1 00:00:03,300 --> 00:00:08,700 So in this session, we are going to talk about various data lives which are available in Redis and also 2 00:00:08,700 --> 00:00:14,840 some of the operations which are available to perform by using these different Data Types. 3 00:00:15,050 --> 00:00:15,330 Okay. 4 00:00:15,360 --> 00:00:16,950 So let's begin. 5 00:00:16,950 --> 00:00:24,450 I'm going to connect to Redis by using Rediscli and if you remember the service is running on Port 6 00:00:24,450 --> 00:00:26,130 6 3 7 0 in this case. 7 00:00:26,850 --> 00:00:29,070 So we need to specify the port explicitly 8 00:00:35,330 --> 00:00:40,920 and now let's begin with String Data Type. So in a String Data Type or a String. 9 00:00:40,920 --> 00:00:47,720 Key Value Pair, usually just write Set Command and we provide the key name and also we provide the value 10 00:00:47,720 --> 00:00:47,950 name. 11 00:00:48,800 --> 00:00:53,540 So let's say, our key is a product which is Chair 12 00:00:53,720 --> 00:00:59,120 And also we want to set the price as a value for these key type. 13 00:00:59,740 --> 00:01:00,020 Okay. 14 00:01:00,050 --> 00:01:05,720 So typically we run command like Set and then space and then we provide the Key Name then space 15 00:01:05,750 --> 00:01:07,700 and also we provide the Value. 16 00:01:07,700 --> 00:01:15,380 So once you do this, the value has been set, which means that this value or key value pair has been written 17 00:01:15,380 --> 00:01:23,880 to Redis. Now to get the same value back you use Get command and also you provided the key name. 18 00:01:24,570 --> 00:01:27,700 So if I do Get Chair, I'm going to get the value back. 19 00:01:27,750 --> 00:01:28,490 Okay. 20 00:01:28,560 --> 00:01:33,510 So similarly you can continue performing this option with different key value pairs 21 00:01:36,950 --> 00:01:46,140 and you will get back the response, you know, depending on the key information you want to get back. 22 00:01:46,190 --> 00:01:52,410 Now let's say, if you want to see all the available key types. For that you can use keys and specify the 23 00:01:52,420 --> 00:01:52,990 pattern. 24 00:01:53,120 --> 00:01:54,650 In this case I'm going to give * 25 00:01:54,650 --> 00:01:59,360 So it is going to be me all the keys which are available in Redis. 26 00:01:59,360 --> 00:02:05,600 So right now we see, we only have 2 keys available and now let's say if you want to delete one of the 27 00:02:05,600 --> 00:02:06,020 keys. 28 00:02:07,010 --> 00:02:15,590 So the command to do that is del space followed by the key and if you want to delete multiple keys 29 00:02:15,590 --> 00:02:18,460 you can also specify Multiple Keys. 30 00:02:18,620 --> 00:02:27,650 But in this case let's say, I want to delete just one key. So I write delete chair and it is giving us 31 00:02:27,650 --> 00:02:30,110 the value of 1, which means the operation is successful. 32 00:02:30,140 --> 00:02:32,420 So one of the Keys has been removed. 33 00:02:32,420 --> 00:02:37,520 Now if I do Keys * again. This time I see only 1 value which is Table, because chair has been 34 00:02:37,520 --> 00:02:39,380 removed. 35 00:02:39,380 --> 00:02:44,300 Now let's see whether Redis is Key Sensitive or not. 36 00:02:44,570 --> 00:02:44,850 Okay. 37 00:02:44,870 --> 00:02:54,000 So I'm setting a value of chair with value 100 and then we'll set value of chair again, but this type 38 00:02:54,000 --> 00:03:02,910 I'll keep C in capitals and remaining in lowercase and we type the same amount and this time I'm going 39 00:03:02,910 --> 00:03:08,050 to keep everything in uppercase and I'm going to hit enter. 40 00:03:08,070 --> 00:03:11,160 Now let's see how many different keys we have. 41 00:03:11,310 --> 00:03:14,790 Now you see in this case, different keys we have are more. 42 00:03:15,270 --> 00:03:23,870 So basically the point which I wanted to tell you, that Redis is Key Sensitive. So there is a difference 43 00:03:23,870 --> 00:03:32,210 between this chair and the way this chair is treated in Redis. So similarly when 44 00:03:32,210 --> 00:03:34,530 you are performing a delete operation. 45 00:03:34,880 --> 00:03:36,070 And if I give 46 00:03:36,860 --> 00:03:43,630 CHAIR in uppercase. it is only going to delete one of the key, which is matching this value. 47 00:03:43,670 --> 00:03:43,930 Okay. 48 00:03:43,940 --> 00:03:50,870 So now if I see keys *, I'm going to get the remaining values and one of the value, one of the 49 00:03:50,870 --> 00:04:01,710 Key Value, which has been removed is the CHAIR, which was in uppercase. 50 00:04:01,740 --> 00:04:06,960 Now let's say, you have some kind of you know, counter or Sequence ID number, which you want to store 51 00:04:07,020 --> 00:04:13,530 and also with each operation you want to increment the value of that counter. So you can do that by using 52 00:04:13,720 --> 00:04:16,410 String key value pair as well. 53 00:04:16,410 --> 00:04:19,320 So the way you do is, going to be same. 54 00:04:19,470 --> 00:04:27,660 Let me clear the screen first and I'm going to set a counter or it can be a Sequence ID. let's call 55 00:04:27,660 --> 00:04:32,230 it Sequence ID and let's say we start the value with 1 56 00:04:32,940 --> 00:04:33,260 Okay. 57 00:04:33,270 --> 00:04:43,010 Now if I see the current value of Sequence ID, it is set to 1 and now let's say, with each operation 58 00:04:43,010 --> 00:04:47,050 or whenever I query Redis, I want to increment the value by 1. 59 00:04:47,060 --> 00:04:55,370 So for that we have a command, which is called incr, Increment and also you provide the keys which 60 00:04:55,370 --> 00:04:57,680 you want to increment. 61 00:04:57,680 --> 00:05:03,320 So in the response, we have got value of 2 which means the existing value of Sequence ID was 1 and 62 00:05:03,320 --> 00:05:08,100 now it has incremented it with 2. 63 00:05:08,250 --> 00:05:12,900 And if you run the same operation again.This time you're going to get value of 3, which means again 64 00:05:12,900 --> 00:05:15,530 it has been incremented by 1 65 00:05:15,680 --> 00:05:15,910 Okay. 66 00:05:15,960 --> 00:05:21,840 So that is the way you can run Increment or Counters or Sequencer. 67 00:05:26,830 --> 00:05:31,960 However, please remember whenever you do get sequence underscore id, you are always going to get the 68 00:05:31,960 --> 00:05:34,530 latest value of sequence ID 69 00:05:34,600 --> 00:05:37,690 Okay so all of these 3 values have not been set. 70 00:05:37,720 --> 00:05:46,390 So each time, this Increment command, it looks for the current value and then it adds it, adds the current 71 00:05:46,390 --> 00:05:50,420 value with 1 and then it writes the same value back to Redis. 72 00:05:50,470 --> 00:05:53,530 That's why you always get the latest Counter Information. 73 00:05:57,440 --> 00:05:58,720 So if we do Key * 74 00:05:58,990 --> 00:06:06,260 total number of value which we see are 4. Other way to count the total number of keys or total number of 75 00:06:07,310 --> 00:06:09,680 records whatever you want to say it. 76 00:06:09,830 --> 00:06:12,730 So available in the Redis right now is, using dbsize command. 77 00:06:12,740 --> 00:06:19,490 So if I write dbsize , hit enter. I get a value of 4, which means right now Redis is storing total 4 78 00:06:19,520 --> 00:06:19,910 keys 79 00:06:23,700 --> 00:06:23,990 okay. 80 00:06:24,000 --> 00:06:29,680 So right now whatever operations, which we have performed these are based on single key value pair 81 00:06:30,120 --> 00:06:35,250 But let's say we want to increase the performance and we want to write multiple operations in one set 82 00:06:35,760 --> 00:06:36,700 or in one go. 83 00:06:36,750 --> 00:06:41,480 So we can do that. The way to do that is by using mset command. 84 00:06:41,580 --> 00:06:44,000 So mset stands for Multiple Set. 85 00:06:44,010 --> 00:06:53,040 So basically you are setting multiple values in one command. So you can set up different product prices. 86 00:06:53,040 --> 00:06:57,250 So let me set something like this. 87 00:06:57,260 --> 00:07:08,000 And then there is another product. Let's set it to 200 and then we can set another key value pair. 88 00:07:08,550 --> 00:07:12,570 So in this one I am setting actually 3 key value pairs, using mset command. 89 00:07:12,570 --> 00:07:15,380 And once you hit enter, you get a response of 90 00:07:15,390 --> 00:07:15,670 Okay. 91 00:07:15,690 --> 00:07:18,610 Which means, the data has been inserted to Redis. 92 00:07:18,690 --> 00:07:24,680 So if you do Keys *. You see 3 values or 3 items has been added. 93 00:07:24,750 --> 00:07:27,170 So one was Sofa, the other one was TV. 94 00:07:27,180 --> 00:07:33,210 And the third one was Bed. So all the three items has been added and by mistake 95 00:07:33,210 --> 00:07:41,830 Sofa we wrote as Soft, so the same has been operated here. Okay, now let's say when you want to get Multiple 96 00:07:42,670 --> 00:07:43,530 Values. 97 00:07:43,540 --> 00:07:43,800 Okay. 98 00:07:43,810 --> 00:07:50,710 So basically you want to ask Redis to provide the multiple, you know, you are going to request Redis 99 00:07:50,710 --> 00:07:55,080 with multiple keys and you want the values back for all of those keys. 100 00:07:55,090 --> 00:08:03,180 So the way to do that is using, mget command and let's say I want value of chair, I want value of TV, 101 00:08:03,610 --> 00:08:10,320 I want value of latest sequence ID. So once you hit enter,you are going to get the values of all of 102 00:08:10,320 --> 00:08:12,800 these three items. OK. 103 00:08:12,810 --> 00:08:18,360 So that's a way to perform mset or mget operation. 104 00:08:19,020 --> 00:08:21,330 And this is going to be faster than Set operation. 105 00:08:21,330 --> 00:08:27,510 The reason being is, you are actually requesting multiple items to Redis and Redis has to perform 106 00:08:27,900 --> 00:08:31,610 this operation and have to respond you back only ones. 107 00:08:31,620 --> 00:08:35,160 So this operation is faster than using Get or Set command. 108 00:08:40,030 --> 00:08:46,030 Now there can be scenario, when you want to see whether a key already exist or not. 109 00:08:46,030 --> 00:08:54,730 So in that kind of scenario, you can use exists command and with exists you need to provide the key name 110 00:08:55,570 --> 00:08:57,430 and also you can provide Multiple Key Name. 111 00:08:57,430 --> 00:09:01,600 So it is going to check whether all of those keys already exist or not. 112 00:09:01,600 --> 00:09:07,300 So let's say before inserting to Redis, I want to see that whether those keys already exist. 113 00:09:07,810 --> 00:09:14,950 So I can do something like exist and then I want to see whether any key with the name sequence_id 114 00:09:14,950 --> 00:09:16,750 exist or not. 115 00:09:17,110 --> 00:09:20,440 So once I hit enter. I'm going to get value of 1 116 00:09:20,440 --> 00:09:23,410 So here 1 means value already exists. 117 00:09:23,410 --> 00:09:30,280 Now let's say if I do the same with something called counter. So Counter is a key here and we want 118 00:09:30,280 --> 00:09:33,880 to see whether this counter already exists in Redis or not. 119 00:09:33,880 --> 00:09:40,750 So once we hit enter, we are getting a response of 0, which means it doesn't already exist. 120 00:09:49,520 --> 00:09:49,840 Okay. 121 00:09:49,850 --> 00:09:57,280 Let me clear the screen and let's again see the total keys we have available right now. So let's say 122 00:09:57,280 --> 00:10:03,050 you have a scenario in which you want keys to Auto expire. You don't want keys to be deleting 123 00:10:03,050 --> 00:10:08,900 manually or programmatically. You don't want to write those things. So Redis has a feature which is called 124 00:10:09,010 --> 00:10:12,590 TTL, which is a time to live. 125 00:10:12,590 --> 00:10:16,610 So you can set up TTL for any keys. 126 00:10:18,230 --> 00:10:26,790 Now the way to do that, is so basically when you are using set command, so along with the set command, 127 00:10:26,790 --> 00:10:32,350 you give key value pair. So let's say, it is a color which is Red. 128 00:10:32,730 --> 00:10:40,380 And now you also pass EX, which denotes that you are setting an expiration for this key. 129 00:10:40,380 --> 00:10:46,760 And let's say, here you need to provide the value in seconds. If you want to provide the value in milliseconds, 130 00:10:46,770 --> 00:10:51,840 then you need to use a PX. If you want to provide value in seconds, 131 00:10:51,840 --> 00:10:55,110 then you want to, or you need to use EX 132 00:10:55,170 --> 00:11:03,850 Now let's say I want this value of Color to be set to Red, only for 60 seconds. 133 00:11:03,980 --> 00:11:04,340 Okay. 134 00:11:04,350 --> 00:11:06,510 So I'm going to write like this. 135 00:11:06,510 --> 00:11:08,980 And once I hit enter, this value has been written. 136 00:11:09,090 --> 00:11:14,750 And once you do Get color, you are going to get Red back. 137 00:11:14,760 --> 00:11:21,250 But if the same command you try, after 60 seconds, the response which you are going to get is Nil 138 00:11:21,820 --> 00:11:26,350 because what Redis is going to do is, it is going to delete this key after 60 seconds 139 00:11:30,470 --> 00:11:31,660 okay let's check 140 00:11:31,670 --> 00:11:40,850 now, we still have the value. So the Threshold still has not reached and also the same thing can 141 00:11:40,850 --> 00:11:43,730 be actually done on, done through programmatically. 142 00:11:43,730 --> 00:11:51,530 So you have like Python or using JAVA, you can write the data along with the Expiration Time. 143 00:12:00,220 --> 00:12:00,770 okay. 144 00:12:00,780 --> 00:12:04,860 Right now if I'm doing Keys * I can see the keys still exist. 145 00:12:04,950 --> 00:12:09,740 So let's wait for some more time and then we will check the value again 146 00:12:16,120 --> 00:12:16,420 okay. 147 00:12:16,420 --> 00:12:23,380 Now if you see, when I type Keys * , we do not see Color. 148 00:12:23,950 --> 00:12:31,650 And also if I type Get Color, we are getting Nil which means, this key has been expired. Okay. 149 00:12:31,660 --> 00:12:39,450 So that is the way to use or set a key value pair along with a TTL. 150 00:12:39,540 --> 00:12:41,170 So this is very good. 151 00:12:41,490 --> 00:12:47,310 This is used more in the use cases, where you want some value to be existing only for some particular 152 00:12:47,310 --> 00:12:47,750 time. 153 00:12:47,760 --> 00:12:55,770 For example let's say, you you want a user to avail some, you know, benefits or some services ones in last 154 00:12:55,770 --> 00:13:03,050 2 hours. So you can set a value or you can set a status flag which you can set it to expire every 2 155 00:13:03,050 --> 00:13:04,140 hours. 156 00:13:04,330 --> 00:13:04,610 Okay. 157 00:13:04,640 --> 00:13:10,610 So if the same person tries to avail the same service again within 2 hours, then you are going to check 158 00:13:10,610 --> 00:13:12,650 in Redis, that the value still exists. 159 00:13:12,650 --> 00:13:15,830 It means the user has already availed the benefits. 160 00:13:15,830 --> 00:13:21,070 And you are basically programmatically going to return or show the error message to the user. 161 00:13:21,740 --> 00:13:27,670 And if it tries again with after 2 hours, then you should be able to check that the value doesn't exist in Redis 162 00:13:27,690 --> 00:13:36,960 And then the user can be allowed to avail that service again. So similarly there can be another 163 00:13:37,290 --> 00:13:43,710 use cases, like if you want to check Duplication, Data Duplication or File Duplication, then you can 164 00:13:43,710 --> 00:13:50,860 use the same feature. Let's say, you want to see Duplication only within last 2 days or 3 days. 165 00:13:51,280 --> 00:14:03,070 So you can use this, this kind of feature where the keys expire after two or three days. 166 00:14:03,130 --> 00:14:09,090 Now let's say there are some existing keys and I want to set the expiration on those key. 167 00:14:09,490 --> 00:14:12,040 So the way to do that is by using Expire 168 00:14:12,040 --> 00:14:12,580 command. 169 00:14:12,580 --> 00:14:17,160 So you provide Expire and you provide the name of the key. 170 00:14:17,200 --> 00:14:18,850 So in this case we are providing 171 00:14:22,100 --> 00:14:28,460 let's make it Bed and let's provide the total number of seconds. So let's again keep it 60 seconds. 172 00:14:28,460 --> 00:14:34,210 So now this value or this key value pair is going to expire in 60 seconds. 173 00:14:34,250 --> 00:14:44,660 So if I do Get command and I do Get space Bed, I'm going to get the price of Bed but after 60 seconds 174 00:14:44,660 --> 00:14:45,410 if I do the same 175 00:14:45,410 --> 00:14:46,250 command. 176 00:14:46,430 --> 00:14:47,180 It is not, 177 00:14:47,180 --> 00:14:53,030 It is going to give us response of null or nil, which means the key has been deleted. 178 00:14:53,030 --> 00:14:58,760 Now let's say if there was a scenario, in which we wrongly set the expiration and actually we don't want 179 00:14:58,760 --> 00:14:59,890 the key to expire. 180 00:15:00,530 --> 00:15:02,450 So you can use persist 181 00:15:02,450 --> 00:15:10,460 command and with the persist command you can also provide the Key Name. So i am providing the Key Name. 182 00:15:10,520 --> 00:15:17,390 Now this value you know, whatever expiration which we had set has been reset and now this value is 183 00:15:17,470 --> 00:15:20,600 or this key value pair is not going to be deleted. 184 00:15:22,960 --> 00:15:23,350 OK. 185 00:15:23,350 --> 00:15:28,480 And now this is going to be basically staying in Redis forever until someone is deleting it manually 186 00:15:29,160 --> 00:15:34,070 or someone is setting expiry on this key. 187 00:15:34,180 --> 00:15:43,700 So if I do Get Bed, I get the value back. 188 00:15:43,930 --> 00:15:44,210 OK. 189 00:15:44,240 --> 00:15:53,920 So these are the, you know, various options which we have available for strings types. Now let's explore about various 190 00:15:53,920 --> 00:16:04,050 Lists option available in Redis. So i will clear the screen and let's also do Flush all. So Flush all 191 00:16:04,060 --> 00:16:09,140 command is going to delete whatever number of keys which we had in Redis. it is a destructive 192 00:16:09,140 --> 00:16:09,530 command. 193 00:16:09,530 --> 00:16:14,200 So please use it with care. OK. 194 00:16:14,200 --> 00:16:20,710 So now if I do dbsize, I'm going to get 0, which means we do not have anything stored in Redis right 195 00:16:20,710 --> 00:16:21,300 now. 196 00:16:21,490 --> 00:16:28,030 or if I do keys *, you see we get empty list in response which means we do not have 197 00:16:28,030 --> 00:16:39,800 anything stored in Redis. Now let's begin with, working with Redis lists. So in Redis list you actually 198 00:16:39,800 --> 00:16:49,050 perform Push Operations. So you can insert a value from left side or right side in a list. For the first 199 00:16:49,050 --> 00:16:53,770 time, when you are creating a list, for the first time it doesn't matter whether you use R push command 200 00:16:53,770 --> 00:16:56,310 or L push command. It is going to work the same way. 201 00:16:56,850 --> 00:17:05,590 So let's say I want to write a value or a key value appear to Redis list and my list is called, let's 202 00:17:05,590 --> 00:17:10,590 say Color and it is having different color names. 203 00:17:11,270 --> 00:17:20,750 Let's say we have Red, we have Blue, we have White and once I hit enter, now three values has been inserted 204 00:17:20,750 --> 00:17:28,180 to Redis and once we do Keys * we can see we have a key which is called Color and if we do, 205 00:17:32,040 --> 00:17:39,350 so if you run Get command with this key, it is not going to work because when you are actually storing 206 00:17:39,440 --> 00:17:46,670 a key, you need to use L range to get the value back. 207 00:17:46,670 --> 00:17:53,450 So right now we have stored 3 Values and remember Array always starts with 0. So this value is 208 00:17:53,450 --> 00:17:54,470 position 0. 209 00:17:54,490 --> 00:17:56,440 And this value is at position 1 210 00:17:56,480 --> 00:17:59,570 And this Value is stored at position 2, in an Array 211 00:18:00,770 --> 00:18:07,880 So if I specify L range starting from 0 and let's say I want to see all the values which is available 212 00:18:07,880 --> 00:18:10,990 in or which are stored in this key. 213 00:18:11,150 --> 00:18:17,140 So I need to type L range. Specify the key name. Specify the starting Array position. 214 00:18:17,210 --> 00:18:22,850 In this case it is going to be 0, because I want to see from beginning and let's say I want to see 215 00:18:22,850 --> 00:18:23,420 everything. 216 00:18:23,420 --> 00:18:24,790 So whatever value which 217 00:18:24,830 --> 00:18:27,560 this list has. I want to see all the values. 218 00:18:27,560 --> 00:18:30,630 So in that case you specify -1 219 00:18:31,370 --> 00:18:38,880 So what this going to do is, it is going to list all the values which is stored in key, which has a name 220 00:18:38,880 --> 00:18:42,280 of Color. Okay. 221 00:18:42,290 --> 00:18:49,090 Now if you want to see only top 2 values. So you can do starting from 0 until 2. 222 00:18:49,110 --> 00:18:49,400 Okay. 223 00:18:49,410 --> 00:18:55,680 This is giving us 3 values because index, remember index starts from 0 so 0 to 2 is going to give 224 00:18:55,680 --> 00:18:56,430 us 3 values. 225 00:18:56,460 --> 00:19:02,390 So if you want to see top 2, you need to provide from 0 until 1. 226 00:19:02,470 --> 00:19:05,050 So as you see now we are getting only top 2 values 227 00:19:10,550 --> 00:19:12,680 now once again let's see all the values. 228 00:19:12,680 --> 00:19:17,800 And now let's see how the L push or R push operation works. 229 00:19:17,810 --> 00:19:22,490 So when I do L push, values are going to be inserted at the top. 230 00:19:22,880 --> 00:19:23,180 Okay. 231 00:19:23,210 --> 00:19:31,910 So if I do L push color and I type Black. Okay I want to set the value of black in this color list the 232 00:19:31,910 --> 00:19:37,330 black is going to be inserted at the top because we are inserting the value from the left. 233 00:19:37,850 --> 00:19:48,160 So you can imagine a list which is actually horizontal and left is actually the top side and right is 234 00:19:48,450 --> 00:19:54,700 at the bottom side. 235 00:19:54,860 --> 00:20:00,490 So once I do this and if I run L range command again. 236 00:20:00,670 --> 00:20:04,870 Now you see we have got the List and Black was inserted at the top. 237 00:20:05,470 --> 00:20:13,280 Okay you are at the top of the list. Now let's say if I use R push and I give a new color, which is let's 238 00:20:13,280 --> 00:20:15,220 say called Magenta. 239 00:20:19,050 --> 00:20:19,460 OK. 240 00:20:19,850 --> 00:20:25,590 So in this case this value is going to be inserted after Red. 241 00:20:25,950 --> 00:20:27,160 Okay. 242 00:20:27,200 --> 00:20:30,320 And also whenever you use L push or R push command, 243 00:20:30,320 --> 00:20:37,790 It tells you the total number of values, which are available in this list. So it has returned us 5 244 00:20:37,800 --> 00:20:45,290 which means current size of list is 5. Now let's run L range again. 245 00:20:45,620 --> 00:20:51,050 And now we see the new value which we had inserted in this list which was Magenta and since we used 246 00:20:51,640 --> 00:20:54,830 R push, this value was inserted at the bottom. 247 00:20:55,070 --> 00:21:04,380 So again depending on the use case, you can use R push or L push and now let's say if I want to always 248 00:21:04,380 --> 00:21:15,320 see top 3 values. I can run, so I just want to see, Yeah, you need to run 0 space 2 249 00:21:15,440 --> 00:21:19,180 So starting index is 0 in last index is 2 250 00:21:19,250 --> 00:21:22,040 So it is always going to give you top 3 values 251 00:21:29,390 --> 00:21:35,670 and let's say if you want to know the total length of the List. You can use a Llen command and you need 252 00:21:35,670 --> 00:21:38,510 to provide the key name.In this case key name is Color. 253 00:21:39,690 --> 00:21:45,810 So once I hit enter, I get a value of 5 which means that right now I have 5 values available in this 254 00:21:45,810 --> 00:21:46,200 keys 255 00:21:50,210 --> 00:21:50,610 okay. 256 00:21:50,630 --> 00:21:52,820 So that's about Singular Operation. 257 00:21:52,820 --> 00:21:58,730 Now let's say we want to provide Multiple Key Value Pairs to L push, so you can do that. 258 00:22:04,720 --> 00:22:08,350 so you type L push space key space all the values 259 00:22:13,850 --> 00:22:16,550 so let's say I have Ping, then I have White, 260 00:22:21,480 --> 00:22:23,610 then we have Dark Brown. 261 00:22:23,610 --> 00:22:25,180 So once I hit enter. 262 00:22:25,470 --> 00:22:29,060 Right now the size of the list has changed from 5 to 8. 263 00:22:29,160 --> 00:22:33,540 So we see total number of elements which are available is 8 264 00:22:33,540 --> 00:22:42,180 And if I do L range color starting from 0 ending with -1, we are going to get all the values. 265 00:22:55,640 --> 00:22:56,060 okay. 266 00:22:56,060 --> 00:23:01,700 Also please notice since we used L push command, so Pink was inserted first. 267 00:23:01,700 --> 00:23:08,640 So our Existing List was until here, until Black and then we inserted Pink. 268 00:23:08,870 --> 00:23:11,310 So that's why Pink is at position this. 269 00:23:11,390 --> 00:23:15,470 And after that White was inserted and then Dark Brown was inserted. 270 00:23:15,480 --> 00:23:18,410 That's why Dark Brown is, at the top of the list. 271 00:23:26,450 --> 00:23:30,010 And now let's see if you want to remove one of the values. 272 00:23:30,010 --> 00:23:33,940 You can do that as well in Lists 273 00:23:34,030 --> 00:23:37,250 So the way to do that is you use a pop command. 274 00:23:37,270 --> 00:23:44,220 So use L pop to pop a value from left. 275 00:23:44,270 --> 00:23:44,490 OK. 276 00:23:44,540 --> 00:23:49,720 So if I do L pop and i provide the key. I don't need to provide any value here. 277 00:23:49,730 --> 00:23:54,430 So the only thing is I can either remove the value from left side or right side. 278 00:23:54,680 --> 00:23:58,060 So I'm going to use L pop, to remove the value from left side. 279 00:23:58,220 --> 00:24:01,410 And I'm going to use R pop to remove the value from right side. 280 00:24:02,120 --> 00:24:08,930 So if we do L pop and provide the name of the key and hit enter. It is returning as Dark Brown which means, 281 00:24:08,930 --> 00:24:16,430 it has removed Dark Brown from the list and we can verify the same by doing L range Color 0 282 00:24:16,430 --> 00:24:17,840 -1 283 00:24:18,340 --> 00:24:18,630 OK. 284 00:24:18,660 --> 00:24:27,320 We see now List doesn't contain Dark Brown and you can perform this operation multiple times. So each 285 00:24:27,320 --> 00:24:30,830 time it is going to pop out, one of the elements from the left. 286 00:24:30,830 --> 00:24:34,420 So if I do L pop color again, it has removed White. 287 00:24:35,030 --> 00:24:44,590 And if I do L pop again, it has removed Pink color. So if I do L range color 0 space 288 00:24:44,590 --> 00:24:47,290 -1, this time we only get 5 items 289 00:24:55,160 --> 00:24:57,290 now R pop is also very similar. 290 00:24:57,920 --> 00:25:03,330 So you use R pop, you provide the name of the key and you hit enter. 291 00:25:03,410 --> 00:25:10,560 Now in this case you see, we get value of Magenta because that was at the right side of the list and 292 00:25:10,560 --> 00:25:12,640 now this has been removed from the list. 293 00:25:12,750 --> 00:25:19,170 And now if we see the total amount of available values, we see only 4 values and Magenta has been removed 294 00:25:19,170 --> 00:25:20,880 from the right side of the list 295 00:25:28,560 --> 00:25:30,300 and now let's 296 00:25:30,330 --> 00:25:33,480 put some more values back to this color. 297 00:25:34,260 --> 00:25:36,210 So I'm going to use L push 298 00:25:49,070 --> 00:25:51,130 Okay and let's see the values again 299 00:25:57,160 --> 00:25:57,460 okay. 300 00:25:57,490 --> 00:26:01,540 So actually, I did not specify the name. 301 00:26:01,540 --> 00:26:09,590 So what it has done is, it has assumed Dark Brown as a key and then it has inserted the value of Magenta and Pink 302 00:26:09,610 --> 00:26:11,650 to this list. 303 00:26:11,650 --> 00:26:14,050 So that's not what we wanted. 304 00:26:14,110 --> 00:26:19,640 So the correct way to do that is, L push, give the name of the key which is Color in our case 305 00:26:24,590 --> 00:26:27,460 and then specify all the values. 306 00:26:27,470 --> 00:26:29,200 Now you see it has changed to 7 307 00:26:37,080 --> 00:26:39,790 and now we see total we have value of 7. 308 00:26:39,830 --> 00:26:45,920 Now let's say we have a scenario that we always just want to keep you know, only top 3 colors regardless 309 00:26:45,920 --> 00:26:49,360 of whatever the values being inserted. 310 00:26:49,360 --> 00:26:54,450 So for that one you can use Ltrim Command. 311 00:26:54,460 --> 00:27:02,440 So now the way to do, or the Syntax to use that is Ltrim and you specify the key name of the 312 00:27:02,440 --> 00:27:02,830 list. 313 00:27:02,830 --> 00:27:10,150 So in this case the name of the key is Color and we specify the starting position which is 0 and we specify 314 00:27:10,150 --> 00:27:11,020 the ending position. 315 00:27:11,020 --> 00:27:18,670 So if you want top 3, you are going to write from 0 until 2 because 0 is the first item in the 316 00:27:18,670 --> 00:27:19,150 Array 317 00:27:19,240 --> 00:27:21,370 And 2 is the third item in the Array. 318 00:27:22,450 --> 00:27:28,540 So what this is going to do is, it is going to remove all the values and going to keep only the values 319 00:27:28,540 --> 00:27:30,580 specified by you, in this list. 320 00:27:31,670 --> 00:27:32,020 OK. 321 00:27:32,050 --> 00:27:33,880 So once we hit enter, it says okay. 322 00:27:33,880 --> 00:27:35,740 which means it has performed the operation. 323 00:27:35,740 --> 00:27:40,430 If I do Lrange Color from 0 until -1. 324 00:27:40,540 --> 00:27:47,630 Now we see our list has been reduced with only the top 3 items. OK. 325 00:27:47,670 --> 00:27:55,240 So when you have you use case of you know, keeping only some certain range of items in the list, you can 326 00:27:55,240 --> 00:28:01,500 use Ltrim command. So it will remove all the values you know, which is outside of that range. 327 00:28:04,510 --> 00:28:11,680 So let's say if you want only items from fifth until tenth, so you could have set ltrim space color 328 00:28:15,160 --> 00:28:18,720 and since you want fifth item. You need to give index position of 4 329 00:28:19,240 --> 00:28:25,110 And since you want only until tenth item, you have to give index position of 9. Okay 330 00:28:25,150 --> 00:28:29,890 So that's the way to get, from fifth item to 10th item 331 00:28:33,960 --> 00:28:34,270 okay. 332 00:28:34,280 --> 00:28:35,330 Let's clear the screen. 333 00:28:38,240 --> 00:28:39,190 Let's connect 334 00:28:39,200 --> 00:28:48,130 back to Redis cli 335 00:28:48,300 --> 00:28:56,690 Okay now we are going to learn about Hashes. so Hashes are very simple and also in operations 336 00:28:56,730 --> 00:28:58,930 It is kind of similar to Strings. 337 00:28:58,970 --> 00:29:06,700 So what it does is, you type h set command to set a value or Key Value Pair. 338 00:29:06,700 --> 00:29:16,360 So rather than usually in use, when you are performing strings data type operations, you are providing 339 00:29:16,360 --> 00:29:17,350 Key and Value Pair. 340 00:29:18,160 --> 00:29:23,860 However, when you are working with Hashes, you provide a Key and then you also provide a Field Value 341 00:29:23,870 --> 00:29:24,190 Pair. 342 00:29:24,610 --> 00:29:24,880 Okay. 343 00:29:24,900 --> 00:29:29,450 So in this case let's say, we want all the product prices to be stored. 344 00:29:29,650 --> 00:29:32,560 So product is going to be the Key in this case. 345 00:29:32,740 --> 00:29:38,740 And then I need to provide all the Field and Value combination. So let's say, the field which I have 346 00:29:38,740 --> 00:29:42,390 is Chair which is having value of 100 or price of 100 347 00:29:42,460 --> 00:29:47,340 And then we have Table which is having price of 200. 348 00:29:47,560 --> 00:29:49,950 We have TV which is having a price of 300. 349 00:29:50,500 --> 00:29:50,740 Okay. 350 00:29:50,740 --> 00:29:51,970 Something like this. 351 00:29:51,970 --> 00:29:59,530 So once you hit enter, you get a response of 3 which means you have put 3 items or 3 field 352 00:29:59,530 --> 00:30:02,860 values in this H set. Okay. 353 00:30:02,990 --> 00:30:04,610 Now to get all the items, 354 00:30:11,150 --> 00:30:12,410 you can use H Get 355 00:30:19,420 --> 00:30:24,360 So you provide the name of the key and you provide the field which you want to see. 356 00:30:24,370 --> 00:30:29,760 So in this case if I do Table, I'm going to get a value of 200 357 00:30:34,660 --> 00:30:35,120 okay. 358 00:30:35,140 --> 00:30:39,800 If I do TV, I'm going to get a value of 300. 359 00:30:39,820 --> 00:30:45,520 Now let's say if you want to see all the values. In that case rather than hget, you can use hmget 360 00:30:45,520 --> 00:30:52,930 which is going to give you multiple fields back. So you specify the Key Name, which is Product in 361 00:30:52,930 --> 00:31:02,840 this case and then you specify all the Field Names. So it is going to be Chair, Table and TV and then you 362 00:31:02,840 --> 00:31:04,620 get 3 values in return.