You can perform a nested query to query the data in the child rows of nested fields. Nested fields cannot be directly queried. To query a nested field, you must specify the path of the nested field and a subquery in a NestedQuery object. The subquery can be a query of any type.
Prerequisites
An OTSClient instance is initialized. For more information, see Initialize an OTSClient instance.
A data table is created and data is written to the data table. For more information, see Create data tables and Write data.
A search index is created for the data table. For more information, see Create a search index.
Parameters
Parameter | Description |
tableName | The name of the data table. |
indexName | The name of the search index. |
path | The path of the nested field. The nested field uses a tree structure. For example, news.title specifies the title subfield in the nested field named news. |
query | The query on the subfield in the nested field. The query can be a query of any type. |
scoreMode | The value that is used to calculate the score if a field contains multiple values. |
InnerHits | The settings of the subfields of the nested field.
|
Examples
Query single-level nested fields
The following sample code provides an example on how to query the rows in which the value of the Sub_Col_Keyword subfield in the Col_Nested nested field is Hangzhou:
/**
* Col_Nested: '[{Sub_Col_Keyword: "Hangzhou"},{Sub_Col_Keyword: "Shanghai"}]'
*/
client.search({
tableName: "<TABLE_NAME>",
indexName: "<SEARCH_INDEX_NAME>",
searchQuery: {
offset: 0,
limit: 10, // To query only the number of rows that meet the query conditions without returning specific data, set the limit parameter to 0.
query: { // Set the query type to TableStore.QueryType.NESTED_QUERY.
queryType: TableStore.QueryType.NESTED_QUERY,
query: {
path: "Col_Nested",
query: {
queryType: TableStore.QueryType.TERM_QUERY,
query: {
fieldName: "Col_Nested.Sub_Col_Keyword",
term: "Hangzhou"
}
},
}
},
getTotalCount: true // Specify whether to return the total number of rows that meet the query conditions. Default value: false.
},
columnToGet: { // Specify the columns that you want to return. You can set the parameter to RETURN_SPECIFIED to return specific columns, RETURN_ALL to return all columns, RETURN_ALL_FROM_INDEX to return all columns in the search index, or RETURN_NONE to return only the primary key columns.
returnType: TableStore.ColumnReturnType.RETURN_ALL
}
}, function (err, data) {
if (err) {
console.log('error:', err);
return;
}
console.log('success:', JSON.stringify(data, null, 2));
});Highlight the query strings in the query results of a nested query
The following sample code provides an example on how to query the rows in which the value of the Sub_Col_Text subfield of the nested field named Col_Nested matches tablestore and highlight the query strings in the query results.
client.search({
tableName: "<TABLE_NAME>",
indexName: "<SEARCH_INDEX_NAME>",
searchQuery: {
offset: 0,
limit: 10, // To query only the number of rows that meet the query conditions without returning specific data, set the limit parameter to 0.
query: { // Set the query type to TableStore.QueryType.NESTED_QUERY.
queryType: TableStore.QueryType.NESTED_QUERY,
query: {
path: "Col_Nested",
query: {
queryType: TableStore.QueryType.MATCH_QUERY,
query: {
fieldName: "Col_Nested.Sub_Col_Text",
text: "tablestore"
}
},
innerHits: {
sort: {
sorters: [
{
scoreSort: {
order: TableStore.SortOrder.SORT_ORDER_DESC
}
},
{
docSort: {
order: TableStore.SortOrder.SORT_ORDER_ASC
}
},
],
},
highlight: {
highlightParameters: [
{
fieldName:"Col_Nested.Sub_Col_Text",
preTag: "<b>",
postTag: "</b>",
fragmentsOrder: TableStore.HighlightFragmentOrder.TEXT_SEQUENCE,
fragmentSize: 20,
numberOfFragments: 3,
}
]
}
},
}
},
getTotalCount: true // Specify whether to return the total number of rows that meet the query conditions. Default value: false.
},
columnToGet: { // Specify the columns that you want to return. You can set the parameter to RETURN_SPECIFIED to return specific columns, RETURN_ALL to return all columns, RETURN_ALL_FROM_INDEX to return all columns in the search index, or RETURN_NONE to return only the primary key columns.
returnType: TableStore.ColumnReturnType.RETURN_ALL
}
}, function (err, data) {
if (err) {
console.log('error:', err);
return;
}
console.log('success:', JSON.stringify(data.rows, null, 2));
printSearchHit(data.searchHits, "");
});
/**
* Display the content that meets the query conditions.
* @param searchHits searchHits
* If the output uses the @param prefix Nested structure, add the prefix to display the hierarchy information.
*/
function printSearchHit(searchHits, prefix) {
TableStore.util.arrayEach(searchHits, function (searchHit) {
if (searchHit.highlightResultItem != null) {
console.log(prefix + "Highlight: \n");
var strBuilder = ""
for (const [key,val] of searchHit.highlightResultItem.highlightFields.entries()) {
strBuilder += key + ":[";
strBuilder += val.fragments.join(",") + "]\n";
console.log(strBuilder);
}
}
for (const [key,val] of searchHit.searchInnerHits.entries()) {
console.log(prefix + "Path: " + key + "\n");
console.log(prefix + "InnerHit: \n");
printSearchHit(val.subSearchHits, prefix + " ");
}
});
}FAQ
References
The following query types are supported by search indexes: term query, terms query, match all query, match query, match phrase query, prefix query, range query, wildcard query, Boolean query, geo query, nested query, vector query, and exists query. You can select a query type to query data based on your business requirements.
If you want to sort or paginate the rows that meet the query conditions, you can use the sorting and paging feature. For more information, see Sorting and paging.
If you want to collapse the result set based on a specific column, you can use the collapse (distinct) feature. This way, data of the specified type appears only once in the query results. For more information, see Collapse (distinct).
If you want to analyze data in a data table, such as obtaining the extreme values, sum, and total number of rows, you can perform aggregation operations or execute SQL statements. For more information, see Aggregation and SQL query.
If you want to quickly obtain all rows that meet the query conditions without the need to sort the rows, you can call the ParallelScan and ComputeSplits operations to use the parallel scan feature. For more information, see Parallel scan.