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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.hazelcast.org.apache.calcite.model;

import com.hazelcast.com.fasterxml.jackson.annotation.JsonCreator;
import com.hazelcast.com.fasterxml.jackson.annotation.JsonProperty;

import com.hazelcast.org.checkerframework.checker.nullness.qual.Nullable;

import java.util.List;
import java.util.Objects;

/**
 * View schema element.
 *
 * 

Like base class {@link JsonTable}, * occurs within {@link JsonMapSchema#tables}. * *

Modifiable views

* *

A view is modifiable if contains only SELECT, FROM, WHERE (no JOIN, * aggregation or sub-queries) and every column: * *

    *
  • is specified once in the SELECT clause; or *
  • occurs in the WHERE clause with a column = literal predicate; or *
  • is nullable. *
* *

The second clause allows Calcite to automatically provide the correct * value for hidden columns. It is useful in, say, a multi-tenant environment, * where the {@code tenantId} column is hidden, mandatory (NOT NULL), and has a * constant value for a particular view. * *

Errors regarding modifiable views: * *

    *
  • If a view is marked modifiable: true and is not modifiable, Calcite * throws an error while reading the schema. *
  • If you submit an INSERT, UPDATE or UPSERT command to a non-modifiable * view, Calcite throws an error when validating the statement. *
  • If a DML statement creates a row that would not appear in the view * (for example, a row in female_emps, above, with gender = 'M'), Calcite * throws an error when executing the statement. *
* * @see JsonRoot Description of schema elements */ public class JsonView extends JsonTable { /** SQL query that is the definition of the view. * *

Must be a string or a list of strings (which are concatenated into a * multi-line SQL string, separated by newlines). */ public final Object sql; /** Schema name(s) to use when resolving query. * *

If not specified, defaults to current schema. */ public final @Nullable List path; /** Whether this view should allow INSERT requests. * *

The values have the following meanings: *

    *
  • If true, Calcite throws an error when validating the schema if the * view is not modifiable. *
  • If null, Calcite deduces whether the view is modifiable. *
  • If false, Calcite will not allow inserts. *
* *

The default value is {@code null}. */ public final @Nullable Boolean modifiable; @JsonCreator public JsonView( @JsonProperty(value = "name", required = true) String name, @JsonProperty("stream") JsonStream stream, @JsonProperty(value = "sql", required = true) Object sql, @JsonProperty("path") @Nullable List path, @JsonProperty("modifiable") @Nullable Boolean modifiable) { super(name, stream); this.sql = Objects.requireNonNull(sql, "sql"); this.path = path; this.modifiable = modifiable; } @Override public void accept(ModelHandler handler) { handler.visit(this); } @Override public String toString() { return "JsonView(name=" + name + ")"; } /** Returns the SQL query as a string, concatenating a list of lines if * necessary. */ public String getSql() { return JsonLattice.toString(sql); } }





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