Support not-null constraints

[eolivelli]

• support 'NOT NULL' at DDL level during "CREATE TABLE' and 'ADD COLUMN'
• enforce "NOT NULL' during DML operations
• inform Calcite that the column is NOT NULL (the Planner will keep it in consideration)

In the first implementation it is not needed to support 'NOT NULL' in ALTER TABLE DDL, because it would imply to check that the column is 'NOT NULL' for each record and this should be done in transaction with the DDL operation.

[eolivelli]

1. Support basic NOT NULL constrains
2. Support for JDBC metadata

beside note:
implicitly PK columns are "not null" so it must be reported by metadata

[eolivelli]

@amitvc this could be a good starting point.

[amitvc]

I will start work on this starting today.

[eolivelli]

@amitvc
this is where we handle columns in CREATE TABLE

herddb/herddb-core/src/main/java/herddb/sql/DDLSQLPlanner.java

Line 351 in 8c371db

for (ColumnDefinition cf : s.getColumnDefinitions()) {

for DDL we are using jsqlparser and not Calcite (it is not directly actually supporteb by Calcite)

You can start checking tests in
https://github.com/diennea/herddb/blob/master/herddb-core/src/test/java/herddb/core/CreateTableTest.java
https://github.com/diennea/herddb/blob/master/herddb-core/src/test/java/herddb/core/AlterTablespaceSQLTest.java
https://github.com/diennea/herddb/blob/master/herddb-core/src/test/java/herddb/core/AlterTableSQLTest.java

The first step is to differenziate NULLABLE data types from NOT_NULLABLE data types here:
https://github.com/diennea/herddb/blob/master/herddb-core/src/main/java/herddb/model/ColumnTypes.java

for instance current 'STRING' data type will become NULLABLE_STRING, and you will introduce NOT_NULLABLE_STRING

[eolivelli]

I will write more ideas this evening

[amitvc]

@eolivelli thanks for the input.

[eolivelli]

@amitvc sorry for late reply.
The idea behind creating new column types is that if we add a new 'boolean' field to 'column' we will have to pass it down in all code paths and this will make us use more CPU cycles (passing parameters....) and error prone

[aluccaroni]

@eolivelli @amitvc this can be closed?

[amitvc]

I think so. This is merged into master.