Tools

Subset-size calculator

Choose a root entity and the fraction of it you want, describe how child tables fan out, and see an estimate of the subset table by table.

Runs in your browser. Nothing you enter is sent anywhere or stored on a server, and no account is needed. Enter table names and counts only.

Root rows selected (%)For example 1 keeps one root entity in a hundred.

Maximum child depth followedDataNivra’s subset policy default is 6; the limit is 12.

Table 1

Table name

Role

Total rows

Average row size (bytes)

Table 2

Table name

Role

Total rows

Average row size (bytes)

Parent table

Average child rows per parent row

Table 3

Table name

Role

Total rows

Average row size (bytes)

Parent table

Average child rows per parent row

Table 4

Table name

Role

Total rows

Average row size (bytes)

Parent table

Average child rows per parent row

Table 5

Table name

Role

Total rows

Average row size (bytes)

Estimated subset

Estimate: about 4,041,380 rows (735 MB) out of 408,100,180 rows (74.2 GB) in the source, before upward closure.

Estimated rows and size per table (estimates only)
Table	Depth	Estimated rows	Estimated size	Share kept	Note
customers	0	20,000	8.00 MB	1.0%
accounts	1	36,000	9.00 MB	1.0%
cards	2	25,200	5.04 MB	1.0%
transactions	2	3,960,000	713 MB	0.990%
currencies	—	180	10.8 KB	100.0%	Reference table: copied in full.

Referential-integrity closure can add rows. This estimate follows child relationships downwards only. A real, referentially intact subset also adds every parent row that a selected row references (at any depth), rows reached through shared lookups and many-to-many link tables, and copies reference tables in full — so the actual subset is often larger than this estimate, never smaller for the same selection.

Learn how subsetting keeps data connected

Read data subsetting and referential integrity, or turn the result into storage and cost with the storage and cost calculator.