limits on search index - Tablestore - Alibaba Cloud Documentation Center

This topic describes the limits on search indexes.

Index limits

The number of rows, total size, number of fields, read/write rate, synchronization latency, nested types, and field usage limits in a search index are detailed in the following table.

Limit item	Limit content	Description
Number of search indexes	Unlimited	It is recommended to create only one search index that contains all the fields you need to retrieve.
Row limit	100 billion	If your business needs exceed the limit, please submit a ticket to contact us.
Total size limit	100 TB	If your business needs exceed the limit, please submit a ticket to contact us.
Number of fields in a search index	1,000	None.
Read/write rate	50,000 rows/s	The first time data is written to a table or when a large volume of data is written in a short period of time, Tablestore balances loads within a few minutes. The maximum rate of indexing for Text fields is limited to 10,000 rows/s because the process consumes many CPU resources for tokenization. If your business needs exceed the limit, please submit a ticket to contact us.
Synchronization latency	3 seconds	In most cases, the synchronization latency is within 3 seconds. If your business needs have higher requirements, please submit a ticket to contact us. Up to 1 minute is required to initialize a new index.
Array length	256	The maximum number of elements in an array.
Nested type field limits	Unique within a search index	A maximum of 5 levels of nested fields are supported for nested type fields. The maximum number of child rows in a nested type field is 256. The maximum number of child fields in a nested type field is 100.
Vector type field limits	Unique within a search index	A search index can contain a maximum of one vector type field. If your business needs exceed the limit, please submit a ticket to contact us. The maximum dimension supported by a vector type field is 2,048.
Total length of values in all primary key columns	1,000 bytes	The total length of values in all primary key columns in each row can be a maximum of 1,000 bytes.
Length of the value in a primary key column of the String type	1,000 bytes	When you create an index for a primary key column of the String type, the length of the column value cannot exceed 1,000 bytes.
Length of the value in an attribute column of the String type when you want to index the column as Keyword	4 KB	None.
Length of the value in an attribute column of the String type when you want to index the column as Text	2 MB	In most cases, the limit is the same as the length limit on an attribute column in a data table. When you perform fuzzy query based on fuzzy tokenization for a Text field and the value of the Text field exceeds 1,024 characters in length, Tablestore truncates and discards the excess characters, and tokenizes only the first 1,024 characters.

Query limits

Search operation

The limits associated with calling the Search operation for querying and analyzing data are described in the following table.

Classification	Limit item	Limit content	Description
General limits	offset+limit	100,000	The default value of the limit is 10. The maximum value is 100. If your business needs exceed the limit, please submit a ticket to contact us. When you use the Search operation to query data of a specified column, if the search index contains data of the queried column, the limit parameter can be set to a maximum of 1,000. This means that a maximum of 1,000 results can be returned in a single request. If your business needs exceed the limit, use next_token to paginate continuously.
	timeout	10 seconds	None.
	CU	Unlimited	None.
	QPS	100,000	The upper limit for lightweight transaction processing (TP) is 100,000 queries per second (QPS). If your business needs exceed the limit, please submit a ticket to contact us.
	Number of queries in a Search operation	1,024	If complex nested queries are specified in a Search call, query performance is compromised. We recommend that you simplify the query.
Terms query	Number of search queries	1,024	Terms query supports a maximum of 1,024 search queries.
Wildcard query	Length of search query	32 characters	The length of a search query in a wildcard query cannot exceed 32 characters.
Prefix query	Length of search query	1,000 characters	The length of a search query in a prefix query cannot exceed 1,000 characters.
Full-text search	Number of highlighted text fragments	500	The total number of highlighted text fragments that can be returned when the conditions specified by the inner_hits and highlight parameters are met.
Full-text search	Number of fields for which you can enable the highlight feature	10	You can specify highlight parameters for a maximum of 10 fields.
Vector retrieval	Number of top K most similar rows returned	1,000	KnnVectorQuery returns a maximum of the top 1,000 rows.
Aggregation	Number of aggregations at the same level	5	The number of aggregations is recalculated each time you add a new aggregation to SubGroupBy.
	Number of GroupBys at the same level	5	The number of GroupBys is recalculated each time you add a new GroupBy to SubGroupBy.
	Number of nested GroupBys	3 levels	The root GroupBy is counted as a nested level.
	Number of filters in GroupByFilter	10	None.
	Number of groups returned by GroupByField	2,000	None.
	Number of sources in GroupByComposite	32	The maximum number of columns supported by a multi-column field group.
	Number of ranges in GroupByRange	100	None.
	Number of ranges in GroupByGeodistance	10	None.

ParallelScan operation

The limits associated with calling the ParallelScan operation for querying and exporting data in parallel are described in the following table.

Classification	Limit item	Limit content	Description
General limits	offset+limit	No supported	When you use parallel scan, you cannot configure the offset and limit parameters. The results that are returned are displayed in chronological order. The maximum value of the limit is 2,000.
	CU	Unlimited	None.
	QPS	Unlimited	None.
Concurrent data export	Maximum concurrency	Equal to the MaxParallel value	The MaxParallel value in the result returned by ComputeSplits.
	Task alive time	10 minutes	None.
	Limit on the number of concurrent ParallelScan tasks	10	Parallel scan tasks that have the same session ID and the same ScanQuery value are considered one task. For more information, see the referenced document.