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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.
*/
/*
* Content before git sha 34fdeebefcbf183ed7f916f931aa0586fdaa1b40
* Copyright (c) 2016, The Gocql authors,
* provided under the BSD-3-Clause License.
* See the NOTICE file distributed with this work for additional information.
*/
package gocql_test
import (
"fmt"
"log"
gocql "github.com/gocql/gocql"
)
// Example_paging demonstrates how to manually fetch pages and use page state.
//
// See also package documentation about paging.
func Example_paging() {
/* The example assumes the following CQL was used to setup the keyspace:
create keyspace example with replication = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };
create table example.itoa(id int, description text, PRIMARY KEY(id));
insert into example.itoa (id, description) values (1, 'one');
insert into example.itoa (id, description) values (2, 'two');
insert into example.itoa (id, description) values (3, 'three');
insert into example.itoa (id, description) values (4, 'four');
insert into example.itoa (id, description) values (5, 'five');
insert into example.itoa (id, description) values (6, 'six');
*/
cluster := gocql.NewCluster("localhost:9042")
cluster.Keyspace = "example"
cluster.ProtoVersion = 4
session, err := cluster.CreateSession()
if err != nil {
log.Fatal(err)
}
defer session.Close()
var pageState []byte
for {
// We use PageSize(2) for the sake of example, use larger values in production (default is 5000) for performance
// reasons.
iter := session.Query(`SELECT id, description FROM itoa`).PageSize(2).PageState(pageState).Iter()
nextPageState := iter.PageState()
scanner := iter.Scanner()
for scanner.Next() {
var (
id int
description string
)
err = scanner.Scan(&id, &description)
if err != nil {
log.Fatal(err)
}
fmt.Println(id, description)
}
err = scanner.Err()
if err != nil {
log.Fatal(err)
}
fmt.Printf("next page state: %+v\n", nextPageState)
if len(nextPageState) == 0 {
break
}
pageState = nextPageState
}
// 5 five
// 1 one
// next page state: [4 0 0 0 1 0 240 127 255 255 253 0]
// 2 two
// 4 four
// next page state: [4 0 0 0 4 0 240 127 255 255 251 0]
// 6 six
// 3 three
// next page state: [4 0 0 0 3 0 240 127 255 255 249 0]
// next page state: []
}
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