A processor determines whether to generate a first entry, based on whether a second entry is in a storage, for each conditional expression included in retrieval expressions. The first entry includes, in association with a first identifier, a first path included in the conditional expression. The second entry includes, a second path identical to the first path in association with a second identifier. The processor determines whether to generate a third entry based on whether a fourth entry is in the storage. The third entry includes a first set and a fifth identifier in association with a third identifier. The first set is included in the conditional expression and includes a first value and a first operator. The fifth identifier is the first identifier or the second identifier. The fourth entry includes a second set identical to the first set and the fifth identifier in association with a fourth identifier.