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17-REDISEARCH-TEXT-AND-TAG.md

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Searching TEXT and TAG Fields

TEXT and TAG fields together allow you to perform most of the types of searches against strings that you'd want to do. TEXT fields provide full-text search so you can find words within blocks of texts. Tags act as keys or collections of keys that match on an entire value.

Searching TEXT Fields

A TEXT field in Redis search indicates a field that contains human-readable text that we want to perform full-text search against. TEXT fields understand related words using a process called stemming. So RediSearch knows that a search for give should match text with gives, gave, given, and giving. TEXT fields also know that certain words—called stopwords—are common and not useful for search. Thus, words like a, and, and the are ignored when searching TEXT fields.

By default, RediSearch will search all text fields in the index. Let's find some Bigfoot sightings with the word creek in any TEXT field:

127.0.0.1:6379> FT.SEARCH bigfoot:sighting:index creek RETURN 0
 1) (integer) 669
 2) "bigfoot:sighting:01G9HSRFRAAS9W8MWBXNQ87C2F"
 3) "bigfoot:sighting:01G9HSRTGFYST26ZEY3JEM6ZT9"
 4) "bigfoot:sighting:01G9HSRR815TDYDF9CG69N2GE8"
 5) "bigfoot:sighting:01G9HSSAJXCAYBJJBXDFFAKM35"
 6) "bigfoot:sighting:01G9HSR97XJF0ZFDN89DRBMYVD"
 7) "bigfoot:sighting:01G9HSRYA6956XAE123A3N1YMY"
 8) "bigfoot:sighting:01G9HSS66A0DY4JB8M2CPWYXDP"
 9) "bigfoot:sighting:01G9HSS3D21Y5BF6V32HTN1TW7"
10) "bigfoot:sighting:01G9HSSJ5DBT3XYPGBYSNHW36H"
11) "bigfoot:sighting:01G9HSRNQ0E24FF71C243NA4NQ"

Looks like we got quite a few. Turns out there are a look of creeks in the woods.

To search a specific field, prefix it with the field name. Let's look for Bigfoot sightings with the word creek in the title:

127.0.0.1:6379> FT.SEARCH bigfoot:sighting:index @title:creek RETURN 0
 1) (integer) 105
 2) "bigfoot:sighting:01G9HSRFRAAS9W8MWBXNQ87C2F"
 3) "bigfoot:sighting:01G9HSR97XJF0ZFDN89DRBMYVD"
 4) "bigfoot:sighting:01G9HSRYA6956XAE123A3N1YMY"
 5) "bigfoot:sighting:01G9HSS66A0DY4JB8M2CPWYXDP"
 6) "bigfoot:sighting:01G9HST2ERPCMGVVSCY429NFVP"
 7) "bigfoot:sighting:01G9HSSVG2H0H6G3302ESHQFNG"
 8) "bigfoot:sighting:01G9HSSBEK06GD4FR29NH37R4Q"
 9) "bigfoot:sighting:01G9HST1M99BN2VDH27RDT3AJV"
10) "bigfoot:sighting:01G9HSRPA24RMQAF0X5D2KQPFJ"
11) "bigfoot:sighting:01G9HSSBDRCTD3WW8NYT6TC8GT"

So far, our queries haven't used quotes. But it's usually needed for anything beyond the most basic searches. Let's search for Bigfoot sightings with the word creek in the title and woods in the observed:

127.0.0.1:6379> FT.SEARCH bigfoot:sighting:index "@title:creek @observed:woods" RETURN 0
 1) (integer) 45
 2) "bigfoot:sighting:01G9HSS32Y030EMK2AHGTG97TF"
 3) "bigfoot:sighting:01G9HSS66A0DY4JB8M2CPWYXDP"
 4) "bigfoot:sighting:01G9HSSD068FVBEDCEKAR90E11"
 5) "bigfoot:sighting:01G9HSRAMMNVR7212JGAC9S4AK"
 6) "bigfoot:sighting:01G9HSRN4NVY2AYHGH194M53ZN"
 7) "bigfoot:sighting:01G9HSSNMEVB4BGJH1M03BME75"
 8) "bigfoot:sighting:01G9HSS28YME96PQGCQT24CY7H"
 9) "bigfoot:sighting:01G9HST2ERPCMGVVSCY429NFVP"
10) "bigfoot:sighting:01G9HSSG2E9RTH7B8676595N76"
11) "bigfoot:sighting:01G9HSS67ZGGS7ANYAGZK7DZTQ"

Searching TAG Fields

TAG fields represent a single string or a collection of strings. They are stored in Hashes and JSON as comma-delimited strings like:

Ohio,West Virginia,Kentucky

In JSON, they can also be stored as any JSONPath that would return an array of strings. For example, look at the following JSON:

{
  "reportId": "1234",
  "counties": [
    {
      "county": "Athens",
      "state": "Ohio"
    },
    {
      "county": "Boone",
      "state": "West Virginia"
    },
    {
      "county": "Flemming ",
      "state": "Kentucky"
    }
  ]
}

You could create a TAG field with a JSONPath of $.bigfootState[*].state.

You can think of TAGs as the tags clouds on a blog. You can search for JSON documents and Hashes that contain a specific value within that TAG. So, you could search for Ohio and any document tagged with Ohio will be returned.

If you provide only a single values in a TAG, it can make excellent key—foreign or primary. In the above JSON, you can specify a TAG field for the reportId property with a JSONPath of $.reportId.

You can search on a TAG field using the following syntax:

FT.SEARCH bigfoot:sighting:index "@state:{Ohio}" RETURN 0
 1) (integer) 257
 2) "bigfoot:sighting:01G9HSSNN8XM2QBJF1P0P6NFZQ"
 3) "bigfoot:sighting:01G9HSRTZ55Z55Q69R2DG9DWAF"
 4) "bigfoot:sighting:01G9HSSP8WHJRCZQ4Z270CS36V"
 5) "bigfoot:sighting:01G9HSRJ1B454H8S1HPFAEW5V0"
 6) "bigfoot:sighting:01G9HSSBQKKVPP7CYZMXXARM41"
 7) "bigfoot:sighting:01G9HSSGAYRG295WPR7TYWNVN3"
 8) "bigfoot:sighting:01G9HSSNSGAJ8SNK7R6S1WJ9CA"
 9) "bigfoot:sighting:01G9HSSG97AVJ9R1TB9X9TKC2Q"
10) "bigfoot:sighting:01G9HSSJD1GHYYMTMDFJEWW0AD"
11) "bigfoot:sighting:01G9HSSNFTE9W8MQ3EVTHPSY6J"

If you want to search on TAGs that contain whitespace, be sure to escape it with backslashes:

127.0.0.1:6379> FT.SEARCH bigfoot:sighting:index "@state:{West\\ Virginia}" RETURN 0
 1) (integer) 99
 2) "bigfoot:sighting:01G9HSS511R305GDJG3NBAJD57"
 3) "bigfoot:sighting:01G9HSRAXN7560P70XYFQTC0DR"
 4) "bigfoot:sighting:01G9HSSFDKPG3XW1C7ZD44XYEV"
 5) "bigfoot:sighting:01G9HSRAYE6JVDE1BF87VBNRJ8"
 6) "bigfoot:sighting:01G9HSSY7V9C2GJE2ZA3YYN8QW"
 7) "bigfoot:sighting:01G9HSRATT7PKKMHCDMA5K9G6G"
 8) "bigfoot:sighting:01G9HSRAX8RHJT94FRMXGQ2AEZ"
 9) "bigfoot:sighting:01G9HSRWTY6YZHJSJWGYZ2MPZB"
10) "bigfoot:sighting:01G9HSRCD3JN3ZJP64Z5TW208X"
11) "bigfoot:sighting:01G9HSS0RWA4QC6B084FT5V9TJ"

You can search on documents tagged with one value or another with a |:

127.0.0.1:6379> FT.SEARCH bigfoot:sighting:index "@state:{Ohio|Kentucky}" RETURN 0
 1) (integer) 365
 2) "bigfoot:sighting:01G9HSSHXK5ARH3PMSDW79MVXT"
 3) "bigfoot:sighting:01G9HSSCQDZ03NQY6RCDT21BZ1"
 4) "bigfoot:sighting:01G9HSSNN8XM2QBJF1P0P6NFZQ"
 5) "bigfoot:sighting:01G9HSRTZ55Z55Q69R2DG9DWAF"
 6) "bigfoot:sighting:01G9HSSP8WHJRCZQ4Z270CS36V"
 7) "bigfoot:sighting:01G9HSRJ1B454H8S1HPFAEW5V0"
 8) "bigfoot:sighting:01G9HSSK5Y1JJRBM8P67P305C2"
 9) "bigfoot:sighting:01G9HSRS8D4EAS1264WG615WJY"
10) "bigfoot:sighting:01G9HSSBQKKVPP7CYZMXXARM41"
11) "bigfoot:sighting:01G9HSSGAYRG295WPR7TYWNVN3"

You can search on documents tagged with one value and another by specifying the same field twice:

127.0.0.1:6379> FT.SEARCH bigfoot:sighting:index "@state:{Ohio} @state:{Kentucky}" RETURN 0
1) (integer) 0

Of course, Bigfoot sightings happen only in a single state so this returns zero results.

Let's find all the Bigfoot sightings in Ohio that are Class A:

127.0.0.1:6379> FT.SEARCH bigfoot:sighting:index "@state:{Ohio} @classification:{Class\\ A}" RETURN 0
 1) (integer) 139
 2) "bigfoot:sighting:01G9HSRTZ55Z55Q69R2DG9DWAF"
 3) "bigfoot:sighting:01G9HSSP8WHJRCZQ4Z270CS36V"
 4) "bigfoot:sighting:01G9HSRJ1B454H8S1HPFAEW5V0"
 5) "bigfoot:sighting:01G9HSSG97AVJ9R1TB9X9TKC2Q"
 6) "bigfoot:sighting:01G9HSSJD1GHYYMTMDFJEWW0AD"
 7) "bigfoot:sighting:01G9HSRY4P8YXBDWS7CJ2ZWQPN"
 8) "bigfoot:sighting:01G9HSSKA7G2E41Y311F7VTCFP"
 9) "bigfoot:sighting:01G9HSSK82V5TQWX2JJ3F5XRWX"
10) "bigfoot:sighting:01G9HSSB9Z4ZG18X644S696QB1"
11) "bigfoot:sighting:01G9HSS146MK9STPD9QGDAB5VS"

Note that TAG fields that contain stopwords result in invalid queries. Escaping the string here keeps the parser from seeing the A in Class A as a stopword.

Now that we have searched TEXT and TAG fields, let's search on NUMERIC and GEO fields.