CODEWITHSUNDEEP
cassandraaltercqlsh
tryingHard
tryingHard

Reputation: 2084

Cassandra 2.2.11 add new map column from text column

Let's say I have table with 2 columns primary key: id - type varchar and non-primary-key: data - type text

Data column consist only of json values for example like:

{
"name":"John",
"age":30
}

I know that i can not alter this column to map type but maybe i can add new map column with values from data column or maybe you have some other idea?

What can i do about it ? I want to get map column in this table with values from data

Upvotes: 1

Views: 489

Answers (1)

rastov
rastov

Reputation: 104

You might want to make use of the CQL COPY command to export all your data to a CSV file.

Then alter your table and create a new column of type map.

Convert the exported data to another file containing UPDATE statements where you only update the newly created column with values converted from JSON to a map. For conversion use a tool or language of your choice (be it bash, python, perl or whatever).

BTW be aware, that with map you specify what data type is your map's key and what data type is your map's value. So you will most probably be limited to use strings only if you want to be generic, i.e. a map<text, text>. Consider whether this is appropriate for your use case.

Upvotes: 1

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