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https://issues.apache.org/jira/browse/KUDU-2280?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Grant Henke updated KUDU-2280:
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Target Version/s: (was: 1.8.0)
> Altering the column default isn't "type safe"
> ---------------------------------------------
>
> Key: KUDU-2280
> URL: https://issues.apache.org/jira/browse/KUDU-2280
> Project: Kudu
> Issue Type: Bug
> Components: client
> Affects Versions: 1.4.0
> Reporter: Grant Henke
> Priority: Critical
> Labels: usability
>
> When creating a table the schema data is used to check that a default value
> is of the right size and type. This is possible because the column schema is
> available and checked via {{KuduValue::Data->CheckTypeAndGetPointer}} in
> {{KuduColumnSpec::ToColumnSchema}}.
> When altering a table {{KuduValue::Data->GetSlice()}} is used instead because
> we don't have the column schema information available. The Slice is then
> added to the alter table request.
> When this request is received server side, we can only check the size (if we
> know the expected size) to validate the correct information was sent and cast
> it to the correct value via {{ColumnSchema::ApplyDelta}}.
> For some examples I can set a DOUBLE type default on an INT64 column, or a
> FLOAT type default on an INT32 column. With the current size check logic (
> {{col_delta.default_value->size() < type_info()->size()}} ) you can
> technically set any type >= your target type.
> An additional issue is that {{KuduValue::FromInt}} treats all integers as
> int64_t values when calling {{KuduValue::Data->GetSlice()}}. This means if we
> made the size check more strict we wouldn't be able to alter the default
> value of any integer columns smaller than INT64 because the data size is too
> large once received by the server. This "size" problem affects the ability to
> support decimal defaults too.
> example (where column "default" is an INT32 column):
> {noformat}
> table_alterer->AlterColumn("default")->Default(KuduValue::FromInt(12345));{noformat}
> To solve this we could require the expected column DataType to be passed
> along with the request so that the server can validate the expected column,
> size, and coerce the values smaller if needed/possible.
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