CODEWITHSUNDEEP
sqlutf-8snowflake-cloud-data-platform
elfersi
elfersi

Reputation: 131

How to find rows with non utf8 characters in Snowflake?

In my snowflake db, a table has non-utf8 characters. How can I create a view on top of it which will only have utf8 characters; either by excluding the rows with non-utf8 characters or by replacing them? Thanks

Upvotes: 4

Views: 6401

Answers (2)

Sarath Subramanian
Sarath Subramanian

Reputation: 21321

Though I tried Hans's solution, it isn't working in all scenarios. Hence, I wrote a very simple Snowflake Javascript stored procedure that will replace all characters that are not part of keyboard.

CREATE OR REPLACE FUNCTION MYSCHEMA.REPLACE_NON_UTF8_CHARS(STR varchar)
RETURNS TEXT LANGUAGE JAVASCRIPT STRICT IMMUTABLE AS '  
  return STR.replace(/[^ -~]+/g, '''')    
';

This can be implemented in the sql like below.

SELECT MYSCHEMA.REPLACE_NON_UTF8_CHARS(MY_STRING) AS MY_STRING
FROM 
(
    SELECT 'ABC,D�E123 5' AS MY_STRING
)

And the output will be like below. You can see the junk character after D is replaced by empty character.

ABC,DE123 5

Upvotes: 2

Hans Henrik Eriksen
Hans Henrik Eriksen

Reputation: 2860

It should be possible to check for non-utf with a test like this:

MY_STRING IS NOT NULL AND TRY_HEX_DECODE_STRING(HEX_ENCODE(MY_STRING)) IS NULL

But then I don't have data to test with.
To reencode the string to utf-8, you can use a JavaScript function:

CREATE OR REPLACE FUNCTION TO_UTF8(BINARY_TEXT BINARY)
RETURNS TEXT LANGUAGE JAVASCRIPT STRICT IMMUTABLE AS '
  var win1252 = [ /* C1 controls */
    8364,  129, 8218,  402, 8222, 8230, 8224, 8225,
     710, 8240,  352, 8249,  338,  141,  381,  143,
     144, 8216, 8217, 8220, 8221, 8226, 8211, 8212,
     732, 8482,  353, 8250,  339,  157,  382,  376
  ];
  return String.fromCharCode(
    ...Array.from(BINARY_TEXT).map(x => (x < 128 || x > 159) ? x : (win1252[x - 128]))
  ); /* .map(...) can be removed if no conversion from win1252 needed */
';

SELECT NVL(TRY_HEX_DECODE_STRING(HEX_ENCODE(MY_STRING)),
           TO_UTF8(HEX_ENCODE(MY_STRING)::BINARY));

Upvotes: 6

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