数据结构查询
可以在缓存中查询数据结构,如果它们有 可搜索属性 在数据结构创建期间与它们相关联。 这些可搜索的属性包括:
先决条件
- 了解与所有人员合作所需的标准先决条件 NCache 客户端功能请参阅给定页面 客户端 API 先决条件.
- 有关 API 详细信息,请参阅: 缓存, 查询命令, 缓存读取器, 搜索服务, 执行阅读器, 取得价值, 分布式列表, 获取组数据, 字段计数, 分布式词典, 获取标签.
- 了解与所有人员合作所需的标准先决条件 NCache 客户端功能请参阅给定页面 客户端 API 先决条件.
- 有关 API 详细信息,请参阅: 缓存, 查询命令, 缓存读取器, 获取搜索服务, 执行阅读器, 获取字段计数, 的getValue, 分布式列表, 获取组数据, 数据结构属性, 分布式地图, 获取标签.
- 了解与所有人员合作所需的标准先决条件 NCache 客户端功能请参阅给定页面 客户端 API 先决条件.
- 有关 API 详细信息,请参阅: 缓存, 查询命令, 搜索服务, 获取搜索服务, 执行阅读器, 获取字段计数, 的getValue, 获取组数据, 缓存读取器, 数据结构属性, 获取标签.
- 了解与所有人员合作所需的标准先决条件 NCache 客户端功能请参阅给定页面 客户端 API 先决条件.
- API详情请参考: 缓存, 查询命令, 缓存读取器, 执行阅读器, 搜索服务, 获取搜索服务, 数据结构属性, 获取字段计数, 获取值, 获取组数据, 通过标签获取.
按组搜索数据结构
SQL查询
以下代码示例从缓存中获取与指定组关联的所有项目, 电子。 该组可以使用关联 DataTypeAttributes
数据结构创建期间的类。
重要
- 如果针对该组指定了多个列表,则所有列表都将返回一个结果,前提是它们的数据结构相似。
- 对于多个缓存项,例如,如果一个
CacheItem
和一个列表属于同一个组,你需要确保数据被相应地处理。
// Preconditions: Cache is already connected
// Items with groups exist in cache
// Custom class is query indexed through the NCache Management Center or config.ncconf
// Search for items with group
// Provide Fully Qualified Name (FQN) of your custom class
string query = "SELECT ProductID FROM FQN.Customer WHERE $Group$ = ?";
/// Use QueryCommand for query execution
var queryCommand = new QueryCommand(query);
// Providing parameters for query
queryCommand.Parameters.Add("$Group$", "Electronics");
// Executing QueryCommand through ICacheReader
ICacheReader reader = cache.SearchService.ExecuteReader(queryCommand);
// Check if the result set is not empty
if (reader.FieldCount > 0)
{
while (reader.Read())
{
string ProductID = reader.GetValue<string>(1);
// Perform operations
}
}
else
{
// Null query result set retrieved
}
// Preconditions: Cache is already connected
// Items with groups exist in cache
// Custom class is query indexed through NCache Management Center or config.ncconf
// Search for items with group
// Provide Fully Qualified Name (FQN) of your custom class
String query = "SELECT productID FROM FQN.Customer WHERE $Group$ = ?";
// Use QueryCommand for query execution
var queryCommand = new QueryCommand(query);
// Providing parameters for query
queryCommand.getParameters().put("$Group$", "Electronics");
// Executing QueryCommand through CacheReader
CacheReader reader = cache.getSearchService().executeReader(queryCommand);
// Check if the result set is not empty
if (reader.getFieldCount() > 0) {
while (reader.read()) {
String productID = reader.getValue(1, String.class);
// Perform operations
}
} else {
// Null query result set retrieved
}
// This is an async method
// Preconditions: Cache is already connected
// Items with groups exist in cache
// Custom class is query indexed through the NCache Management Center or config.ncconf
// Search for items with group
// Provide Fully Qualified Name (FQN) of your custom class
var query = "SELECT productID FROM FQN.Customer WHERE $Group$ = ?";
/// Use QueryCommand for query execution
var queryCommand = new ncache.QueryCommand(query);
// Providing parameters for query
let map = new Map();
var parameters = map.set("$Group$", "Electronics");
queryCommand.setParameters(parameters);
// Executing QueryCommand through CacheReader
var searchService = await this.cache.getSearchService();
var reader = await searchService.executeReader(queryCommand);
// Check if the result set is not empty
if (reader.getFieldCount() > 0) {
while (reader.read()) {
var productID = reader.getValue(1, Number());
// Perform operations
}
} else {
// Null query result set retrieved
}
# Preconditions: Cache is already connected
# Items with groups exist in cache
# Custom class is query indexed through NCache Management Center or config.ncconf
# Search for items with group
# Provide Fully Qualified Name (FQN) of your custom class
query = "SELECT product_id FROM FQN.Customer WHERE $Group$ = ?"
# Use QueryCommand for query execution
query_command = ncache.QueryCommand(query)
# Providing parameters for query
parameters = {"$Group$": "Electronics"}
query_command.set_parameters(parameters)
# Executing QueryCommand through CacheReader
search_service = cache.get_search_service()
reader = search_service.execute_reader(query_command)
# Check if the result set is not empty
if reader.get_field_count() > 0:
while reader.read():
product_id = reader.get_value(str, 1)
# Perform operations
else:
# None query result set retrieved
print("Query result is None")
组 API
以下代码示例从缓存中获取与指定组相关联的所有列表, 电子. 该组可以使用关联 DataTypeAttributes
在数据结构创建期间的类。
// List with this group already exists in cache
string groupName = "Electronics";
IDictionary<string, IDistributedList<Product>> result = cache.SearchService.GetGroupData<IDistributedList<Product>>(groupName);
if (result != null && result.Count > 0)
{
// Iterate over list
foreach (var item in result)
{
foreach (var i in item.Value)
{
// Perform operations
}
}
}
else
{
// No data against the group found
}
// Precondition: Cache is already connected
// List with this group already exists in the cache
String groupName = "Electronics";
Map<String, DistributedList<Product>> result = cache.getSearchService().getGroupData(groupName);
if (result != null && result.size() > 0) {
// Iterate over list
for (var item : result.entrySet()) {
// Perform operations
}
} else {
// No data against the group found
}
// This is an async method
// Precondition: Cache is already connected
// List with this group already exists in the cache
var groupName = "Electronics";
var result = await (
await this.cache.getSearchService()
).getGroupData(groupName);
if (result != null && result.size() > 0) {
// Iterate over list
for (var item in result.entrySet()) {
// Perform operations
}
} else {
// No data against the group found
}
# Precondition: Cache is already connected
# List with this group already exists in the cache
group_name = "Electronics"
result = cache.get_search_service().get_group_data(group_name)
if result is not None and len(result) > 0:
# Iterate over list
for item in result:
# Perform operations
print(item)
else:
# No data against the group found
print("No data found")
备注
为确保操作是故障安全的,建议处理应用程序中的任何潜在异常,如中所述 处理故障.
SQL查询
以下代码示例从缓存中获取与指定标签关联的项目, 不锈钢. 标签可以使用关联 DataTypeAttributes
在数据结构创建期间的类。
// Items are already present in the cache with tags
// Custom class is query indexed through NCache Management Center or config.ncconf
// Search for items with tags
// Use the Fully Qualified Name (FQN) of your own custom class
string query = "Select $Value$ FROM FQN.Product WHERE $Tag$ = ?";
// Use QueryCommand for query execution
var queryCommand = new QueryCommand(query);
queryCommand.Parameters.Add("$Tag$", "Stainless Steel");
// Executing query
ICacheReader reader = cache.SearchService.ExecuteReader(queryCommand);
// Check if result set is not empty
if (reader.FieldCount > 0)
{
while (reader.Read())
{
// Get the value of the result set
Product result = reader.GetValue<Product>(1);
}
}
else
{
// Null query result set retrieved
}
// Pre-conditions: Cache is already connected
// Items are already present in the cache with tags
// Custom class is query indexed through NCache Management Center or config.ncconf
// Search for items with tags
// Use the Fully Qualified Name (FQN) of your own custom class
String query = "Select $Value$ FROM FQN.Product WHERE $Tag$ = ?";
// Use QueryCommand for query execution
var queryCommand = new QueryCommand(query);
queryCommand.getParameters().put("$Tag$", "Stainless Steel");
// Executing query
CacheReader reader = cache.getSearchService().executeReader(queryCommand);
// Check if result set is not empty
if (reader.getFieldCount() > 0) {
while (reader.read()) {
// Get the value of the result set
Product result = reader.getValue(1, Product.class);
}
} else {
// Null query result set retrieved
}
// This is an async method
// Pre-conditions: Cache is already connected
// Items are already present in the cache with tags
// Custom class is query indexed through NCache Management Center or config.ncconf
// Search for items with tags
// Use the Fully Qualified Name (FQN) of your own custom class
var query = "Select $Value$ FROM FQN.Product WHERE $Tag$ = ?";
// Use QueryCommand for query execution
var queryCommand = new ncache.QueryCommand(query);
var map = new Map();
var parameters = map.set("$Tag$", "Stainless Steel");
queryCommand.setParameters(parameters);
// Executing query
var searchService = await this.cache.getSearchService();
var reader = await searchService.executeReader(queryCommand);
// Check if result set is not empty
if (reader.getFieldCount() > 0) {
while (reader.read()) {
// Get the value of the result set
var result = reader.getValue(1, ncache.JsonDataType.Object);
// Perform operations
}
} else {
// Null query result set retrieved
}
# Pre-conditions: Cache is already connected
# Items are already present in the cache with tags
# Custom class is query indexed through NCache Management Center or config.ncconf
# Search for items with tags
# Use the Fully Qualified Name (FQN) of your own custom class
query = "Select $Value$ FROM FQN.Product WHERE $Tag$ = ?"
# Use QueryCommand for query execution
query_command = ncache.QueryCommand(query)
parameters = {"$Tag$": "Stainless Steel"}
query_command.set_parameters(parameters)
# Executing query
search_service = cache.get_search_service()
reader = search_service.execute_reader(query_command)
# Check if result set is not empty
if reader.get_field_count() > 0:
while reader.read():
# Get the value of the result set
result = reader.get_value(Product, 1)
# Perform operations
else:
# Null query result set retrieved
print("Query result is None")
标签 API
以下代码示例从缓存中获取与指定标签相关联的所有字典实例, 不锈钢. 标签可以使用关联 DataTypeAttributes
在数据结构创建期间的类。
// Items against this tag exist in cache
Tag tag = new Tag("Stainless Steel");
// Get dictionary against tag
IDictionary<string, IDistributedDictionary<string, Product>> result = cache.SearchService.GetByTag<IDistributedDictionary<string, Product>>(tag);
if (result != null && result.Count > 0)
{
foreach (var item in result)
{
// Perform operations
}
}
else
{
// Dictionary does not exist against tag
}
// Precondition: Cache is already connected
// Items against this tag already exist in the cache
Tag tag = new Tag("Stainless steel");
// Get map against tag
Map<String, DistributedMap<String, Product>> result = cache.getSearchService().getByTag(tag);
if (result != null && result.size() > 0) {
for (var item : result.entrySet()) {
// Perform operations
}
} else {
// Dictionary does not exist against tag
}
// This is an async method
// Precondition: Cache is already connected
// Items against this tag already exist in the cache
var tag = [new ncache.Tag("Stainless steel")];
// Get map against tag
var result = await (await this.cache.getSearchService()).getByTag(tag);
if (result != null && result.size() > 0) {
for (var item in result.entrySet()) {
// Perform operations
}
} else {
// Dictionary does not exist against tag
}
# Precondition: Cache is already connected
# Items against this tag already exist in the cache
tag = ncache.Tag("Stainless steel")
# Get map against tag
result = cache.get_search_service().get_by_tag(tag)
if result is not None and len(result) > 0:
for item in result:
# Perform operations
print(item)
else:
# Dictionary does not exist against tag
print("Dictionary not found")
NCache 使用 $DataType$
将获取具有指定命名标签的所有数据结构的关键字。 以下代码假定已添加带有命名标签的列表 已优惠 有价值 0.4 并使用查询获取它。
// Data Structures exist with NamedTag Discount and value 0.4
// Create query
string query = "SELECT * FROM $DataType$ WHERE Discount = 0.4";
// Use QueryCommand for query execution
var queryCommand = new QueryCommand(query);
// Execute Query to search cache
ICacheReader queryResult = cache.SearchService.ExecuteReader(queryCommand);
// queryResult contains all the keys and metadata of result
if (queryResult.FieldCount > 0)
{
while (queryResult.Read())
{
// Key of list can be fetched through
queryResult.GetValue<DistributedList>(1);
}
}
else
{
// Null query result set retrieved
}
// Pre-conditions: Cache is already connected
// Data Structures exist with NamedTag "Discount" and value 0.4
// Create query
String query = "SELECT * FROM $DataType$ WHERE Discount = 0.4";
// Use QueryCommand for query execution
var queryCommand = new QueryCommand(query);
// Execute Query to search cache
CacheReader queryResult = cache.getSearchService().executeReader(queryCommand);
// queryResult contains all the keys and metadata of result
if (queryResult.getFieldCount() > 0) {
while (queryResult.read()) {
// Key of list can be fetched through
queryResult.getValue(0, DistributedList.class);
// Perform operations
}
} else {
// Null query result set retrieved
}
// This is an async method
// Pre-conditions: Cache is already connected
// Data Structures exist with NamedTag "Discount" and value 0.4
// Create query
var query = "SELECT * FROM $DataType$ WHERE Discount = 0.4";
// Use QueryCommand for query execution
var queryCommand = new ncache.QueryCommand(query);
// Execute Query to search cache
var searchService = await this.cache.getSearchService();
var queryResult = await searchService.executeReader(queryCommand);
// queryResult contains all the keys and metadata of result
if (queryResult.getFieldCount() > 0) {
while (queryResult.read()) {
// Key of list can be fetched through
queryResult.getValue(0, Number());
// Perform operations
}
} else {
// Null query result set retrieved
}
# Pre-conditions: Cache is already connected
# Data Structures exist with NamedTag "Discount" and value 0.4
# Create query
query = "SELECT * FROM $DataType$ WHERE discount = 0.4"
query_command = ncache.QueryCommand(query)
# Execute Query to search cache
search_service = cache.get_search_service()
query_result = search_service.execute_reader(query_command)
# queryResult contains all the keys and metadata of result
if query_result.get_field_count() > 0:
while query_result.read():
# Key of list can be fetched through
query_result.get_value(int, 1)
# Perform operations
else:
# No data containing the named tag(s) exist
print("Data not found")
更多资讯
NCache 提供了一个用于查询数据结构的示例应用程序 GitHub上.
参见
.NET: Alachisoft.NCache.Client.DataTypes 命名空间。
Java的: COM。alachisoft.ncache.client.数据结构 命名空间。
节点.js: 数据结构管理器 类。
Python: ncache.client.数据结构 类。