WEBVTT 00:04.400 --> 00:11.090 Now, let's try to list all topics in our coffeecake last year and afterwards read the tales about particular 00:11.090 --> 00:15.160 topic in our case, so we will read the tales about topic animals. 00:15.500 --> 00:21.600 So let's first entered this command that is located after topic comment, this one. 00:21.770 --> 00:24.200 And let me do that in a separate tab. 00:24.530 --> 00:25.880 Let me send you to Kafka. 00:27.480 --> 00:28.830 And here is this command. 00:29.660 --> 00:31.620 And as a result, I got two topics. 00:31.640 --> 00:37.520 One is system topic gold to underscore consumer offsets, and the next one is animals. 00:37.570 --> 00:39.860 That is a topic we have created ourselves. 00:40.240 --> 00:45.830 Let's not read the tales about topic animals that we could use this common topic details. 00:45.830 --> 00:47.420 And here will be option. 00:47.430 --> 00:49.240 Describe and name of the topic. 00:49.460 --> 00:52.760 Let me replace death with animals like Soul. 00:53.030 --> 00:55.740 Copy this comment and paste here. 00:55.940 --> 00:59.930 Notice how fast we move when we have all commands here in one single file. 01:00.230 --> 01:00.590 Great. 01:00.740 --> 01:01.700 Let's press enter. 01:03.590 --> 01:10.640 And let me make this output a bit smaller, like Seoul and the U.S. following information, thrust topic 01:10.640 --> 01:13.510 name animals, partition count is three. 01:13.670 --> 01:17.570 That is the count we have specified when we have created this topic. 01:17.930 --> 01:20.240 Next, replication factor one. 01:20.480 --> 01:22.520 We have also specified this option. 01:22.520 --> 01:26.030 If I will get back here to this list, you'll see this option here. 01:26.030 --> 01:28.730 But basically, it is a default option. 01:28.730 --> 01:31.400 Replication factor is set to one by default. 01:31.580 --> 01:36.140 And one of the next examples, we will try to adjust it and make it two or three. 01:36.500 --> 01:41.210 For now, it is one grade after application of Aktau for this particular topic. 01:41.390 --> 01:49.250 You'll see it segment by its option and it is set actually to one gigabyte and it is the size of every 01:49.250 --> 01:51.800 segment for this particular topic. 01:52.130 --> 01:57.350 What the segment segment is actually single file that stores log messages. 01:57.710 --> 02:03.830 And in our case, if I look at the visual studio called files here in animals folders in partitioned 02:03.830 --> 02:06.350 folders, you'll see those log files. 02:06.800 --> 02:12.070 And this option actually specifies maximum size of every log file. 02:12.410 --> 02:19.310 For example, when this log file reaches size one gigabyte, COFCO will create one more log file in 02:19.310 --> 02:25.340 this same partition, Animals one and messages will arrive there to that new file. 02:25.700 --> 02:28.250 That's what segment by its option means. 02:28.700 --> 02:35.020 Next, after details of this specific topic, you'll see the details about every partition of this topic. 02:35.360 --> 02:38.570 So here on this line, you see the tales about partition zero. 02:38.750 --> 02:40.970 On the next line, the tales about partition one. 02:41.240 --> 02:44.000 And finally, last, partition with idee two. 02:44.570 --> 02:51.020 For every partition, you'll see information about LIDAR replicas and in-sync replicas. 02:51.380 --> 02:56.000 And in our case, in this example, everywhere you'll see number zero. 02:56.420 --> 03:00.050 And basically this is idea of specific Breuker. 03:00.260 --> 03:03.500 In our case, we have only a single broker this way. 03:03.500 --> 03:09.500 Everywhere you see here, number zero, it means that for every partition, this one, this one and 03:09.500 --> 03:14.450 this one broker with a zero is leader for this particular partition. 03:15.080 --> 03:19.960 Also, there are no replicas except Brolga with a zero. 03:19.970 --> 03:24.610 So every message is thought only in a single place on a single brolga. 03:24.740 --> 03:32.300 That's why here you see in the replicas list is zero and in-sync replicas parameter shows of replicas 03:32.300 --> 03:34.910 that are synchronized with leader. 03:34.910 --> 03:40.850 And again, in this first example we see here, ID zero, which side of our single broker, because 03:40.850 --> 03:44.840 the single place where our messages for every partition are stored. 03:45.140 --> 03:51.170 And of course, in this example, if this broker fails, we will be able to retrieve messages anymore 03:51.320 --> 03:55.540 and the producers and consumers will be able to communicate with Kafka. 03:55.550 --> 04:00.740 Kloster, this are details about a particular topic, in our case, animals. 04:01.070 --> 04:04.360 Let's not try to read details also about this system topic. 04:04.490 --> 04:11.540 Let me copy its name like so go back to notepad and adjust the name of the topic we want to details 04:11.540 --> 04:13.670 about here like soul. 04:14.630 --> 04:15.860 Copy this command. 04:16.950 --> 04:18.780 And pasted here in the terminal. 04:19.670 --> 04:21.300 And make it a bit smaller. 04:22.350 --> 04:28.950 And here you'll see basically information about 50 partitions of the topic, consumer offsets, and 04:28.950 --> 04:35.220 again, everywhere, leader replicas and in some replicas are set to broker with a zero. 04:35.550 --> 04:42.600 And now you'll see that this topic has 50 partitions and replication factor is one, does default one. 04:42.780 --> 04:47.090 And here you'll see configuration details of this particular topic. 04:47.490 --> 04:51.570 But what is the purpose of this system topic called consumer offsets? 04:52.140 --> 04:56.910 Inside of it, Kafka stories committed of offsets of consumers. 04:57.390 --> 05:04.570 In our case, we have only a single consumer that is around, and the Kafka now knows that it has read 05:04.570 --> 05:12.540 the old messages in Patison number two, starting from Offset Zero, and currently it is at Offset one 05:12.540 --> 05:17.280 and is ready to read new messages that will arrive to this particular partition. 05:17.760 --> 05:24.390 And this information is again stored somewhere in one of partitions here in this system topic. 05:24.720 --> 05:31.170 In simple words, its tracks location of every consumer in Matthijs consumption brought us again. 05:31.290 --> 05:32.850 That's Consumer Offset Storbeck. 05:33.180 --> 05:33.750 Wonderful. 05:33.930 --> 05:38.670 Let's do one more step and let's try to observe logs of Kafka Breuker. 05:38.910 --> 05:41.940 So let me go to this step where we have started Kafka. 05:42.450 --> 05:48.510 And you see here some periodic messages like this one removed zero expired offsets in zero milliseconds. 05:48.690 --> 05:52.310 That actually tracks whether there are some expired offsets. 05:52.320 --> 05:58.380 Also, if you scroll up, you'll see some messages related to console groups like this one, for example, 05:58.530 --> 06:03.660 group console consumer with ID six one one two transitions to death in generation two. 06:04.020 --> 06:10.170 Also, if you scroll up and we see other messages related to consumer groups like this one preparing 06:10.170 --> 06:16.140 to rebalance the group and so on, Rigoberta, they have told you that technically every consumer must 06:16.140 --> 06:18.540 belong to specific consumer group. 06:18.930 --> 06:25.350 And if you don't specify a consumer group name in your consumer group, in our case, in this example, 06:25.350 --> 06:31.700 we didn't specify it then group name will be created automatically and it will get the same unique number. 06:31.920 --> 06:33.660 We will explore it a bit later. 06:33.660 --> 06:39.720 And also later in one of the next examples, we will create the consumer in specific consumer group. 06:39.960 --> 06:41.490 For now, that's all for this example. 06:41.490 --> 06:43.530 And next, let's make a short summary of it. 06:43.830 --> 06:44.460 See you next. 06:44.460 --> 06:44.920 Bye by.