Database-table sampling-percentage selection

A method comprising:

• determining, with the processor, a first sampling percentage value of a column of a database table based on at least one characteristic of the column, wherein the first sampling percentage value is a first percentage of the column;
• determining, with the processor, a second sampling percentage value of the column based on at least one characteristic of the database table, wherein the second sampling percentage value is a second percentage of the column;
• comparing, with the processor, the first sampling percentage value to the second sampling percentage value;
• and
• in response to the comparison, selecting, with the processor, one of the first sampling percentage and the second sampling percentage value, wherein the selected sampling percentage value is a percentage of the column to be used to collect statistics on the column, and wherein collected statistics based on the selected sampling percentage value are used to generate at least one database query response plan associated with the column.

A non-transitory computer-readable medium encoded with a plurality of instructions executable by a processor, the plurality of instructions comprising:

• instructions to determine a first sampling percentage value of a column of a database table based on at least one characteristic of the column, wherein the first sampling percentage value is a first percentage of the column;
• instructions to determine a second sampling percentage value of the column based on at least one characteristic of the database table, wherein the second sampling percentage value is a second percentage of the column;
• instructions to compare the first sampling percentage value to the second sampling percentage value;
• and
• instructions to, in response to the comparison, select one of the first sampling percentage value and the second sampling percentage value, wherein the selected sampling percentage value is a percentage of the column to be used to collect statistics on the column, and wherein collected statistics based on the selected sampling percentage value are used to generate at least one database query response plan associated with the column.

The non-transitory computer-readable medium of 17, wherein the instructions to determine the first sampling percentage value comprise instructions to determine the first sampling percentage value according to the equation:

• p
• 1
• =
• 1
• 1
• +
• e
• a
• ⁢
• ⁢
• 1
• ·
• s
• +
• b
• ⁢
• ⁢
• 1
• where p1 is the first sampling percentage value, a1 is a first predetermined coefficient and b1 is a second predetermined coefficient, and s is the ratio of a column value having a highest frequency in the column to an average row per column value of the column.