Rules for estimating the cost of queries to YDB via ad-hoc APIs

ReadTableReadTable

The ReadTable operation lets you efficiently read large ranges of data from a table. The request cost only depends on the amount of data read based on the rate of 128 RU per 1 MB. When calculating the cost, the amount is rounded up to a multiple of 1 MB.

BulkUpsertBulkUpsert

BulkUpsert lets you efficiently upload data to the database. The cost of writing a row using the BulkUpsert operation is 0.5 RU per 1 KB of written data. When calculating the cost, the data amount is rounded up to a multiple of 1 KB. The total cost of the operation is calculated as the sum of costs for all rows written, with the result rounded up to the nearest integer.

**Example of cost calculation **

For example, as part of the BulkUpsert operation, you write four data items of 2500 bytes, 100 bytes, 1200 bytes, and 1024 bytes.

The cost of this operation is:

0.5 RU × 3 + 0.5 RU × 1 + 0.5 RU × 2 + 0.5 RU × 1 = 3.5 RU

Total, rounded up to the nearest integer: 4 RU

Where:

• 0.5 is the cost in request units per 1 KB of written data.
• 3 is the rounded up size of the first item in KB (2500 bytes = 1024 bytes + 1024 bytes + 452 bytes).
• 1 is the rounded up size of the second item in KB.
• 2 is the rounded up size of the third item in KB (1200 bytes = 1024 bytes + 176 bytes).
• 1 is the size of the fourth item in KB.

Building a secondary indexBuilding a secondary index

The cost of building an index is the sum of the cost of ReadTable from the source table and BulkUpsert to the index table. The total amount of work is charged: the number and size of rows read from the source table and written to the index table. The index building process can be canceled by the user. The canceled index-building operations are also billed based on the amount of work done before the operation was canceled.