Hex value of database varchar field / removing non utf-8 characters

Forum|Forum|8 years ago
July 6, 2018
4 replies
19 views

martinc123
Participating Frequently

Is there a way how to get hex value of varchar field in vertica?

This works for literal (which is a varchar, no?) :

select to_hex('abc'::VARBINARY);
616263

but this doesn't for db varchar value:

select to_hex(table_name::VARBINARY) from tables
Error: Cannot cast varchar to varbinary

I was eventually able to do it using ascii() function but that only works on 1 character. ie need to use substring and it's not flexible.

I am asking because there were some non UTF-8 bytes/characters loaded into database, and I need to know what hex value they are, as pyodbc driver is throwing errors when reading.

As a secondary question, is there a way of replacing or removing non UTF-8 characters, either before loading ( COPY command options?) or after loading (update column with some SQL functions) ?

+2

Jim_Knicely
Participating Frequently
Forum|Forum|8 years ago
July 6, 2018

Here's how to use TO_HEX on a table's VARCHAR column:

dbadmin=> CREATE TABLE hex (c VARCHAR(3));
CREATE TABLE

dbadmin=> INSERT INTO hex SELECT 'abc';
 OUTPUT
--------
      1
(1 row)

dbadmin=> SELECT c, to_hex(c::LONG VARCHAR::LONG VARBINARY) FROM hex;
  c  | to_hex
-----+--------
 abc | 616263
(1 row)