
>> >> >> Are the CRUD Operations not referencing this correctly?
>> >> >>
>> >> >>
>> >> >>
>> >> >> -----Original Message-----
>> >> >> From: Jonathan Shook [mailto:jsh...@gmail.com]
>> >> >> Sent: Friday, July 23, 2010 1:34 PM
>> >> >> To: user@cassandra.apache.org
>> >> >> Subject: Re: CRUD test
>> >> >>
>> >> >> There seem to be data consistency bugs in the test. Are "name" and
>> >> >> "hotel" being used in a pair-wise way?
>> >> >> Specifically, the first test is using creating one and checking for
>> >> >> the
>> >> >> other.
>> >> >>
>> >> >> On Fri, Jul 23, 2010 at 2:46 PM, Oleg Tsvinev
>> >> >> <oleg.tsvi...@gmail.com>
>> >> >> wrote:
>> >> >>> Johathan,
>> >> >>> I followed your suggestion. Unfortunately, CRUD test still does not
>> >> >>> work for me. Can you provide a simplest CRUD test possible that
>> >> >>> works?
>> >> >>> On Fri, Jul 23, 2010 at 10:59 AM, Jonathan Shook <jsh...@gmail.com>
>> >> >>> wrote:
>> >> >>>>
>> >> >>>> I suspect that it is still your timestamps.
>> >> >>>> You can verify this with a fake timestamp generator that is simply
>> >> >>>> incremented on each getTimestamp().
>> >> >>>>
>> >> >>>> 1 millisecond is a long time for code that is wrapped tightly in a
>> >> >>>> test. You are likely using the same logical time stamp for
>> >> >>>> multiple
>> >> >>>> operations.
>> >> >>>>
>> >> >>>>
>> >> >>>> On Thu, Jul 22, 2010 at 6:29 PM, Peter Minearo
>> >> >>>> <peter.mine...@reardencommerce.com> wrote:
>> >> >>>> > I am able to reproduce his problem. If you take the default
>> >> >>>> > storage-conf.xml file and utilize the "Super2" ColumnFamily with
>> >> >>>> > the code below. You will see that the data is not getting
>> >> >>>> > created
>> >> >>>> > once you run the delete. It seems to not allow you to create
>> >> >>>> > data
>> >> >>>> > via Thrift. HOWEVER, data can be created via the command line
>> >> >>>> > tool.
>> >> >>>> >
>> >> >>>> > import java.io.UnsupportedEncodingException;
>> >> >>>> > import java.util.List;
>> >> >>>> >
>> >> >>>> > import org.apache.cassandra.thrift.Cassandra;
>> >> >>>> > import org.apache.cassandra.thrift.Column;
>> >> >>>> > import org.apache.cassandra.thrift.ColumnOrSuperColumn;
>> >> >>>> > import org.apache.cassandra.thrift.ColumnParent;
>> >> >>>> > import org.apache.cassandra.thrift.ColumnPath;
>> >> >>>> > import org.apache.cassandra.thrift.ConsistencyLevel;
>> >> >>>> > import org.apache.cassandra.thrift.InvalidRequestException;
>> >> >>>> > import org.apache.cassandra.thrift.NotFoundException;
>> >> >>>> > import org.apache.cassandra.thrift.SlicePredicate;
>> >> >>>> > import org.apache.cassandra.thrift.SliceRange;
>> >> >>>> > import org.apache.cassandra.thrift.SuperColumn;
>> >> >>>> > import org.apache.cassandra.thrift.TimedOutException;
>> >> >>>> > import org.apache.cassandra.thrift.UnavailableException;
>> >> >>>> > import org.apache.thrift.TException; import
>> >> >>>> > org.apache.thrift.protocol.TBinaryProtocol;
>> >> >>>> > import org.apache.thrift.protocol.TProtocol;
>> >> >>>> > import org.apache.thrift.transport.TSocket;
>> >> >>>> > import org.apache.thrift.transport.TTransport;
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > public class CrudTest {
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > private static final String KEYSPACE = "Keyspace1";
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > public static void main(String[] args) {
>> >> >>>> > CrudTest client = new CrudTest();
>> >> >>>> >
>> >> >>>> > try {
>> >> >>>> > client.run();
>> >> >>>> > } catch (Exception e) {
>> >> >>>> > e.printStackTrace();
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > public void run() throws TException,
>> >> >>>> > InvalidRequestException, UnavailableException,
>> >> >>>> > UnsupportedEncodingException, NotFoundException,
>> >> >>>> > TimedOutException
>> >> >>>> > {
>> >> >>>> > TTransport tr = new TSocket("localhost", 9160);
>> >> >>>> > TProtocol proto = new TBinaryProtocol(tr);
>> >> >>>> > Cassandra.Client client = new
>> >> >>>> > Cassandra.Client(proto);
>> >> >>>> > tr.open();
>> >> >>>> >
>> >> >>>> > System.out.println("******** CREATING DATA
>> >> >>>> > *********");
>> >> >>>> > createData(client);
>> >> >>>> > getData(client);
>> >> >>>> > System.out.println();
>> >> >>>> > System.out.println("******** DELETING DATA
>> >> >>>> > *********");
>> >> >>>> > deleteData(client);
>> >> >>>> > getData(client);
>> >> >>>> > System.out.println();
>> >> >>>> > System.out.println("******** CREATING DATA
>> >> >>>> > *********");
>> >> >>>> > createData(client);
>> >> >>>> > getData(client);
>> >> >>>> >
>> >> >>>> > tr.close();
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > private void createData(Cassandra.Client client) throws
>> >> >>>> > InvalidRequestException, UnavailableException,
>> >> >>>> > TimedOutException,
>> >> >>>> > TException {
>> >> >>>> > ColumnPath cp1 = new ColumnPath("Super2");
>> >> >>>> > cp1.setSuper_column("hotel".getBytes());
>> >> >>>> > cp1.setColumn("Best Western".getBytes());
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > client.insert(KEYSPACE,
>> >> >>>> > "name",
>> >> >>>> > cp1,
>> >> >>>> > "Best Western of SF".getBytes(),
>> >> >>>> > System.currentTimeMillis(),
>> >> >>>> > ConsistencyLevel.ALL);
>> >> >>>> >
>> >> >>>> > ColumnPath cp2 = new ColumnPath("Super2");
>> >> >>>> > cp2.setSuper_column("hotel".getBytes());
>> >> >>>> > cp2.setColumn("Econolodge".getBytes());
>> >> >>>> >
>> >> >>>> > client.insert(KEYSPACE,
>> >> >>>> > "name",
>> >> >>>> > cp2,
>> >> >>>> > "Econolodge of SF".getBytes(),
>> >> >>>> > System.currentTimeMillis(),
>> >> >>>> > ConsistencyLevel.ALL);
>> >> >>>> >
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > private void deleteData(Cassandra.Client client) throws
>> >> >>>> > InvalidRequestException, UnavailableException,
>> >> >>>> > TimedOutException,
>> >> >>>> > TException {
>> >> >>>> >
>> >> >>>> > client.remove(KEYSPACE,
>> >> >>>> > "hotel",
>> >> >>>> > new ColumnPath("Super2"),
>> >> >>>> > System.currentTimeMillis(),
>> >> >>>> > ConsistencyLevel.ONE);
>> >> >>>> >
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > private void getData(Cassandra.Client client) throws
>> >> >>>> > InvalidRequestException, UnavailableException,
>> >> >>>> > TimedOutException,
>> >> >>>> > TException {
>> >> >>>> > SliceRange sliceRange = new SliceRange();
>> >> >>>> > sliceRange.setStart(new byte[] {});
>> >> >>>> > sliceRange.setFinish(new byte[] {});
>> >> >>>> >
>> >> >>>> > SlicePredicate slicePredicate = new
>> >> >>>> > SlicePredicate();
>> >> >>>> > slicePredicate.setSlice_range(sliceRange);
>> >> >>>> >
>> >> >>>> > getData(client, slicePredicate);
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > private void getData(Cassandra.Client client,
>> >> >>>> > SlicePredicate
>> >> >>>> > slicePredicate) throws InvalidRequestException,
>> >> >>>> > UnavailableException, TimedOutException, TException {
>> >> >>>> > List<ColumnOrSuperColumn> coscList =
>> >> >>>> > client.get_slice(KEYSPACE, "hotel", new ColumnParent("Super2"),
>> >> >>>> > slicePredicate, ConsistencyLevel.ALL);
>> >> >>>> >
>> >> >>>> > if (coscList.isEmpty()) {
>> >> >>>> > System.out.println("Column Or Super
>> >> >>>> > Column
>> >> >>>> > is EMPTY");
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> > for (ColumnOrSuperColumn cosc: coscList) {
>> >> >>>> >
>> >> >>>> > if (cosc == null) {
>> >> >>>> > System.out.println("NULL RETURN
>> >> >>>> > VALUE");
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> > SuperColumn superColumn =
>> >> >>>> > cosc.getSuper_column();
>> >> >>>> >
>> >> >>>> > if (superColumn == null) {
>> >> >>>> > System.out.println("Super Column
>> >> >>>> > is
>> >> >>>> > NULL");
>> >> >>>> > }
>> >> >>>> > else {
>> >> >>>> > showSuperColumnInfo(superColumn);
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > private void showSuperColumnInfo(SuperColumn superColumn)
>> >> >>>> > {
>> >> >>>> > System.out.println("######## Super Columns
>> >> >>>> > ###########");
>> >> >>>> > System.out.println("Super Column Name = " + new
>> >> >>>> > String(superColumn.getName()));
>> >> >>>> > List<Column> columnList =
>> >> >>>> > superColumn.getColumns();
>> >> >>>> >
>> >> >>>> > System.out.println("--------- Start Columns
>> >> >>>> > -----------");
>> >> >>>> > for (Column column: columnList) {
>> >> >>>> > System.out.println("Column Name = " + new
>> >> >>>> > String(column.getName()));
>> >> >>>> > System.out.println("Column Value = " +
>> >> >>>> > new
>> >> >>>> > String(column.getValue()));
>> >> >>>> > }
>> >> >>>> > System.out.println("--------- End Columns
>> >> >>>> > -----------");
>> >> >>>> >
>> >> >>>> > System.out.println("##################################");
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > }
>> >> >>>> >
>> >> >>>> >
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > -----Original Message-----
>> >> >>>> > From: Oleg Tsvinev [mailto:oleg.tsvi...@gmail.com]
>> >> >>>> > Sent: Thu 7/22/2010 1:56 PM
>> >> >>>> > To: user@cassandra.apache.org
>> >> >>>> > Subject: Re: CRUD test
>> >> >>>> >
>> >> >>>> > Yes, and that was the issue. But now after I delete a row from
>> >> >>>> > cassandra-cli, I cannot insert anything back with my code.
>> >> >>>> > Insert
>> >> >>>> > code works does not throw any exceptions but when I read just
>> >> >>>> > inserted columns I get NotFoundException at the last line:
>> >> >>>> >
>> >> >>>> > client = borrowClient();
>> >> >>>> > Keyspace keyspace = client.getKeyspace(KEYSPACE,
>> >> >>>> > CONSISTENCY_LEVEL);
>> >> >>>> > ColumnPath cp = new ColumnPath(application);
>> >> >>>> > cp.setSuper_column(uuid.getBytes());
>> >> >>>> > SuperColumn sc = keyspace.getSuperColumn(category,
>> >> >>>> > cp);
>> >> >>>> >
>> >> >>>> > It makes me think that once I remove supercolumn it cannot be
>> >> >>>> > created again.
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > On Jul 22, 2010 1:13 AM, "Colin Vipurs" <zodiac...@gmail.com>
>> >> >>>> > wrote:
>> >> >>>> >
>> >> >>>> > Have you checked the timestamp you're using for the subsequent
>> >> >>>> > inserts is higher than that used in the delete?
>> >> >>>> >
>> >> >>>> >
>> >> >>>> > On Thu, Jul 22, 2010 at 2:29 AM, Oleg Tsvinev
>> >> >>>> > <oleg.tsvi...@gmail.com>
>> >> >>>> > wrote:
>> >> >>>> >> Hi there,
>> >> >>>> >> I'm try...
>> >> >>>> > --
>> >> >>>> > Maybe she awoke to see the roommate's boyfriend swinging from
>> >> >>>> > the
>> >> >>>> > chandelier wearing a boar's head.
>> >> >>>> >
>> >> >>>> > Something which you, I, and everyone else would call "Tuesday",
>> >> >>>> > of
>> >> >>>> > course.
>> >> >>>> >
>> >> >>>> >
>> >> >>>
>> >> >>>
>> >> >>
>> >> >
>> >> >
>> >
>> >
>
>
