Hazelcast SQL information_schema Schema

Giriş

Bu schema altında iki tane tablo var. Açıklaması şöyle

Currently, two tables are exposed:

mappings: contains information about existing mappings

columns: contains information about mapping columns

1. columns Tablosu

Sütunlar şöyle

1. column_name

2. data_type

3. is_nullable

Örnek

Şöyle yaparız

String query = "SELECT * FROM information_schema.columns WHERE table_name = ? 
  ORDER BY ordinal_position ASC";
try (SqlResult result = sqlService.execute(query, mapping)) {
  return StreamSupport
    .stream(result.spliterator(), false)
    .map(row -> {
      String name = row.getObject("column_name");
      SqlColumnType type = SqlColumnType.valueOf(row.getObject("data_type"));
      boolean isNullable = Boolean.parseBoolean(row.getObject("is_nullable"));
      return new SqlColumnMetadata(name, type, isNullable);
    })
    .collect(Collectors.toList());
}

2. mappings Tablosu

Sütunlar şöyle

1. table_catalog

Hep hazelcast

2. table_schema

Hep public

3. table_name

Mesela mykafka1

4. mapping_external_name

Mesela mykafka1

5. mapping_type

Mesela Kafka

6. mapping_options

CREATE MAPPING cümlesinde belirtilen OPTION alanlarını içerir.

Mesela

{
 "valueFormat":"json-flat",
 "bootstrap.servers":""a.b.c.d:9092",
 "security.protocol":"SASL_SSL",
 "sasl.jaas.config":"org.apache.kafka.common.security.plain.PlainLoginModule required username="..." password="...";",
"sasl.mechanism":"PLAIN",
"auto.offset.reset":"earliest"
}"

Örnek

Şöyle yaparız. Bunun yerine SHOW MAPPINGS de kullanılabilir

SELECT table_name, mapping_external_name, mapping_type FROM information_schema.mappings