A computer program product and method for estimating a filter factor for access path optimization in a database are provided. The method includes extracting from a statement segment for database query a relation condition which defines the relationship between a variable and a first table. The method includes obtaining first statistics information according to the relation condition and the statistics information of the first table. The method includes extracting from the statement segment a filter condition which defines the relationship between the variable and a second table. The method includes obtaining second statistics information according to the filter condition and the statistics information of the second table, and according to the first statistics information and the second statistics information, estimating the filter factor of the filter condition. The method and computer program product according to the embodiments of the disclosure may more accurately estimate filter factor of the filter condition.