Automatic consistent sampling for data analysis

1. A computer program product for analyzing data within one or more databases, comprising:

a computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising computer readable program code configured to:

select one or more databases for analysis, each database comprising one or more database objects comprising one or more data values, wherein the data values in each database object are arranged in columns;

apply a function to each data value in each database object within the one or more databases, wherein the function produces function values limited to a predetermined range;

identify for analysis the data values producing a certain function value within the predetermined range to form a sampled data set;

identify for analysis the data values that produce function values other than the certain function value and reside in one or more columns lacking high cardinality to form an unsampled data set, wherein a column has a high cardinality when data values in the column satisfy one or more from a group of a predetermined cardinality threshold and a predetermined selectivity threshold; and

analyze the sampled data set with the unsampled data set by matching data values within these data sets to determine relationships between the database objects within and across the one or more databases.

2. The computer program product of claim 1 , wherein the computer readable program code is further configured to:

determine one or more primary key-foreign key relationships between the database objects within and across the one or more databases.

3. The computer program product of claim 1 , wherein a column is a high cardinality column if a number of data values in the column that produce the certain function value exceeds the predetermined cardinality threshold.

4. The computer program product of claim 1 , wherein a column is a high cardinality column if a number of unique data values in the column divided by the number of data values in the column exceeds the predetermined selectivity threshold.

5. The computer program product of claim 1 , wherein the function is a hash function.

6. The computer program product of claim 1 , wherein the database objects are tables.

7. A system for analyzing data within one or more databases, comprising:

one or more databases, each database comprising one or more database objects comprising one or more data values stored in memory, wherein the data values in each database object are arranged in columns; and

a processor configured with logic to:

select one or more databases from the one or more databases for analysis;

apply a function to each data value in each database object within the selected one or more databases, wherein the function produces function values limited to a predetermined range;

identify for analysis the data values producing a certain function value within the predetermined range to form a sampled data set;

identify for analysis the data values that produce function values other than the certain function value and reside in one or more columns lacking high cardinality to form an unsampled data set, wherein a column has a high cardinality when data values in the column satisfy one or more from a group of a predetermined cardinality threshold and a predetermined selectivity threshold; and

analyze the sampled data set with the unsampled data set by matching data values within these data sets to determine relationships between the database objects within and across the one or more databases.

8. The system of claim 7 , wherein the processor being further configured with logic to:

determine one or more primary key-foreign key relationships between the database objects within and across the one or more databases.

9. The system of claim 7 , wherein a column is a high cardinality column if a number of data values in the column that produce the certain function value exceeds the predetermined cardinality threshold.

10. The system of claim 7 , wherein the function is a hash function.

11. The system of claim 7 , wherein the database objects are tables.

12. The system of claim 7 , wherein a column is a high cardinality column if a number of unique data values in the column divided by the number of data values in the column exceeds the predetermined selectivity threshold.