ptupitsyn commented on issue #10746:
URL: https://github.com/apache/ignite/issues/10746#issuecomment-1566857529
Adding or deleting a column with SQL API should be fairly quick, because it
does not modify the data. The data is always stored in schemaless format
(key/value pairs).
For example:
```csharp
using Apache.Ignite.Core;
using Apache.Ignite.Core.Cache.Configuration;
using Apache.Ignite.Core.Cache.Query;
var ignite = Ignition.Start();
var cfg = new CacheConfiguration("c", new QueryEntity(typeof(Person)));
var cache = ignite.GetOrCreateCache<int, Person>(cfg);
cache[1] = new Person(1, "Foo", 123);
Query("SELECT * FROM PERSON");
Query("ALTER TABLE Person ADD COLUMN Age INT");
Query("SELECT * FROM PERSON");
Query("ALTER TABLE Person DROP COLUMN Age");
// "Age" value is not affected by DDL.
Console.WriteLine("Person = " + cache[1]);
void Query(string sql)
{
Console.WriteLine(" >>> " + sql);
using var cursor = cache.Query(new SqlFieldsQuery(sql));
foreach (var name in cursor.FieldNames)
{
Console.Write($"{name}\t");
}
Console.WriteLine();
foreach (var row in cursor)
{
foreach (var val in row)
{
Console.Write($"{val}\t");
}
}
Console.WriteLine();
Console.WriteLine();
}
// Initial configuration does not include SQL Age column.
public record Person(
[property: QuerySqlField] int Id,
[property: QuerySqlField] string Name,
int Age);
```
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