KDB+ DB maintenance

Question

in my table I am seeing mixed datatypes which I want to fix by running dbmaint

I need to make sure that eventType holds a list of symbols so anything that doesnt match that needs ran against db maint however Im not sure how to do that. Using fnCol or castCol?

rianoc · Accepted Answer · 2024-09-13 11:24:54Z

2

With mixed types it is not a simple cast.

You should use: https://github.com/KxSystems/kdb/blob/master/utils/dbmaint.md#fncol

Something along the lines of:

Finds all cells containing strings
Cast the strings to symbols
Enlist the symbols (an assumption this is needed as your enumerated symbol is a list as shown by , in the output)
Enumerate the symbol list

fncol[`:/full/path/to/HDB;
      `table;
      `eventType;{
                  @[x;
                    where 10h=type each x;
                    {`:/full/path/to/HDB/sym?enlist `$x}]}
     ]

Make sure to take a backup of your data before attempting this change. One option on this is to use copycol and then perform fncol on the original. Once you confirm the data is correct after you can deletecol the backup column.

Test on a small dummy HDB first to write and confirm your logic is correct

edited Sep 13, 2024 at 11:24

answered Sep 13, 2024 at 11:16

rianoc

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2 Comments

kka Over a year ago

.ds.hdb.fnCol[:.; materialEvents; eventType;{@[x;where 10h=type each x;{:/app/source/DEV/HDB/IBS/sym?enlist `$x}]} ] have ran the following but seem to have some strange values coming in now.Whats the "sym" part for?

rianoc Over a year ago

code.kx.com/q/basics/enumerations symbols are stored on disk as enumerations

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