Update Dynamo DB column based on GSI

Question

I have created a table TEST which has 4 columns:

column1 : Range key

column2: Sort key

column3: GSI

column4: normal attribute

Now I want to update value of column4 based on GSI value. I tried with the following code but it works only when I pass both the range and sort key. In my usecase at the time of update I would have only the value of GSI not the range/sort key.

Map<String, AttributeValue> key = new HashMap<>();
key.put(“column1”, new AttributeValue().withS(column1Value));
key.put(“column2”, new AttributeValue().withS(column2Value));
Map<String, AttributeValue> attributeValues = new HashMap<>();

attributeValues.put(“column4”, new AttributeValue().withS(column4Value));
attributeValues.put(“column3”, new AttributeValue().withS(column3Value));

UpdateItemRequest updateItemRequest = new UpdateItemRequest()
                .withTableName(emailsTableName)
                .withKey(key)
                .withUpdateExpression(“set column4 = :column4”)
                .withConditionExpression(“column3 = :column3”)
                .withExpressionAttributeValues(attributeValues);
UpdateItemResult updateItemResult = dynamoDBClient.updateItem(updateItemRequest);

Is this possible to update column of Dynamo DB based on GSI only?

Is there a connection between the column3 value and an actual Global Secondary index on the table? Why are you storing GSI? — jarmod
@jarmod Column name is not GSI . Column name is column4 only and we have created GSI over this column. — priyadhingra19
To update an item you need its primary key. If you have a secondary index that will help you locate the item of interest then you can do that, retrieve the primary key, then perform an update. — jarmod
@jarmod So you are saying GSI is only used for locating . we cannot perform updated based on them? — priyadhingra19
To issue an update, you need a primary key. That will be available if you used a GSI query, because the base table's primary key attributes are always projected into an index. — jarmod

Jason Wadsworth Jason Wadsworth · Accepted Answer · 2020-02-04T18:34:44

GSIs are for querying data, so to do this you'd need to first query the data with the GSI, and then use the results from that to know what record(s) to update, using the keys in the response. Keep in ming that with a GSI it is potentially records, plural. There is no guarantee of uniqueness.

Update Dynamo DB column based on GSI

1 Answers