如何在Java中使用大型数据库表而不会遇到性能问题

We have a table of vocabulary items that we use to search text documents. The java program that uses this table currently reads it from a database, stores it in memory and then searches documents for individual items in the table. The table is brought into memory for performance reasons. This has worked for many years but the table has grown quite large over time and now we are starting to see Java Heap Space errors. We have a table of vocabulary items that we use