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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.
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package com.hazelcast.org.apache.calcite.schema;

import com.hazelcast.org.apache.calcite.linq4j.tree.Expression;
import com.hazelcast.org.apache.calcite.rel.type.RelProtoDataType;

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

import java.util.Collection;
import java.util.Set;

/**
 * A namespace for tables and functions.
 *
 * 

A schema can also contain sub-schemas, to any level of nesting. Most * providers have a limited number of levels; for example, most JDBC databases * have either one level ("schemas") or two levels ("database" and * "catalog").

* *

There may be multiple overloaded functions with the same name but * different numbers or types of parameters. * For this reason, {@link #getFunctions} returns a list of all * members with the same name. Calcite will call * {@link Schemas#resolve(com.hazelcast.org.apache.calcite.rel.type.RelDataTypeFactory, String, java.util.Collection, java.util.List)} * to choose the appropriate one.

* *

The most common and important type of member is the one with no * arguments and a result type that is a collection of records. This is called a * relation. It is equivalent to a table in a relational * database.

* *

For example, the query

* *
select * from sales.emps
* *

is valid if "sales" is a registered * schema and "emps" is a member with zero parameters and a result type * of Collection(Record(int: "empno", String: "name")).

* *

A schema may be nested within another schema; see * {@link Schema#getSubSchema(String)}.

*/ public interface Schema { /** * Returns a table with a given name, or null if not found. * * @param name Table name * @return Table, or null */ @Nullable Table getTable(String name); /** * Returns the names of the tables in this schema. * * @return Names of the tables in this schema */ Set getTableNames(); /** * Returns a type with a given name, or null if not found. * * @param name Table name * @return Table, or null */ @Nullable RelProtoDataType getType(String name); /** * Returns the names of the types in this schema. * * @return Names of the tables in this schema */ Set getTypeNames(); /** * Returns a list of functions in this schema with the given name, or * an empty list if there is no such function. * * @param name Name of function * @return List of functions with given name, or empty list */ Collection getFunctions(String name); /** * Returns the names of the functions in this schema. * * @return Names of the functions in this schema */ Set getFunctionNames(); /** * Returns a sub-schema with a given name, or null. * * @param name Sub-schema name * @return Sub-schema with a given name, or null */ @Nullable Schema getSubSchema(String name); /** * Returns the names of this schema's child schemas. * * @return Names of this schema's child schemas */ Set getSubSchemaNames(); /** * Returns the expression by which this schema can be referenced in generated * code. * * @param parentSchema Parent schema * @param name Name of this schema * @return Expression by which this schema can be referenced in generated code */ Expression getExpression(@Nullable SchemaPlus parentSchema, String name); /** Returns whether the user is allowed to create new tables, functions * and sub-schemas in this schema, in addition to those returned automatically * by methods such as {@link #getTable(String)}. * *

Even if this method returns true, the maps are not modified. Calcite * stores the defined objects in a wrapper object. * * @return Whether the user is allowed to create new tables, functions * and sub-schemas in this schema */ boolean isMutable(); /** Returns the snapshot of this schema as of the specified time. The * contents of the schema snapshot should not change over time. * * @param version The current schema version * * @return the schema snapshot. */ Schema snapshot(SchemaVersion version); /** Table type. */ enum TableType { /** A regular table. * *

Used by DB2, MySQL, PostgreSQL and others. */ TABLE, /** A relation whose contents are calculated by evaluating a SQL * expression. * *

Used by DB2, PostgreSQL and others. */ VIEW, /** Foreign table. * *

Used by PostgreSQL. */ FOREIGN_TABLE, /** Materialized view. * *

Used by PostgreSQL. */ MATERIALIZED_VIEW, /** Index table. * *

Used by Apache Phoenix, PostgreSQL. */ INDEX, /** Join table. * *

Used by Apache Phoenix. */ JOIN, /** Sequence table. * *

Used by Apache Phoenix, Oracle, PostgreSQL and others. * In Phoenix, must have a single BIGINT column called "$seq". */ SEQUENCE, /** A structure, similar to a view, that is the basis for auto-generated * materializations. It is either a single table or a collection of tables * that are joined via many-to-one relationships from a central hub table. * It is not available for queries, but is just used as an intermediate * structure during query planning. */ STAR, /** Stream. */ STREAM, /** Type. * *

Used by PostgreSQL. */ TYPE, /** A table maintained by the system. Data dictionary tables, such as the * "TABLES" and "COLUMNS" table in the "metamodel" schema, examples of * system tables. * *

Specified by the JDBC standard and used by DB2, MySQL, Oracle, * PostgreSQL and others. */ SYSTEM_TABLE, /** System view. * *

Used by PostgreSQL, MySQL. */ SYSTEM_VIEW, /** System index. * *

Used by PostgreSQL. */ SYSTEM_INDEX, /** System TOAST index. * *

Used by PostgreSQL. */ SYSTEM_TOAST_INDEX, /** System TOAST table. * *

Used by PostgreSQL. */ SYSTEM_TOAST_TABLE, /** Temporary index. * *

Used by PostgreSQL. */ TEMPORARY_INDEX, /** Temporary sequence. * *

Used by PostgreSQL. */ TEMPORARY_SEQUENCE, /** Temporary table. * *

Used by PostgreSQL. */ TEMPORARY_TABLE, /** Temporary view. * *

Used by PostgreSQL. */ TEMPORARY_VIEW, /** A table that is only visible to one connection. * *

Specified by the JDBC standard and used by PostgreSQL, MySQL. */ LOCAL_TEMPORARY, /** A synonym. * *

Used by DB2, Oracle. */ SYNONYM, /** An alias. * *

Specified by the JDBC standard. */ ALIAS, /** A global temporary table. * *

Specified by the JDBC standard. */ GLOBAL_TEMPORARY, /** An accel-only table. * *

Used by DB2. */ ACCEL_ONLY_TABLE, /** An auxiliary table. * *

Used by DB2. */ AUXILIARY_TABLE, /** A global temporary table. * *

Used by DB2. */ GLOBAL_TEMPORARY_TABLE, /** A hierarchy table. * *

Used by DB2. */ HIERARCHY_TABLE, /** An inoperative view. * *

Used by DB2. */ INOPERATIVE_VIEW, /** A materialized query table. * *

Used by DB2. */ MATERIALIZED_QUERY_TABLE, /** A nickname. * *

Used by DB2. */ NICKNAME, /** A typed table. * *

Used by DB2. */ TYPED_TABLE, /** A typed view. * *

Used by DB2. */ TYPED_VIEW, /** * A temporal table. * *

Used by MS SQL, Oracle and others */ TEMPORAL_TABLE, /** Table type not known to Calcite. * *

If you get one of these, please fix the problem by adding an enum * value. */ OTHER; /** The name used in JDBC. For example "SYSTEM TABLE" rather than * "SYSTEM_TABLE". */ public final String jdbcName; TableType() { this.jdbcName = name().replace('_', ' '); } } }





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